Gut Bacterium Found to Promote Colorectal Cancer Growth; Chinese University of Hong Kong Identifies Growth Signal

A gut bacterium that promotes KRAS-mutant colorectal cancer has been identified. Researchers at The Chinese University of Hong Kong found that a bacterium called Bacteroides acidifaciens boosts growth signals in mutant cancer cells, driving tumor growth.

A team led by Yu Jun and Professor Qi Chun Wong at The Chinese University of Hong Kong published the findings on the 4th in the international journal Cell Stem Cell.

The researchers analyzed microbes in tumors from patients with KRAS-mutant colorectal cancer and laboratory mice. They found that Bacteroides acidifaciens accumulated at particularly high levels in individuals with the mutation.

The bacterium promoted cancer cell proliferation in conjunction with KRAS mutations, which are found in about 45% of patients with colorectal cancer. By contrast, it had no notable effect in the control group with normal genes.

Specifically, the researchers found that SusF, a surface protein on the bacterium, binds to and stabilizes the host-cell protein ARHGEF2, promoting activated KRAS and RAF-MEK-ERK growth signaling.

The researchers said, “Targeting Bacteroides acidifaciens or the SusF-ARHGEF2 interaction could inhibit the progression of KRAS-mutant colorectal cancer.”

Colorectal cancer is the third most common cancer worldwide. KRAS mutations are known not only to be essential for tumor formation but also to cause resistance to epidermal growth factor receptor (EGFR) therapies.