erb-041, an estrogen receptor-b agonist, inhibits skin...

Research ArticleSee related commentary by Yao et al., p. 182

Erb-041, an Estrogen Receptor-b Agonist, Inhibits SkinPhotocarcinogenesis in SKH-1 Hairless Mice byDownregulating the WNT Signaling Pathway

Sandeep C. Chaudhary1, Tripti Singh1, Sarang S. Talwelkar1, Ritesh K. Srivastava1, Aadithya Arumugam1,Zhiping Weng1, Craig A. Elmets1, Farrukh Afaq1, Levy Kopelovich2, and Mohammad Athar1

AbstractEstrogen receptors (ER), including ER-a and ER-b, are known to regulate multiple biologic responses in

various cell types. The expression of ER-b is lost in various cancers. ER-b agonists were shown to modulate

inflammation, cancer cell proliferation, and differentiation. Here, we investigated the cancer chemopreven-

tive properties of Erb-041, an ER-b agonist, using a model of UVB-induced photocarcinogenesis in SKH-1

mice. Erb-041 significantly reducedUVB-induced carcinogenesis. Tumornumbers and volumewere reduced

by 60% and 84%, respectively, in the Erb-041–treated group as compared with UVB (alone) control. This

inhibition in tumorigenesis was accompanied by the decrease in proliferating cell nuclear antigen (PCNA),

cyclin D1, VEGF, and CD31, and an increase in apoptosis. The lost ER-b expression in squamous cell

carcinomas (SCC) was significantly recovered by Erb-041 treatment. In addition, the UVB-induced inflam-

matory responses were remarkably reduced. Myeloperoxidase activity, levels of cytokines (interleukin (IL)-

1b, IL-6, and IL-10), and expressionof p-ERK(extracellular signal–regulated kinase) 1/2, p-p38, p-IkB, iNOS,

COX-2, and nuclear NF-kBp65 were diminished. The number of tumor-associated inflammatory cells

(GR-1þ/CD11bþ and F4/80þ) was also decreased. Tumors excised from Erb-041–treated animal were less

invasive and showed reduced epithelial–mesenchymal transition (EMT). The enhanced expression of

E-cadherin with the concomitantly reduced expression of N-cadherin, Snail, Slug, and Twist characterized

these lesions. TheWNT/b-catenin signalingpathway,whichunderlies pathogenesis of skin cancer,was foundto be downregulated by Erb-041 treatment. Similar but not identical changes in proliferation and EMT

regulatory proteinswere noticed following treatment of tumor cells with aWNT signaling inhibitor XAV939.

Our results show that Erb-041 is a potent skin cancer chemopreventive agent that acts by dampening the

WNT/b-catenin signaling pathway. Cancer Prev Res; 7(2); 186–98. �2013 AACR.

IntroductionNonmelanoma skin cancers (NMSC), which include

basal cell carcinomas and squamous cell carcinoma(SCC), are the most commonly diagnosed cancers in theUnited States. Their incidence exceeds the combinedincidence of cancers of the breast, prostate, lung, andcolon (1). UVB radiation (280–320 nm) from the sun andtanning beds are the main etiologic cause of skin cancer(2). UVB induces DNA damage, inflammatory response,and alters multiple cell signaling events, which altogether

lead to initiation, promotion, and progression of epider-mal neoplasm (3). During the past decade, a number ofattempts have been made to understand the pathogenesisof these cancers and to identify novel molecular targets tointervene the disease progression. In this regard, we andothers have demonstrated the involvement of p53, orni-thine decarboxylase, cyclooxygenases, retinoid receptorsignaling, oxidative stress, etc., besides many others in themolecular pathogenesis of these cancers (3–8). Strategieshave also been developed to modify these targets toprevent NMSCs both in humans and in experimentalanimals (5, 9, 10). However, these approaches have beenonly partially successful.

The modulation of estrogen receptor (ER) activity hasproved therapeutically valuable for the treatment of variousepithelial cancers in experimental models (11–15). The ERsexist in two distinct forms ER-a and ER-b. Their splicevariants, which are also biologically active, have been iden-tified (13). Estrogens exert their tissue-specific responses viaER-a or ER-b or their splice variants by activating diversesignaling pathways that mediate both genomic and non-genomic events (11). It is interesting that despite remarkable

Authors' Affiliations: 1Department of Dermatology, University of Alabamaat Birmingham, Birmingham, Alabama; and 2Division of Cancer Prevention,National Cancer Institute, Bethesda, Maryland

Note:Supplementary data for this article are available atCancer PreventionResearch Online (http://cancerprevres.aacrjournals.org/).

Corresponding Author: Mohammad Athar, Department of Dermatology,University of Alabama at Birmingham, 1530 3rd Avenue South, VH 509,Birmingham, AL 35294-0019. Phone: 205-934-7554; Fax: 205-934-7500;E-mail: [email protected]

doi: 10.1158/1940-6207.CAPR-13-0276

�2013 American Association for Cancer Research.

CancerPreventionResearch

Cancer Prev Res; 7(2) February 2014186

Research. on February 3, 2019. © 2014 American Association for Cancercancerpreventionresearch.aacrjournals.org Downloaded from

Published OnlineFirst November 11, 2013; DOI: 10.1158/1940-6207.CAPR-13-0276

http://cancerpreventionresearch.aacrjournals.org/

similarities in the two receptors, ER-a and ER-b are oftenantagonistic in nature. Altered ratio of ER-a/ER-b in a cell isthe major determinant of responses of the cell to estrogen.ER-a/ER-b–mediated activation or deactivation is depen-dent on the effects of coactivator and corepressor proteinson estrogen-responsive element (14, 15).ER-b is a member of the nuclear receptor superfamily (13)

and is produced from eight exons. Upon ligand activation, itregulates gene expression by modulating transcription fac-tors, such as NF-kB, activating protein-1 (AP-1), and stimu-lating protein-1 (SP-1) through transcription factor crosstalk (16, 17). The nongenomic effects of ER-b are regulatedby the activation of protein kinases (A and C) and MAPK(mitogen-activated protein kinase) signaling pathways (18).The expression of ER-b is considered an important determi-nant of tumor phenotype and has also been suggested as ausefulbiomarker in the rheumatoiddiseaseprogression(19).ER-b–selective agonists have been shown to possess antic-arcinogenetic and anti-inflammatory properties in experi-mental model systems (20, 21). Loss of ER-b expression hasbeen reported in various cancers, such as prostate, colorectal,thyroid carcinoma, etc. (22–24).Methylation ofCpG islandsin the promoter of ER-b is considered as one of the putativemechanisms involved in the loss of its expression (25). Erb-041, a selective ER-b agonist, has been reported to possessstrong anti-inflammatory activity and is under clinical trialfor its potential use in rheumatoid arthritis (20, 26, 27).In this study, we investigated the cancer chemopreventive

effects of Erb-041 on the UVB-induced skin photocarcino-genesis using SKH-1 hairless mice. We observed a potentcancer chemopreventive activity of Erb-041 in this experi-mental animal model. Erb-041 affects the growth of UVB-induced murine SCCs. We show that the mechanism bywhich this ER-b agonist manifests cancer chemopreventiveeffects involves inhibition of the WNT/b-catenin–depen-dent signaling pathway.

Materials and MethodsReagents and antibodiesErb-041 (C15H10FNO3) was procured from IRIX Phar-

maceuticals Inc. and was supplied by the NCI chemopre-vention branch. Details of antibodies used in this study areprovided as Supplementary Table S1.

Human tissueFresh skin tumor samples were collected according to

our approved Institutional Review Board (IRB) protocol(N081204004) for undesignated samples. Human sampleswere carefully handled according to IRB guidelines.

AnimalsSix- to 8-week-old SKH-1 hairless female mice were used

for this study. Animals were housed in groups of five in eachcage under conditions of constant temperature of 24�C �2�C and relative humidity of 50% � 10%, and were main-tained on a 12 hours light/12 hours dark cycle with foodand drinking water ad libitum. The animal studies describedhere were approved by the Institutional Animal Care and

Use Committee (IACUC) of the University of Alabama atBirmingham (Birmingham, AL).

Cell culture and treatmentHuman immortalized keratinocyte (HaCaT) and human

epidermoid carcinoma (A431) cells were purchased fromthe American Type Culture Corporation and SCC13 cellswere gifted by Dr. S. K. Katiyar (University of Alabama atBirmingham, Birmingham, AL). These cells were routinelycultured in the recommended growth medium containing10% FBS, 100 U/mL of penicillin, and 100 mg/mL ofstreptomycin in humidified incubators at 37�C under 5%CO2.Cells (60%–70%confluent)were treatedwithErb-041or WNT signaling inhibitor or vehicle (dimethyl sulfoxide,DMSO) in complete culture medium. After 24 hours oftreatment, mediumwas removed and the cells were washedand harvested to prepare cell lysates.

UV light sourceThe UVB light source was a UVA/UVB Research Irradi-

ation Unit (Daavlin Co.), which is fitted with an elec-tronic controller to regulate dose of irradiated UVB. TheUVB irradiation procedure was identical to that describedearlier (7).

Experimental protocolAnimals were randomly divided into three groups of 20

mice each. Group I animals received topical treatment withethanol and served as age-matched vehicle control (negativecontrol). Group II and III animals were irradiated with UVB(180 mJ/cm2; twice/week) for 30 weeks. In addition, groupII received vehicle and group III animals received topicaltreatments with Erb-041 (2 mg/mouse in 200 mL ethanol),30minutes before UVB irradiation. The tumor number andsize were recorded weekly using electronic Vernier Caliperas described earlier (7). Data were presented as mean � SEand plotted as a function of weeks on test. After 30 weeks,the experiment was terminated and all mice were eutha-nized as per the IACUC recommendations. Skin and tumortissues were harvested and processed for histologic andbiochemical analysis as described in the following sections.

Histology, immunohistochemistry,immunofluorescence staining, and terminaldeoxynucleotidyl transferase–mediated nick endlabeling assay

Of note, 10% neutral-buffered formalin-fixed tissueswere embedded, and cut in the serial sections of 5 mm. Forhistologic evaluation, tissues were stained with hematoxy-lin and eosin (H&E). Immunohistochemical and immuno-fluorescence staining were performed as described earlier(7). The Vector Red Alkaline Phosphatase Substrate Kit (Catno. SK5100) was also used according to the manufacturer’sguidelines for immunohistochemistry (IHC). TUNEL (ter-minal deoxynucleotidyl transferase–mediated dUTP nickend labeling) assay was done using an in situ cell deathdetection, fluorescein kit from Roche Applied Science (Cat.no.1684795) following the manufacturer’s guidelines.

ER-b Agonist, Erb-041, Inhibits Skin Photocarcinogenesis

www.aacrjournals.org Cancer Prev Res; 7(2) February 2014 187




Myeloperoxidase activityMyeloperoxidase activity in the skin samples was deter-

mined as described earlier (28). The change in absorbancewas recorded at 460 nm using a PerkinElmer 1420 Multi-label Counter Victor 3. The data are expressed as meanmyeloperoxidase U/mg protein per minute.

Western blot analysisTissues were lysed in ice-cold lysis buffer containing 50

mmol/L Tris pH, 1% Triton X 100, 0.25% NaF, 10 mmol/Lb-glycerophosphate, 1 mmol/L EDTA, 5 mmol/L sodiumpyrophosphate, 0.5 mmol/L Na3VO4, 10 mmol/L dithio-threitol, 1% phenylmethylsulfonylfluoride, and proteaseinhibitors cocktail. For Western blot analysis, proteins(60–80 mg) were resolved on 10% to 15% SDS–PAGE andtransferred onto a nitrocellulose membrane (Bio-Rad) asdescribed previously (7). Membrane was stripped andreprobed with anti-b-actin antibody to confirm equal pro-tein loading. In instances, in which a blot was strippedmultiple times and probedwith different antibodies but thedata are presented as a part of more than one figure, thesame b-actin image was placed multiple times to representloading controls in the figures.

Qualitative and quantitative polymerase chainreaction (PCR)

Extraction of total RNA, cDNA preparation and real-timePCR (RT-PCR) were performed as described previously(29). Relative quantification of the steady-state targetmRNA levels was calculated after normalization of totalamount of cDNA to GAPDH (glyceraldehyde-3-phosphatedehydrogenase) endogenous reference. The list of primersused in this study is described in Supplementary Table S2.

Flow cytometryA431 and SCC13 cells were treatedwith andwithout Erb-

041 for 0, 24, 36, and 48 hours. The cells were trypsinized,washed, and fixed with ice-cold 70% ethanol at �20�Covernight. Thereafter, the cells were washed and incubatedwith 20mg/mL RNase A and 200mg/mL propidium iodideinPBS at roomtemperature for 30minutes, and subjected toflow cytometry using the BDAccuri C6 or FACSCalibur flowcytometer. Cell-cycle distribution was analyzed and pro-vided as percentage of the G1, S, and G2–M phase of cells.

Colony forming assayA431 and SCC13 cells (500 cells/well) were seeded into

6-well plates andwere allowed to growovernight. Cellsweretreated with and without Erb-041 for 24 hours and incu-bated in humidified chamber at 37�C for additional 10days. Cell colonies were fixed with 4% paraformaldehydefor 5 minutes and stained with 0.5% crystal violet for 30seconds, and cell colonies were counted (30).

Wound healing assayBriefly, A431 and SCC13 cells were allowed to grow up to

90% to 100% confluence, and a fine scratch wasmade usinga sterile pipette tip. Then, these cells were treated with and

withoutErb-041and incubatedat 37�Cfor24hours. The cellmotility was observed at 12 and 24 hours using anOlympusCK2 microscope with Olympus DP20 digital camera.

ImmunocytostainingHaCaT,A431, andSCC13cellsweregrown in24-well plate

on roundglass cover slipswithorwithoutErb-041 slides. Thecells were fixedwith 4%paraformaldehyde for 15minutes atRT. Cells were permeabilized and blocked with 1% bovineserum albumin, 10% goat serum, 0.3 mol/L glycine, and0.1% Tween X for 1 hour at RT. Then, cells were incubatedwith primary antibodies for 2 hours at RT. After washing, thecells were incubated with appropriate Dylight 488 or AlexaFluor 594 secondary antibodies for 1 hour at RT in humid-ified chamber,washed, andmountedwith40,6-diamidino-2-phenylindole, andobservedusingOlympusBX51TRFmicro-scope with an Olympus DP71 digital camera.

Densitometry and statistical analysisRelative density of Western blot analysis bands was

analyzed by using ImageJ software downloaded fromhttp://rsbweb.nih.gov/ij/. All values are expressed as mean� SE. Statistical analysis was performed using MicrosoftExcel software 2007. The significance between two testgroups was determined using the Student t test. A P valueof <0.05 was considered to be significant.

ResultsErb-041 treatment reduces UVB-induced skinphotocarcinogenesis

Topical treatment with Erb-041 substantially diminishedUVB-induced skin tumor development in SKH-1 hairlessmice as compared with vehicle-treated and UVB (alone)-irradiated mice. At the time of termination of experiment atweek 30, the percentage ofmice bearing tumors, tumors permouse and tumor volume per mouse were significantlyreduced in Erb-041–treated mice. The tumor incidence was75% in the Erb-041þUVB group, whereas it was 100% inUVB-irradiated (alone) mice (Fig. 1A). The number oftumors per mouse was reduced to 3.3 � 0.62 per mousefrom 8.95 � 0.94 per mouse in the UVB (alone) group,which represents >60% inhibition (Fig. 1B). Similarly, a50% reduction (P < 0.001) in the number of tumors/tumor–bearing mouse was observed (Supplementary Fig.S1A). About 84% reduction in tumor volume (P < 0.005)was noted in the Erb-041–treated group (Fig. 1C). Erb-041treatment increased latency period of tumor induction from17 to 21weeks. Overall, the number of SCCs permouse wasalso reduced by 86% (P < 0.001; Supplementary Fig. S1B).To analyze tumor burden in these animals, we divided eachgroup with respect to the number of animals bearing 0 to 5,6 to 10, 11 to 15, or 16 to 20 tumors per mouse. Of note,15% of UVB-irradiated mice were bearing 0 to 5 tumors permouse, 45% 6 to 10 tumors per mouse, 30% 10 to 15tumors per mouse, and 10% 16 to 20 tumors per mouse.However, in the Erb-041 treatment group, 70%ofmicewerebearing 0 to 5 tumors per mouse, whereas 30% had 6 to 10tumors per mouse (Fig. 1D and E). Histologically, SCCs at

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Cancer Prev Res; 7(2) February 2014 Cancer Prevention Research188




week 30were characterized as amix of poorly-differentiatedSCCs (pSCC), moderately-differentiated SCCs (mSCC),and well-differentiated SCCs (wSCC). We also observed afew invasive keratoacanthomas. In the UVB (alone) group,SCC spectrum comprised of mice with 19% pSCC, 17%mSCC, and 14% (wSCC) of the total tumors, whereas in theErb-041 treatment group, only 1% pSCC, 6% mSCC, and11% wSCC were observed (Fig. 1F). UVB-irradiated pSCCswere distinguished by the absence of keratin pearls, aggres-sive spindle cells with hyperchromatic pleomorphic nuclei,and invasion of dermis. However, wSCCs were character-

ized by the frequent presence of well-defined keratin pearls(Fig. 1G).

Erb-041 reduces proliferation and angiogenesis andinduces apoptosis in UVB-induced skin tumors

We investigated the effects of Erb-041 treatment on theexpression of proliferative biomarkers such as proliferatingcell nuclear antigen (PCNA), cyclin D1, and Ki67 in UVB-induced skin tumors. As assessed by IHC as well as Westernblot analysis, Erb-041 treatment significantly (P < 0.05)reduced the expression of these proteins (Fig. 2A and

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Figure 1. ER-b agonist, Erb-041 suppresses development of SCC in SKH-1 hairless mice. SKH-1 hairless mice were topically treated with Erb-041(2 mg/mouse in ethanol), 30 minutes before UVB (180 mJ/cm2) irradiation for 30 weeks. Tumor number and size were recorded weekly. A, percentageincidence of mice bearing tumor; B, tumor/mouse; C, tumor volume/mouse (mm3); D, tumor spectrum of mice; E, representative photograph of UVB-treatedand Erb-041–treated SKH-1 hairless mice; F, pie chart showing percentage distribution of pSCC, mSCC, and wSCC and papilloma; and G, histology oftumor tissues showing pSCCs and wSCCs. KP ¼ keratin pearls. ��, P < 0.005; ��, P < 0.001.






Supplementary Fig. S1C). Angiogenesis biomarkers such asCD31/VEGF were assessed in UVB (alone)-irradiated andUVBþErb-041–treated tumors. As shown in Fig. 2B, theimmunostaining forCD31/VEGFwas considerably reducedby Erb-041 treatment. The apoptosis in cutaneous tumortissueswas assessedby the presence of TUNEL-positive cells.The number of TUNEL-positive cellswas highly increased inthe Erb-041 treatment group as compared with the UVB(alone) group (Fig. 2C). Because induction of apoptosis isoften correlated with the increased expression of proapop-totic Bax anddecreased expression of antiapoptotic Bcl-2, oran increased Bax/Bcl-2 ratio (31), we also assessed theseparameters in this study. Erb-041 treatment altered theexpression of Bax and Bcl-2 in these tumor lesions (Sup-plementary Fig. S1D) in such a way that Bax/Bcl-2 ratio wassignificantly (P < 0.005) increased in tumors (Fig. 2C).

Erb-041 treatment augments the expression of ER-b inmurine tumor keratinocytes

Earlier studies suggested that ER-b is a potent tumorsuppressor and plays a crucial role in various cancers(22, 32, 33). Its expression is lost during the pathogenesisof various epithelial neoplasms (33). We, therefore, firstassessed its expression in human cutaneous SCCs and tumorcells derived from SCCs. As shown in Fig. 3A, the expression

of ER-b in histologically normalhuman skinwas confined tothe basal layer of the epidermis. Loss of expression in ER-bwas noted in murine SCCs. Interestingly, Erb-041 treatmentrestored or even enhanced the expression of ER-b not only atprotein level but also at transcriptional level inUVB-inducedmurine SCCs and human SCC cells in culture (Fig. 3Band C). Moreover, its expression was also apparent in thehyperplastic skin adjacent to papilloma and/or SCCs. How-ever, a significant loss of its expression can be seen in humanSCCs as well as SCCs-derived A431 and SCC13 cells ascompared with immortalized HaCaT keratinocytes (Fig.3D). Consistent with our in vivo results, Erb-041 treatmentinduced expression of ER-b in these human cells (Fig. 3E),which was confirmed with immunoblot analysis. Reducedexpression of p-c-Jun and SP-1 was also associated withincrease in ER-b expression (Fig. 3E).

Erb-041 suppresses the proinflammatory signalingpathway in UVB-induced skin tumors

We examined the effects of Erb-041 on UVB-inducedinflammation and inflammation-regulating MAPK signal-ing pathways. UVB-induced inflammatory responses inmurine skin are characterized by the development of edemaand hyperplasia, enhanced leukocyte infiltration in thedermis, leukocytes-secreted inflammatory cytokines, and

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Figure 2. Erb-041 blocksproliferation andangiogenesis, andinduces apoptosis in UVB-inducedcutaneous lesions in SKH-1hairless mice. A, immunostainingshowing expression of PCNA,cyclin D1, Ki67, and Western blotanalysis showing expression ofPCNA and cyclin D1; B,immunostaining of CD31 andVEGF; C, TUNEL staining and Bax:Bcl2 ratio. ��, P < 0.005 whencompared with UVB (alone)-treated positive control.

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increased level of COX-2 and prostaglandins (3, 34). Con-sistently, as shown in Fig. 4A, the chronic exposure ofmurine skin to UVB-induced epidermal hyperplasia anddermal leukocytes infiltration, which was significantlyreduced by Erb-041 treatment. Myeloperoxidase activity,a marker of neutrophil infiltration, was also decreasedsignificantly (P < 0.05; Fig. 4B). Tumor microenviron-ment–associated inflammatory responses, which are knownto accelerate tumorigenesis (35, 36), were found to beattenuated by Erb-041. Thus, a decrease in proinflammatorycytokines [interleukin (IL)-1b, IL-6, and IL-10] in tumor-associated skinwasnoted in Erb-041–treatedmice (Fig. 4C).CD11bþ/GR1þ myeloid cell population and macrophagesin the dermis of UVB-irradiated skin as well as in tumor–stroma contribute to proinflammatory skin tumor progres-sion (36, 37). As shown in Fig. 4D, the numbers of CD11bþ

/GR1þ myeloid cells and F4/80þ macrophages were signif-icantly decreased by Erb-041 treatment. This was alsoaccompanied by a reduction in the phosphorylation-depen-dent activation of ERK1/2 and p38 MAPKs (Fig. 4E andSupplementary Fig. S2A). Earlier Kim and colleaguesreported that chronic UVB irradiation of the skin induces

cytokine production, and activates the MAPK signalingpathway (35), which was confirmed this study. UVB-induced inflammation is also known to be associated withNF-kB activation (38, 39). NF-kB exists as a heterotrimericcomplex in cytoplasm, which consists of p65, p52/p50 andinhibitory kappa B (IkB) proteins. Phosphorylation of IkBvia inhibitor of I-kB kinases (IKKs) leads to release oftranscriptionally active p65-p52/p65-p50 complexes andenable them to translocate to the nucleus (38, 39). Tran-scriptionactivationofNF-kB is also evidentby the enhancedexpression of its target genes including proinflammatoryCOX-2 and iNOS (Fig. 4E and F). The Erb-041 treatmentsuppressed phosphorylation of IkBa resulting in the accu-mulation of IkBa as a heterotrimeric complex in the cyto-plasm. Concomitantly, by inhibiting the activation of NF-kB, Erb-041 also reduced the expression of UVB-inducediNOS and COX-2 in these neoplastic lesions (Fig. 4E and Fand Supplementary Fig. S2A). Similarly, nuclear NF-kBp65and phosphorylated NF-kBp65 were reduced drastically inErb-041–treated tumors as compared with the UVB (alone)tumors (Fig. 4E and F). These data provide a basis for theanti-inflammatory action of Erb-041 in the skin.

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Figure 3. Erb-041 treatmentenhances expression of ER-b. A,immunostaining of ER-b in humannormal, tumor-adjacent, andSCC/skin; B, immunostainingshowing nuclear and cytoplasmicexpression of ER-b; C, mRNAexpression (semiquantitativePCR) of ER-b in UVB (alone)-induced and Erb-041þUVB–induced SCCs; D,immunocytostaining of ER-b inHaCaT, A431, and SCC13 cellstreated with vehicle or Erb-041 for24 hours; E, Western blot analysisshowing expression of ER-b andits responsive genes p-c-Jun, SP-1 in A431 cells treatedwith vehicleor Erb-041. ��, P < 0.001.






Erb-041 diminished tumor invasiveness via the PI3K–AKT pathway and WNT signaling

Epithelial–mesenchymal transition (EMT) is a process bywhich polarized epithelial cells transform to a mesenchy-mal fibroblast-like cell phenotype via multiple molecularcascades that result into apoptosis-resistance, enhancedmigration, and invasiveness. EMT also increases compo-nents of extracellular matrix (40, 41). In malignant neo-plasm, repression of E-cadherin by transcription factorssuch as Snail and Twist, ultimately leads to upregulation

of mesenchymal marker proteins such as vimentin, fibro-nectin, and N-cadherin (41). EMT is known to be regulatedby multiple mechanisms, including those dependent onphosphoinositide 3-kinase (PI3k)/Akt signaling pathways(7, 41). Therefore, we investigated whether Erb-041 inter-feres with the EMT progression in UVB-induced tumors.Immunoblot analysis and immunofluorescence analysisconfirmed that Erb-041 increased the expression of epithe-lial biomarker E-cadherin and reduced the expression ofmesenchymal markers N-Cadherin, Snail, Slug, and Twist

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Figure 4. Erb-041 treatmentattenuates UVB-inducedinflammatory cells infiltration inthe skin and tumor stroma. A, H&Estaining of vehicle- and Erb-041–treatedUVB-inducedhyperplasticskin showing infiltration ofinflammatory cells in the dermis;B, cutaneous myeloperoxidase(MPO) activity; C, RT-PCRanalysis showing expressionof IL-1b, IL-6, and IL-10; D,immunofluorescence analysis ofGR-1 (green)/CD11b (red)-positive myeloid cells and F4/80(green)-positive macrophages;E, Western blot analysis ofinflammatory signaling regulatoryproteins Erk1/2, p38, IkBa (Ser32/36), iNOS and COX-2, andnuclear p-NF-kBp65; and F,immunofluorescence stainingof p-NF-kBp65 and COX-2.�, P < 0.05; ��, P < 0.001.

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(Fig. 5A–C and Supplementary Fig. S2B). This is consistentwith the observations that Erb-041 reduces the incidence ofpoorly-differentiated invasive SCCs in this study. In addi-

tion, in a wound-healing in vitro assay, we also found thatErb-041 treatment reducedmigration potential of SCC cells(Supplementary Fig. S2C). Erb-041 inhibited about 55%

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Figure 6. Erb-041 treatment induces G1 cell-cycle arrest, inhibits colony forming potential, inflammation, and EMT via theWNT/b-catenin pathway. Cells wereseeded in100-mmplates at 1�106 cell density and incubatedovernight at 37�C.Thereafter, these cellswere treatedwithErb-041 (0, 20, 40, and60mmol/L) for24 hours and subjected to Western blot analysis. (Continued on the following page.)

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and 71% cell migration when assessed for A431 and SCC13cells, respectively (Fig. 5D). We also determined the effectsof Erb-041on the phosphorylation-dependent activation ofPI3k and AKT in UVB-induced tumor (Fig. 5E and Supple-mentary Fig. S3A). These proteins are associated with thecell survival signaling pathway (41). UVB-induced patho-genesis of cutaneous neoplasm is known to be associatedwith the activation of this pathway (7, 41). Interestingly,Erb-041 treatment reduced phosoho-PI3k–AKT axis inUVB-induced tumor tissues.Epithelial cell adhesion complex involves binding of E-

cadherin/b-catenin/a-catenin complex to F-actin at trans-membrane region, and plays a key role in EMT processduring tumorigenesis (41, 42). Numerous studies reportedthat the release of b-catenin in cytoplasm, and then itsmigration to the nucleus are associated with loss ofE-cadherin (41, 43). The b-catenin–dependent WNT sig-naling pathway is known to play essential roles in theregulation of cell polarity, proliferation, fate, survival, dif-ferentiation, and migration (43). In the presence of WNTligands, the destruction complex containing proteins ade-nomatous polyposis coli, glycogen synthase kinase 3b(GSK3b), casein kinase 1 (CK1), b-catenin, and Axin getsdissociated. As a consequence, b-catenin releases, whichleads to activation of transcription factors TCF/LEF (T-cellfactor/lymphoid enhancer factor) and dependent targetgenes (43). In this study, we observed that augmentedexpression of WNT3a, WNT7b, FZD1, and b-catenin inUVB-induced skin tumors were reduced following Erb-041 treatment (Fig. 5F and Supplementary Fig. S3B). Inaddition, in immunofluorescence staining, we noted nucle-ar localization of b-catenin in UVB (alone)-induced tumor,whereas it was considerably reduced in Erb-041–treatedUVB-induced tumors (Fig. 5G).

Erb-041 treatment of human SCC cells induced celldifferentiation, cell-cycle arrest, and reduced colonyformation in vitroIn an effort to unravel the underlying mechanism of this

ER-b agonist, we treated human epidermal immortalized(HaCaT) and A431 and SCC13 cells with various concen-tration of Erb-041 in vitro. As shown in Supplementary Fig.S4A and S4B, Erb-041 treatment induced expression ofcytokeratin 10, a differentiation marker. We next analyzedits effects on cell-cycle progression in these cells. Erb-041treatment induced G1 phase cell-cycle arrest in A431 cells,whichwas associatedwith the reduction in the expressionofG1 cyclins (D1, D2, and D3) and CDK4. A slight butinsignificant reduction in the expression of cyclin B1/E,CDC-2, and CDK2 was also noted (Fig. 6A and B andSupplementary Fig. S4C). In a colony formation assay,

consistent with its effects on cell-cycle progression, Erb-041 dramatically reduced the number and size of A431 andSCC13 colonies (Fig. 6C).

Similar to our observations in murine skin, a markedreduction in the expression of inflammation regulatoryproteins such as p-NF-kBp65, iNOS, and COX-2 wasobserved in A431 cells (Fig. 6D and Supplementary Fig.S4D). Erb-041 treatment diminished phosphorylated-PI3Kand -Akt, which was associated with the enhancement in E-cadherin expression and reduction in migration of thesecells in an in vitro scratch assay (Fig. 6E).

We also observed that Erb-041 dampened the WNTsignaling pathway in the murine skin. The WNT signalingpathway is known to be associated with the pathogenesisof skin cancer (37). It is known to be involved in thedevelopment of invasive SCCs by modulating EMT atleast partially (24, 43). We, therefore, tested whetherErb-041 manifests similar effects in human carcinomacells. Erb-041 treatment reduced expression of WNT7b,b-catenin, and p-GSK3b (Fig. 6F and G). These changeswere accompanied by the diminished nuclear localizationof b-catenin (Fig. 6F). Consistently, we also observed asignificant reduction in the expression of its downstreamtarget proteins c-Myc and cyclin D1 (Fig. 6H). The acti-vation of the WNT/b-catenin pathway leads to inhibitionof axin-mediated b-catenin phosphorylation, leading tothe accumulation of nuclear b-catenin and transcriptionof the WNT pathway–responsive genes (43). To confirmthat the reduction in the WNT signaling pathway inepidermal carcinoma cells may decrease EMT, we useda small molecule pharmacologic inhibitor of the WNTsignaling pathway, XAV939. XAV939 stabilizes axinthrough tankyrase inhibition and modulates Wnt targeteffectors (44). As shown in Fig. 6H, XAV939 treatment ofHaCaT, A431, and SCC13 cells dramatically suppressedthe expression of the Wnt signaling pathway proteins,WNT3a, WNT7b, FZD1, b-catenin, and GSK3b along withcyclin D1. Importantly, XAV939 treatment did not induceER-b expression, although, it reduced the expression ofER-b’s cofactors SP-1 and p-c-Jun (Fig. 6H, bottom).Earlier, SP-1 and p-c-Jun were shown to be regulated bythe WNT signaling pathway (44). XAV939 treatmentalso ameliorated the expression of EMT-regulating pro-teins. The expression of E-cadherin was increased, where-as the expression of N-cadherin, Twist, and Slug wasdecreased (Fig. 6I, top). Interestingly, the expression ofinflammatory signaling molecules p-IkBa, p-NF-kBp65,iNOS, and COX-2 were also reduced in all the cell linestested in this study (Fig. 6I, lower panel). Many of theseeffects were similar to those manifested by Erb-041 inthese cells (26).

(Continued.) A, expression of cell-cycle regulatory proteins in A431 cells; B, graphical representation of flowcytometric cell-cycle analysis of A431 andSCC13cells; C, colony forming potency of A431 and SCC13; D, Western blots showing expression of p-NF-kBp65, iNOS, and COX-2 proteins in A431 cells;E, Western blots showing expression of p-PI3k (85 kDa), PI3k (110 kDa), and p-AKT1/2/3(ser473) in A431 cells; F and G, immunostaining showingcoexpression of WNT7b and b-catenin in A431 cells and Western blot analysis of WNT7b, b-catenin, p-GSK3b, GSK3b, and E-cadherin proteins;H and I, Western blot analysis showing expression of ER-b and WNT signaling proteins, cMyc, SP-1, p-c-Jun together with expression of proteins involvedin EMT and inflammation in HaCaT, A431, and SCC13 cells, which were treated with DMSO (vehicle), Erb-041 or XAV939.






DiscussionEstrogen signaling particularly that regulated by ER-b is

considered important in the pathogenesis of variouscancers. ER-b expression is often lost during the progres-sion of epithelial cancers (22, 23). This signaling is notonly mediated through the estrogen response elementsbut also impacts cellular growth by modulating varioustranscription factors AP-1, SP-1, NF-kB, etc. (16, 17).Consistently, we also observed a decreased in p-c-Junand SP-1 by Erb-041 in UVB-induced cutaneous tumors.Although the loss of expression of ER-b receptor mayoccur through multiple mechanisms, promoter methyla-tion of ER-b is considered as an important downregulatorof its expression (25). The importance of upregulation ofER-b was shown by the studies in which valproic acid-mediated demethylation of ER-b, which restored itsexpression in cancer cells, led to antiproliferative effects(45). Similarly, small molecule antagonists of ER-b,BAG1, and BAG2 resulted in tumor growth arrest andshrinkage (15). However, our results provide additionalnovel effects of ER-b agonist, Erb-041. Erb-041 not onlyrestored or augmented the expression of ER-b in murineSCCs and in human carcinoma cells but reduced inproliferation and induced differentiation and apoptosisin these models of skin carcinogenesis. Significantly,these effects together led to a profound reduction in thegrowth of SCCs and the residual SCCs were found to bemostly highly differentiated carcinoma types.

A link between tumor growth and inflammation is nowwell established (37, 38). Inflammatory immune cells arerecruited to cancer sites and lead to development of aconducive neoplastic environment, which is responsiblefor facilitating tumor progression (37, 39). These inflam-matory hematopoietic cells by virtue of their capabilities tosupply soluble growth factor, matrix remodeling enzymes,and other bioactive molecules influence cancer cell prolif-eration, angiogenesis, invasion, andmetastasis (36, 37, 39).Interestingly, we found that Erb-041 not only reducedcutaneous hyperplasia but also reduced cytokine produc-tion, including those of IL-1b, IL-6, and IL-10. Thesechanges were associated with a significant decrease in thenumber of GR1/CD11b–positive myeloid cells, F4/80macrophages, and neutrophils as ascertained by significantdecrease in myeloperoxidase activity. Thus, these resultsprovide evidence that Erb-041 acts by modulating proin-flammatory tumor microenvironment.

Transcription factor NF-kB is a key regulator of many ofinflammatory responses. This transcription factor upregu-lates the expression of multiple inflammation-linked genesincluding COX-2, IL-1b, IL-6, p38, iNOS etc. The observa-tions in this study that these proteins are also downregu-lated by Erb-041 treatment in the skin and in residualtumors provide evidence that Erb-041 may act by modu-lating the NF-kB–dependent signaling pathway. A signifi-cant decrease in the nuclear expression of p65, togetherwith a decrease in its target genes, suggests that ER-b andNF-kB function in coordination to dampen inflammatorysignaling and SCC growth in this mouse model. However,

it is also known that immunosurveillance is impairedduring the progression of tumorigenesis (36, 37) and ER-b has recently been shown to modulate tumor immuno-surveillance (19, 20). Therefore, participation of this addi-tional mechanism in the reduction of cutaneous tumori-genesis by Erb-041 cannot be ruled out at this stage. Inflam-mation is known to augment invasive tumor growth bypromoting EMT (46, 47). Earlier, we showed that anti-inflammatory agents not only block UVB-induced inflam-mation but also reduced EMT progression (7, 41). Parallelto these studies, the observations that Erb-041 treatmentreduced inflammation and EMT associated with theenhanced expression of E-cadherin and reduced expressionof mesenchymal proteins N-cadherin, Snail, Slug, Twist,and matrix metalloproteinases (MMP) suggest a role ofUVB-induced cutaneous inflammation in regulatory EMTin skin SCCs. The reduction in EMT was associated with thediminution of PI3K/AKT signaling provide a molecularbasis for the action of Erb-041 for blocking EMT in themalignant cutaneous keratinocytes. Role of PI3K/AKT isalready described in EMT (7, 41). Thus, ER-b receptor notonly reduced tumorigenesis and inflammation but alsodiminished progression to an aggressive and invasive tumorphenotype.

The mechanism by which these multitarget effects canoccur is not currently well understood. However, recentstudies described a crucial role of WNT signaling in con-necting inflammatory and tumor promoting responses (47,48). Autocrine WNT signaling plays a crucial role in thegrowth and survival of various cancer cells (43, 49). In thisstudy, we found that WNT3a as well as WNT7b are upre-gulated during the UVB-induced carcinogenesis in experi-mental animals and in humans. This leads to TCF/LEF–dependent transcriptional activation contributing to thepromotion of tumor growth (43). Erb-041 treatmentdecreased both WNT3a and WNT7b expression in immor-talized human skin keratinocytes and SCC cells. Thisdecrease in Wnt ligands was also associated with a decreasein overall nuclear b-catenin and its target genes such ascyclin D1, c-Myc, and SP-1. Earlier,WNT signaling has beenshown to regulate the EMTby balancing the expression of E-cadherin andmesenchymal proteins (41, 43). For example,in various epithelial tumors, activation of WNT signalingdrives a transcriptional program reminiscent of EMT, whichpromote cell migration and invasiveness (43). To confirmthe role of WNT signaling in regulating ER-b–dependentdiminution in EMT and invasive tumor phenotype, weinvestigated the effects of small molecule XAV939. XAV939is known to inhibit Wnt signaling (44) and blocks accu-mulation of b-catenin in colorectal cancer. The mechanismby which this agent acts involves stabilization of axin byinhibiting the poly-ADP-ribosylating enzymes tankyrase 1and tankyrase 2 (44). In our studies, XAV939 manifestedsimilar results as have been observed by the treatmentwith Erb-041, suggesting a role of WNT signaling in ER-b–mediated attenuation of EMT in cutaneous SCCs. Insummary, our results show that Erb041 is a potent chemo-preventive agent that blocks tumorigenesis by inhibiting

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proliferation and inducing differentiation and apoptosis.The mechanism by which ER-b agonist Erb-041 actsinvolves diminution of the WNT signaling pathway.

Disclosure of Potential Conflicts of InterestNo potential conflicts of interest were disclosed.

Authors' ContributionsConception and design: S.C. Chaudhary, T. Singh, S.S. Talwelkar,R.K. Srivastava, C.A. Elmets, F. Afaq, L. Kopelovich, M. AtharDevelopment of methodology: S.C. Chaudhary, T. Singh, S.S. Talwelkar,A. Arumugam, L. Kopelovich, M. AtharAcquisitionofdata (provided animals, acquired andmanagedpatients,provided facilities, etc.): S.C. Chaudhary, T. Singh, R.K. Srivastava,A. Arumugam, Z. WengAnalysis and interpretation of data (e.g., statistical analysis, biosta-tistics, computational analysis): S.C. Chaudhary, T. Singh, R.K. Srivastava,A. Arumugam, Z. Weng, F. Afaq, L. Kopelovich, M. Athar

Writing, review, and/or revision of the manuscript: S.C. Chaudhary,T. Singh, R.K. Srivastava, A. Arumugam, Z. Weng, C.A. Elmets, F. Afaq,L. Kopelovich, M. AtharAdministrative, technical, or material support (i.e., reporting or orga-nizing data, constructing databases): S.C. Chaudhary, S.S. Talwelkar,A. Arumugam, Z. WengStudy supervision: C.A. Elmets, M. Athar

Grant SupportThis study was supported by grants NIH/NCI N01-CN-43300 274 and

R01 CA138998 from National Cancer Institute (to M. Athar).The costs of publication of this article were defrayed in part by the

payment of page charges. This article must therefore be hereby markedadvertisement in accordance with 18 U.S.C. Section 1734 solely to indicatethis fact.

Received July 26, 2013; revised October 18, 2013; accepted October 28,2013; published OnlineFirst November 19, 2013.

References1. Cancer facts & figures: American Cancer Society. Available from:

http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-036845.pdf 2013.

2. Skin cancer facts: skin cancer. Available from: http://www.skincancer.org/skin-cancer-information/skin-cancer-facts.

3. Bickers DR, Athar M. Oxidative stress in the pathogenesis of skindisease. J Invest Dermatol 2006;126:2565–75.

4. Athar M, Elmets CA, Kopelovich L. Pharmacological activation of p53in cancer cells. Curr Pharm Des 2011;17:631–9.

5. Tang X, Kim AL, Feith DJ, Pegg AE, Russo J, Zhang H, et al.Ornithine decarboxylase is a target for chemoprevention of basaland squamous cell carcinomas in Ptch1þ/� mice. J Clin Invest2004;113:867–75.

6. So PL, Fujimoto MA, Epstein EH Jr. Pharmacologic retinoid signalingand physiologic retinoic acid receptor signaling inhibit basal cellcarcinoma tumorigenesis. Mol Cancer Ther 2008;7:1275–84.

7. Chaudhary SC, Singh T, Kapur P, Weng Z, Arumugam A, Elmets CA,et al. Nitric oxide-releasing sulindac is a novel skin cancer chemo-preventive agent for UVB-induced photocarcinogenesis. Toxicol ApplPharmacol 2013;268:249–55.

8. Mikulec CD, Rundhaug JE, Simper MS, Lubet RA, Fischer SM. Thechemopreventive efficacies of nonsteroidal anti-inflammatory drugs:the relationship of short-term biomarkers to long-term skin tumoroutcome. Cancer Prev Res 2013;6:675–85.

9. Lyseng-Williamson KA, Keating GM. Vismodegib: a guide to its use inlocally advanced or metastatic basal cell carcinoma. Am J Clin Der-matol 2013;14:61–4.

10. Elmets CA, Viner JL, Pentland AP, Cantrell W, Lin HY, Bailey H, et al.Chemoprevention of nonmelanoma skin cancer with celecoxib: arandomized, double-blind, placebo-controlled trial. J Natl Cancer Inst2010;102:1835–44.

11. Zhao C, Dahlman-Wright K, Gustafsson JA. Estrogen signaling viaestrogen receptor {beta}. J Biol Chem 2010;285:39575–9.

12. Leung YK, Ho SM. Estrogen receptor beta: switching to a new partnerand escaping from estrogen. Sci Signal 2011;4:pe19.

13. Ogawa S, Inoue S, Watanabe T, Orimo A, Hosoi T, Ouchi Y, et al.Molecular cloning and characterization of human estrogen receptorbetacx: a potential inhibitor of estrogen action in human. NucleicAcids Res 1998;26:3505–12.

14. Heldring N, Pike A, Andersson S, Matthews J, Cheng G, Hartman J,et al. Estrogen receptors: howdo they signal andwhat are their targets.Physiol Rev 2007;87:905–31.

15. Warner M, Gustafsson JA. The role of estrogen receptor beta (ERbeta)in malignant diseases–a new potential target for antiproliferative drugsin prevention and treatment of cancer. BiochemBiophysResCommun2010;396:63–6.

16. MarinoM,GalluzzoP,Ascenzi P. Estrogen signalingmultiple pathwaysto impact gene transcription. Curr Genomics 2006;7:497–08.

17. Wu WF, Tan XJ, Dai YB, Krishnan V, Warner M, Gustafsson JA.Targeting estrogen receptor beta in microglia and T cells to treatexperimental autoimmune encephalomyelitis. Proc Natl Acad SciU S A 2013;110:3543–8.

18. Kang L, Zhang X, Xie Y, Tu Y, Wang D, Liu Z, et al. Involvement ofestrogen receptor variant ER-alpha36, not GPR30, in nongenomicestrogen signaling. Mol Endocrinol 2010;24:709–21.

19. Islander U, Jochems C, Lagerquist MK, Forsblad-d'Elia H, Carlsten H.Estrogens in rheumatoid arthritis; the immune system and bone. MolCell Endocrinol 2011;335:14–29.

20. Catley MC, Birrell MA, Hardaker EL, de Alba J, Farrow S, Haj-YahiaS, et al. Estrogen receptor beta: expression profile and possibleanti-inflammatory role in disease. J Pharmacol Exp Ther 2008;326:83–8.

21. Cotrim CZ, Fabris V, Doria ML, Lindberg K, Gustafsson JA, Amado F,et al. Estrogen receptor beta growth-inhibitory effects are repressedthrough activation of MAPK and PI3K signalling in mammary epithelialand breast cancer cells. Oncogene 2013;32:2390–402.

22. Rudolph A, Toth C, Hoffmeister M, Roth W, Herpel E, Jansen L, et al.Expression of oestrogen receptor beta and prognosis of colorectalcancer. Br J Cancer 2012;107:831–9.

23. Heikkila A, Hagstrom J,MaenpaaH, Louhimo J, Siironen P, HeiskanenI, et al. Loss of estrogen receptor Beta expression in follicular thyroidcarcinoma predicts poor outcome. Thyroid 2013;23:456–65.

24. Mak P, Leav I, Pursell B, Bae D, Yang X, Taglienti CA, et al. ERbetaimpedes prostate cancer EMT by destabilizing HIF-1alpha and inhibit-ing VEGF-mediated snail nuclear localization: implications for Gleasongrading. Cancer Cell 2010;17:319–32.

25. Zhu X, Leav I, Leung YK,WuM, Liu Q, Gao Y, et al. Dynamic regulationof estrogen receptor-beta expression by DNA methylation duringprostate cancer development and metastasis. Am J Pathol 2004;164:2003–12.

26. Cvoro A, Tatomer D, Tee MK, Zogovic T, Harris HA, Leitman DC.Selective estrogen receptor-beta agonists repress transcription ofproinflammatory genes. J Immunol 2008;180:630–6.

27. Xiu-li W, Wen-jun C, Hui-hua D, Su-ping H, Shi-long F. ERB-041, aselective ER beta agonist, inhibits iNOS production in LPS-activatedperitoneal macrophages of endometriosis via suppression of NF-kappaB activation. Mol Immunol 2009;46:2413–8.

28. Bradley PP, Christensen RD, Rothstein G. Cellular and extracellularmyeloperoxidase in pyogenic inflammation. Blood 1982;60:618–22.

29. Kaylani SZ, Xu J, Srivastava RK, Kopelovich L, Pressey JG, Athar M.Rapamycin targetingmTOR and hedgehog signaling pathways blockshuman rhabdomyosarcoma growth in xenograft murine model. Bio-chem Biophys Res Commun 2013;435:557–61.

30. Kurundkar D, SrivastavaRK, Chaudhary SC, BallestasME, KopelovichL, Elmets CA, et al. Vorinostat, an HDAC inhibitor attenuates epider-moid squamous cell carcinoma growth by dampeningmTOR signaling






pathway in a human xenograft murine model. Toxicol Appl Pharmacol2013;266:233–44.

31. Chaudhary SC, Kurundkar D, Elmets CA, Kopelovich L, Athar M.Metformin, an antidiabetic agent reduces growth of cutaneous squa-mous cell carcinoma by targeting mTOR signaling pathway. Photo-chem Photobiol 2012;88:1149–56.

32. Mak P, Chang C, Pursell B, Mercurio AM. Estrogen receptor betasustains epithelial differentiation by regulating prolyl hydroxylase 2transcription. Proc Natl Acad Sci U S A 2013;110:4708–13.

33. Mancuso M, Gallo D, Leonardi S, Pierdomenico M, Pasquali E, DeStefano I, et al. Modulation of basal and squamous cell carcinoma byendogenous estrogen in mouse models of skin cancer. Carcinogen-esis 2009;30:340–7.

34. Mukhtar H, Elmets CA. Photocarcinogenesis: mechanisms, modelsand human health implications. Photochem Photobiol 1996;63:356–7.

35. Kim AL, Labasi JM, Zhu Y, Tang X, McClure K, Gabel CA, et al. Role ofp38MAPK inUVB-induced inflammatory responses in theskin ofSKH-1 hairless mice. J Invest Dermatol 2005;124:1318–25.

36. SullivanNJ, Tober KL, Burns EM, Schick JS, Riggenbach JA,Mace TA,et al. UV light B-mediated inhibition of skin catalase activity promotesGr-1þ CD11b þmyeloid cell expansion. J Invest Dermatol 2012;132:695–702.

37. Di Piazza M, Nowell CS, Koch U, Durham AD, Radtke F. Loss ofcutaneous TSLP-dependent immune responses skews the balance ofinflammation from tumor protective to tumor promoting. Cancer Cell2012;22:479–93.

38. Gilmore TD. Introduction to NF-kappaB: players, pathways, perspec-tives. Oncogene 2006;25:6680–4.

39. DiDonato JA, Mercurio F, Karin M. NF-kappaB and the link betweeninflammation and cancer. Immunol Rev 2012;246:379–400.

40. Thiery JP, Acloque H, Huang RY, Nieto MA. Epithelial–mesenchymaltransitions in development and disease. Cell 2009;139:871–90.

41. Kalluri R. EMT: when epithelial cells decide to become mesenchymal-like cells. J Clin Invest 2009;119:1417–9.

42. Sanchez-Tillo E, de Barrios O, Siles L, Cuatrecasas M, Castells A,Postigo A. b-catenin/TCF4 complex induces the epithelial-to-mesen-chymal transition (EMT)-activator ZEB1 to regulate tumor invasive-ness. Proc Natl Acad Sci U S A 2011;108:19204–9.

43. Anastas JN,MoonRT.WNTsignalling pathways as therapeutic targetsin cancer. Nat Rev Cancer 2013;13:11–26.

44. Huang SM, Mishina YM, Liu S, Cheung A, Stegmeier F, Michaud GA,et al. Tankyrase inhibition stabilizes axin and antagonizes Wnt signal-ling. Nature 2009;461:614–20.

45. StettnerM, Kaulfuss S, BurfeindP, Schweyer S, Strauss A, Ringert RH,et al. The relevance of estrogen receptor-beta expression to theantiproliferative effects observed with histone deacetylase inhibitorsand phytoestrogens in prostate cancer treatment. Mol Cancer Ther2007;6:2626–33.

46. Wong CE, Yu JS, Quigley DA, To MD, Jen KY, Huang PY, et al.Inflammation and Hras signaling control epithelial–mesenchymal tran-sition during skin tumor progression. Genes Dev 2013;27:670–82.

47. Fuxe J, Karlsson MC. TGF-beta-induced epithelial–mesenchymaltransition: a link between cancer and inflammation. Semin CancerBiol 2012;22:455–61.

48. Du Q, Geller DA. Cross-Regulation Between Wnt and NF-kappaBSignaling Pathways. For Immunopathol Dis Therap 2010;1:155–81.

49. Davidson KC, Adams AM, Goodson JM, McDonald CE, Potter JC,Berndt JD, et al. Wnt/beta-catenin signaling promotes differentiation,not self-renewal, of human embryonic stem cells and is repressed byOct4. Proc Natl Acad Sci U S A 2012;109:4485–90.

Chaudhary et al.





2014;7:186-198. Published OnlineFirst November 11, 2013.Cancer Prev Res Sandeep C. Chaudhary, Tripti Singh, Sarang S. Talwelkar, et al. the WNT Signaling PathwayPhotocarcinogenesis in SKH-1 Hairless Mice by Downregulating

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