Figure 1. Lactate Levels are Significantly Increased in MYC-induced but not in MET-induced Murine Liver Tumors.

(A and B) Glucose and lactate levels in tumor and normal liver tissue extracts measured by enzyme-based assays. Normal tissue was from wild type FVBN mice and transgenic mice kept on doxycycline. (C and D) Representative profiles of ¹H NMR performed on extracts from tumors and adjacent liver tissues from animals injected with [U-¹³C]-glucose (number of animals analyzed is indicated in 1E). Two satellite peaks at 1.21 and 1.42 ppm represent fully-labeled ¹³C-lactate. The profiles were normalized to the initial dry weight of tissue. (E) Quantification of ¹³C-lactate concentration in the samples from 1C and 1D. #, p = 0.050 for MET-induced tumors vs. MYC-induced tumors. (F) Ldha RNA levels estimated by real-time PCR in the samples outlined in A and B. Mouse β-actin served as an internal control. One of the FVBN normal livers was used as a reference. (G) Ldha expression estimated by immunoblotting of whole tissue lysates of normal livers and tumors. Ponceau staining of membranes was used to confirm the protein loading. (H) LDH activity measured in the cytosolic fractions of tumors and normal livers from transgenic mice kept on doxycycline. All values are given as the mean ± s.d. See also Figure S1.