Breast Cancer Cell Detachment from Placenta Conditioned ECM Activates Integrin-TGFβ/JNK Axis and Enhances their Metastatic Potential - ICMS2015 Abstract Submission Form Tumor Microenvironment Conference

Shelly Tartakover Matalon ^1,5 Gali Epstein Shochet ^1,5 Oded Komemi ^1,5 Meir Pomeranz ^2,5 Ami Fishman ^2,5 Metsada Pasmanik-Chor ⁴ Liat Drucker ^1,5 Michael Lishner ^1,3,5

¹Oncogenetic Laboratory, Meir Medical Center, Israel
²Obstetrics & Gynecology, Meir Medical Center, Israel
³Internal Medicine A, Meir Medical Center, Israel
⁴Bioinformatics Unit G.S.W., Faculty of Life Sciences, Tel Aviv University, Israel
⁵Sackler Faculty of Medicine, Tel Aviv University, Israel

Background: Extracellular matrix (ECM) affects cell characteristics. Detachment from the ECM induces cell apoptosis, termed anoikis. Cancer cells can develop anoikis resistance, a mandatory step for metastasis, by switching integrins, over-expressing EGFR members and inducing epithelial mesenchymal transition (EMT). The placenta is described in the literature as a non-supportive microenvironment for cancer cells. We showed that breast cancer cells (BCCL) were eliminated from placental implantation sites. During implantation, the placenta manipulates its surrounding matrix, which may induce the BCCL elimination. Aim: Exploring the effect of placental induced ECM manipulations on BCCL. Methods: BCCL (MCF-7/T47D) were cultured on placenta/BCCL conditioned ECM (matrigel used for first trimester placenta/BCCL culture and cleared by NH₄OH). Following culture we analyzed BCCL phenotype (death, count, aggregation, MMP) and signaling (microarray analysis and validation (qPCR, western-blot)). Results: BCCL migrated away from previous placental implantation sites, displayed elevated MMP activity and mRNA, formed aggregates in distant areas and enhanced proliferation (all p<0.05). MCF-7 were significantly more affected then T47D, their cell death was modestly elevated (p<0.05), they underwent EMT, expressed elevated level of CD44⁺\CD24^low (stem-cell markers) and developed drug resistance. Microarray analysis of the MCF-7 highlighted changes in integrin, estrogen, EGFR and TGFβ pathways. Indeed, placental ECM reduced ERα, induced Smad3/JNK phosphorylation and elevated integrin-α5 expression (RGD dependent integrin) in the BCCL (all p<0.05). Addition of RGD or TGFβR/JNK inhibitors reversed some of the phenotype observations. Conclusions: BCCL detachment from the placental ECM induces cell characteristics that facilitate metastasis as EMT and drug-resistance. ITGα5, TGFβ/JNK and RGD dependent pathways are activated in these cells. These molecules may be activated in cells that detached from the primary tumors and serve as therapeutic targets.