Can Bacteria and Fungi Control Tumors?
Written by Aditi Mahajan
Edited by Carolyn Chiu
Jan 23rd 2022
Edited by Carolyn Chiu
Jan 23rd 2022
Cancer is the second leading cause of death in the United States of America. Different cancer treatments include: chemotherapy, immunotherapy, surgery, and radiation. Previous research has found that the efficacy of both chemotherapy and immunotherapy are related to the gut microbiome of the patient. The gut microbiome is composed of a large variety of bacteria, fungi, viruses, and archaea. However, little has been studied about how our microbiome responds to radiation therapy. Dr. Shiao and his colleagues at the Department of Biomedical Sciences in Los Angeles, CA sought to remedy this.
Dr. Shiao and his team found that certain bacteria help one another to bolster a T-cell response that fights tumorous growths after radiation therapy (Shiao eat al., 2021). T-cells are immune cells in the body that protect it from infection and control the body’s response to cancerous growths. Some of the bacteria he found that could cause this tumor-killing response are Enterococcus hirae and Barnesiella intestinihominis (Shiao eat al., 2021). Interestingly, this regulatory response that the body undergoes, is controlled by another component in our microbiomes: fungi. When bacteria in the human intestine are depleted, symbiotic fungi can overrun the intestines and take their place. Fungi help macrophages, white blood cells that surround and kill organisms, suppress anti-tumor T-cells (Shiao eat al., 2021). They are also partially responsible for preventing the T-cells from attacking the natural cell growth in the body. The researchers have also found that tumor-associated macrophages can detect the presence of fungi through a controlled mechanism (Shiao eat al., 2021). Different species of bacteria and fungi in our intestines have what is called a commensal symbiotic relationship. In a commensal relationship, one species benefits from the other while the other species is unaffected. The human gut has commensal bacteria and commensal fungi that work together to create many controlled feedback loops to protect the body from cancer.
Looking at the microbiome and the body’s natural regulatory responses towards tumors can help us understand more about who is at risk for certain cancers and how tumors can be controlled. More research needs to be done to identify the specific pathways that allow fungi and bacteria to work together to fight tumors in the body, but the current findings are hopeful.
Works Cited
Shiao, S. L., Kershaw, K. M., Limon, J. J., You, et al. (2021). Commensal bacteria and fungi differentially regulate tumor responses to radiation therapy. Cancer cell, 39(9), 1202–1213.e6. https://doi.org/10.1016/j.ccell.2021.07.002