Abstract 2880: Role of Akt isoforms in chemoresistance of endometrial carcinoma cells

Abstract

Abstract Akt (PKB) is a crucial survival kinase that is normally activated by a variety of growth factors. In tumours, its upstream regulation is affected by oncogenic events, which leads to the constitutive activation of the protein. Since studies have demonstrated that the three Akt isoforms exhibit different physiological functions, our hypothesis is that Akt isoforms may contribute differently in chemoresistance of endometrial carcinoma cells. The aim of this study is to determine the effect of a loss of function of each of Akt isoform in chemoresistant KLE endometrial carcinoma cells. In order to determine the specific role of each Akt isoform in cell survival/resistance to apoptosis and proliferation, we stably transfected KLE cells, which normally express Akt1, Akt2 and Akt3, with specific shRNA for each Akt isoform. We treated Akt isoform-specific transfectants for a period of 48 hour with different chemotherapeutics drugs and we performed western blot analysis for pro-apoptotic and anti-apoptotic factors. In this study, we have demonstrated that Akt1 and Akt2 downregulation sensitize KLE cells to cisplatin, doxorubicin and taxol. After treatment of KLE transfectants with all three drugs, we were able to see that activation pro-apoptotic factors such as cleaved caspase-3, -6 and -9 as well as cleaved PARP were induced. Moreover, the expression of anti-apoptotic factor XIAP was downregulated after drug treatment in these cells. Finally, Bcl-2 expression was inhibited after cisplatin treatment in Akt2 negative cells. We also performed MTT proliferation assay after a 72 hours treatment with chemotherapeutic drugs. Results gained from this study show that each Akt isoform is specifically implicated in cell survival. Akt1 and Akt2 shRNA clones were more sensitive to cisplatin, doxorubicin and taxol treatment. Akt3 shRNA clones were also more sensitive to cisplatin and doxorubicin but were less affected by taxol treatment. Our findings highlight the contribution of Akt isoforms in the molecular mechanisms that confer KLE cells resistance to chemotherapeutics drugs-induced apoptosis. According to our hypothesis, results show the differential implication of each Akt isoform in cell resistance to different chemotherapeutics drugs. We also showed that each isoform have a distinct impact on resistance to apoptosis induced by a given drug. Thus, the results confirm that Akt isoforms could be putative targets for therapy of endometrial cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2880. doi:10.1158/1538-7445.AM2011-2880