Abstract 2787: Expression of Olfactomedin 4 is regulated by methylation in the benign prostate epithelial cell-RWPE1 and PC-3 prostate cancer cells

Abstract

Abstract Expression of Olfactomedin 4 gene (OLFM4) plays a critical tumor suppressor role in human and murine prostate cancer. We have previously reported that loss or reduced OLFM4 expression is associated with the progression of human prostate cancer. We and others have further determined that deletions within the OLFM4 gene are present in about 10 to 25% of human prostate cancer samples. However, we have observed that loss of expression of OLFM4 were found in more than 58% of the samples obtained from advanced prostate cancer patients. Therefore, we sought to study the role of epigenetic factors in the regulation of OLFM4 gene expression in normal and prostate cancer cell lines. Methylation of CpG sites in the promoter region of key genes is an important epigenetic mechanism in cancer development. We examined the methylation status of CpG sites in the OLFM4 promoter region in the benign immortalized prostate epithelial cell line (RWPE1), androgen-responsive cancer cells (LNCaP, VCaP), and androgen-independent cancer cells (PC-3 and DU145). There are eight CpG sites (-681, -666, -562, -486, -91, +4, +34) in the promoter regions of OLFM4 gene. The pattern of methylation status was detected and compared between RWPE1 cell and cancer cell lines LNCaP, VCaP, PC-3 and Du145. To test whether hypermethylation of CpG sites of OLFM4 gene can block the expression of OLFM4 gene, RWPE1 cells were treated with 5-azadeoxycytidine (5-Aza.) (5 μM) from 24h to 96h and PC-3 cells were treated with 5-azadeoxycytidine (5-Aza.) (5 μM) for 3 days and 7 days. The methylation status of CpG sites was compared in the presence or absence of 5-Aza. at different time points. The addition of 5-Aza. consistently reduced the percent methylation of the CpG sites. Correspondingly, the expression of the OLFM4 gene was induced after treatment with 5-Aza. in both RWPE1 and PC-3 cells. These results suggest that expression of OLFM4 is regulated by the methylation status of OLFM4 gene in the RWPE1 and PC-3 prostatic cell lines. Citation Format: Hongzhen Li. Expression of Olfactomedin 4 is regulated by methylation in the benign prostate epithelial cell-RWPE1 and PC-3 prostate cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2787.