Studying metabolic stress signaling in renal cancer

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Project Summary Renal cell carcinoma (RCC) is a major metabolic cancer, and several well-known renal cancer genes are involved in pathways that respond to metabolic stress. Thus, there is a critical need to understand the metabolic stress pathways involved in RCC development and to develop treatments that target the fundamental metabolic vulnerabilities in RCC. BAP1 acts as a tumor suppressor gene in RCC, with inactivating mutations in up to 15% of cases and frequent deletion in clear cell RCCs (ccRCCs), and patients with BAP1-mutant ccRCC exhibit particularly poor clinical outcomes. However, how BAP1 functions as a tumor suppressor in renal cancer remains unclear, and currently there is no effective therapy to treat RCC patients with BAP1 mutations. BAP1 and its associated proteins form the polycomb repressive deubiquitinase (PR-DUB) complex, which reduces histone 2A ubiquitination (H2Aub) on chromatin and regulates gene transcription. SLC7A11 is a cystine transporter. Our recent publications and preliminary data link BAP1 to SLC7A11 and support the central hypotheses of our proposal that (i) the BAP1-containing PR-DUB complex mediates H2Aub de-ubiquitination and transcriptional repression of SLC7A11, and BAP1 deficiency or alteration of other components in the PR-DUB complex de- represses SLC7A11 expression, rendering renal cancer cells more resistant to ferroptosis (a non-apoptotic cell death induced by metabolic stress) and contributing to RCC development; and (ii) BAP1-deficient/mutant renal tumors are more dependent on glucose for survival, partly due to high SLC7A11 expression in these tumors, thus exposing a metabolic vulnerability for therapeutic targeting. In this proposal, we will employ multi-disciplinary approaches to test our hypotheses. The rationale for the proposed research is that studying the roles of the BAP1-SLC7A11 signaling axis in ferroptosis and glucose dependency will not only advance our understanding of how renal cancer cells bypass ferroptotic cell death to survive and grow but also provide important insights into the development of novel therapeutic strategies to target accompanying metabolic vulnerabilities in RCC. With respect to expected outcomes, our proposed studies will identify novel regulatory mechanisms of ferroptosis pathways, clarify the tumor suppression function of BAP1, and identify new effective therapies to target metabolic vulnerabilities in renal cancer. Our proposal is highly innovative because it focuses on a previously unexplored pathway to link metabolic stress signaling to tumor development and treatment. Our proposed studies will have significant impact on both our understanding of the fundamental mechanisms of metabolic stress response and our ability to target nutrient dependency in renal cancer treatment.