Oral administration of dietary scallion extract suppresses colorectal tumor growth in murine model

Colorectal cancer is a common malignancy and a leading cause of cancer death worldwide. Diet is known to play an important role in the etiology of colon cancer and dietary chemoprevention has recently received increasing attention for prevention and/or alternative treatment of colon cancers. Allium fistulosum L., also commonly known as scallion, is used as a popular spice or vegetable worldwide, and as traditional medicines in Asian cultures for treating a variety of diseases. The possible beneficial effects of dietary scallion on chemoprevention of colon cancer are evaluated in this study, using a subcutaneously inoculated CT-26 colon tumor model in BALB/c mice. Tumor lysates were subjected to western blotting for analysis of key inflammatory markers, ELISA for analysis of cytokines, and immunohistochemistry for analysis of inflammatory markers. Metabolite profiling of scallion extracts were analyzed by LC-MS/MS. Scallion extracts, particularly the hot-water extract, orally fed to mice at 50mg (dry weight)/kg body weight resulted in a significantly suppression of tumor growth and enhanced the survival rate of test mice. At the molecular level, scallion extracts inhibited the key inflammatory markers COX-2 and iNOS, and suppressed the expression of various cellular markers known to be involved in tumor apoptosis (apoptosis index), proliferation (cyclin D1 and c-Myc), angiogenesis (VEGF and HIF-1α), and tumor invasion (MMP-9 and ICAM-1), when compared with vehicle control-treated mice. Our findings may warrant further investigation for the use of common scallion as a chemopreventive dietary agent to lower the risk of colon cancer.