Figure 3.

Increased glycolysis observed in PC3 tumors with hyperpolarized pyruvate. (a) The schematic illustrates the different pathways through which hyperpolarized 1-¹³C pyruvate can be metabolized in the cell. Because of the quick loss of polarization, resonances for lactate and alanine are the main metabolites detected in vivo. (b) Spectra from representative PC3M and PC3 tumor-bearing mice taken 21 s after tail vein injection of hyperpolarized pyruvate. The faster conversion rate in PC3 is readily seen. (c) ¹H image of a representative PC3M tumor-bearing mouse. Slice-selective ¹³C spectroscopy was utilized to capture the ¹³C signal in the tumor tissue after injection of hyperpolarized pyruvate. (d) Hyperpolarized pyruvate data were processed to generate dynamic curves characterizing the arrival of hyperpolarized pyruvate and its chemical conversion into lactate. Normalized lactate (nLac), defined as the ratio of total cumulative lactate signal to the total carbon-13 signal, was calculated for each ¹³C scan. Normalized lactate conversion was greater in PC3 tumor-bearing animals (0.44 ± 0.09) than in PC3M tumor-bearing animals (0.29 ± 0.02). The statistical significance of the difference between tumor groups was determined by unpaired two-tailed t-test (P < 0.03).