Alterative Expression of Angiogenic Proteins by Arginine in SW620 Cell-Inoculated Nude Mice

Background: Arginine (Arg) has been shown to possess numerous useful physiological properties. However, the effect of Arg on various cancers remains controversial. This study investigated the effect of Arg supplementation on highly metastatic human colorectal adenocarcinoma xenograft in nude mice. Methods: Nude mice (n=20) were inoculated with 1×10⁷ SW620 cells and randomly assigned to two groups. The control group (n=10) was fed a semipurified diet, the experimental group (n=10) was supplied an identical diet except that part of the casein was replaced by Arg, which provided 2% of the total energy intake. After consuming the respective diets for 5 weeks, tumors and blood were obtained for angiogenic protein measurement, and immunocytochemical findings of CD31 expressions in tumor tissues were analyzed. Results: Plasma matrix metalloproteinase-9, epidermal growth factor, vascular endothelial growth factor receptor concentrations, and tumor homogenate matrix metalloproteinase-9 and nitric oxide levels were higher in the Arg group than those of the control group (p<0.05). There were more CD31-positive cells and higher immunoreactive intensities in mice fed with Arg than those fed with the control diet. Conclusion: The results of this study suggest that dietary Arg supplementation may enhance angiogenic protein production in metastatic human colon cancer-implanted nude mice.