Targeting stathmin in prostate cancer.

Stathmin is the founding member of a family of microtubule-destabilizing proteins that regulate the dynamics of microtubule polymerization and depolymerization. Stathmin is expressed at high levels in a variety of human cancers and provides an attractive molecule to target in cancer therapies that disrupt the mitotic apparatus. We developed replication-deficient bicistronic adenoviral vectors that coexpress green fluorescent protein and ribozymes that target stathmin mRNA. The therapeutic potential of these recombinant adenoviruses was tested in an experimental androgen-independent LNCaP prostate cancer model. Adenovirus-mediated transfer of anti-stathmin ribozymes resulted in efficient transduction and marked inhibition of stathmin expression in these cells. Cells that were transduced with the anti-stathmin adenoviruses showed a dramatic dose-dependent growth inhibition. This was associated with accumulation of LNCaP cells in the G2-M phases of the cell cycle. A similar dose-dependent inhibition of clonogenic potential was also observed in cells infected with anti-stathmin adenoviruses. Morphologic and biochemical analysis of infected cells showed a marked increase in apoptosis characterized by detachment of the cells, increased chromatin condensation, activation of caspase-3, and fragmentation of internucleosomal DNA. If these findings are confirmed in vivo, it may provide an effective approach for the treatment of prostate cancer.