Figure 5. Dietary methionine restriction enhances the antitumor effects of cycloleucine in vivo.

Female NSG mice with orthotopic GILM2-mCherry mammary tumors were randomized into four groups (10 mice per group): control diet plus vehicle, control diet plus cycloleucine (25 mg/kg twice weekly for 4 doses, indicated by arrows), methionine-free diet plus vehicle, or methionine-free diet plus cycloleucine (25 mg/kg twice weekly for 4 doses). Mice were started on their respective diets 2 weeks after tumor cell inoculation, and the diets were continued throughout the treatment period. a, Left panel, percentage original mammary tumor volume (at 2 weeks) in each treatment group (mean ± SEM, n = 10 mice per group). Right panel, body weight of mice at the end of the study. b, Plasma levels of Met, SAM and SAH in the mice in each treatment group after two weeks (mean ± SEM, n = 3 mice per group). c, Immunoblot analysis of MAT2A expression in mammary tumors from mice receiving control diet or methionine-free diet for 2 weeks. d, Left panel, representative whole lung images by fluorescence microscopy. Right panel, the percentage of the surface area occupied by lung metastases (mean ± SEM, n = 10 mice per group). e, the percentage active caspase-3-positive tumor cells in mammary tumors (left panel) or metastatic lung tumors (right panel) at the end of the study (mean ± SEM, n = 3 tumors per group). In all panels, *, P < 0.05, **, P < 0.01, ***, P < 0.001 versus vehicle-treated mice or the indicated comparison.