Promoter Region Methylation Analysis Of The Glutathione S-transferase P1 Gene In Prostate Carcinoma

[Background] Prostate cancer (PCA) is the second leading cause of male cancer-related death and it affects one of nine males older than age 65 in the United States. In 2001, around 200,000 men were diagnosed with PCa and 31,500 died of the disease. Men diagnosed with early-stage, small-volume prostate disease have the best outcomes following curative treatment. Therefore, the aim of early-detection programs is to diagnose prostate cancer when it is at an early and curable stage. Prostate cancer diagnosis currently entails a digital rectal examination and the measurement of serum prostate-specific antigen (PSA) levels, which are frequently elevated in men with prostate cancer, followed by a transrectal prostatic needle biopsy. However, low specificity of serum PSA leads to many false-positive and false-negative results and clinical uncertainty. Development of CaP-specific diagnostic markers is needed.Transcriptional silencing of tumor suppressor genes associated with the hypermethylation of the CpG islands located in their promoter regions has been accepted as a common feature of human cancer.Glutathione S-transferases (GSTs) are a family of enzymes that catalyze intracellular detoxification of a variety of electrophiles, including a number of xenobiotics and carcinogens, by conjugation to glutathione. Among the isozymes, the pi class enzyme GSTP1-1 is the most widely distributed and has been well studied in cancer. Hypermethylation of the 5' promoter region of the gene encoding glutathione S-transferaseπ(GSTP1) occurs at a very high frequency (90%-96%) in prostate adenocarcinoma.However, it has been report that the rate of unmethylation of GSTP1 gene promoter in PCA was 86% by MSP,while none of patients with aberrant promoter CpG islands methylafion status of GSTP1 gene was found in China. Therefore, investigate the GSTP1 gene promoter region methylation status of Chinese are worth studying.[Objective] To investigate the GSTP1 gene promoter region methylation status of PCA,BPH and NP tissues in Chinese and explore a new molecular markers in the early diagnosis of prostate cancer.[Methods] 31PCA tissues,18 BPH tissues and 3 NP tissues collected from each patient immediately after operation. Genomic DNA was isolated from prostate tissue and subjected to sodium bisulfite modification. Methylation of the GSTP1 promoter was examined by nest methylation-specific PCR analysis and correlated with pathology results, and clinical information was obtained from the patient record.[Results] The mehtyation rate of GSTP1 in PCA,BPH and NP tussis were 83%,0 %and 0%.The mehtyation rate of 722 CG sites of 19 PCA sequences,1064 CG sites of 28 BPH sequences and 1102 CG sites of 29 NP sequences were 96%,34% and 37%.A Chi-square test analysis suggested a significant discrimination between PCA and BPH or NP. (P < 0.01), there was no different betweent BPH and NP( P > 0.05). Combining NMSPand PSA concentration for PCa screening in much better than Prostate-specific Antigen (PSA) alone.[Conclusion] Nest MSP is a high specifically and sensitivity technique to detect GSTP1 CpG island DNA hypermethylation in PCA.The methylation frequencies of GSTP1 were significantly higher in prostate carcinoma compared with BPH and NP.This GSTP1 CG island DNA methylation assay, may be a early diagnostic marker for PCA.