THERAPEUTIC TUMOR-SPECIFIC CELL-CYCLE BLOCK INDUCED BY METHIONINE STARVATION IN-VIVO

The ability to induce a specific cell cycle block selectively in the t umor could have many uses in chemotherapy. In the present study we hav e achieved this goal of inducing a tumor-specific cell cycle block in vivo by depriving Yoshida sarcoma-bearing nude mice of dietary methion ine. Further, we demonstrate that methionine depletion also causes the tumor to eventually regress. The antitumor effect of methionine deple tion resulted in the extended survival of the tumor-bearing mice. The mice on the methionine-deprived diets maintained their body weight for the time period studied, indicating that tumor regression was not a f unction of body weight loss. The data reported here support future exp eriments utilizing methionine depletion as a target for tumor-selectiv e cell cycle-dependent therapy.