Epstein Shochet Gali1,2, Tartakover Matalon Shelly1,2, Drucker Liat1,2, Pomeranz Meir1,3, Fishman Ami 1,3, Pasmanik-Chor Metsada1, Lishner Michel1,2,4
Tel-Aviv University, Tel-Aviv1, Israel; Oncogenetic laboratory2, Obstetric and genecology3 and Internal Medicine A4 Meir Medical Center, Kfar-Saba
Background: Placental factors, progesterone included, facilitate breast cancer cell line (BCCL) motility and thus may contribute to the advanced breast cancer found during pregnancy. Cancer and placental implantations are similar; the last is accompanied by extravillous trophoblast cell invasion and autophagy which are interlinked.
Aim: to analyze the effect of first trimester human placenta on breast cancer cell autophagy.
Methods: BCCLs (MCF-7/T47D) were cultured with placental explants (60hr) or placental supernatants (24hr). Following cultures, BCCLs were retrieved and sorted out for RNA/protein extraction. RNA served for microarray/qPCR (BNIP3) and protein for western blot (HIF1α and LC3BII) analyses. Inhibitors were added to the placenta-MCF-7 coculture or placental supernatants (autophagy inhibitor-3MA and progesterone receptor inhibitor-RU486) in order to evaluate their effects on BCCL motility and LC3BII/HIF1α expression.
Results: LC3BII (an autophagy marker) expression was elevated in BCCLs following placental explant coculture and exposure to placental supernatants. The autophagy inhibitor (3MA) repressed the placenta induced MCF-7/T47D cell migration, establishing a connection between BCCL autophagy and migration. Microarray analysis of MCF-7 following placenta-MCF-7 coculture showed that “HIF1α pathway”, a well known autophagy facilitator, was significantly manipulated. Indeed, placental factors elevated HIF1α and its target BNIP3 in the BCCLs, verifying array results. Lastly, progesterone receptor inhibitor reduced LC3BII and HIF1α expression in the MCF-7 cells, suggesting a possible role for progesterone in the autophagy process.
Discussion: Placental factors induced BCCL autophagy that is interlinked to their motility. This suggests that autophagy related molecules may serve as targets for therapy in pregnancy associated breast cancer.