Chronic Administration Of Valproic Acid Inhibits Prostate Cancer PC-3 Cell Growth

Objective. To study the effect of valproic acid on the proliferation, cell cycle, apoptosis and morphological and structural changes of the prostate cancer cell line PC-3 in vitro.Methods. Prostate cancer cell line PC-3 was cultured with valproic acid of diferent concentration (0, 1.0, 4.0, 8.0mM) in vitro. MTT was used to examine the proliferation rate; FCM was used to determine the phase of cell cycle. All numerical data were expressed as the average of the values obtained±SD. Statistical significance was calculated by the Student's t test for paired comparisons, when appropriate, by Wilcoxon rank-sum test, or by repeated measures one-way ANOVA with post-hoc testing for comparison of dose treatment effects, where applicable. P <0. 05 was considered statistically significant.Results. (1) The A values of the cancer cells treated with 1.0, 4.0, 8. 0 mM of valproic acid were similar to that of controls(P>0. 05), (2) The A values of the cancer cells treated with 1.0mM of valproic acid were similar to that of controls(P>0. 05), while those of the cells treated with 4.0, 8.0mM of valproic acid were significantly different from that of controls (P<0. 01). The inhibition effect of valproic acid was enhanced in time-and-dose dependent manner; (3) Flow cytometry analysis showed the prostate cancer cells treated with valproic acid were blocked cell cycle progression in G₀/G₁ phase. The early apoptosis rates ofmifeipristone for prostate cancer cells were decraesed in dose-dependent manner,as compared with control cells, which was a significantly different from thatof controls (P<0.01).Conclusion. After acute VPA treatment ,no difference was seen between VPA treated oruntreated cells .Valproic acid could significantly inhibit the proliferation of PC-3in dose-and-time dependent manner in vitro. The inhibition mechanisms wereassociated with blocking cell cycle at G0/G1 phase. Objective. Valproic acid (VPA) is an established drug in the long-term therapy of seizure disorders. Recently, VPA has been associated with anticancer activity, an effect thought to be mediated through the inhibition of cellular histone deacetylase 1. We investigated the mechanisms of chronic Valproic acid inhibiting PC3 cells growth in the study.Methods. We established PC-3 cell line tumor xenografts. There was a treatment arm consisting of a set of animals given 0.4% VPA in their drinking water until tumors reach a size of at least 5 mm in longest dimension. At the end of the 28 day experiment, tumors were harvested, whole blood collected and serum analyzed for VPA, liver function tests (transaminases) and complete blood count. DNA strand breaks were identified by terminal deoxynucleotidyltransferase-mediated UTP end labeling technique using the in situ Cell Death Detection Kit. We investigated the effect of VPA administered chronically on histone acetylation, P21WAF1/CIP1 and VEGF gene expression by Western blot. Ki67, p21WAF1/CIP1 and VEGF were detected by Immunohistochemistry in tissue of PC-3 cell line tumor exongrafts. We detected the effect of VPA chronic administration on VEGF expression by reverse-transcription PCR analysis. All numerical data were expressed as the average of the values obtained±SD. Statistical significance was calculated by the Student's t test for paired comparisons, when appropriate, by Wilcoxon rank-sum test, or by repeated measures one-way ANOVA with post-hoc testing for comparison of dose treatment effects, where applicable. P <0.05 was considered statistically significant.Results. Chronic VPA treatment results in statistically significant reduction of tumor xenograft growth in vivo. Tumor volumes were measured and compared using the Wilcoxon rank-sum test and one-way ANOVA with post-hoc testing. Animals treated with VPA showed statistically significant reduction in tumor volume compared with controls with 77.27% growth inhibition. Treatment of xenografts with VPA induced significant increase in levels of acetylated histone H3 and p21WAFl/CIPl compared to the untreated control (p<0.01). In the VPA treated tumors, apoptotic cell death was markedly increased compared with control tumors (p<0.01). Ki67 expression in control was stronger than the treated arm (p<0.01).Conclusion. We conclude that chronic administration of VPA results in significant reduction in PC-3 cell line tumor exongraft volume in vivo. These data provide compelling evidence that additional studies are warranted in evaluating the potential use of chronic VPA as a means of altering androgen independent prostate cancer cell growth and progression. VPA can inhibit PC-3 cells proliferation and induce cells apoptosis. We conclude that chronic VPA results in profound decreases in proliferation of PC-3 cell not only by increases histone H3 acetylation and up-regulates p21WAF1/CIP1 expression but also by down-regulates VEGF.