Abstract 3226: Validation of novel RCC targets discovered by global metabolomics.
Authors: Weiss Robert H. , Wettersten Hiromi , Aboud Omran Abu , Mall Christine , Tan Matthewe , Alexander Danny 
Published: August 2014

Of the omics sciences, metabolomics is one of the newer methodologies. In this technique, all of the small molecule substances produced during bodily processes are measured. This includes endogenous metabolites as well as small peptides, amino acids, and (usually) body flora and drug metabolites. Rather than being participators in these processes, as are genes and transcripts, the metabolites produced are sentinels of “what is actually happening” in an organism. The so-called “cancer metabolome” is loosely defined as the entire suite of relatively low molecular weight (∼&lt;1.5 kD) metabolites germane to cancer and includes their changes relative to a control non-cancerous group of subjects or tissues. Using a human Caki-1 xenograft subcapsular mouse model of RCC (Ca. Res., 2012), we have performed non-targeted metabolomics of tumor tissue, blood, and urine. By correlation of this data with non-targeted metabolomics analysis from RCC patient urine (Int. J. Ca., 2012), we have identified three novel therapeutic targets for RCC: peroxisome proliferator-activated receptor alpha (PPARα), carnitine palmitoyltransferase-1 (CPT-1), and the tryptophan metabolic enzyme indoleamine-2,3-dioxygenase (IDO). We have performed in vitro validation of these potential targets using specific inhibitors. Incubation of RCC cells with inhibitors of PPARα (GW6471 and MK886) and CPT-1 (etomoxir) yields dose-dependent decreases in viability and/or cell cycle progression using multiple and disparate human RCC cell lines. In the case of IDO, selected downstream tryptophan metabolites had no effect on RCC viability when added directly to RCC cells, yet when incubated with CD3/CD28 stimulated peripheral blood mononuclear cells (PBMC), these metabolites decreased PBMC proliferation, suggesting that tryptophan metabolites may indeed attenuate immune surveillance in RCC. Furthermore, addition of the IDO inhibitor 1-methyltryptophan (1-MT) to RCC/PBMC co-cultures showed an 1-MT dose-dependent increase in proliferation of PBMCs. In vivo validation of all of these potential targets is currently underway in our laboratory. In summary, in this study we have used global, non-targeted metabolomics analysis to identify and begin to validate novel therapeutic targets which decrease RCC cell viability and proliferation (PPARα and CPT-1 inhibitor) or potentially enhance immunosurveillance (the IDO inhibitor 1-MT). This work shows for the first time the tremendous power of metabolomics starting from urine analysis to discovery to validation of new targets for RCC therapy.

Citation Format: Robert H. Weiss, Hiromi Wettersten, Omran Abu Aboud, Christine Mall, Matthewe Tan, Danny Alexander. Validation of novel RCC targets discovered by global metabolomics. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3226. doi:10.1158/1538-7445.AM2013-3226