Down-regulation of Hsp27 radiosensitizes human prostate cancer cells

Aim: In this study, we examined whether human Hsp27 is involved in the radiation sensitization induced by gamma radiation in cultured human prostate cancer cells. Methods: We transfected DU145 cells with full length Hsp27 antisense cDNA to obtain viable cell lines which expressed reduced Hsp27. Selected individual clones were subjected to western blot analyses to confirm reduced expression of Hsp27. Results: Hsp27 belongs to a family of abundant and ubiquitous stress proteins, the small heat shock proteins. It has been shown that Hsp27 can inhibit apoptosis both in a caspase-dependent and independent manner. Colony assays showed that the cells engineered to express reduced Hsp27 levels had a significantly increased sensitivity to gamma radiation compared with control cells that were transfected with the vector alone. However, there was also a significant difference in viability of cells with reduced Hsp27 levels and control cells 72 h after gamma-irradiation. Conclusions: Our results suggest the possible application of antisense Hsp27 cDNA or other methods to reduce Hsp27 expression as a radiation sensitizer in radiation oncology.