Dietary branched-chain amino acid (BCAA) and tumor growth

The effects of high dietary BCAA on tumor growth was examined in adult male Fischer 344 rats inoculated with 106 viable MCA fibrosarcoma cells. Ten days after tumor inoculation, when tumors were of palpable size, rats were divided into two groups at random. The experimental(E) group was fed the AIN-76 diet supplemented with 4X the BCAA content of diet casein and the control(C) group was fed the AIN-76 made isonitrogenous with the E diet by glutamic acid supplementation. Five rats from each group were killed at days 0,3,6, and 9. Rats were injected with 14C-Tyrosine and 3H-Thymidine i.p. (2 and 4 uCi/100g BW, respectively) an hour before they were killed. The incorporation of 14C and 3H into the acid insoluble fraction of the tumor tissues samples were measured. Single cell suspension of tumor were prepared for cell cycle kinetics analysis using a Coulter EPICS IV flow microflorometer. The percentage of normal and hyperdiploid cells were analyzed. Results showed that both tumor size and weight were doubled at each time point the rats were killed. At day 0, the 3H and 14C incorporation were 32 +/- 10dpm and 27 +/- 4dpm/mg tumor, respectively. The 3H incorporation dropped in both diet groups at days 6 and 9 but the 14C incorporation showed a decrease only at day 9. These changes were statistically significant, P>0.05. No difference in the tumor growth parameters used in this study can be attributed to the high dietary BCAA