Targeting the Metabolome in Androgen Receptor-driven Castration-resistant Prostate Cancer

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Alterations in metabolism especially lipogenesis are unique to prostate cancer progression and the changes from benign to malignant prostate epithelium involves a switch from mitochondrial oxidative metabolism to generate energy needs for cellular processes to aerobic glycolysis in cancer cells. This process is critical for cell proliferation and new cell membrane synthesis including the continued proliferation driven by the androgen receptor in most castration resistant prostate cancers (CRPC). Mechanisms driving these metabolic alterations are not fully understood but the endogenous increase in endogenous lipogenesis by fatty acid synthase (FASN), an androgen receptor driven gene, and a decrease in 5’AMP-activated kinase (AMPK) activity are crucial components of the altered metabolic processes driving CRPC. In our Preliminary Data we demonstrate that alteration in function of these two genes, inhibition of FASN and activation of AMPK, by two new drugs will suppress growth of enzalutamide castrate resistant tumors in vitro and in vivo. We have shown that alteration in metabolism will suppress the growth of tumors driven by AR constitutively active variants that were the basis of my current VA Merit Review. The hypothesis of this project is that targeting activation of AMPK suppresses PCa proliferation by regulating lipogenesis with subsequent inhibition of AR expression and activity. In order to address this hypothesis we will first demonstrate expression of AMPK, AMPK-related subunits (e.g., phospho serine 486, p-acetyl coenzyme A carboxylase), and FASN in tissue microarrays (TMA) of primary prostate cancer, metastatic CRPC tumors, and prostate cancer patient-derived (PDX) models, and determine correlation with AR, AR-V7, and AR-variants. We have previously shown a strong correlation between FASN expression and AR in CRPC in metastatic prostate cancer. In addition, other studies have shown activated AMPK levels decrease in progression from primary to metastatic prostate cancer and for primary PCa, this may be predictive of development of metastatic disease. Therefore, we will examine use the extensive patient material available in the University of Washington/Fred Hutchison prostate cancer program to determine clinical expression of these cancer progression factors. Next we will determine the mechanism by which AMPK is activated by BKI 1553 and affects AR transcriptional output. Our preliminary data indicates that activation of AMPK by the dephosphorylation of Ser486 suppresses growth of AR-driven CRPC. Further, this activity is activated by BKI 1553 but only in PCa cells that are AR positive. In this aim we will determine the MOA of BKI 1553 activation of AMPK, potential target(s) and its subsequent mechanism of suppression of AR expression and transcriptional activity. Next we will assess if antiproliferative actions of BKI 1553 include transcriptional and post-transcriptional regulation of enzymes in monounsaturated fatty acids (MUSFAs) metabolism. Finally, demonstrate in vivo activity of AMPK activation and FASN inhibition on CRPC. We will expand to PCa PDX models identified in Aim 1 where FASN and/or AMPK expression has changed in progression to CRPC in order to better show the applicability of BKI 1553 and IP1991 to a range of CRPCs.