Oxidative Stress in Prostate Cancer: Efficacy of Antioxidants in Nkx3.1; Pten Mod

The long latency in clinically significant prostate cancer development provides numerous intervention opportunities. The existence of oxidative stress markers in prostate cancer patients suggests that oxidative stress signaling may be a reasonable target to prevent clinical prostate cancer. Although the failure of the SELECT trial argues against this approach; we propose that a cocktail of antioxidants with the capacity to neutralize several classes of reactive species would be an excellent prophylactic remedy. We argue that several classes of reactive species are produced from cellular metabolism therefore a single or a combination of two antioxidants (like the SELECT trial) is not only archaic but also absurd. Our preliminary published results show that level of NADPH: Quinone Oxidoreductase (NQO1), a phase II detoxifying enzyme in the prostate from hormone stimulated rats that develop Prostatic Intraepithelial Neoplasia (PIN) is undetectable compared to hormone naive animals. In keeping with our antioxidant prevention approach we developed a combination of antioxidants (patent pending). Interestingly, NQO1 in rats receiving antioxidants was comparable to that of the unstimulated basal level. Further, intervention with this combination of antioxidants caused significant decrease (p = 0.04) in prevalence of PIN. Based on these data we propose to test the hypothesis that restoration of NQO1 by a combination of antioxidants is sufficient to inhibit inflammatory signaling-mediated development of PIN and progression to prostate cancer. Three specific aims have been proposed. Aim 1 will determine the ability of the antioxidant(s) to quench hormone-induced reactive species and restore redox balance in cultured immortalized human prostate epithelial, benign prostate hyperplasia as well as prostate epithelial cells from the Nkx3.1; Pten compound mutant mice. In aim 2 we will evaluate the role of NQO1 in hormone-induced oxidative stress during prostate carcinogenesis using a variety of human and mouse prostate epithelial and tumor cells. In aim 3 we will determine whether maintaining redox balance through upregulation of NQO1 is sufficient to prevent prostate cancer in Nkx3.1; Pten compound mutant mouse model. A variety of biochemical, molecular biological and genomics approaches will be used. Experiments proposed here will establish the ability of a combination of antioxidants to prevent clinical prostate cancer. This has the potential for immediate clinical translation. Further these studies may also lead to the development of additional targets such as NQO1 and or its regulators for prostate cancer management. PUBLIC HEALTH RELEVANCE: Reactive species produced from cellular metabolism leads to changes in inflammatory signaling that can lead to neoplastic changes. Incapability to neutralize these reactive species and their downstream biological effects leads to oxidative stress, an environment that enables cancer progression. Our approach to break this chain is to use a cocktail of antioxidants that can quench several classes of reactive species. Our results show that such a cocktail inhibits the preliminary inflammatory changes associated with prostate cancer. In this proposal we will (i) understand the role of each of the components in quenching oxidative stress-induced inflammatory signaling in the prostate; (ii) establish the ability of the cocktail to prevent oxidative stress and therefore clinical prostate cancer using a preclinical animal model that most appropriately mimics the human disease; and (iii) identify novel targets for intervention through understanding the role of NQO1 in prostate carcinogenesis.