Identification of bio-functions of cancer stem-like cells and differentially expressed membrane proteins in side population cells from human epithelial ovarian cancer cell lines

Objective To validate the stemness bio-function of side population (SP) cells from epithelial ovarian cancer cell lines and to detect the differentially expressed cellular membrane proteins in SP cells. Methods SP cells of human ovarian cancer cell lines SKOV3 and A2780 which secreted bisbenzimide Hoechst33342 and located as side population were sorted by flow cytometry. Bio-functions of stemness of SP cells were validated. Through stable isotope labeling by amino acids in cell culture (SILAC), differentially expressed membrane proteins in SP cells were detected. Results SP cells of SKOV3 and A2780 were sorted successfully. The ratio of SP cells was about 0.5% and increased significantly through repeated sorting. SP cells differentiated into non-SP (NSP) cells. Stemness of SP cells was validated in vitro, including cell clone forming, resistance to cisplatin and paclitaxel in NOD/SCID mice. SILAC technique was used to detect differentially expressed membrane proteins in SP cells. Results showed that 1 561 and