Biomarkers of Oxidative Injury and Their Modulation in Prostate Tissue from Patients with Prostatic Tissue from Patients with Prostate Cancer

摘要

Development of prevention strategies to diminish prostate cancer (PCa) risk is in order. One possible etiologic factor in the development of PCa is cellular exposure to chronic oxidative stress (COS). COS can lead to the accumulation of promutagenic oxidized DNA bases such as 8-hydroxydeoxyguanosine (8-OHdG). The detoxifying enzyme GSTP1 is inactivated in nearly 100% of PCa. We have successfully developed a model system to determine the role of OSTP 1 protein in the response of the human PCa to COS. Through this grant, we have also developed an accurate HPLC-MS-MS method for measuring intracellular reduced and oxidized glutathione. Experiments revealed re-expression of OSTPl results in an increase in oxidized glutathione following low dose radiation (LDR) but does not significantly diminish intracellular reduced glutathione levels. These data solidify% our preliminary results implicating GSTPl as a major regulator of oxidative DNA damage and suggest that its inactivation may provide a necessary step in the neoplastic process in PCa. We have also developed an HPLC-MS-MS method for measurement of 8OHdO in genomic DNA. This technique is more quantitative than the older HPLC-ECD method. This new technique has allowed precise measurement of 8-OHdG in DNA extracted from human PCa (LNCaP) xenografts before and after exposure to oxidative injury by LDR. These data reveal that human PCA xenografts expressing GSTP1 do not accumulate significant levels of 8-OHdG following exposure to LDR. These data confirm our ability to measure 8-OHdG via HPLC-MS-MS in DNA extracted from tissues. Finally we completed a clinical trial evaluating the level of 8-OHdG in PCa and associated normal tissue derived from patients undergoing prostatectomy. These data reveal significant levels of 8-OHdG in the prostate but this was not ubiquitous among all patients evaluated.