Profiling stress genes regulated by the oncoprotein LEDGFp75 in prostate cancer cells using real time PCR arrays Free

PR-9

Increased inflammation and oxidative stress induced by environmental factors such as infections or poor dietary habits have been associated with the development of prostate cancer (PCa). In response to increased oxidative stress, prostate cells activate stress response genes that promote resistance to cell death, and hence to therapy. These genes are being increasingly implicated in the development of advanced PCa, a therapy-resistant stage of the disease that cause a disproportionately high mortality rate among African American (AA) men in the United States. A comprehensive molecular approach to understand the biological basis of the increased PCa mortality in AA men is critically needed to eliminate these disparities. Our laboratory seeks to understand the biological basis of these disparities by studying oxidative stress-dependent cellular survival pathways operating in advanced prostate tumors. We hypothesize that the lens epithelium-derived growth factor p75 (LEDGF/p75), an emerging oncoprotein regulated by oxidative stress and overexpressed in high stage prostate tumors, promotes PCa cell resistance to stress-induced cell death by transcriptionally regulating genes controlling the cellular redox environment. As a first step in the identification of these genes we have initiated a stress-focused gene expression analysis in PCa cell lines using the Real Time Profiler PCR Array System (SuperArray Bioscience Corp.). This array contains 84 genes involved in the cellular stress response and in redox control, and was used to determine quantitatively changes in stress gene expression in PCa cell lines that were either depleted of LEDGF/p75 by RNA interference, or were overexpressing this protein. The experiments were conducted in the presence and absence of sublethal doses of the strong oxidant tert-butyl hydroperoxide (TBHP). Our results revealed a set of stress genes that appear to be differentially regulated by LEDGF/p75, including phosphoinositide-binding protein E, cytoglobulin, superoxide dismutase 3, thyroid peroxidase, selenoprotein P, aldehyde oxidase 1, and apolipoprotein E. These studies set the stage for assessing, using immunohistochemistry, differences in the expression of LEDGF/p75 and its target genes in prostate tumors from diverse ethnic populations. Initial studies will be conducted using ethnicity prostate tissue microarrays that include tissue from healthy donors, as well as from Caucasian and African American donors with PCa. The therapeutic targeting of LEDGF/p75 and the stress genes it regulates might attenuate tumor resistance to therapy in advanced PCa, potentially reducing the racial disparities associated with the mortality from this disease.