Regulation of Mitochondrial Metabolism by Tyr-phosphorylated ATP Synthase Alpha-Subunit and its Therapeutic Implications in Prostate Cancer

项目摘要

Project Abstract Cancer cell mitochondria switch their metabolic phenotypes to meet the challenges of high-energy demand and macromolecular synthesis. Acute dependence of tumors on oncogenic tyrosine kinase signaling support their rapid proliferation, however, direct relevance of the kinase activity for mitochondria to support these high-energy processes remains obscure. Serendipitously, we uncovered that a non-receptor tyrosine kinase, ACK1, phosphorylates ATP synthase F1 α-subunit (ATP5F1a) at Tyr243 and Tyr246 (Tyr200 & 203 in mature protein, respectively) that increased ATP synthase activity specifically in the cancer cells. Mechanistically, ATP5F1a- phosphorylation not only excluded its binding to its physiological inhibitor, ATPase Inhibitory Factor 1 (IF1), but also created a supporting structure that extended from the bound non-catalytic nucleotide to the surface, reducing the flexibility and thereby increasing the stability of the enzyme. A new class of ACK1 inhibitor, (R)-9b reversed this process, inducing mitophagy and mitigating tumor growth. Consistently, a marked increase in ATP5F1a-phosphorylations was observed as normal prostate progressed to the malignant stage. Overall, these data provide the molecular evidence for cancer cell `mitochondrial addiction’ to Tyr-kinase indulgence, and reveals (R)-9b as a ‘mitocan’ that compromises the unique metabolic needs of cancer cells. Castration resistant prostate cancer (CRPC) remains an incurable malignancy with limited treatment options and is a significant cause of deaths in men worldwide (15). Limited efficacy and rapid development of resistance for Enzalutamide and Abiraterone, AR antagonist treatment have established a new paradigm-to achieve realistic remission, other cancer specific pathways, including metabolic must be compromised. This proposal is directed towards detailed characterization of mitochondrial metabolism modulatory properties of ACK1/ATP5F1a signaling and examine ability of (R)-9b to overcome Enzalutamide and abiraterone-resistant CRPCs. The specific aims are as follows: Specific Aim 1. Examine the mechanism by which ATP5F1a-phosphorylation regulates its activity in prostate cancer Specific Aim 2. Explore the role of ACK1/ATP5F1a signaling in prostate cancer models Specific Aim 3. Detail in vivo characterization of ACK1/ATP5F1a signaling in enzalutamide and abiraterone- resistance in mouse models of prostate cancer and patient derived xenografts (PDXs)