oexpression and Epigenetic Regulation of Candidate R or Suppressor Gene CADM - 2 in Human Prostate Cancer

Download pose: Cell adhesion molecules (CADM) comprise a newly identified protein family whose funcinclude cell polarity maintenance and tumor suppression. CADM-1, CADM-3, and CADM-4 have shown to act as tumor suppressor genes in multiple cancers including prostate cancer. However, -2 expression has not been determined in prostate cancer. erimental Design: The CADM-2 gene was cloned and characterized and its expression in human tic cell lines and cancer specimens was analyzed by reverse transcription-PCR and an immunohemical tissue array, respectively. The effects of adenovirus-mediated CADM-2 expression on prostate cells were also investigated. CADM-2 promoter methylation was evaluated by bisulfite sequencing ethylation-specific PCR. ults: We report the initial characterization of CADM-2 isoforms: CADM-2a and CADM-2b, each separate promoters, in human chromosome 3p12.1. Prostate cancer cell lines, LNCaP and 5, expressed negligible CADM-2a relative to primary prostate tissue and cell lines, RWPE-1 and , whereas expression of CADM-2b was maintained. Using immunohistochemistry, tissue array from clinical specimens showed statistically significant decreased expression in prostate carcinoma ared with normal donor prostate, benign prostatic hyperplasia, prostatic intraepithelial neoplasia, ormal tissue adjacent to tumor (P < 0.001). Adenovirus-mediated CADM-2a expression suppressed 5 cell proliferation in vitro and colony formation in soft agar. The decrease in CADM-2a mRNA in cell lines correlated with promoter region hypermethylation as determined by bisulfite sequencing ethylation-specific PCR. Accordingly, treatment of cells with the demethylating agent 5-aza-2′cytidine alone or in combination with the histone deacetylase inhibitor trichostatin A resulted in activation of CADM-2a expression. clusions: CADM-2a protein expression is significantly reduced in prostate cancer. Its expression is Con regulated in part by promoter methylation and implicates CADM-2 as a previously unrecognized tumor suppressor gene in a proportion of human prostate cancers. Clin Cancer Res; 16(22); 5390–401. ©2010 AACR.