American cancer biologists have discovered that lung tumors could hijack bacteria within the lung to promote their own survival.
The study published on Thursday in the journal Cell showed that the altered bacterial population creates an inflammatory environment that helps the tumor cells to grow.
This research "opens up multiple potential avenues toward lung cancer interception and treatment," said the paper's senior author Tyler Jacks, director of Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology (MIT).
The researchers found those mice with lung cancer and raised in a sterile condition had smaller tumors than those raised under normal conditions.
Therefore, treating the mice with antibiotics or blocking the immune cells provoked by the bacteria can significantly reduce the size of tumors, according to the study.
A possible reason for the intensified bacterial activity is that tumors obstruct the airway and prevent bacteria from being cleared from the lungs.
The study showed that the bacterial expansion induced immune cells called gamma delta T cells to proliferate and begin secreting inflammatory molecules called cytokines. Those molecules create a pro-growth environment for the tumor cells.
Jin Chencheng, an MIT postdoc and the lead author of the paper, called it a "feed-forward loop" that forms a vicious cycle to further promote tumor growth.
The researchers found that when they treated the mice with antibiotics either two or seven weeks after the tumors began to grow, the tumors shrank by about 50 percent.
The tumors in mice also shrank if they were given drugs that block immune cells, according to the study.