Inositol hexaphosphate-induced enhancement of natural killer cell activity correlates with suppression of colon carcinogenesis in rats

Abstract

To investigate the anti-neoplastic effect of inositol hexaphosphate (InsP(6) or phytic acid) on dimethylhydrazine (DMH)-induced colon tumor in rats and its effect on blood natural killer (NK) cell activity. Healthy Wistar rats, 4 wk old, were divided into control group (fed with common food) and InsP(6) group (fed with common food +2% sodium inositol hexaphosphate in the drinking water), 15 rats in each group. Both groups were injected with 1,2-dimethylhydrazine subcutaneously (20 mg/kg body weight) once a week for 20 wk. Rats were killed after 21 wk. The whole large intestine was isolated to determine the general condition of tumors and to test blood NK cell activity by lactate-dehydrogenase-release assay. Administration of InsP(6) significantly increased blood NK cell activity in DMH-induced colorectal tumor in rats. InsP(6) group had a smaller tumor size on average and a smaller number of tumors than the control group. Its mortality was also higher than that in control. However, the variables of body weight and tumor incidence were not significantly different between the two groups. InsP(6) can increase blood NK cell activity in DMH-induced colon tumor in rats and inhibit tumor growth and metastasis in rats.