Abstract 2674: High fat diet accelerates MYC-driven prostate cancer through metabolic and epigenomic rewiring
Authors: Labbe’ David P. , Zadra Giorgia , Yang Meng , Lin Charles Y. , Reyes Jaime M. , Cacciatore Stefano , Ebot Ericka M. , Cotter Maura B. , Creech Amanda L. , Jaffe Jacob D. , Kantoff Philip W. , Bradner James E. , Mucci Lorelei A. , Chavarro Jorge E. , Loda Massimo , Brown Myles 
Published: July 2016

Abstract
Introduction: The mechanisms underlying the association between high dietary fat intake and prostate cancer (PCa) are unknown. Using a MYC-driven PCa mouse model, we sought to identify metabolic and epigenomic alterations driven by high fat diet (HFD) that facilitate PCa progression. Additionally, we investigated whether these alterations were relevant to PCa progression and lethality in humans.
Material and Methods: Wild-type (WT) and transgenic Hi-MYC (MYC) mice were assigned either a HFD or control diet and were sacrificed at 12, 24, and 36 weeks of age for histologic and phenotypic characterization. Metabolic and epigenomic analyses were carried on the ventral prostates of 12-week old mice. Human PCa gene expression profiling data were obtained from 319 men with PCa and well-annotated post-diagnostic saturated fat intake (SFI) data from the Physicians’ Health Study and Health Professionals Follow-up Study prospective cohorts.
Results: HFD does not affect the incidence of MYC-induced murine prostate intraepithelial neoplasia (mPIN) at 12 weeks, but increases mPIN proliferative index (Ki-67) at 24 weeks and tumor burden at 36 weeks.
MYC overexpression, as expected, induces a significant metabolic reprogramming and HFD further enhances this rewiring to provide additional anabolic metabolites to sustain the increased proliferation of MYC prostate while having little effect on the WT prostate. Moreover, MYC altered key metabolites of the methionine cycle in a direction suggestive of a global hypomethylation, again amplified by HFD. Targeted quantitative histone mass spectrometry revealed a robust MYC-driven signature, including a global demethylation of H3K27 and H4K20 marks, the latter enhanced by HFD. Moreover, ChIP-seq revealed an intricate crosstalk between MYC and the H4K20me1 demethylase PHF8, resulting in enhanced genomic instability in the context of HFD. Finally, RNA-seq and ATAC-seq analyses showed that HFD rewires MYC-driven PCa through the alteration of genes implicated in chromatin function and remodeling. In humans, SFI was associated with enrichment in genes associated with increased MYC transcriptional activity in the prostate. Furthermore, this MYC transcriptional signature was associated with PCa lethality overall (OR = 3.21; 95% CI = 1.47, 7.35 comparing extreme score tertiles), and the association was stronger among men with high post-diagnostic SFI (OR = 1.32; 95%CI = 1.11, 1.66) than those with low SFI (OR = 1.05; 95%CI = 0.98, 1.12).
Conclusions: HFD supports a coordinated metabolomic and epigenomic rewiring to increase epigenomic plasticity and MYC transcriptional activity prior to the appearance of phenotypic alterations in the prostate. Importantly, HFD requires MYC-mediated transformation to trigger its deleterious effects. In humans, SFI also enhances MYC transcriptional activity, which is associated with increased PCa lethality.
Citation Format: David P. Labbe’, Giorgia Zadra, Meng Yang, Charles Y. Lin, Jaime M. Reyes, Stefano Cacciatore, Ericka M. Ebot, Maura B. Cotter, Amanda L. Creech, Jacob D. Jaffe, Philip W. Kantoff, James E. Bradner, Lorelei A. Mucci, Jorge E. Chavarro, Massimo Loda, Myles Brown. High fat diet accelerates MYC-driven prostate cancer through metabolic and epigenomic rewiring. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2674.