AKT involvement in cisplatin chemoresistance of human uterine cancer cells

Objective. The aim of this study was to investigate the possible involvement of Akt activity and specific isoforms (Akt1, Akt2, and Akt3) in the resistance of human uterine cancer cells to cisplatin. Methods. Two different endometrial (HEC-1-A and KLE) and one cervical (HeLa) cancer cell lines all known as wild-type PTEN (tumor suppressor phosphatase tensin homologue, a lipid phosphatase involved in the negative regulation of Akt activity) were used for these studies. Results. Basal levels of Akt1, Akt2, and Akt3 mRNAs were determined by real-time quantitative RT-PCR studies and Western blot analyses were carried out to determine protein abundance of each isoforms. Akt1 mRNA and protein were present in all cell lines studied. Akt2 and Akt3 mRNAs and proteins were strongly expressed in KLE cells. Surprisingly, Akt phosphorylation was found in KLE expressing high levels of wild-type PTEN protein. KLE cells remained resistant to PI 3-K inhibitor, indicating that Akt phosphorylation might be, in part, independent of PI 3-K in this cell line. Cisplatin induced apoptosis in HeLa and HEG-1-A cells, but KLE cells expressing Akt2 and Akt3 remained more resistant to cisplatin. Knockout of Akt isoforms using specific siRNA technology increased the sensitivity of KLE cells toward cisplatin and caused a significant induction of cell death. Conclusion. Taken together, these results suggest that specific Akt isoforms such as Akt2 and Akt3 might be involved in chemoresistance to cisplatin and that these isoforms could be putative targets for gene therapy in uterine cancers. (C) 2004 Elsevier Inc. All rights reserved.