Our overarching goal is to identify a novel mechanism-driven chemoprevention strategy that can effectively prevent or delay the development and progression of currently incurable castration-resistant prostate cancer (CRPC) to revolutionize long-term survival. In the United States, prostate cancer strikes one in six men and is the second leading cause of cancer-related deaths in men. Clinically, androgen deprivation therapy (ADT) with surgical or medical castration remains standard-of-care for advanced/metastatic prostate cancer for decades. Despite its efficacy in the short term, ADT is inevitably followed by the development of CRPC in the majority of patients. The discovery that persistent AR signaling axis plays a crucial role in CRPC led to FDA-approval of ?second-generation? ADT drugs, such as the novel AR antagonist enzalutamide/Xtandi, providing 4-5 months survival benefits. However, nearly all the patients will develop resistance to these new drugs within 6 to 12 months. Thus, development of CRPC following ADT is a major clinical problem but presents a unique window for innovative secondary/tertiary chemoprevention. We demonstrate that Warburg effect caused by the elevated hexokinase 2 (HK2), which catalyzes the irreversible first step of glycolysis by phosphorylating glucose to glucose-6-phosphate (G-6-P), is required for tumor growth of CRPC. Accordingly, targeting HK2 enzymatic activity could prevent or delay CRPC. Unfortunately, current HK2 inhibitors, such as 2-deoxyglucose (2-DG), are not specific with side effects due to inhibition of ubiquitously expressed HK1, which is required for glucose metabolism of normal cells. Based on our published data and preliminary studies, we hypothesize that inhibition of HK2-mediated Warburg effect by targeting eIF4A1-dependent HK2 protein synthesis prevents or delays CRPC progression. We will test this central hypothesis by accomplishing 3 specific aims.
Aim 1 is to structurally elucidate the molecular mechanism underlying eIF4A1-dependent HK2 mRNA translation in CRPC.
Aim 2 is to genetically demonstrate that targeting eIF4A1 blocks HK2 mRNA translation to prevent tumor growth of CRPC in vivo;
and Aim 3 is to pharmacologically demonstrate that eIF4A1specific inhibitor silvestrol blocks HK2 mRNA translation to prevent tumor growth in preclinical CRPC models. Successful accomplishment of the proposed studies will provide Proof-of-Principle that targeting eIF4A1-HK2 translation axis serves as a mechanisms-driven novel and actionable strategy to prevent CRPC progression at structural, genetic and pharmacological levels.
/PUBLIC HEALTH RELEVANCE Androgen deprivation therapy (ADT) is the standard-of-care therapy for advanced/metastatic prostate cancer. Although effective in the short term, ADT is consistently followed by the emergence of castration-resistant prostate cancer (CRPC) in nearly all patients, which represents a major clinical problem but provides a unique window for innovative secondary/tertiary chemoprevention. Our studies will identify a crucial ?druggable? target for tumor growth of CRPC and provide a novel and effective chemoprevention strategy to prevent or delay CRPC progression, and therefore will have direct translational impact on currently incurable CRPC patients.