Abstract:     Background and purpose: Ovarian cancer is associated with a high recurrence and mortality due to the existence of cancer stem cells. The purpose of this study was to investigate the effect of casticin (CAS) on the capability of self-renewal in ovarian cancer stem cell like cells (OCSLCs) derived from SKOV3 cell line. Methods: SKOV3 cell line cells were cultured in vitro, and OCSLCs were obtained and amplified through suspended culture with conditioned medium of the stem cells. The phosphorylation level of FoxO3a was analyzed using Western blot. The protein expression of FoxO3a was inhibited by FoxO3a specific siRNA transfection, and then the ratio of sphereformation was detected. Results: Compared with parental cells, OCSLCs over-expressed phosphorylated FoxO3a (pFoxO3a) and had elevated ratio of sphere-formation [(3.1±0.3)% vs (34.8±6.8)%, P<0.05]. CAS significantly inhibited the capability of sphere-formation in OCSLCs and down-regulated the expression level of pFoxO3a. And the transfection of FoxO3a specific siRNA suppressed the protein expression of FoxO3a and attenuated the inhibitory effect of CAS on the sphere-formation of OCSLCs. Conclusion: Reduced expression level of pFoxO3a is involved in the effect that CAS inhibits sphere-formation of OCSLCs derived from SKOV3 cell line.

Key words: Ovarian cancer, Cancer stem cell, FoxO3a, Self-renewal