Endometrial carcinomas often show resistance to cisplatin. Bcl2 has been shown to be associated with cisplatin resistance in different types of cancers. However, there is no information concerning its possible involvement in chemoresistance and its regulation in endometrial carcinomas. We have tested the ability of cisplatin to induce apoptosis in KLE, a resistant endometrial carcinoma cell line, and examined the putative role for Bcl2 in regulating drug sensitivity. We have investigated the impact of cisplatin treatment on Bcl2 family members and Xiap, an inhibitor of caspase activity. Cisplatin treatment upregulated Bcl2 protein expression in a time-dependant manner in KLE cells, but had no significant impact on the levels of Bax, Bcl-xL and Xiap proteins. As demonstrated by RT-PCR, Bcl2 mRNA was not upregulated in response to cisplatin, suggesting that cisplatin act on Bcl2 expression through a post-translational mechanism. In KLE cells, Bcl2 inhibition by HA14-1 led to increased apoptosis induced by cisplatin. It has been shown that Akt, MAPK and PKC pathways are involved in the regulation of Bcl2 under various conditions and in different cell types. Therefore, KLE cells were treated with inhibitors of MAPK (PD98059) and PKC (CalphostinC) prior to cisplatin treatment. Inhibition of PKC prevented cisplatin-dependant upregulation of Bcl2 protein, while MAPK inhibition had no impact. We previously showed that KLE cell line express high levels of phosphorylated Akt (pAkt) isoforms. Then, KLE cells stably expressing shRNA for all three Akt isoforms were established. Treatment of these cells with cisplatin prevented the increase of Bcl2 expression and led to increased apoptosis by cisplatin. These data suggest a role for Bcl2 in cisplatin resistance in endometrial carcinoma cells. Also, they indicate that PKC and Akt are involved in regulation of Bcl2 expression in this experimental model.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1035.