Abstract 672: Histone deacetylase inhibition has potential to suppresse growth of androgen dependent and independent prostate cancer in vitro and in vivo.

Abstract

Abstract Histone acetylation plays an important role in chromatin remodeling and gene expression. Histone deacetylase (HDAC) inhibitors regulate gene expressions through the induction of histone acetylation and have been reported to suppress growth of several malignancies including lymphoma. In this study, we examined the effects of one example on androgen dependent and independent prostate cancer growth in vivo and in vitro. In in vitro study, androgen dependent and independent prostate cancer cell lines (LNCaP and VCaP) were used. The HDAC inhibitor, OBP-801 (Generously donated by Dr. Urata, Oncolys Biopharma), significantly suppressed cell proliferation with induction of G2/M arrest, and decreased expression of cdc2, androgen receptor (AR) and PSA protein in both cell lines. OBP-801 also significantly induced apoptosis with activation of caspase 3 in LNCaP. Next, we performed two in vivo experiments. First, we transplanted an androgen independent rat prostate cancer (PLS-P) into the femurs and backs of male F344 rats, and OBP-801 was administered intravenously at doses of 0, 2.5 and 5mg/kg every other day for 2 weeks. OBP-801 significantly reduced the volume of the transplanted tumor, while inducing cleaved caspase 3 protein expression. OBP-801 also suppressed bone destruction and induction of osteoclasts in xenografts transplanted to femurs. Second, we prepared male Transgenic Rat for Adenocarcinoma of Prostate (TRAP) rats which spontaneously develop androgen dependent rat prostate cancers, and OBP-801 was given intravenously at doses of 0, 0.5 and 2mg/kg once a week for 8 weeks. As a result, body weight loss was observed in treated groups, and numbers of carcinoma acini in the lateral and ventral prostates were significantly decreased compared with the control group values. In conclusion, the obtained data suggests that OBP-801 may be a candidate therapeutic or preventing agent for androgen dependent and independent prostate cancer, although side effects such as body weight loss may occur. Elucidation of mechanisms of HDAC underlying these effects is needed. Citation Format: Shinya Sato, Shugo Suzuki, Aya Naiki-Ito, Yoriko Yamashita, Makoto Asamoto, Tomoyuki Shirai, Satoru Takahashi. Histone deacetylase inhibition has potential to suppresse growth of androgen dependent and independent prostate cancer in vitro and in vivo. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 672. doi:10.1158/1538-7445.AM2013-672