Molecular pathology of endometrial carcinoma Dr 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 pathology Endometrial carcinoma Molecular alterations MSI PTEN KRAS PIK3CA Beta-catenin P53 LOH in several chromosomes/aneuploidy STK15, P16, E-Cadherin, HER2

Molecular pathology Endometrial 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 % 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 classification Luminal A Luminal B HER2 positive Basal like

Gene expression Endometrial carcinoma Confirms a dualistic model Endometrioid tumours Overexpression of genes under cyclic hormonal regulation and endometrial homeostasis Type 2 tumours Overexpression 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 profiles MSI 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 profiles Endometrium v Ovary Clear cell carcinoma Similar profiles regardless of site of origin Endometrioid and Serous carcinoma Striking 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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