Molecular pathology of endometrial carcinomaDr James Duhig

Can form ever fully inform us of function?

Molecular pathology

Tumours defined by their molecular abnormality

CML

GIST

Ewing’s sarcoma

Synovial sarcoma

Epithelial cancers typically have multiple genetic abnormalities

Molecular pathology

EGFR mutation - NSCLC

BRAF V600E mutation - melanoma

KRAS – colorectal carcinoma

Molecular pathologyEndometrial carcinoma

Molecular alterationsMSI

PTEN

KRAS

PIK3CA

Beta-catenin

P53

LOH in several chromosomes/aneuploidy

STK15, P16, E-Cadherin, HER2

Molecular pathologyEndometrial carcinoma

Type 1 tumours (low-grade estrogen dependent endometrioid carcinomas)

MSI, PTEN, KRAS, PIK3CA, Beta-catenin

Type 2 tumours (Mainly serous and clear cell)

P53, LOH, STK15, P16, E-Cadherin, HER2

Microsatellite instability

Occurs in 75% of EC associated with HNPCC

25-30% of sporadic EC (secondary to MLH-1 promotor hypermethylation)

MSI associated mismatch repair deficiency leads to accumulation of many mutations including in STR’S (microsatellites) located within coding sequences of genes

Associated with high histologic grade and earlier presentation in inherited form

PTEN

Phosphatase and tensin homolog – tumour suppressor gene preventing cells from growing and dividing too rapidly

40% of EC show LOH of PTEN

37-61% of endometrioid carcinomas show PTEN mutations.

60-80% of MSI positive tumours have PTEN mutations

PTEN

Identical PTEN mutations occur in coexisting hyperplasia's suggesting an early event in tumour progression

Some data suggests an association with favorable prognostic factors

PIK3CA

Mutations contribute to alterations in PI3K-AKT pathway

Mutations in exon 9 – mostly low grade endometrioid tumours

Mutations in exon 20 – high grade tumours – worse prognosis

Beta-catenin

Component of the E-cadherin-catenin unit

Plays a role in cell differentiation and maintenance of normal tissue architecture

Mutations occur in 14-44% of EC

Alterations described in endometrial hyperplasia with squamous morules

Probably associated with a good prognosis

Non-endometrioid carcinomas

P53 -90%

Loss/reduced expression of E-cadherin – 80-90%

HER2 amplification 30%

Widespread chromosomal gains and losses - aneuploidy

High grade endometrioid carcinoma and mixed tumours

Confound the dualistic model

Appear to originate from endometrioid carcinomas at a molecular level

Some pure non-endometrioid tumours show MSI, along with alterations in PTEN, K-RAS and beta-catenin suggesting an endometrioid origin

Gene expression profiles

Can look at the expression patterns of thousands of genes at a time.

Revolutionized breast cancer classificationLuminal A

Luminal B

HER2 positive

Basal like

Gene expression Endometrial carcinoma

Confirms a dualistic model

Endometrioid tumoursOverexpression of genes under cyclic hormonal regulation and endometrial homeostasis

Type 2 tumoursOverexpression of genes involved in mitotic spindle regulation and genes associated with aneuploidy and aggressive behavior

Gene expression Endometrial carcinoma

High grade endometrioid tumours and mixed tumours cluster with the type 2 tumours

Gene profilesMSI

MSI and MSS tumours appear to have distinct gene expression profiles

392 genes showed different expression at a high statistical value

In MSI tumours down regulation of SFRP1 and SFRP4

SFRP1 shows tumour suppressor activity

Down regulated in several malignancies

Gene profilesEndometrium v OvaryClear cell carcinoma

Similar profiles regardless of site of origin

Endometrioid and Serous carcinomaStriking differences between the 2 sites

Carcinosarcoma

Probably evolve from endometrial carcinomas through epithelial-to-mesenchymal transformation (EMT)

Epithelial cells lose polarity and cell-cell contacts

Reorganise cytoskeleton

Express mesenchymal markers

EMT can be induced by various signals and pathways leading to repression of E-cadherin

Transiently seen in myometrial invasion in conventional EC, permanent in MMMT

MicroRNA

Small non-coding single-stranded RNA molecules regulating expression of target genes

Repress translation or lead to degradation of mRNA of target gene

2000 thousand identified

Each miRNA targets several hundred genes and a single gene can bind multiple miRNAs

MicroRNA

Dysfunctional expression of miRNA a frequent attribute of malignant behavior

May act as – Oncogenes – miR-155

Tumour suppressor genes – miR-15a and miR-16

Targeted therapies

Targeted therapies - UPSC

Her2(C-erb-B2)Transmembrane protein

Overexpression associated with cancer cell proliferation, poor survival and resistance to therapy in multiple human tumours

Overexpression in 20-50% of UPSC and correlates with gene amplification by FISH

Her2(C-erb-B2)

Herceptin (Trastuzamab)GOG 181b

Advanced/recurrent EC of any histology

HER2 2+,3+ immunoperoxidase or FISH positive

No demonstrable single agent activity

Some case reports of significant partial responses

Epithelial cell adhesion molecule - EPCAM

Found in 96% of UPSC

Cell lines highly sensitive to MT201(adectumumab) – mediated antibody dependent cellular cytotoxicity in vitro

Claudin 3&4

Tight junction proteins

Upregulated 8-12 times in UPSC relative to normal endometrium

Epithelial receptors for Clostridium Perfringens enterotoxin(CPE)– a potent cytolytic toxin

Animal models have shown some response to CPE

Kallikrein 6 & 10

Serine proteases

PSA and kallikrein 2 are prostate cancer biomarkers

Kallikrein 6 &10 are present in high levels in the circulation of some ovarian cancer patients and correlate with chemoresistance and poor prognosis.

Highly expressed in UPSC – May serve as biomarkers or potential therapeutic targets

Targeted therapies - UPSC

Human immunoconjugate molecule

IL-6

av-integrins

Trophoblast cell-surface marker

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