Abstract
We have reported that purvalanol A, an inhibitor of Cdc2 kinase, sensitized X-ray-induced apoptosis by the inhibition of Cdc2 kinase activity and through the abrogation of G2/M arrest. But the interaction between the abrogation of G2/M arrest and induction of apoptosis remains unclear. In this study, we investigated the expression of anti-apoptotic proteins, i.e., survivin, XIAP, Bcl-2 and Bcl-XL, at sensitization to radiation-induced apoptosis by purvalanol A. Western blot analysis showed that purvalanol A inhibited the radiation-induced upregulation of Bcl-2 and Bcl-XL. The expression of survivin and XIAP were not increased by X irradiation, but were also inhibited by purvalanol A. On the other hand, pro-apoptotic protein, Bax, did not increased by X irradiation but slightly decreased by purvalanol A. semi-quantitative RT-PCR analysis showed that the expression of mRNA of Bcl-2 and survivin were inhibited by purvalanol A but not Bcl-XL and XIAP. These results indicated that the sensitization to radiation-induced apoptosis by purvalanol A was occurred by downregulation of these anti-apoptotic proteins.
