Prostate cancer is one of the most common diagnoses in the oncology clinic, and most men with the disease will have a self-limiting and indolent course. However, approximately 15% of these patients display in essence a different disease, one that progresses rapidly, becomes quickly resistant to treatment, and metastasizes to bones and visceral organs. Carrying high morbidity and mortality, and with limited therapeutic options, metastatic disease is one of the most urgent, unmet medical needs in the management of prostate cancer patients. However, our understanding of how these tumors acquire metastatic competency is incomplete, and this has severely limited the introduction of new, more effective treatments. Since the inception of this highly collaborative P01 grant, Project 1 has shed new lights onto mechanisms of mitochondrial function in advanced prostate cancer. Progress made during the last budget cycle established a novel role of mitochondria-localized Heat Shock Protein 90 (Hsp90) chaperones as broad regulators of tumor adaptation and important therapeutic targets. These molecules promoted cell survival, maintained mitochondrial bioenergetics and buffered the cellular stress response in tumors, enabling aggressive disease traits, in vivo. Specifically, reprogramming of mitochondrial oxidative phosphorylation emerged as an unexpected driver of disease progression, fueling tumor cell motility, invasion and metastatic dissemination, in vivo. Now, fresh experimental evidence has uncovered a mechanistic basis for the interface between mitochondrial bioenergetics and metastatic competency in prostate cancer. In response to stress stimuli commonly seen in the tumor microenvironment, we show that energetically active mitochondria reposition to the cortical cytoskeleton in prostate cancer cells, co-localize with membrane protrusions implicated in cell motility, and support tumor cell migration and invasion. Therefore, the hypothesis that oxidative phosphorylation provides an efficient, ?regional? energy source to fuel membrane dynamics, tumor cell motility and metastatic competency in prostate cancer can be formulated, and will constitute the focus of the present continuation application. Fully integrated with the experimental plans of the two other Projects in this application, Project 1 will characterize the requirements of mitochondrial bioenergetics in the regulation of membrane dynamics and cell movements (specific aim 1), define the protein interactions and signaling mechanisms that control the trafficking of mitochondria to the cortical cytoskeleton (specific aim 2), and utilize a complement of xenograft and genetic mouse models to define the impact of this pathway on prostate cancer metastasis, in vivo (specific aim 3). The overall experimental plan is designed to merge mechanistic studies of mitochondrial bioenergetics, cytoskeletal dynamics and cell invasion into a single signaling network that enables metastatic competency in prostate cancer. The results will create novel, ?actionable? therapeutic opportunities for patients with advanced disease.
Metastatic disease is the primary cause of death for patients with prostate cancer, but our understanding of this process is incomplete, and ?actionable? therapeutic targets in these settings are scarce. The present application is designed to bridge this knowledge gap, and define a novel role of spatiotemporal mitochondrial bioenergetics in fueling tumor cell motility and metastatic competency in prostate cancer. In collaboration with the other Projects on this Program, these studies will identify novel therapeutic targets for patients with advanced and disseminated disease.
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