Cadherin switch and ovarian cancer: Studies using in vitro models and patient samples

ROSSO, M; MAJEM, B; DEVIS, L; LLAURADO, M; LANAU, L; ABASCAL, MF; MATOS, ML; BESSO, MJ; CASTELLVI, J; SANCHEZ IGLESIS, JL; PÉREZ-BENAVENTE, A; GIL-MORENO, A; REVENTOS, J; RIGAU, M; VAZQUEZ- LEVIN MH

Philadelphia

Congreso; AACR 106th Annual Meeting 2015; 2015

AACR

Ovarian cancer (OC) is the 5th leading cause of cancer deaths in women worldwide due to late symptoms and its diagnosis at advanced stages. Epithelial to mesenchymal transition (EMT) is an important step in cancer invasion/metastasis and downregulation of Epithelial cadherin (Ecad) is a critical feature of this process. Ecad expression was evaluated in 100 OC tissue sections, finding a decreased Ecad signal along tumor stage, with highest expression in stage I/II (no invasive) and lowest in stage IV (invasive) tumors. These results are in agreement with previous reports showing reduced Ecad expression in correlation with poor prognosis in OC patients. In some cases, Ecad downregulation is accompanied by increased Neural cadherin (Ncad) expression and acquisition of migratory/mesenchymal features. Although this cadherin ?switch? has been reported in OC, current data is inconclusive. Expression of Ecad, Ncad and other EMT markers was studied in 4 OC cell lines and according to their levels they were classified as epithelial (OV90), intermediate epithelial (OAW42), intermediate mesenchymal (SKOV3) and mesenchymal (TOV112) cells. The mechanisms underlying regulation of Ecad levels were evaluated by assessing expression of its transcriptional repressors Twist, Snail, Slug, Zeb1. Migration properties were also studied, being significantly higher in TOV112 and SKOV3 cells. It has been proposed that OC cells shed from the primary tumor aggregate as spheroids in the ascites, maintain cellular contacts and survive in suspension. To mimic ovarian tumor cell dissemination through the ascites and to evaluate the role of the cadherin ?switch? in this process, cell lines were grown under anchorage-independent conditions. The aggregates number/area was analyzed, being the SKOV3 spheroids the most compacted. When Ecad, Ncad and EMT markers expression was determined similar findings were obtained when spheroids were compared to monolayers, suggesting an intrinsic cell gene expression pattern rather than a response to a cell culture growth condition. The OC spheroids survival was assessed by estimating cell death, finding a positive correlation between high Ncad levels and cell aggregates with low% cell death. Spheroid adhesion/dissemination in extracellular matrices and 3D-spheroid matrigel assays were done to assess invasion at a secondary site. Spheroids from cells with mesenchymal/intermediate mesenchymal phenotypes adhered to extracellular matrices and invaded more than cells with intermediate epithelial/epithelial phenotypes. Finally, Ecad/Ncad expression studies done on primary cultures derived from tumor and ascitic cells from patients with OC revealed a diminished Ecad and a higher Ncad expression in ascitic cells compared to primary tumor cells. Altogether, the data here presented reveals an association between OC cell aggressiveness and a mesenchymal-like molecular profile; and it depends on the expression of Ecad and Ncad markers.