Up-regulation of cyclin B1 and cdc2 expression during 9-nitrocamptothecin-induced regression of DU145 prostate tumor.

Background: We investigated changes in the content and subcellular localization of the cell cycle regulators, cyclin B1 and cyclin-dependent kinase cdc2: in human prostate DU145 tumor and cultured cells treated with the anticancer drug 9-nitrocamptothecin (9NC). Materials and Methods: Proteins of interest were identified by Western blot methodology using specific antibodies. Results: The cyclin B1 and cdc2 contents were dramatically elevated in biopsies of DU145 tumor regressing upon 9NC-treatment. In vitro, 9NC-induced apoptosis of DU145 cells was associated with up-regulation of expression and nuclear accumulation of cyclin B1 and cdc2 No changes were observed in cyclins A and E and the cyclin-dependent kinase cdk2 in 9NC-treated DU145 tumor and cultured cells. Conclusion: 9NC-induced apoptosis in DU145 cells in vivo and in vitro is associated with up-regulation of expression and nuclear localization of cyclin B1 and cdc2.