RÉSUMÉ
OBJECTIVE: To evaluate the effects of both exogenous and endogenous osteopontin on normal and malignant ovarian epithelial cell growth, and on paclitaxel chemo-resistance. METHODS: The ovarian cancer cell line OV429, which showed low level of endogenous osteopontin and paclitaxel sensitive cell line OV420, which showed high level of endogenous osteopontin, and a normal ovarian epithelial (HOSE: Human ovarian surface epithelial) cells were treated with purified osteopontin. Furthermore, OV420 was treated with osteopontin siRNA alone or in combination with paclitaxel. Proliferation rates and cell cycle progression of treated cells were determined by the tetrazolium colorimetric (XTT) assay and FACS analysis, respectively. RESULTS: Exogenous osteopontin increased the proliferation rate of OV429 and OV420 but had negligible effect on normal HOSE. Ovarian cancer cell lines treated with siRNA showed significantly reduced the growth rates (P<0.05), and they were arrested in G2/M phase of the cell cycle. Furthermore, OV420 treated with paclitaxel in the presence of osteopontin siRNA showed significantly decreased the survival rate. CONCLUSION: Osteopontin promote cell growth in malignant but not in normal ovarian epithelial cells, and may confer paclitaxel-resistance by adhesion to each cell and minimized the cell surface which exposure to chemo-agents.