Arginine (Arg) is a nonessential amino acid which has many physiologic functions, especially in regard to nitric oxide (NO) and immunity. An enzyme, nitric oxide synthase (NOS), converts arginine to NO. There is evidence that NO plays a role in the anti-cancer activity of the immune system. On the other hand, NO has been implicated with negative effects in some diseases.
The authors say we need a dietary strategy to reduce the incidence of colorectal cancer and to improve cancer prognosis. Previous studies suggest a positive role of arginine in colorectal carcinoma. The present study tested the effect of arginine on cells, the importance of NO on angiogenesis and the effect of dietary Arg on the development of colorectal tumor grafts and natural killer (NK) cell activity in mice. (NK cells are part of the immune system which hunts and kills abnormal cells in the body.)
The study showed that the mice treated with dietary Arg had smaller tumor sizes than the control animals which were not treated. Mice treated with Arg had higher NK cell activity in the spleen.
Growing colorectal adenocarcinoma cells at physiologic, or higher, concentrations of Arg reduced angiogenesis, a beneficial effect, in colorectal cancer cells. (Angiogenesis is necessary for tumor growth and metastasis.) NOS inhibitors abolished the effect of high Arg use.
NO plays many roles in the progression of cancer. NO levels were higher in tumors when mice were supplemented with arg. Arg supplementations may have increased NO in the tumor and host cells and, thereby, may have reduced tumor progression.
NK cell activity is increased by Arg supplementation of the mice.
CONCLUSION: The findings of this study are consistent with idea that Arg supplementation inhibits colon cancer progression by increasing the NO production and increasing NK cell activity.
NOTE: Read about the chemoprevention of intestinal cancer with milk thistle.
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PMID: 19447018.
Summary #374.
