Effect of Bmi-1 knockdown on orthotopic chemoresistant ovarian cancer growth.

<p>To assess the effects of siRNA therapy on tumor growth, treatment was initiated 1 wk after i.p. injection (1.0×10⁶ CP20) of tumor cells. Mice were divided into four groups (n = 10 mice per group): (a) control siRNA-DOPC (150 µg/kg i.p. twice weekly), (b) control siRNA-DOPC + cisplatin (160 µg/mouse i.p. weekly), (c) Bmi-1 siRNA-DOPC (150 µg/kg i.p. twice weekly), and (d) Bmi-1 siRNA-DOPC + cisplatin (doses same as individual treatments). Treatment was continued until 4 weeks after tumor inoculation before sacrifice. (A) Total RNA was isolated from a portion of the tumor tissues and subjected to RT-PCR using primers for Bmi-1 and beta actin. The comparative C_t method was used to calculate the relative abundance of mRNA compared with that of beta actin expression. The experiment was performed in triplicate and significance determined using two-sided Student's t test, P<0.05 was considered significant. (B) Mouse and tumor weights and (C) the number of tumor nodules for each group were compared using Student's t test (for comparisons of two groups). A two-tailed P≤0.05 was deemed statistically significant.