Abstract: Objective To screen methylations of CpG islands in prostate cancer using restriction landmark genomic scanning
(RLGS). Methods The DNA was extracted from homogeneous cells captured by laser capture microdissection in 20 prostate
cancer and 18 benign prostatic hyperplasia (BPH) tissues for scanning the CpG islands using RLGS. The methylation status of
each CpG island was compared between the cancer and BPH samples to screen the genes involved in prostate cancer
development. The screened genes were uploaded to DAVID database for GO analysis, and the genes with the most significant
methylation were analyzed by pyrosequencing. Results and Conclusion Among all the tested CpG islands, 10245 (37.2% ) in
prostate cancer and 8658 (30.3%) in BPH samples were found to be abnormally methylated, and >60% of the methylated CpG
islands were in the promoter region. Compared with BPH samples, the prostate cancer samples showed differential
methyation in 735 CpG islands, including 458 hepermethyated and 256 hypomethelated ones. Seven genes (DPYS, P16, APC,
GSTP1, TMEM122, RARB, and ARHGAP20) in prostate cancer were identified to have distinct methylations. Bioinformatics
analysis suggested that these genes were associated with several biomolecular and biological processes, and among them
DPYS gene was involved in 13 GO anotated biologic functions, development of 50 diseases and 47 protein interactions.
Pyrosequencing of 7 sites of the CPG island in DPYS gene showed a methylation frequency of 32.7% , suggesting the
importance of DPYS gene in the carcinogenesis and progression of prostate cancer.