Bacteria Could Be Targets for a Colon Cancer Vaccine

Two bacterial strains may be linked to higher rates of colon cancer in some countries. This may provide a target for the development of measures such as vaccines to cut rates of colon cancer.

The paper was published as a Personal View in The Lancet Microbe.

E. coli linked to several cancer types

Certain bacterial species have been linked to colon cancer, but to date, researchers have been unable to find a direct link between the bacteria and cancer-causing mutations.

Two major strains of Escherichia coli (E. coli) primarily increase colon cancer risk. They are common in industrialized countries, where they primarily cause urinary and bloodstream infections but not food poisoning.

The increased cancer risk from these strains is thought to be due to the production of the molecule colibactin. According to a previous study, colibactin causes DNA breaks in human cells and can damage surrounding tissue.

However, colibactin production is a rare feature of E. coli. Just two strains out of several hundred have managed to establish stable maintenance of the colibactin-producing genes, and its production requires a lot of cellular energy.

As the urinary tract is a common site of E. coli infection, these strains may also play a role in the development of bladder and prostate cancers. If this is indeed the case, vaccines or probiotics may be able to prevent the circulation of these bacteria and reduce cancer risk.

To probe the risk between the colibactin-producing E. coli and cancer incidence, researchers compared rates of colon, bladder and prostate cancer against global data tracking strains of E. coli bacteria.

Colon cancer more common in industrialized countries

“E. coli can be found around the world, in many different forms, and understanding how strains of this bacteria impact humans differently can give us a more complete picture of health and disease,” said Dr. Tommi Mäklin.

“Having access to global genomic data on which strains are found in an area can uncover new trends and possibilities, such as strains in industrialised countries potentially being linked to the risk of certain cancers,” said Mäklin.

The data revealed that the two colibactin-producing E. coli strains were commonly detected in industrialized countries. These countries in turn also had higher rates of bowel, bladder and prostate cancers.

Meanwhile, the same strains were rarely found in relatively under-resourced countries such as Bangladesh and Pakistan, where rates of these cancers are also lower.

Though large-scale investigation is needed, the researchers hypothesize that differences in cancer incidence globally could be affected by exposure to these colibactin-producing strains. Further studies, including widespread tumor sampling, may help to clarify the findings.

“Understanding more about the interactions between E. coli and cancer risk highlights the impact our microbiome has on our health and is a crucial avenue to explore if we want to work with our bodies to help combat certain conditions,” said Dr. Trevor Lawley, co-senior author of the study and a group leader at the Wellcome Sanger Institute.

Teasing out links between E. coli and colon cancer

The findings provide a strong foundation for further research into links between bacteria and various cancer types and may drive the search for interventions to reduce the risk of colibactin-related cancers, such as vaccines or probiotics.

“Vaccines or other interventions that target these E. coli strains could offer huge public health benefits,” said Prof. Jukka Corander, co-senior author of the study and associate faculty at the Wellcome Sanger Institute. “Such as reducing the burden of infections and lessening the need for antibiotics to treat these, as well as reducing the risk of cancers that could be linked to the effects of colibactin exposure.”

“As not all bacterial strains can live in your gut at the same time, they have to compete for space and resources,” said Lawley. “In the future, it could be possible to develop therapeutic probiotics that help to displace unwanted bacterial strains, such as the ones that release colibactin.”

Reference: Mäklin T, Taira A, Arredondo-Alonso S, et al. Geographical variation in the incidence of colorectal cancer and urinary tract cancer is associated with population exposure to colibactin-producing Escherichia coli. Lancet Microbe. 2024. doi: 10.1016/j.lanmic.2024.101015