Molecular determinants of cell death induction following adenovirus-mediated gene transfer of wild-type p53 in prostate cancer cells

Role of class I histone deacetylases in the regulation of maspin expression in prostate cancer

Maspin repression is frequently observed in prostate cancer; however, the molecular mechanism(s) causing the loss is not completely understood. Here, we demonstrate that inhibition of class I histone deacetylases (HDACs) mediates re-expression of maspin which plays an essential role in suppressing proliferation and migration capability in prostate cancer cells. Human prostate cancer LNCaP and DU145 cells treated with HDAC inhibitors, sodium butyrate, and trichostatin A, resulted in maspin re-expression. Interestingly, an exploration into the molecular mechanisms demonstrates that maspin repression in prostate tumor and human prostate cancer cell lines occurs via epigenetic silencing through an increase in HDAC activity/expression, independent of promoter DNA hypermethylation. Furthermore, transcriptional activation of maspin was accompanied with the suppression of HDAC1 and HDAC8 with significant p53 enrichment at the maspin promoter associated with an increase in histone H3/H4 acetylation. Our results provide evidence of maspin induction as a critical epigenetic event altered by class I HDACs in the restoration of balance to delay proliferation and migration ability of prostate cancer cells.

Therapeutic efficacy of adenoviral-mediated p53 gene transfer is synergistically enhanced by combined use of antisense oligodeoxynucleotide targeting clusterin gene in a human bladder cancer model

To establish a more effective therapeutic strategy against advanced bladder cancer, we investigated the effects of combined treatment with antisense (AS) oligodeoxynucleotide (ODN) targeting the anti-apoptotic gene clusterin and adenoviral-mediated p53 gene transfer (Ad5CMV-p53) using the human bladder cancer KoTCC-1 model. Clusterin expression in KoTCC-1 cells was highly upregulated by Ad5CMV-p53 treatment; however, AS clusterin ODN treatment further suppressed clusterin expression in KoTCC-1 cells after Ad5CMV-p53 treatment. AS clusterin ODN treatment synergistically enhanced the cytotoxic effect of Ad5CMV-p53, and DNA fragmentation characteristic of apoptosis was observed only after combined treatment with AS clusterin ODN and Ad5CMV-p53, but not after treatment with either agent alone. Administration of AS clusterin ODN and Ad5CMV-p53 into nude mice resulted in a significant inhibition of KoTCC-1 tumor growth as well as lymph node metastases compared to administration of either agent alone. Furthermore, combined treatment with AS clusterin ODN, Ad5CMV-p53, and cisplatin completely eradicated KoTCC-1 tumors and lymph node metastases in 60% and 100% of mice, respectively. These findings suggest that combined treatment with AS clusterin ODN and Ad5CMV-p53 could be a novel strategy to inhibit bladder cancer progression, and that further additional use of a chemotherapeutic agent may substantially enhance the efficacy of this combined regimen.