Picropodophyllin inhibits epithelial ovarian cancer cells in vitro and in vivo

Epithelial ovarian cancer (EOC) is one of the leading causes of gynecological cancer death. Approximately 70% of the patients experience recurrence accompanied by the development of drug resistance 2-3 years after chemotherapy. Picropodophyllin (PPP) is a newly identified insulin-like growth factor-1 receptor (IGF-1R) inhibitor that has been shown to have anticancer properties. In this study, we investigated the effect of PPP on EOC growth in vitro and in vivo. The EOC cell line SKOV-3 was treated with increasing concentrations of PPP or cisplatin, and cell viability and apoptosis were evaluated. To study the effects of PPP on EOC growth, apoptosis, and toxicity in vivo, a BALB/c nude mouse xenograft model was established. Mice were treated with normal saline (controls), PPP, cisplatin, or PPP in combination with cisplatin. In addition, the expression of phosphorylated IGF-1R (pIGF-1R) was examined in vitro and in vivo. PPP induced a dose-dependent decrease in SKOV-3 cell viability in vitro and reduced tumor volume and weight in the in vivo xenograft model. Furthermore, PPP in combination with cisplatin was more effective in inhibiting the growth of SKOV-3 cells and xenografts than either drug alone. PPP-mediated growth inhibition was associated with apoptosis induction in vitro and in vivo. PPP was well tolerated in vivo and exerted its effects with minimal hepatotoxicity and renal toxicity. PPP downregulated the expression of pIGF-1R in vitro and in vivo, an effect that appeared to be associated with its growth inhibitory properties. Our results indicate that PPP may have therapeutic application in the treatment of EOC.