The Role of CXCL12 Signaling in Obesity-Induced Prostate Cancer Progression

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 DESCRIPTION (provided by applicant): A number of studies indicate that dietary energy balance plays a significant role in prostate cancer (PCa) as well as many other cancers. Our recent studies have shown that diet-induced obesity (DIO) enhanced progression of PCa in HiMyc transgenic mice whereas calorie restriction (CR) inhibited progression in this mouse model of PCa. In addition, we have found that dietary energy balance affects PCa progression in HiMyc mice, at least in part, through modulation of tissue inflammation and angiogenesis. These cellular changes are associated with local changes in expression of a large number of cytokines, chemokines and growth factors. Collectively, our current data suggest that certain growth factor/inflammatory signaling pathways may be key targets for preventing and controlling PCa progression and especially obesity-related PCa progression. In this project, we propose to use the well-characterized HiMyc mouse prostate tumor model as well as a novel tumor cell line derived from HiMyc mice (called HMVP2) that we have recently developed to continue studies of the mechanisms associated with dietary energy balance effects, and in particular obesity, on PCa progression. We will focus these studies on the tumor microenvironment and, in particular, on the role of white adipose tissue (WAT) in driving PCa progression using the HiMyc mouse model. We will also focus on the preliminary finding that the chemokine CXCL12 (SDF-1) is highly upregulated in the stromal vascular fraction (SVF) of WAT from obese HiMyc mice and will study its role in obesity-driven PCa progression in this mouse model. The hypothesis to be tested is that in obesity, the recruitment of adipose stromal cells (ASC) promotes PCa progression in part through CXCL12 signaling via its G-protein coupled receptors, CXCR4 and CXCR7. By using a peptide (D-WAT) that specifically ablates ASC, we will test the importance of this cell population in cancer progression and determine its contribution to CXCL12 signaling in the tumor microenvironment. By using knockout, knockdown, and overexpression mouse models, we will examine whether targeting CXCL12, CXCR4, and CXCR7 can offset the effects of obesity on PCa progression. Finally, we will test the efficacy of a small molecule inhibitor targeting CXCL12/receptor interactions alone or in combination with a naturally occurring anti-inflammatory phytochemical [6-shogaol (6-SHO)] found in ginger to offset the effects of obesity on PCa progression. The Specific Aims are to: i) identify the cells that produce CXCL12 in prostate-associated WAT; ii) determine the importance of ASC-derived CXCL12 on obesity-driven PCa progression; iii) investigate the specific roles of CXCR4 and CXCR7 signaling in obesity-driven PCa progression; and iv) test pharmacologic approaches to inhibition of CXCL12 signaling via CXCR4 in obesity-driven PCa progression. Completion of this project will provide the basis for future translational studies targeting specific signaling pathways and/or cell populations to reduce PCa mortality and prevent the effects of obesity on PCa progression.