What is already known
Gut microbes have been linked to various cancers, and several studies have shown that administering certain gut bacteria to people with some cancers can boost the recruitment of specific immune cells. However, little is known about the relationship between the microbiota and ovarian cancer — one of the most common causes of cancer death in women.
What this research adds
Researchers found that the feces of women with ovarian cancer differ from those of controls. Transferring gut microbes from ovarian cancer patients to mice with ovarian tumors accelerated tumor development. However, adding Akkermansia bacteria to the microbiota transplant reduced cancer progression — likely through the upregulation of T cell activation and the increased production of specific immune cells.
Conclusions
The findings tie the gut microbiota to immune surveillance of ovarian cancer and may inform new treatment approaches.
Although ovarian cancer is one of the most common causes of cancer death in women, the disease is challenging to diagnose early and is often resistant to treatments. Now, a study done in mice shows that specific gut bacteria can suppress the progression of ovarian cancer.
The findings, published in Cell Reports, tie the gut microbiota to immune surveillance of ovarian cancer and may inform new treatment approaches.
Gut microbes have been linked to various cancers, and several studies have shown that administering certain gut bacteria to people with some cancers can boost the recruitment of specific immune cells. However, little is known about the relationship between the microbiota and ovarian cancer.
To investigate this relationship, researchers led by Chaoyang Sun and Gang Chen at Huazhong University of Science and Technology set out to compare stool samples from 40 women with ovarian cancer to 40 women with a benign form of the disease.
Microbiota disturbance
The team found that the feces of women with ovarian cancer differ from those of controls. In particular, the levels of Akkermansia bacteria were reduced in ovarian cancer patients. “Loss of the Akkermansia genus is a featuring characteristic of patients with [ovarian cancer] that accompanies tumor progression upon the perturbance of gut microbiota composition,” the researchers say.
Transferring gut microbes from ovarian cancer patients to mice with ovarian tumors accelerated tumor development. Mice treated with antibiotics to deplete the gut microbiota before the transplant showed increased tumor progression compared to controls.
The abundance of Akkermansia was also reduced in mice treated with antibiotics. “These data suggest that the gut microbiota disturbance, especially the alteration of Akkermansia abundance, was closely related to [ovarian cancer] progression,” the researchers say.
Cancer progression
Adding Akkermansia bacteria to the microbiota transplant reduced cancer progression, further experiments showed. In mice that received the microbiota transplant from ovarian cancer patients, Akkermansia supplementation restored the gut barrier function and resulted in upregulated T cell activation.
Akkermansia supplementation was also linked to increased levels of the short-chain fatty acid acetate, which was in turn associated with an improved cancer-cell-killing ability of specific T cells.
“Considering gut bacteria administration is convenient to access, biologically safe, and possesses the ability to facilitate immune surveillance of [ovarian cancer], the Akkermansia or its analogs might warrant being validated in clinical trials for late-stage [ovarian cancer] in the near future,” the researchers say.
