Abstract 4480: Associations between phytanic acid and alpha-methylacyl-CoA racemase (AMACR) expression in the normal human prostate

Alpha-methylacyl-CoA racemase (AMACR) is an enzyme that is overexpressed in prostate cancer, with lower levels present in normal prostatic tissues. AMACR is involved in the metabolism of phytanic acid - a branched chain saturated fatty acid that has been linked with elevated risks of prostate cancer in several epidemiologic studies. Although considerable research has been done on AMACR as a clinical biomarker in prostate cancer, no study has evaluated the possible link between phytanic acid and AMACR gene expression in the normal human prostate, and thus the possibility that AMACR plays a causal role in prostate carcinogenesis. Fasting blood and histologcally benign prostate tissue samples were obtained from 31 men undergoing radical prostatectomy for the treatment of localized disease. Concentrations of phytanic acid in serum and tissues were determined by isotope dilution gas chromatography-mass spectrometry. RNA was extracted from epithelial cells isolated from fresh-frozen prostate tissues by laser capture microdissection, and AMACR mRNA levels were quantified using real time polymerase chain reaction. Tissue phytanic acid concentrations were not significantly correlated with serum levels nor with prostatic AMACR mRNA levels. Notably, AMACR was significantly inversely correlated with body mass index (Spearman correlation coefficient (r)= –0.43, p=0.02) and directly correlated with Gleason score (r=0.35, p=0.05). Stratification by body mass index revealed an unexpected inverse correlation between wAMACR gene expression levels and phytanic acid concentrations in the prostate (r= –0.95, p= 0.001) in obese men. In conclusion, blood and tissue levels of phytanic acid were not correlated, which suggests that blood measures should not be utilized as a surrogate measure of this fatty acid in the target organ. Contrary to expectation, tissue phytanic acid levels were significantly inversely associated with AMACR gene expression levels in the prostate, but only among obese men.These findings require confirmation in other, larger studies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4480. doi:1538-7445.AM2012-4480