If your neighbor tells you about using antibiotics to treat liver cancer you might think he's insane. Surprisingly, he's not, because scientists have found the connection of certain bad bacteria living in the human intestines and antitumor immune function, and antibiotic can deplete those bad bacteria.
Researchers in the Center for Cancer Research (CCR) at the National Cancer Institute (NCI) have published the research paper in Science today. It showed that bacteria found in the gut of mice affect the liver's antitumor immune function.
The researchers carried out a series of experiments with mice. They used three mouse liver cancer models, and found that when they depleted gut bacteria using an antibiotic "cocktail," the mice that had the antibiotics developed fewer and smaller liver tumors and had reduced metastasis to the liver. As the research went deeper, it's found that antibiotic treatment increased the numbers of a type of immune cell called NKT cells in the livers of the mice, and the accumulation of the NKT cells in the liver resulted from an increase in the expression of a protein called CXCL16 on cells that line the inside of capillaries in the liver, and the expression of CXCL16 can be controlled by bile acids, which are formed in the liver and help to break down fats during digestion.
What affects bile acids then? This becomes the critical problem.
Finally, the investigators found that one bacterial species, Clostridium scindens, controls metabolism of bile acids in the mouse gut—and ultimately CXCL16 expression, NKT cell accumulation, and tumor growth in the liver.
These research results are still preliminary, but the novel mechanism described in this study could potentially apply to cancer patients.