Introduction/Background S6 kinase is a protein kinase that is involved in signal transduction. S6 kinase is thought to play an important role in the compensatory adaptive response of various cancers against anti-cancer drug. We examined whether inhibition of phospho-S6 can increase the treatment effect of carboplatin in ovarian cancer.

Methodology We used a western blot analysis to pS6 expression after carboplatin treatment and addition of BX795 which is pS6 inhibitor on ovarian cancer cells. We used a cell viability assay to examine whether addition of BX795 to carboplatin increase the therapeutic effect of carboplatin on ovarian cancer cells. C57BL/6 mice were injected intraperitoneally with ID8 mouse ovarian cancer cells. Thirty days after the injection of ID8 cells, mice were treated with PBS (control group), carboplatin, BX795, and carboplatin + BX795. All of drugs were subcutaneously injected into the nuchal region of the mice. For each mouse, body weight, waist length, and ascites amount were measured.

Results Carboplatin induced the upregulation of pS6 in ovarian cancer cells. BX795 as inhibitor induced the downregulation of pS6 with concentration dependent pattern on cancer cells. Combination of carboplatin and BX795 induced stronger inhibition of pS6 in ovarian cancer cells compared with carboplatin only. Compared to carboplatin only, additional treatment of BX795 to carboplatin brought the bigger decrease of viability on ovarian cancer cells. However, there was no significant difference between PBL, carboplatin, BX795, and carboplatin + BX795 treatment groups on mean body weight, mean waist length, and mean ascites amount at the sacrifice day.

Conclusion Addition inhibition of pS6 by BX795 increased the therapeutic efficacy of carboplatin on ovarian cancer cells. However, increase of therapeutic effect of carboplatin was not showed on mouse model.

Disclosures There was no funding for this research.

The Authors declare no conflicts of interest.