Implication of the Akt2/survivin pathway as a critical target in paclitaxel treatment in human ovarian cancer cells

Purpose: Although multiple mechanisms have been implicated in paclitaxel (PTX)-induced resistance in ovarian cancer, recent evidence has suggested that Akt2 has an important role in the protection of cells from paclitaxel-induced apoptosis. In the present study, we investigated the role of the Akt2/survivin pathway in paclitaxel-induced resistance by a modified method to generate an effective shRNA vector. Methods: We applied RNAi-mediated silencing techniques to investigate the mechanism of the Akt2/survivin pathway on M-induced resistance in ovarian cancer cells (A2780 and SKOV3). The expression of Akt2 and survivin mRNA and related protein levels were evaluated with semiquantitative real-time RT-PCR and western blot analysis, respectively. Inhibition of cell proliferation was determined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay, and the induction of apoptosis was examined through flow cytometry (FACS) and Hoechst staining. Results: Akt2 down-regulation sensitized ovarian cancer cells to paclitaxel-induced apoptosis, and inhibited survivin expression. We further demonstrated that suppressing the inhibition of survivin expression can induce the drug-resistance to paclitaxel. We introduced a modified vector to generate shRNA to induce RNA interference, which contained three U6 promoters to express different shRNAs: it severely reduced Akt2 gene expression and showed good specificity. Conclusion: Our findings will aid in understanding the molecular mechanism of paclitaxel-induced resistance in ovarian cancer and facilitate the development of novel anti-neoplastic strategies. (C) 2008 Elsevier Ireland Ltd. All rights reserved.