Biological characteristics of side population cells in a self-established human ovarian cancer cell line

The aim of the present study was to establish an ovarian cancer (OC) cell line from ascites of an ovarian serous cystadenocarcinoma patient and investigate the biological characteristics of its side population (SP) cells. The OC cell line was established by isolating, purifying and subculturing primary cells from ascites of an ovarian serous cystadenocarcinoma patient (stage IIIc; grade 3). SP and non-SP (NSP) cells were isolated by fluorescence-activated cell sorting and cultured in serum-free medium and soft agar to compare the tumorsphere and colony formation capacities. Furthermore, SP and NSP cell tumorigenesis was examined by subcutaneous and intraperitoneal injection of the cells to non-obese diabetic/severe combined immune deficiency (NOD/SCID) mice. Drug resistance to cisplatin was examined by cell counting kit-8. The OC cell line was successfully established from ascites of an ovarian serous cystadenocarcinoma patient, which exhibited properties similar to primary tumors subsequent to >50 passages and >2 years of culture. The SP cell ratio was 0.38% in the OC cell line, and a similar SP cell ratio (0.39%) was observed when sorted SP cells were cultured for 3 weeks. Compared with NSP cells, SP cells exhibited increased abilities in differentiation and tumorsphere and colony formation, in addition to the formation of xenografted tumors and ascites and metastasis of the tumors in NOD/SCID mice, even at low cell numbers (3.0×10(3) cells). The xenografted tumors demonstrated histological features similar to primary tumors and expressed the ovarian serous cystadenocarcinoma marker CA125. In addition, SP cells demonstrated a significantly stronger drug resistance to cisplatin compared with NSP and unsorted cells, while treatment with verapamil, an inhibitor of ATP-binding cassette transporters, potently abrogated SP cell drug resistance. In conclusion, the present study verified SP cells from an established OC cell line and characterized the cells with self-renewal, differentiation, proliferation, tumorigenesis and stronger drug resistance capacities.