Application Note 43

Analysis of Whole-Body Branched-Chain Amino Acid Metabolism in Mice Utilizing 20% Leucine ¹³C₆ and 20% Valine ¹³C₅ Mouse Feed

Jared R. Mayers, Margaret E. Torrence, Brian P. Fiske, Shawn M. Davidson, and Matthew G. Vander Heiden

Koch Institute for Integrative Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA USA

Cancer cells have altered metabolism relative to normal cells. To date, most cancer metabolism research has focused on understanding the mechanisms of cell autonomous metabolic alterations such as the influence of different oncogenic signals on nutrient utilization and the effects of altered regulation of specific enzymes on metabolic fluxes through different pathways (Cairns RA et al. 2011). While these studies have provided insight into metabolic needs of proliferating cancer cells (Vander Heiden MG et al. 2009), they do not address potential interactions between tumor and normal tissues. 

Research on whole-body metabolic alterations associated with type 2 diabetes (T2DM) provides insight into how altered metabolite sensing can affect the metabolism of specific tissues. Intriguingly, there are clear epidemiological connections between diabetes and several types of cancer, especially pancreatic adenocarcinoma (PDAC) (Everhart J et al. 1995; Wang F et al. 2003). Indeed, epidemiologic evidence indicates that pancreatic cancer can be both a consequence of longstanding diabetes (Ben Q et al. 2011) and cause of new-onset cases (Huxley R et al. 2005). Methods to study metabolism across tissues are needed to understand how whole-body metabolic alterations influence tumor metabolism, and to understand the systemic changes associated with metabolic disease.

In a recent study, we found that elevated branched-chain amino acids (BCAAs – leucine, isoleucine and valine) are found in the serum of patients with early pancreatic cancers (Mayers JR et al. 2014). Using a genetically engineered mouse model of PDAC (Bardeesy N et al. 2006) we used isotope-labeled diets to assess the sources of these plasma BCAA elevations and distinguish between short-term pools defined by acute dietary uptake and disposal, and long-term pools defined by turnover of whole-body protein stores. In this note, we describe the experimental approaches we used to define the contribution of each of these pools to plasma BCAA levels. A critical tool for these experiments was the custom-designed 20% leucine ¹³C₆ and 20% valine ¹³C₅ mouse feed diet developed in collaboration with Cambridge Isotope Laboratories, Inc. (CIL) and Harlan Laboratories, Inc.*

*For additional information on original content and its broader application, please refer to Vander Heiden et al.’s 2016 Science article PMID: 27609895