Effect of arginine on tumor growth in rats

1954 Cancer Research  
The experiments reported in this paper were undertaken because of the apparently conflicting findings that arginine both stimulates (1, 7) and inhibits (2â€"5, 13) the growth of tumor tissue. EXPERIMENTAL Solutions (at pH 7.4) of i@-arginine monohydro chlorid& (50 mg/ml in Experiments A and B [Table 1] and 100 rng/ml in Experiments C to H [Tables 1 and 2]) were injected subcutaneously into half of the 805 rats, weighing 2OOâ€"2@5O gm., of the Long-Evans strain bearing subcutaneous implants of
more » ... ther the U.C.L.A. fibrosarcoma or the Jensen sarcoma. An approximately 75-mm. cube of tumor tissue was implanted by trocar at one ventral site per animal in Experiments D to H, two such sites in Experiment C, and four sites in Experiments A and B. The administration of arginine was begun at the time of tumor implanta tion in Experiments A and B but was delayed until the tumor became palpable in all other ex periments. The control and experimental groups were matched as closely as possible in respect to the body weight of animals and size of tumors. The rats were maintained on Rockland pellets (Experiments A and B) or a modified Ershoff (12) diet (Experiments C to H). Body weight was de terinined periodically, and tumor size was esti mated from caliper measurements. RESULTS Some of the tumors (designated as â€oesmall―) grew very slowly and tended to regress, while others (designated as â€oelarge―) grew comparatively rapidly with no regression. At the end of the ex periments the average size of the â€oelarge― tumors was 3-25 times that of the â€oesmall― tumors. Every tumor could be classed clearly in one of these categories. In experiments (A and B) with the U.C.L.A. fibrosarcoma the percentage of small (measurable and nonmeasurable) tumors in creased following injections (starting the day of implantation) of 50 mg of arginine/rat/day. In Experiment A the incidence of small tumors was 30 per cent (26 of 87) in the treated rats, compared to I 1 per cent (9 of 83) in the control animals. In Experiment B, 95.5 per cent (84 of 88) of the tumors were classified as small in the treated ani mals, compared to 77 per cent (54 of 70) in the controls. On the other hand, 35 per cent (19 of 54) of the tumors were classified as large in rats following the injection (starting 6 days after implantation) of 50 mg of arginine/rat/day, compared to 19 per cent (11 of 58) in the controls. The large tumors grew more rapidly, and the small tumors regressed more rapidly in the treated than in the control rats. The results of Experiment D (under identical conditions) were the same as Experiment C in respect to the distribution of large and small tumors, although the two large tumors of the con trols grew more rapidly than the large tumors in the treated rats.
pmid:13150333 fatcat:ozvg6jlgarcpzj2gznyyaqyqzm