The Effects of Intestinal Bacteria On the Growth of Cancer Cells

Abstract

There is increasing evidence that the microbiome within individuals can influence on the overall health of those individuals. Many bacteria are considered probiotic in which their presence in the intestine benefits the health of the individual. The bacteria that belong to the genus Bifidobacterium are Gram-positive anaerobic bacteria which are normal intestinal inhabitants that have demonstrated to have probiotic properties. Bacterial strains that were isolated from the feces of residents of a top five longevity village in China were examined. The number of residents in the village who live to be 100 years old is five time the international average and the incidence of cancer is ten times lower than in the United States. One bacterial strain was identified as Bifidobacterium longum while two strains were identified as a members of the Lactobacillus genus. In order to investigate the possible contributing role of these bacteria to the longevity and low cancer rates of this population, supernatants from these bacteria were added to a colon cancer line, HCT-8. The growth of the cancer cells were determined by a MTT assay. The results demonstrate supernatants from these bacterial strains inhibit the growth and/or kill the HCT-8 cells. Boiling the bacterial supernatants before adding it to the HCT-8 did not affect the detrimental effect on the HCT-8 cells indicating that the inhibitory substance is heat stable.