Induction of cell cycle arrest and apoptosis in human prostate carcinoma cells by a recombinant adenovirus expressing p27^Kip1

Adrienne L. Katner, Qiangwei Ma, James R. Gnarra and Walter Rayford²

ABSTRACT

We evaluated the effects of over-expression of the cyclin-dependent kinase inhibitor, p27^Kip1, using adenoviral-mediated transduction of the human prostate carcinoma cell lines, LNCaP, DU-145 and PC-3. p27^Kip1 protein expression increased in a dose-dependent manner but stabilized after transduction at a titer of 200 pfu/cell. Expression of p27^Kip1 protein was detected within 6 hours of transduction with Adp27^Kip1 and remained stable for at least 48 hours. Growth curve analyses demonstrated that Adp27^Kip1 transduction resulted in an inhibition of proliferation of all cell lines tested and a decrease in cell numbers for Adp27^Kip1-transduced LNCaP and PC-3 cells by 96 hours. Cell cycle analysis of DNA content demonstrated an accumulation of cells in G0/G1-phase of Adp27^Kip1-transduced prostate carcinoma cells. In addition, BrdU incorporation demonstrated a corresponding decrease in S-phase cells within 72 hours after transduction. The cyclin-dependent kinase activities of Cdk2, Cdk4, and Cdc2 kinase activities were all inhibited with p27^Kip1 over-expression. TUNEL analysis revealed an induction of apoptosis at high viral titer (200 pfu/cell) within 72 hours of transduction. Therefore, ectopic p27^Kip1 over-expression results in cell cycle regulation and induction of apoptosis in the human prostate carcinoma cell lines tested. Moreover, this strategy may provide a therapeutic alternative for the treatment of adenocarcinoma of the prostate.