Increased Heparanase Expression Is Caused by Promoter Hypomethylation and Up-Regulation of Transcriptional Factor Early Growth Response-1 in Human Prostate Cancer

Purpose: Heparanase degrades heparan sulfate and has been implicated in tumor invasion and metastasis. The transcription factor, early growth response 1 (EGR1), is associated with the inducible transcription of the heparanase gene. We hypothesize that CpG hypomethylation in the heparanase promoter coupled with up-regulation of EGR1 levels may induce heparanase expression in human prostate cancer. Experimental Design: Cultured prostate cancer cell lines (Du145, DuPro, LNCaP, and PC-3) with and without 5′-aza-2-deoxycytidine treatment, 177 prostate cancer samples, and 69 benign prostatic hyperplasia (BPH) samples were used. The frequency and level of heparanase promoter methylation were analyzed by methylation-specific primers which covered the core binding motif of EGR1 (GGCG) or SP1 (GGGCGG) or both. Results: In cultured Du145, DuPro, LNCaP, and PC-3 cell lines, mRNA transcripts of heparanase were significantly increased after 5′-aza-2-deoxycytidine treatment, suggesting that promoter methylation was involved in the regulation of heparanase mRNA transcript. Significantly higher methylation was found in BPH samples than in prostate cancer samples ( P P P P P Conclusions: To our knowledge this is the first comprehensive study demonstrating that increased heparanase expression in prostate cancer tissues is due to promoter hypomethylation and up-regulation of transcription factor EGR1.