review article immune escape mechanisms in colorectal cancer pathogenesis … · 2019. 7. 31. ·...

Review ArticleImmune Escape Mechanisms in Colorectal Cancer Pathogenesisand Liver Metastasis

Massimo Pancione1 Guido Giordano2 Andrea Remo3 Antonio Febbraro2 Lina Sabatino1

Erminia Manfrin4 Michele Ceccarelli15 and Vittorio Colantuoni1

1 Department of Sciences and Technologies University of Sannio 82100 Benevento Italy2Medical Oncology Unit Fatebenefratelli Hospital 82100 Benevento Italy3 Department of Pathology ldquoMater Salutisrdquo Hospital 37045 Legnago (VR) Italy4Department of Surgery and Oncology University of Verona 37129 Verona Italy5 Bioinformatics Lab BIOGEM scrl 83031 Ariano Irpino (AV) Italy

Correspondence should be addressed to Massimo Pancione massimopancioneunisannioit and Vittorio Colantuoni colan-tuoniunisannioit

Received 8 September 2013 Revised 18 November 2013 Accepted 18 November 2013 Published 16 January 2014

Academic Editor Saied Mirshahidi

Copyright copy 2014 Massimo Pancione et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Over the past decade growing evidence indicates that the tumor microenvironment (TME) contributes with genomicepigenomicaberrations of malignant cells to enhance cancer cells survival invasion and dissemination Many factors produced or de novosynthesized by immune stromal or malignant cells acting in a paracrine and autocrine fashion remodel TME and the adaptiveimmune response culminating in metastasis Taking into account the recent accomplishments in the field of immune oncologyand using metastatic colorectal cancer (mCRC) as a model we propose that the evasion of the immune surveillance and metastaticspread can be achieved through a number of mechanisms that include (a) intrinsic plasticity and adaptability of immune andmalignant cells to paracrine and autocrine stimuli or genotoxic stresses (b) alteration of positional schemes of myeloid-lineagecells produced by factors controlling the balance between tumour-suppressing and tumour-promoting activities (c) acquisitionby cancer cells of aberrant immune-phenotypic traits (NT5ECD73 CD68 and CD163) that enhance the interactions amongTME components through the production of immune-suppressive mediators These properties may represent the driving forceof metastatic progression and thus clinically exploitable for cancer prevention and therapy In this review we summarize results andsuggest new hypotheses that favour the growing impact of tumor-infiltrating immune cells on tumour progression metastasis andtherapy resistance

1 Introduction

More than 12 million colorectal cancers (CRCs) are diag-nosed every year worldwide accounting for approximately10 of all cancers [1 2] The death rate from CRC hasbeen dropping for more than 20 years mostly due to earlierscreenings and improved treatments In spite of this CRCremains the fourth most common cause of cancer-relateddeath in western countries [1ndash5] Recent evidence suggeststhat accumulation of genetic and epigenetic alterations inmalignant colonic cells progresses through at least three dis-tinct pathways chromosomal instability (CIN)microsatellite

instability (MSI) and CpG island methylator phenotype(CIMP) [6ndash8] CIN is the most common type of genomicinstability occurring in 60ndash80 of CRCs and results inan imbalance of the chromosome number ldquomanifested asaneuploidyrdquoMSI is an alternative pathway accounting for 15ndash20 of sporadic CRCs in which the characteristic signatureis deletion of repetitive regions of DNA that in most casesgenerates frameshift mutations in the coding sequences ofgenes leading to their inactivation CIMP is a novel molec-ular instability pathway characterized by the widespreadhypermethylation of CpG islands at several genomic loci[6ndash8] Up to date massive genomic studies have discovered

Hindawi Publishing CorporationJournal of Immunology ResearchVolume 2014 Article ID 686879 11 pageshttpdxdoiorg1011552014686879

2 Journal of Immunology Research

ERBB2 and IGF2 amplifications as novel potential therapeutictargets extensive molecular profiling studies have identifiedclinically and molecularly distinct subtypes of CRC [9ndash11] Inaddition to cancer genome abnormalities also the formationof an inflammatory microenvironment plays a pivotal rolein CRC development and progression [12 13] CRC survivalis highly dependent on the tumour stage at the time ofdiagnosis over one-third of patients die within five yearsfrom the initial diagnosis and most of fatal outcomes resultfrom liver metastases [14ndash17] The metastatic process is amultistep event that entails cancer cells to escape from theprimary tumour survive in the circulation seed at distantsites and grow [14 15] It is well established that themetastaticspread is promoted by communications between tumourand immune cells via the secretion of cytokines growthfactors and proteases that remodel the tumour microenvi-ronment (TME) [12 13] Consistent with this idea drivergene mutations (APC TP53 SMAD4 PIK3CA and KRAS)along with genomic and epigenomic instability determinetumour initiation while the interaction of cancer cells withmicroenvironmental stimuli provided by nontransformedcells is needed to evolve towards a metastatic cancer [15ndash19]The underlying molecular mechanism by which cancer cellsacquire the ability to escape the primary tumour site evadeimmune system eradication and reestablish a new order iscurrently under intense investigation [19ndash23] A number ofstudies have shown that infiltration and density of immuno-logic cells within primary tumours aremostly associated withpatientsrsquo prognosis and sensitivity to therapy [19ndash23] In par-ticular tumour associated-macrophages (TAMs) regulatoryT cells (Treg) and the so-called purinergic signaling cascadeare considered attractive targets for antitumour interven-tions [19ndash26] This field is drawing increasing attention toidentify new pharmaceutical targets and improve therapiesrsquoefficacy In this review we present results and suggest newhypotheses that underscore the growing impact of tumour-infiltrating immune cells in CRC progression Furthermorewe discuss the advances in our understanding as to howthe reciprocal communications between cancer and stromalcells impact liver metastasis formation and response to thetherapy

2 Infiltrating Immune Cells andCRC Progression

Most of cancer hallmarks are sustained to varying degree bygenetic and epigeneticmodifications of colon cancer cells andby stromal and immune cell types that contribute to generatea specific TME A recent model proposed by Yamauchi et alsuggests that the CRC molecular features gradually changealong bowel subsites and factors such as the interactionswith the gut microbiota biochemical components innateimmune system and epithelial cells might trigger the ini-tiating molecular events or alternatively influence tumourmicroenvironment to promote neoplastic progression [27](Figure 1) CRC and other solid tumours contain infiltratesof diverse leukocyte subsets including both myeloid- andlymphoid lineages that do not conform to the classical picture

Rectum

Bowel microenvironment (microbiome food

debris and fermentation)

Epithelial andimmune cells

interactions

Ascendingcolon

Caecum

Colon tumorigenesis

MSSCIMP-L

KRAS CIMP-HMSI-HBRAF+

Figure 1 Bowel microenvironment influences CRC molecularfeatures and progression The CIMP-high MSI-high and BRAFmutations frequencies gradually increase from the rectum toascending colon Caecal cancers seem to represent a distinct subtypecharacterized by a higher frequency of KRAS mutations a MSSand CIMP-L phenotype In the bowel microenvironment changesin the balance between (1) microbiome food debris and bacterialfermentation products and (2) interactions with host cells (epithelialand immune cells) might predispose colon epithelial cells to certainmolecular insults and differentially influence tumour developmentaccording to molecular features in preneoplastic cells CpG islandmethylator phenotype CIMPmicrosatellite instabilityMSI CIMP-low CIMP-L

of an inflammatory immune responseThe evidence providedis particularly robust for tumour infiltrating T lymphocytes(TILs) or tumour associatedmacrophages (TAMs) suggestingthat both adaptive and innate antitumour immune responsesplay key roles in cancer progression [28] By contrastthe potential role in human cancers of short-lived innateimmunity cells such as dendritic cells or tumor-associatedpolymorphonuclear neutrophils (TAN) has received poorattention However recent studies have revealed the existenceof potential neutrophil subsets in CRC patients showing atumor-promoting (N2) or tumor-inhibiting (N1) phenotypein response to the transforming growth factor-120573 (TGF-120573) [29 30] In addition evidence supports the ability ofTAN to express cytokine chemokine-encoding genes anda wider array of growth factors such as tumour-necrosisfactor (TNF) hepatocyte growth factor (HGF) and vascularendothelial growth factor (VEGF) suggesting a potentialrole in tumor progression and angiogenesis [28ndash30] Astriking finding is that an elevated neutrophils blood count ineither tumour or blood has a prognostic significance in sev-eral neoplasms Accordingly also the neutrophillymphocyteratio has been associated with poor clinical outcome inCRC [30] The significance of TAN in human cancersremains to be fully clarified and needs further experimentalconfirmation

Journal of Immunology Research 3

3 T-Cell Signature and Immune Escapein CRC

Tumour tissues infiltration by immune cells particularlythose of the lymphoid-lineage has extensively been studiedand associatedwith the destruction of tumour cells reductionof the tumour burden and improved clinical prognosis [31]Unfortunately the underlying rationale of these observationsremains elusive Functional studies have established theexistence of a tight interplay between genetic instabilityof tumour cells and the degree of antitumour immuneresponses mediated mainly by CD8+ T cells also referredto as cytotoxic T cells (CTLs) [20 31ndash33] Moreover thelocal immune infiltration appears to be closely associatedwith the different genetic instability signature (MSI and CIN)[32 33] CRCs with high levels of MSI (MSI-H+ CRC) arecharacterized by a strong local immune reaction mainly byperitumoural lymphoid nodules (Crohnrsquos-like reaction) and adense infiltration of TILs part of which are ldquoactivated andorcytotoxicrdquo [20 31ndash38] CIN+ CRCs instead exhibit reducedexpression of cytotoxic T-cell markers and intratumouraldensity of Foxp3-positive regulatory T cells (Treg cells) [38ndash43]

These observations would explain why MSI-H+ CRCstend to be more immunogenic than CIN+ CRCs and suggestthat a dense infiltration of CTLs within TME could effectivelymediate tumour cells destruction by releasing their lyticcomponents [39ndash46] Several studies have shown that MSI-H+ CRCs are associated with a better prognosis than CIN+CRCs Conversely our own data indicate that some MSI-H+ CRCs are extremely aggressive and characterized by areduced infiltration of ldquoTILsrdquo suggesting that the mechanismunderlying immune surveillance is only partially dependenton the MSI signature [46 47] The higher immunogenicityassociated with MSI-H+ CRCs is currently explained byframeshift mutations in coding microsatellites that wouldrender tumour cells vulnerable to recognition and attack bythe hostrsquos immune system In agreement truncating muta-tions affecting the genes coding for human leukocyte antigen(HLA) class I antigen components have been identified asthe major mechanism mediating HLA antigen presenta-tion impairment in MSI-H+ CRC that has been found inabout 30ndash60 of the lesions [48 49] Antigen presentationabrogation by HLA class I antigens therefore represents apotent mechanism of immune evasion that protects tumourcells from the attack by cytotoxic T cells Concomitantlymismatch repair (MMR) deficiency provokes a strong localand systemic antitumoural immune response the so-calledldquoTh1-responserdquo due to the generation of frameshift peptideantigens or novel tumour-specific antigensThis suggests thatHLA class I alterations while offering protection againstlocal antitumoural immune responses might interfere withthe ability to form distant metastases Whether MSI-H+CRCs infiltrating T cells are recruited from the periphery orlocally expanded due to cytokines or chemokines generatedby tumour cells remains unknown at present

4 Tumour Associated Macrophages andCRC Progression

Macrophages are one of the most common nontumourcell types present in the TME and play a central role ininflammation and tumour development The significance ofmacrophages in the metastatic process has recently beenemphasized and drawn a great deal of interest [50ndash54]Tumour infiltrating macrophages also indicated as TAMs(Figure 2(a)) derive from circulating monocytic precursorsand are recruited to tumour sites by several moleculessuch as the chemokines CCL2 and CCL5 VEGF TGF-120573and colony stimulating factors (GM-CSF and M-CSF) [5355] Tumours also recruit a variety of immature myeloidcells often referred to as myeloid-derived suppressor cells(MDSCs) thought to create a permissive environment forsubsequent invasion and tumour growth [56ndash58] Interest-ingly recent findings have shown that mononuclear MDSCscan further mature into macrophages [53ndash57] At leasttwo TAMs phenotypes contribute to cancer initiation andpromotion M1 proinflammatory macrophages have pro-nounced antitumour activity being cytotoxic to tumour cellsPersistence of an inflammatory response however can bedetrimental and help cancer initiation andor progressionthrough the generation of mutation-inducing reactive oxy-gen species and nitrogen-free radicals Macrophages can besubverted to a tumour-promotingM2 phenotype in responseto immune-suppressive cytokines secreted by tumour tis-sues that can foster metastasis through extracellular matrixremodeling angiogenesis and suppression of antitumourimmune responses (Figure 2(a)) [58ndash62] M-CSF PGE2TGF-120573 IL-6 and IL-10 have the potential to modulateand polarize monocytes mainly into M2 macrophages byinfluencing fundamental aspects ofCRCbiology [57ndash62]Theprotumoural effects of TAMs are due to the fact that theysynthesize a large array of growth factors including epidermalgrowth factors (EGF) TGF-120573 VEGF and several proteolyticenzymes such as matrix metalloproteinases (MMPs) thatdegrade ECMproteinsThese factors in turn promote tumorexpansion neoangiogenesis switch motility and invasion(Figure 1(a)) Recent evidence suggests that TAMs are edu-cated to perform tasks that enhance metastasis through theconstruction of a premetastatic niche that represents a newenvironment favourable to seeding and growth of tumourcells (Figure 1(b)) [52ndash58] Macrophages density in CRChas also been linked with patientsrsquo prognosis although aconsiderable body of data has been produced their role incolorectal cancer is still controversial [61ndash65]

5 Polarized TAMs and Development ofLiver Metastasis

Taking into account the recent trends in cancer immunologywe report here some representative examples of the roles thatTAMs play in fostering metastasis and maintaining evasionof the immune surveillanceWe propose that themany TAMsdistinct functions during tumour progressionmay depend ontheir intrinsic adaptability to positional schemes obtained by


factors controlling the balance between tumour-suppressingand tumour-promoting activities (Figures 2(a) and 2(b)) [6066] In normal conditions the interplay between colonic cellsand host immune system is preserved by a highly structuredorganization with specialized macrophages residing in well-defined niches to fulfill their physiological functions Inprimary tumours either oncogenic alterations or changes inTMEestablish a new equilibrium that can be furthermodifiedduring metastatic progression We suggest that at least twomechanisms underlie the TAMs prometastatic functions (1)M2-macrophages can form a dense barrier around invasivecancer cells resulting in heterotypic interactions betweentumour cells and the surrounding stroma that compromisethe integrity of the host tissues (2) invasive cancer cellscan acquire immunophenotypic traits for example due tofusion of macrophages with cancer cells which facilitatehomotypic interactions between the host stroma and TAMs(Figure 2(b)) Collectively these observations suggest thatTAMs protumour activity is associated with distinct mecha-nisms that are independent of theMSI signature as suggestedby our own data (Figure 2(c)) Accordingly an increased M1-macrophages infiltration at the tumour front has recentlybeen correlated with a better prognosis in CRC patients [65]The antitumour effects of TAMs could then potentially bedue to the presence of a significant number of M1-polarizedmacrophages able to mediate killing of tumour cells inperitumoural areas In contrast a density ofM2-macrophagesat the invasive front higher than in intraepithelial regions ofthe tumour leads to enhanced invasion through secretion ofchemokinetic growth factors that remodel the extracellularmatrix thus shortening patientsrsquo survival (Figures 2(b) and2(c)) In conclusion still little is known about themacrophagesubtypes and their associated molecular profiles in cancerGiven that multiple subpopulations of TAMs exist within atumour a promising field of research is focused on ques-tioning as to how the phenotypic equilibrium temporally andspatially changes over the course of tumour progression

6 The Evolution of the Cancer Niche andImmune Suppressive Pathways

According to the linear progression model of tumour devel-opment genetic damages mutations and deregulated sig-naling pathways establish the initiation step Subsequentlythe immune cell populations that infiltrate the tumour massexert a primary suppressive role however these immunecells due to their intrinsic plasticity can undergo phenotypicchanges that enhance tumour cell dissemination and metas-tasis depending on the presence of accessory stromal cellsthe local cytokine milieu and tumour-specific interactions(Figure 2(a)) Several lines of evidence suggest that MDSCsestablish cell clusters called ldquopremetastatic nicherdquo that pre-cede the arrival of even a single metastatic tumour cell atdistant sites whether MDSCs have a direct role in enhancingthemetastatic process is only at the beginning to be elucidated[66ndash68] In this perspective it has been suggested that theproperties of an ldquoinvasive nicherdquo are already establishedwithin the primary tumour where cancer cells macrophages

and endothelial cells establish a special setting in whichparacrine signaling loops lead to increased intravasation anddissemination of cancer cells [66ndash73] Accordingly the abilityto metastatic dissemination could be viewed as the evolutionof the cancer niche in which (1) interactions of a geneti-cally initiated cancer cell with specific host cells facilitatesurvival and a malignant behavior (2) inflammation-drivenphenotypic plasticity alters the antigenic landscape of tumourcells (3) secreted factors such as chemokines cytokinesand exosomes generate a ldquomicroenvironmentrdquo that remod-els local tissues by promoting malignant phenotypes andimmune escape Intriguingly the recently proposed mecha-nisms to explain both metastatic niche evolution and tumourimmune escape include (1) malignant cells that acquirefunctional and phenotypic characteristics of immune cellsby expressing the macrophage scavenger receptors CD163or CD68 (2) aberrant activation of oncogenic pathways incancer cells which facilitates the interaction with stromalcells (3) production of anti-inflammatory cytokines andimmunosuppressive metabolites (adenosine) that ultimatelygenerates a poorly immunogenic TME [26 68ndash73]

7 Novel Immune Suppressive Pathwaysand Metastatic Evolution A Key Role ofNT5ECD73

Among the factors capable of evading immune surveil-lance and altering the tumour cell antigenic landscapeNT5ECD73 has recently received great attention [74ndash78]NT5ECD73 encodes a GPI-anchored cell surface enzymeabundantly expressed in hematopoietic and endothelial cellsthat converts ATP to adenosine a potent immunosuppressorAdenosine exerts its tumour-promoting effects in a paracrineand autocrine fashion by activating its cognate receptors (theadenosine receptors) expressed by tumour endothelial orimmune cells [76ndash78] Interestingly NT5ECD73 is the rate-limiting enzyme in the production of extracellular adeno-sine thus representing a checkpoint in the conversion ofproinflammatory ATP into immunosuppressive adenosine[76ndash78] By applying a new bioinformatic approach werecently identified NT5ECD73 as a novel CRC prognosticbiomarker [79] Elevated NT5ECD73 levels in either malig-nant epithelial cells or TME strongly correlate with poorpatientsrsquo outcome [79] Consistently NT5ECD73 expressionis higher in liver metastasis than in primary tumour or nor-mal mucosa and is significantly linked with TAMs expressionprofile but not with the MMR status (Figures 3(a) and 3(b))Our findings and those reported in the literature suggesta schematic and simplified model in which NT5ECD73metastasis-promoting actions appear to be the result of aclose cooperation between cancer stromal and inflamma-tory cells (Figure 3(c)) A variety of protumorigenic path-ways (hypoxia-inducible factor (HIF-1120572) Wnt120573-cateninand TNF-120572NF120581B) can synergize to induce NT5ECD73expression in malignant cells enhancing paracrineautocrineinteractionswithmalignant colonic hematopoietic and non-hematopoietic cells to sustain immune surveillance evasionpremetastatic-niche evolution and cancer cell migration


Months

Cum

surv

ival

100806040200

PosNeg

CD68 cancer cell

0

50

100

150

Low

Inte

rH

igh

Low

Inte

rH

igh

Neg Po

s

MMR negMMR pro

Escape from immune system Cancer progression

Months

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 IMIEMonths

120

100806040200

120

100806040200

120

100806040200

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 total number

CD68 total IMIE Cancer

M1M2

(1) (2)

Normal Carcinoma Liver metastases

Microenvironment modifiersMutationMacrophages

Invasive tumour cell

IEIM

P = 067 P = 0057 P = 0120 P = 0197

Metastasis

Cancer(invasive)

Epithelium

Transitamplifying

compartment

Crypt stem cells(Lgr5+ CD133+)

Differentiatedcells

(a)

(b)

(c)

Figure 2 Recruitment of tumour-promoting immune cells contributes to progression and metastasis (a) Representative images of tissuesections (normal colonic mucosa carcinoma and liver metastases) immunostained with CD68 a marker of macrophages with a M2-phenotype (b) A schematic and simplified model as to how TAMs might contribute to tumour development and metastasis CRC arises bygenetic damagesmutations and deregulated signaling pathwaysmetastatic spread instead is promoted by communications between tumourand immune cells Normal colonic tissues show specialized macrophages residing in well-defined niches The functions of TAMs duringtumour progressionmay depend on their intrinsic plasticity and adaptability mediated by factors controlling the balance between theM1 andM2 phenotypeWe suggest that at least twomechanismsmay play a role in the prometastatic function of TAMs (1)M2-macrophages producea dense layer surrounding invasive cancer cells resulting in heterotypic interactions between the tumour and the host stroma (2) invasivecancer cells can acquire immunophenotypic traits (ie CD68) due to cell fusion betweenmacrophages and cancer cells facilitating homotypicinteractions with the host stroma and TAMs (c) Polarized CD68 positive M2-macrophages may have distinct functions depending ontheir density or distribution between the invasive edges and intraepithelial areas (ratio IMIE times100) CD68 expression is not confined to theinfiltrating TAMs but is extended to a significant fraction of the malignant cellsThese parameters correlate with the mismatch repair (MMR)status and patientsrsquo disease specific survival in our cohort of 82 CRC patients IE intraepithelial IM invasive margin MMR pro and MMRneg indicate MMR proficient and deficient tumours respectively The 119875 value is reported in each graph


Carcinoma Liver metastasis

020406080

100

NM Tum Liv met

Case

s (

)

NT5ECD73 levels

NT5ECD73 expression in tumour microenvironment

N = 25

N = 60

N = 134P = 0023

(a)

0

100

200

High Low

MMR negMMR pro

NT5E

P = 0567

0

50

100

150

NT5E highNT5E low

IMIE Cancer cell

P = 0042

Low

Inte

r

Hig

h

Low

Inte

r

Hig

h

Neg Po

s

CD68 total

(b)

NT5E induction

Bloo

d ve

ssel

Fibr

obla

st

Mac

roph

age

NT5

E

(+)(+)∙ WNT120573-catenin∙ HIF-1120572∙ TNF-120572NF120581B

∙ Immunoescape∙ Premetastatic niche∙ Liver dissemination

∙ Cytokines∙ Chemokines∙ PGE∙ Adenosine

Metastasis

PPAR120574

(c)

Figure 3 NT5ECD73 facilitates escape from immune-surveillance and orchestrates the tumour-stroma interplay to promote cancer growthandmetastasis (a) Representative images of NT5ECD73 immunostaining in a primary carcinoma and corresponding liver metastasisWhiteand black arrows indicate the immunostaining in the stromal compartment and malignant colonic cells respectively magnification 10X(b) NT5ECD73 immunostaining is higher in liver metastatic tissues than in primary tumours or normal colonic mucosa and significantlycorrelates with CD68 infiltration NT5ECD73 expression is not correlated with the MMR status in our cohort of CRC patients (c)Schematic drawing of the proposed mechanism(s) involved in metastasis-promoting actions of NT5ECD73 In physiological conditionsNT5ECD73 hydrolyzes AMP to adenosine an important mediator that binds A2A receptors on activated CD4 effector T-cells decreasingtheir proliferation and cytokine production hencemediating immunosuppressive effects NT5ECD73 is expressed in a variety of stromal cells(macrophages endothelial cells B-lymphocytes and Treg-cells) A variety of oncogenic pathways can induce ectopic NT5ECD73 expressionin CRC cells enhancing paracrineautocrine interactions (activation of A2B receptors) between malignant colonic hematopoietic andnonhematopoietic cells to sustain immunosurveillance escape and cancer cell migration PPAR120574 (peroxisome proliferator-activated receptorgamma) has been suggested as a possible NT5ECD73 antagonist through still unknownmechanisms IE intraepithelial IM invasivemarginLiv Met liver metastases MMR pro and MMR neg indicate MMR proficient and deficient tumours respectively The 119875 value is reported ineach graph


OncogenesTumor suppressor

genes

Liver metastasisPrimary tumour

Immuno-cellrecruitment andpolarization

DNA damageresponse

Therapy-induced injuryand inflammation

∙ Biological plasticity∙ Phenotypic and

epigenetic changes

∙ Cytokines∙ Growth factors∙ Purinergic pathways

Tumour regrowth

Tumor cells

TAM

S

MDSC

s

Figure 4 Tumour and immune cells plasticity in therapy-induced tumour tissue damage and development of therapy resistance Immunecells polarization soluble mediators and extracellular matrix components of the tumour microenvironment contribute to progression andlivermetastasis by constructing the so-called ldquopremetastatic nicherdquoTherapy-induced tumour tissue injuries lead to interconnected phenotypicalterations of tumour and immune cells Activity of several drugs (5-FU gemcitabine and other cytotoxic agents) on (the) malignant cellscan be associated with the concomitant TAMs and MDSCs activation or expansion due to enhanced polarization and phenotypic plasticityin metastatic tissues Consistent with this hypothetical model extensive tumour tissue injuries and necrosis activate the ldquoinflammasomerdquo andenhance the release of cytokines (IL-1120573) and growth factors (TGF-120573) and likely activate immune-suppressive pathwaysmediated by adenosineproduction (purinergic pathways) In addition tumour tissue damage following cytoreductive therapy results in epigenetic alterations DNAdamage response increased expression of drug transporters and DNA-repair enzymes in malignant cells which contribute to protect againstcytotoxic drugs and result in therapy resistance and tumour relapse

Only limited information is available about NT5ECD73downregulation we recently suggested PPAR120574 (peroxisomeproliferator-activated receptor 120574) as a possible NT5ECD73repressor [79] All together these results suggest that multiplemechanisms affect NT5ECD73 expression in cancer andstromal cells (endothelial cells fibroblasts and TAM) con-tributing to the evolution of metastatic niches and evasion ofimmune surveillance (Figure 3(c)) Further studies and newmodel systems are required to study the dynamic changesoccurring in stromal cells that enable initiated tumour cellsto survive and progress towards metastasis

8 Tumour Microenvironment Plasticity as aDeterminant of the Response to Therapy

Over the past decade the scenario of metastatic CRC(mCRC) treatment has deeply changedThe benefits of classicanticancer agents have been strenghtened by novel target-oriented molecules whose efficacy in combination withstandard chemotherapy has been demonstrated [80ndash84] Anemerging concept in anticancer therapy involves the mobi-lization of several types of MDSCs following treatment withtraditional or targeted therapies that may contribute eitherto a lack of response or to an acquired drug resistance [84ndash88] Although it is still unknown how MDSCs mobilizationoccurs it has been demonstrated that MDSCs precursorsare recruited to metastases by VEGFA signaling throughVEGFR2 [84 85]

Endothelial cells among the stromal cell types are crucialto metastatic dissemination and outgrowth accordinglydrugs able to target these cells are the most advanced in clin-ical trials [84ndash89] A VEGF antagonist commercially knownas ldquoBevacizumabrdquo increases survival in patients with mCRCwhen combined with chemotherapy in particular with flu-oropyrimidines Irinotecan and Oxaliplatin [84] Recentlya wide range of new molecules targeting angiogenesis havebeen tested in clinical trials Interestingly two drugs ldquoAfliber-ceptrdquo a VEGF and PIGFs-antagonist and ldquoRegorafenibrdquo amulti-Tyrosine Kinase Inhibitor have significantly improvedthe progression free survival in a Phase III randomized trial[89ndash92]

Therapeutic blockade of macrophage recruitment orchemokine signalling has recently been shown to improvesurvival after chemotherapy [88ndash94] Accordingly the anti-cancer agent ldquoTrabectedinrdquo employed in the treatment of softtissue sarcomas selectively depletes TAMs in vivo [95] TAMsor MDSCs in contrast can activate the ldquoinflammasomerdquothrough the release of cathepsin B and IL1120573 in response to 5-FU a mechanism that reduces the anticancer activities of thisdrug [85]The effects of other classic cytotoxic agents such asOxaliplatin and Irinotecan on TAMs remain to be elucidatedFurthermore anti-EGFR therapy activates M2-macrophagesor MDSCs resulting in release of immunosuppressive andtumour-promoting mediators (Figure 4) [85 96] Accordingto these data irradiated macrophages produce signals thatinclude CD95 ligand TNF120572 nitric oxide and superox-ide suggesting a model based on the intrinsic adaptabilityof immune and cancer cells in response to a genotoxic


therapy [87 88 97] Anticancer drugs can determine rapidor slow interactions among TME components promotingDNA damages or epigenetic modifications which resultin increased expression of drug transporters DNA-repairenzymes and chromosomal instability genes all mechanismsleading to tumour regrowth (Figure 4) In spite of the trans-lational promise of the targeted therapy our understandingof the relationships between mechanisms of resistance andTME remodeling remains very limited This reinforces theimportance of a full comprehension of the intricacy of cellinteractions occurring in TME

9 Immunogenic Cell Death and the PurinergicSignalling in Cancer Therapy

Collectively MDSCs can either enhance or antagonizethe antitumour efficacy of cytotoxic chemotherapy cancer-cell targeting antibodies and immuno therapeutic agentsdepending on the treatment and tumour type Therapyresistance has been linked with a new concept definedas ldquoimmunogenic cell deathrdquo (ICD) [24 26] an eventmainly mediated by damage-associated molecular patterns(DAMPs) DAMPs are either secreted or released (such asATP) some become enriched or are de novo exposed on theouter leaflet of the plasma membrane (such as calreticulin(CRT) and heat shock protein 90 (HSP90) This mechanismis characteristic of dying stressed or injured cells and thesemolecules can act as either adjuvant or danger signals forthe innate immune system [24 26] Studies have showntheir interactions with phagocytosis purinergic and pattern-recognition receptors (PRRs) are required for ICD thatultimately leads to the activation of a potent anticancerimmunity In this context accumulating data underscore thetherapeutic potential for targeting the adenosinergic system[26 76 77] in particular the key molecule NT5ECD73Numerous studies in a variety of murine tumour modelshave also highlighted that loss of NT5ECD73 functioncan efficiently delay tumour growth and confer metastasisresistance [76 77 79] In the TME a shift towards ATPaccumulation might be crucial in mediating an effectiveantitumour response thus depletion of NT5ECD73 may beclinically relevant as an ICD inducer supporting the notionthat the adenosinergic system is a relevant target in can-cer Blocking NT5ECD73 signaling could have two impor-tant effects to rescue the endogenous adaptive antitumourimmune responses and to inhibit the metastatic potential oftumour cells Therefore investigations aimed at elucidatingthe mechanisms underlying the signalling activated by theadenosinergic system-ICD interactions not only will improveour understanding of this important process but will alsocontribute to the development of new strategies for cancertherapy

10 Concluding Remarks

Genetic and epigenetic alterations are the key driver eventsin the initial transformation of normal colonocytes growinglines of evidence suggest that the stromal and inflammatory

cells within the tumour microenvironment and the circu-lation play a fundamental role in metastatic disseminationIn fact a large series of factors routinely synthesized orde novo expressed by the microenvironment during tumourdevelopment act in paracrine and autocrine fashion andinduce immunosuppression immune-mediated tumour pro-gression achieving a new metastable order On the basis ofthe various trends developed over the past decade in thecancer immune surveillance field cancer inflammation andcancer therapy we suggest a list of biologic properties thatare crucial to modify the tumour microenvironment andeducate malignant stromal and inflammatory cells towardsa metastatic phenotype (1) the intrinsic plasticity of immunecells in response to paracrine and autocrine signals and adapt-ability to novel and adverse environmental conditions (ieresponse to genotoxic stimuli) (2) alterations of positionalschemes by factors controlling the balance between tumour-suppressing and tumour-promoting activities (ie evolu-tion of a premetastatic niche) (3) acquisition of immune-phenotypic traits (NT5ECD73 CD68 and CD163) by cancercells that enhance the interactions with TME componentsthrough the production of immune-suppressive mediatorsIf confirmed this working hypothesis could be used tostratify patients carrying defined genetic lesions and identifymolecular profiles of TME subtypes in cancer biopsies beforeduring and after therapy The mechanisms regulating TMEfunctions in normal conditions and in response to therapyhowever are still far to be completely understood especiallyfor the possibility to exploit such information in the clinicalmanagement of patients and development of new strategiesof cancer therapy

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] D M Parkin F Bray J Ferlay and P Pisani ldquoGlobal cancerstatistics 2002rdquo CA Cancer Journal for Clinicians vol 55 no2 pp 74ndash108 2005

[2] A Jemal F Bray M M Center J Ferlay E Ward andD Forman ldquoGlobal cancer statisticsrdquo CA Cancer Journal forClinicians vol 61 no 2 pp 69ndash90 2011

[3] J Ferlay H-R Shin F Bray D Forman C Mathers and DM Parkin ldquoEstimates of worldwide burden of cancer in 2008GLOBOCAN2008rdquo International Journal of Cancer vol 127 no12 pp 2893ndash2917 2010

[4] N H Segal and L B Saltz ldquoEvolving treatment of advancedcolon cancerrdquo Annual Review of Medicine vol 60 pp 207ndash2192009

[5] A Bardelli and S Siena ldquoMolecular mechanisms of resistanceto cetuximab and panitumumab in colorectal cancerrdquo Journal ofClinical Oncology vol 28 no 7 pp 1254ndash1261 2010

[6] J-P Issa ldquoColon Cancer itrsquos CIN or CIMPrdquo Clinical CancerResearch vol 14 no 19 pp 5939ndash5940 2008

[7] M Pancione A Remo and V Colantuoni ldquoGenetic and epi-genetic events generate multiple pathways in colorectal cancer


progressionrdquo Pathology Research International vol 2012 ArticleID 509348 11 pages 2012

[8] A Remo M Pancione C Zanella and R VendraminellildquoMolecular pathology of colorectal carcinoma A systematicreview centred on the new role of the pathologistrdquo Pathologicavol 104 no 6 pp 432ndash441 2012

[9] Cancer Genome Atlas Network ldquoComprehensive MolecularCharacterization of Human Colon and Rectal Cancerrdquo Natureno 487 pp 330ndash337 2012

[10] E M Felipe De Sousa X Wang M Jansen et al ldquoPoorprognosis colon cancer is defined by a molecularly distinctsubtype and develops from serrated precursor lesionsrdquo NatureMedicine vol 19 pp 614ndash618 2013

[11] A SadanandamCA Lyssiotis KHomicsko et al ldquoA colorectalcancer classification system that associates cellular phenotypeand responses to therapyrdquoNature Medicine vol 19 pp 619ndash6252013

[12] F Balkwill and A Mantovani ldquoInflammation and cancer backto VirchowrdquoThe Lancet vol 357 no 9255 pp 539ndash545 2001

[13] A Mantovani P Allavena A Sica and F Balkwill ldquoCancer-related inflammationrdquo Nature vol 454 no 7203 pp 436ndash4442008

[14] L R Rudmik and A M Magliocco ldquoMolecular mechanismsof hepatic metastasis in colorectal cancerrdquo Journal of SurgicalOncology vol 92 no 4 pp 347ndash359 2005

[15] D G DeNardo M Johansson and L M Coussens ldquoImmunecells as mediators of solid tumor metastasisrdquo Cancer andMetastasis Reviews vol 27 no 1 pp 11ndash18 2008

[16] J Condeelis and J W Pollard ldquoMacrophages obligate partnersfor tumor cellmigration invasion andmetastasisrdquoCell vol 124no 2 pp 263ndash266 2006

[17] O Tredan C M Galmarini K Patel and I F Tannock ldquoDrugresistance and the solid tumor microenvironmentrdquo Journal ofthe National Cancer Institute vol 99 no 19 pp 1441ndash1454 2007

[18] I P Witz ldquoThe tumor microenvironment the making of aparadigmrdquo Cancer Microenvironment vol 2 supplement 1 ppS9ndashS17 2009

[19] B B McConnell and V W Yang ldquoThe role of inflammationin the pathogenesis of colorectal cancerrdquo Current ColorectalCancer Reports vol 5 no 2 pp 69ndash74 2009

[20] M H McLean G I Murray K N Stewart et al ldquoTheinflammatorymicroenvironment in colorectal NeoplasiardquoPLoSONE vol 6 no 1 Article ID e15366 2011

[21] N Sethi andYKang ldquoUnravelling the complexity ofmetastasis-molecular understanding and targeted therapiesrdquo NatureReviews Cancer vol 11 no 10 pp 735ndash748 2011

[22] H Smith and Y Kang ldquoThe metastasis-promoting role oftumor-associated immune cellsrdquo Journal of MolecularMedicinevol 91 no 4 pp 411ndash429 2013

[23] J Wels R N Kaplan S Rafii and D Lyden ldquoMigratoryneighbors and distant invaders tumor-associated niche cellsrdquoGenes and Development vol 22 no 5 pp 559ndash574 2008

[24] M De Palma andC E Lewis ldquoMacrophage regulation of tumorresponses to anticancer therapiesrdquoCancer Cell vol 23 no 3 pp277ndash286 2013

[25] A Mantovani T Schioppa C Porta P Allavena and A SicaldquoRole of tumor-associated macrophages in tumor progressionand invasionrdquo Cancer and Metastasis Reviews vol 25 no 3 pp315ndash322 2006

[26] A D Garg D Nowis J Golab P Vandenabeele D V Kryskoand P Agostinis ldquoImmunogenic cell death DAMPs and anti-cancer therapeutics an emerging amalgamationrdquo Biochimica etBiophysica Acta vol 1805 no 1 pp 53ndash71 2010

[27] M Yamauchi P Lochhead T Morikawa et al ldquoColorectalCancer a tale of two sides or a continuumrdquo Gut vol 61 no6 pp 794ndash797 2012

[28] D Hanahan and L M Coussens ldquoAccessories to the crimefunctions of cells recruited to the tumor microenvironmentrdquoCancer Cell vol 21 no 3 pp 309ndash322 2012

[29] C Tecchio P Scapini G Pizzolo and M A Cassatella ldquoOn thecytokines produced by human neutrophils in tumorsrdquo Seminarsin Cancer Biology vol 3 pp 159ndash170 2013

[30] F Donskov ldquoImmunomonitoring and prognostic relevance ofneutrophils in clinical trialsrdquo Seminars in Cancer Biology vol23 pp 200ndash207 2013

[31] F Prall T Duhrkop V Weirich et al ldquoPrognostic role of CD8+tumor-infiltrating lymphocytes in stage III colorectal cancerwith and without microsatellite instabilityrdquo Human Pathologyvol 35 no 7 pp 808ndash816 2004

[32] F Pages A Berger M Camus et al ldquoEffector memory T cellsearly metastasis and survival in colorectal cancerrdquo The NewEngland Journal of Medicine vol 353 no 25 pp 2654ndash26662005

[33] F Pages J Galon andW H Fridman ldquoThe essential role of thein situ immune reaction in human colorectal cancerrdquo Journal ofLeukocyte Biology vol 84 no 4 pp 981ndash987 2008

[34] J R Jass ldquoLymphocytic infiltration and survival in rectalcancerrdquo Journal of Clinical Pathology vol 39 no 6 pp 585ndash5891986

[35] KM RopponenM J Eskelinen P K Lipponen E Alhava andV M Kosma ldquoPrognostic value of tumour-infiltrating lympho-cytes (TILs) in colorectal cancerrdquo The Journal of Pathology no3 pp 318ndash324 1997

[36] H Ohtani ldquoFocus on TILs Prognostic significance of tumorinfiltrating lymphocytes in human colorectal cancerrdquo CancerImmunity vol 7 2007

[37] J Galon A Costes F Sanchez-Cabo et al ldquoType densityand location of immune cells within human colorectal tumorspredict clinical outcomerdquo Science vol 313 no 5795 pp 1960ndash1964 2006

[38] F Pages A Kirilovsky B Mlecnik et al ldquoIn situ cytotoxic andmemory T cells predict outcome in patients with early-stagecolorectal cancerrdquo Journal of Clinical Oncology vol 27 no 35pp 5944ndash5951 2009

[39] L Laghi P Bianchi EMiranda et al ldquoCD3+ cells at the invasivemargin of deeply invading (pT3-T4) colorectal cancer and riskof post-surgical metastasis a longitudinal studyrdquo The LancetOncology vol 10 no 9 pp 877ndash884 2009

[40] A Buckowitz H-P Knaebel A Benner et al ldquoMicrosatelliteinstability in colorectal cancer is associated with local lympho-cyte infiltration and low frequency of distantmetastasesrdquoBritishJournal of Cancer vol 92 no 9 pp 1746ndash1753 2005

[41] V Deschoolmeester M Baay E Van Marck et al ldquoTumorinfiltrating lymphocytes an intriguing player in the survival ofcolorectal cancer patientsrdquo BMC Immunology vol 11 article 192010

[42] P Salama M Phillips F Grieu et al ldquoTumor-infiltratingFOXP3+ T regulatory cells show strong prognostic significancein colorectal cancerrdquo Journal of Clinical Oncology vol 27 no 2pp 186ndash192 2009


[43] R Kirk ldquoRisk factors CD8+FOXP3+ cell ratio is a novelsurvival marker for colorectal cancerrdquo Nature Reviews ClinicalOncology vol 7 no 6 p 299 2010

[44] P Wagner M Koch D Nummer et al ldquoDetection and func-tional analysis of tumor infiltratingT-lymphocytes (TIL) in livermetastases from colorectal cancerrdquoAnnals of Surgical Oncologyvol 15 no 8 pp 2310ndash2317 2008

[45] M Morris C Platell and B Iacopetta ldquoTumor-infiltratinglymphocytes and perforation in colon cancer predict posi-tive response to 5-fluorouracil chemotherapyrdquo Clinical CancerResearch vol 14 no 5 pp 1413ndash1417 2008

[46] S Ogino K Nosho N Irahara et al ldquoLymphocytic reaction tocolorectal cancer is associated with longer survival indepen-dent of lymph node count microsatellite instability and CpGisland methylator phenotyperdquo Clinical Cancer Research vol 15no 20 pp 6412ndash6420 2009

[47] M Pancione A Remo L Sabatino et al ldquoRight-sided rhabdoidcolorectal tumors might be related to the Serrated PathwayrdquoDiagnostic Pathology vol 8 article 31 2013

[48] S Michel A Benner M Tariverdian et al ldquoHigh densityof FOXP3-positive T cells infiltrating colorectal cancers withmicrosatellite instabilityrdquo British Journal of Cancer vol 99 no11 pp 1867ndash1873 2008

[49] M Kloor S Michel and M Von Knebel Doeberitz ldquoImmuneevasion of microsatellite unstable colorectal cancersrdquo Interna-tional Journal of Cancer vol 127 no 5 pp 1001ndash1010 2010

[50] JW Pollard ldquoTumour-educatedmacrophages promote tumourprogression and metastasisrdquo Nature Reviews Cancer vol 4 no1 pp 71ndash78 2004

[51] A Mantovani S K Biswas M R Galdiero A Sica and MLocati ldquoMacrophage plasticity and polarization in tissue repairand remodellingrdquoThe Journal of Pathology no 229 pp 176ndash1852013

[52] W Zhang X-D Zhu H-C Sun et al ldquoDepletion of tumor-associated macrophages enhances the effect of sorafenib inmetastatic liver cancer models by antimetastatic and antiangio-genic effectsrdquo Clinical Cancer Research vol 16 no 13 pp 3420ndash3430 2010

[53] A Sica and AMantovani ldquoMacrophage plasticity and polariza-tion in vivo veritasrdquo Journal of Clinical Investigation vol 122no 3 pp 787ndash795 2012

[54] M L Squadrito and M De Palma ldquoMacrophage regulation oftumor angiogenesis implications for cancer therapyrdquoMolecularAspects of Medicine vol 32 no 2 pp 123ndash145 2011

[55] A Mantovani S Sozzani M Locati P Allavena and A SicaldquoMacrophage polarization tumor-associated macrophages as aparadigm for polarizedM2mononuclear phagocytesrdquoTrends inImmunology vol 23 no 11 pp 549ndash555 2002

[56] A Sica T Schioppa A Mantovani and P Allavena ldquoTumour-associated macrophages are a distinct M2 polarised populationpromoting tumour progression Potential targets of anti-cancertherapyrdquo European Journal of Cancer vol 42 no 6 pp 717ndash7272006

[57] M Erreni A Mantovani and P Allavena ldquoTumor-associatedmacrophages (TAM) and inflammation in colorectal cancerrdquoCancer Microenvironment vol 4 no 2 pp 141ndash154 2011

[58] R N Kaplan S Rafii and D Lyden ldquoPreparing the ldquosoilrdquo thepremetastatic nicherdquoCancer Research vol 66 no 23 pp 11089ndash11093 2006

[59] A Jedinak S Dudhgaonkar and D Sliva ldquoActivatedmacrophages induce metastatic behavior of colon cancercellsrdquo Immunobiology vol 215 no 3 pp 242ndash249 2010

[60] A Mantovani A Sica P Allavena C Garlanda and M LocatildquoTumor-associated macrophages and the related myeloid-derived suppressor cells as a paradigm of the diversity ofmacrophage activationrdquoHuman Immunology vol 70 no 5 pp325ndash330 2009

[61] A A Khorana C K Ryan C Cox S Eberly and D MSahasrabudhe ldquoVascular endothelial growth factor CD68 andepidermal growth factor receptor expression and survival inpatients with stage II and stage III colon carcinoma a role forthe host response in prognosisrdquo Cancer vol 97 no 4 pp 960ndash968 2003

[62] S K Biswas A Sica and C E Lewis ldquoPlasticity of macrophagefunction during tumor progression regulation by distinctmolecular mechanismsrdquo Journal of Immunology vol 180 no 4pp 2011ndash2017 2008

[63] J Forssell A ObergM L Henriksson R Stenling A Jung andR Palmqvist ldquoHigh macrophage infiltration along the tumorfront correlateswith improved survival in colon cancerrdquoClinicalCancer Research vol 13 no 5 pp 1472ndash1479 2007

[64] Q Zhou R-Q Peng X-J Wu et al ldquoThe density ofmacrophages in the invasive front is inversely correlated to livermetastasis in colon cancerrdquo Journal of Translational Medicinevol 8 article 13 2010

[65] S Edin M LWikberg A M Dahlin et al ldquoThe distribution ofmacrophages with a m1 or m2 phenotype in relation to progno-sis and the molecular characteristics of colorectal cancerrdquo PLoSOne no 7 Article ID e47045 2012

[66] I Kareva and P Hahnfeldt ldquoThe emerging ldquohallmarksrdquo ofmetabolic reprogramming and immune evasion distinct orlinkedrdquo Cancer Research vol 73 pp 2737ndash2274 2013

[67] D I Gabrilovich and S Nagaraj ldquoMyeloid-derived suppressorcells as regulators of the immune systemrdquo Nature ReviewsImmunology vol 9 no 3 pp 162ndash174 2009

[68] D I Gabrilovich S Ostrand-Rosenberg and V Bronte ldquoCoor-dinated regulation of myeloid cells by tumoursrdquoNature ReviewsImmunology vol 12 no 4 pp 253ndash268 2012

[69] M B Maniecki A Etzerodt B P Ulhoslashi et al ldquoTumor-promoting macrophages induce the expression of themacrophage-specific receptor CD163 in malignant cellsrdquoInternational Journal of Cancer no 131 pp 2320ndash2331 2012

[70] I Shabo H Olsson X-F Sun and J Svanvik ldquoExpressionof the macrophage antigen CD163 in rectal cancer cells isassociated with early local recurrence and reduced survivaltimerdquo International Journal of Cancer vol 125 no 8 pp 1826ndash1831 2009

[71] J A Joyce and JW Pollard ldquoMicroenvironmental regulation ofmetastasisrdquo Nature Reviews Cancer vol 9 no 4 pp 239ndash2522009

[72] B-Z Qian and J W Pollard ldquoMacrophage diversity enhancestumor progression and metastasisrdquo Cell vol 141 no 1 pp 39ndash51 2010

[73] A Mantovani ldquoCancer inflaming metastasisrdquo Nature vol 457no 7225 pp 36ndash37 2009

[74] H K Eltzschig L F Thompson J Karhausen et al ldquoEndoge-nous adenosine produced during hypoxia attenuates neu-trophil accumulation coordination by extracellular nucleotidemetabolismrdquo Blood vol 104 no 13 pp 3986ndash3992 2004

[75] J J Kobie P R Shah L Yang J A Rebhahn D J Fowell andT R Mosmann ldquoT regulatory and primed uncommitted CD4T cells express CD73 which suppresses effector CD4 T cells byconverting 51015840-adenosinemonophosphate to adenosinerdquo Journalof Immunology vol 177 no 10 pp 6780ndash6786 2006


[76] J Stagg ldquoThe double-edge sword effect of anti-CD73 cancertherapyrdquo Oncoimmunology vol 1 no 2 pp 217ndash218 2012

[77] B Zhang ldquoCD73 A novel target for cancer immunotherapyrdquoCancer Research vol 70 no 16 pp 6407ndash6411 2010

[78] B Allard M Turcott e and J Stagg ldquoCD73-generated Adeno-sine orchestrating the tumor stroma interplay to promotecancer growthrdquo Journal of Biomedicine and Biotechnology vol2012 Article ID 485156 8 pages 2012

[79] S M Pagnotta C Laudanna M Pancione et al ldquoEnsemble ofgene signatures identifies novel biomarkers in colorectal Canceractivated through PPAR120574 and TNF120572 signalingrdquo PLoSOne vol8 Article ID e72638 2013

[80] D Cunningham Y Humblet S Siena et al ldquoCetuximabmonotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancerrdquoThe New England Jour-nal of Medicine vol 351 no 4 pp 337ndash345 2004

[81] H Hurwitz L Fehrenbacher W Novotny et al ldquoBevacizumabplus irinotecan fluorouracil and leucovorin for metastaticcolorectal cancerrdquo The New England Journal of Medicine vol350 no 23 pp 2335ndash2342 2004

[82] P Carmeliet and R K Jain ldquoAngiogenesis in cancer and otherdiseasesrdquo Nature vol 407 no 6801 pp 249ndash257 2000

[83] N Ferrara ldquoVEGF and the quest for tumour angiogenesisfactorsrdquoNature Reviews Cancer vol 2 no 10 pp 795ndash803 2002

[84] L M Ellis and D J Hicklin ldquoVEGF-targeted therapy mecha-nisms of anti-tumour activityrdquo Nature Reviews Cancer vol 8no 8 pp 579ndash591 2008

[85] M Bruchard G Mignot V Derangere et al ldquoChemotherapy-triggered cathepsin B release in myeloid-derived suppressorcells activates the Nlrp3 inflammasome and promotes tumorgrowthrdquo Nature Medicine no 19 pp 57ndash64 2013

[86] A Zoccoli M Iuliani F Pantano et al ldquoPremetastatic nicheReady for new therapeutic interventionsrdquo Expert Opinion onTherapeutic Targets vol 16 supplement 2 pp S119ndashS129 2012

[87] M Holzel A Bovier and T Tuting ldquoPlasticity of tumor andimmune cells a source for heterogeneity and cause for therapyresistancerdquo Nature Reviews Cancer vol 13 no 5 pp 365ndash3762013

[88] E S Nakasone H A Askautrud T Kees et al ldquoImaging tumor-stroma interactions during chemotherapy reveals contributionsof the microenvironment to resistancerdquo Cancer Cell vol 21 no4 pp 488ndash503 2012

[89] S Nucera D Biziato and M de Palma ldquoThe interplay betweenmacrophages and angiogenesis in development tissue injuryand regenerationrdquo International Journal of Developmental Biol-ogy vol 55 no 4-5 pp 495ndash503 2011

[90] E Van Cutsem J Tabernero R Lakomy et al ldquoAddi-tion of aflibercept to fluorouracil leucovorin and irinotecanimproves survival in a phase III randomized trial in patientswith metastatic colorectal cancer previously treated with anoxaliplatin-based regimenrdquo Journal of Clinical Oncology no 30pp 3499ndash33506 2012

[91] A Grothey E Van Cutsem A Sobrero et al ldquoRegorafenibmonotherapy for previously treated metastatic colorectal can-cer (CORRECT) an international multicentre randomisedplacebo-controlled phase 3 trialrdquoThe Lancet vol 381 no 9863pp 303ndash312 2013

[92] S M Zeisberger B Odermatt C Marty A H M Zehnder-Fjallman K Ballmer-Hofer and R A SchwendenerldquoClodronate-liposome-mediated depletion of tumour-asso-ciated macrophages a new and highly effective antiangiogenic

therapy approachrdquo British Journal of Cancer vol 95 no 3 pp272ndash281 2006


[94] S J Galli N Borregaard and T A Wynn ldquoPhenotypic andfunctional plasticity of cells of innate immunity macrophagesmast cells and neutrophilsrdquo Nature Immunology vol 12 no 11pp 1035ndash1044 2011

[95] G Germano R Frapolli C Belgiovine et al ldquoRole ofmacrophage targeting in the antitumor activity of trabectedinrdquoCancer Cell no 23 pp 249ndash262 2013

[96] J PanderMHeusinkveld T VanDer Straaten et al ldquoActivationof tumor-promoting type 2 macrophages by EGFR-targetingantibody cetuximabrdquoClinical Cancer Research vol 17 no 17 pp5668ndash5673 2011

[97] H He J Xu C M Warren et al ldquoEndothelial cells providean instructive niche for the differentiation and functionalpolarization of M2-like macrophagesrdquo Blood no 120 pp 3152ndash3162 2012

Submit your manuscripts athttpwwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


ERBB2 and IGF2 amplifications as novel potential therapeutictargets extensive molecular profiling studies have identifiedclinically and molecularly distinct subtypes of CRC [9ndash11] Inaddition to cancer genome abnormalities also the formationof an inflammatory microenvironment plays a pivotal rolein CRC development and progression [12 13] CRC survivalis highly dependent on the tumour stage at the time ofdiagnosis over one-third of patients die within five yearsfrom the initial diagnosis and most of fatal outcomes resultfrom liver metastases [14ndash17] The metastatic process is amultistep event that entails cancer cells to escape from theprimary tumour survive in the circulation seed at distantsites and grow [14 15] It is well established that themetastaticspread is promoted by communications between tumourand immune cells via the secretion of cytokines growthfactors and proteases that remodel the tumour microenvi-ronment (TME) [12 13] Consistent with this idea drivergene mutations (APC TP53 SMAD4 PIK3CA and KRAS)along with genomic and epigenomic instability determinetumour initiation while the interaction of cancer cells withmicroenvironmental stimuli provided by nontransformedcells is needed to evolve towards a metastatic cancer [15ndash19]The underlying molecular mechanism by which cancer cellsacquire the ability to escape the primary tumour site evadeimmune system eradication and reestablish a new order iscurrently under intense investigation [19ndash23] A number ofstudies have shown that infiltration and density of immuno-logic cells within primary tumours aremostly associated withpatientsrsquo prognosis and sensitivity to therapy [19ndash23] In par-ticular tumour associated-macrophages (TAMs) regulatoryT cells (Treg) and the so-called purinergic signaling cascadeare considered attractive targets for antitumour interven-tions [19ndash26] This field is drawing increasing attention toidentify new pharmaceutical targets and improve therapiesrsquoefficacy In this review we present results and suggest newhypotheses that underscore the growing impact of tumour-infiltrating immune cells in CRC progression Furthermorewe discuss the advances in our understanding as to howthe reciprocal communications between cancer and stromalcells impact liver metastasis formation and response to thetherapy

2 Infiltrating Immune Cells andCRC Progression

Most of cancer hallmarks are sustained to varying degree bygenetic and epigeneticmodifications of colon cancer cells andby stromal and immune cell types that contribute to generatea specific TME A recent model proposed by Yamauchi et alsuggests that the CRC molecular features gradually changealong bowel subsites and factors such as the interactionswith the gut microbiota biochemical components innateimmune system and epithelial cells might trigger the ini-tiating molecular events or alternatively influence tumourmicroenvironment to promote neoplastic progression [27](Figure 1) CRC and other solid tumours contain infiltratesof diverse leukocyte subsets including both myeloid- andlymphoid lineages that do not conform to the classical picture

Rectum

Bowel microenvironment (microbiome food

debris and fermentation)

Epithelial andimmune cells

interactions

Ascendingcolon

Caecum

Colon tumorigenesis

MSSCIMP-L

KRAS CIMP-HMSI-HBRAF+

Figure 1 Bowel microenvironment influences CRC molecularfeatures and progression The CIMP-high MSI-high and BRAFmutations frequencies gradually increase from the rectum toascending colon Caecal cancers seem to represent a distinct subtypecharacterized by a higher frequency of KRAS mutations a MSSand CIMP-L phenotype In the bowel microenvironment changesin the balance between (1) microbiome food debris and bacterialfermentation products and (2) interactions with host cells (epithelialand immune cells) might predispose colon epithelial cells to certainmolecular insults and differentially influence tumour developmentaccording to molecular features in preneoplastic cells CpG islandmethylator phenotype CIMPmicrosatellite instabilityMSI CIMP-low CIMP-L

of an inflammatory immune responseThe evidence providedis particularly robust for tumour infiltrating T lymphocytes(TILs) or tumour associatedmacrophages (TAMs) suggestingthat both adaptive and innate antitumour immune responsesplay key roles in cancer progression [28] By contrastthe potential role in human cancers of short-lived innateimmunity cells such as dendritic cells or tumor-associatedpolymorphonuclear neutrophils (TAN) has received poorattention However recent studies have revealed the existenceof potential neutrophil subsets in CRC patients showing atumor-promoting (N2) or tumor-inhibiting (N1) phenotypein response to the transforming growth factor-120573 (TGF-120573) [29 30] In addition evidence supports the ability ofTAN to express cytokine chemokine-encoding genes anda wider array of growth factors such as tumour-necrosisfactor (TNF) hepatocyte growth factor (HGF) and vascularendothelial growth factor (VEGF) suggesting a potentialrole in tumor progression and angiogenesis [28ndash30] Astriking finding is that an elevated neutrophils blood count ineither tumour or blood has a prognostic significance in sev-eral neoplasms Accordingly also the neutrophillymphocyteratio has been associated with poor clinical outcome inCRC [30] The significance of TAN in human cancersremains to be fully clarified and needs further experimentalconfirmation

















Months

Cum

surv

ival

100806040200

PosNeg

CD68 cancer cell

0

50

100

150

Low

Inte

rH

igh

Low

Inte

rH

igh

Neg Po

s

MMR negMMR pro


Months

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 IMIEMonths

120

100806040200

120

100806040200

120

100806040200

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 total number


M1M2

(1) (2)




IEIM

P = 067 P = 0057 P = 0120 P = 0197

Metastasis

Cancer(invasive)

Epithelium

Transitamplifying

compartment


Differentiatedcells

(a)

(b)

(c)




020406080

100

NM Tum Liv met

Case

s (

)

NT5ECD73 levels


N = 25

N = 60

N = 134P = 0023

(a)

0

100

200

High Low

MMR negMMR pro

NT5E

P = 0567

0

50

100

150

NT5E highNT5E low

IMIE Cancer cell

P = 0042

Low

Inte

r

Hig

h

Low

Inte

r

Hig

h

Neg Po

s

CD68 total

(b)

NT5E induction

Bloo

d ve

ssel

Fibr

obla

st

Mac

roph

age

NT5

E




Metastasis

PPAR120574

(c)




genes



DNA damageresponse



epigenetic changes


Tumour regrowth

Tumor cells

TAM

S

MDSC

s
















References












































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
































Months

Cum

surv

ival

100806040200

PosNeg

CD68 cancer cell

0

50

100

150

Low

Inte

rH

igh

Low

Inte

rH

igh

Neg Po

s

MMR negMMR pro


Months

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 IMIEMonths

120

100806040200

120

100806040200

120

100806040200

Cum

surv

ival

100806040200

HighIntermediateLow

CD68 total number


M1M2

(1) (2)




IEIM

P = 067 P = 0057 P = 0120 P = 0197

Metastasis

Cancer(invasive)

Epithelium

Transitamplifying

compartment


Differentiatedcells

(a)

(b)

(c)




020406080

100

NM Tum Liv met

Case

s (

)

NT5ECD73 levels


N = 25

N = 60

N = 134P = 0023

(a)

0

100

200

High Low

MMR negMMR pro

NT5E

P = 0567

0

50

100

150

NT5E highNT5E low

IMIE Cancer cell

P = 0042

Low

Inte

r

Hig

h

Low

Inte

r

Hig

h

Neg Po

s

CD68 total

(b)

NT5E induction

Bloo

d ve

ssel

Fibr

obla

st

Mac

roph

age

NT5

E




Metastasis

PPAR120574

(c)




genes



DNA damageresponse



epigenetic changes


Tumour regrowth

Tumor cells

TAM

S

MDSC

s
















References












































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















020406080

100

NM Tum Liv met

Case

s (

)

NT5ECD73 levels


N = 25

N = 60

N = 134P = 0023

(a)

0

100

200

High Low

MMR negMMR pro

NT5E

P = 0567

0

50

100

150

NT5E highNT5E low

IMIE Cancer cell

P = 0042

Low

Inte

r

Hig

h

Low

Inte

r

Hig

h

Neg Po

s

CD68 total

(b)

NT5E induction

Bloo

d ve

ssel

Fibr

obla

st

Mac

roph

age

NT5

E




Metastasis

PPAR120574

(c)




genes



DNA damageresponse



epigenetic changes


Tumour regrowth

Tumor cells

TAM

S

MDSC

s
















References












































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















genes



DNA damageresponse



epigenetic changes


Tumour regrowth

Tumor cells

TAM

S

MDSC

s
















References












































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

























References












































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















review article immune escape mechanisms in colorectal cancer pathogenesis … · 2019. 7. 31. ·...

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