UCSF

Metabolic reprogramming is known to occur with development and progression of prostate cancer. Based on preliminary studies, it is hypothesized that changes in metabolism will also predict, at an early time, whether men with prostate cancer are developing resistance to a common form of therapy, androgen deprivation therapy. Early knowledge of resistance would allow more effective intervention with secondary therapies. Hyperpolarized MRI (hpMRI) is a promising new metabolic MRI technique that allows the in vivo real-time assessment of metabolism in patients. In order to identify hpMRI metabolic probes for assessing resistance to ADT, this study used a NMR based metabolic approach to investigate changes in metabolic pathways with the development of resistance in the TRAMP murine model of prostate cancer. Infusion of uniformly labeled 13C glucose allowed for the NMR analysis of metabolites (lactate, glutamate, alanine) in three key pathways (glycolysis, TCA cycle and amino acid synthesis). To accomplish this, two methods of metabolite extraction, the methanol/chloroform/water extraction and the perchloric acid extraction, were explored. High resolution 1D proton NMR, carbon-decoupled NMR, TOCSY, and HSQC analysis allowed for calculation of fractional enrichment, comparing androgen sensitive with resistant tumors. Overall, the perchloric acid extraction method was more time-consuming and less reproducible, so the methanol/chloroform/water extraction was chosen to be optimized further. Fractional enrichment calculations revealed that lactate fractional enrichment increased from 34.59% to 41.30%, glutamate increased from 8.16% to 9.27%, and alanine increased from undetectable to 37.13%. The increase in every biomarker, especially the dramatic increase in alanine, suggests that these may be appropriate targets for future hyperpolarized studies using [1-C13]pyruvate and [2-C13]pyruvate to track lactate, alanine, and glutamate.