Metabolic profiling of Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) tissue by ¹H-NMR analysis as evidence for unusual phospholipid metabolism

Friederike Teichert

Cancer Biomarkers and Prevention Group, University of Leicester, UK

BACKGROUND. The TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) mouse model has frequently been used in preclinical studies with chemotherapeutic/chemopreventive rationales. Here the hypothesis was tested using
¹H-NMR-based metabolic profiling that the TRAMP tumor metabolic phenotype resembles that reported for human prostate cancer.

METHODS. Extracts or intact tissues of normal prostate from 8 (young) or 28 (old) week old C57BL/6J wild-type mice or of prostate tumor from age-matched TRAMP mice were analyzed by ¹H-NMR. Results were compared with immunohistochemical findings. Expression of choline kinase was studied at the protein and mRNA levels.

RESULTS. In young TRAMP mice presenting with zonal hyperplasia, the ratio of glycero-phosphocholine (GPC) to phosphocholine (PC) was 22 % below that in wild-type mice (p<0.05). In old TRAMP mice with well-defined malignancy, reduced tumor levels of citrate (49%), choline (33%), PC (57%), GPC (66%) and glycero-phosphoinositol (61%) were observed relative to normal prostate (p<0.05). Hierarchical cluster analysis of metabolite levels distinguished between normal and malignant tissue in old, but not young mice. While the reduction in tissue citrate resembles human prostate cancer, low levels of choline species in TRAMP tumors suggest atypical phospholipid metabolism as compared to human prostate cancer. TRAMP tumor and normal prostate tissues did not differ in expression of choline kinase, which is over-expressed in human prostate cancer.

CONCLUSION. Although prostate cancer in TRAMP mice shares some metabolic features with that in humans, it differs with respect to choline phospholipid metabolism, which could impact upon the interpretation of results from biomarker or chemotherapy/chemoprevention studies.