According to the paper, microbiota might delay the onset of cancer, with probiotic supplementation playing a role.
Data shows the gut microbiome influences many bodily processes and systems however the exact implications of dysbiosis are yet to be fully explained.
The microbiota has been shown to influence energy metabolism, beta-oxidation of lipids and bile acid.
In addition, its role in glutamine and tryptophan metabolism, as well as oxidative stress and immune response metabolites has been well documented.
Recent studies have largely focused on the regulatory and signalling pathways that are directly affected by the microbiome.
However, studies that directly examine the metabolic consequences of gut microbiome alterations are few and far between.
The science part
Researchers from the University of California, Los Angeles (UCLA) began by isolating the bacterium Lactobacillus johnsonii 456, which is abundant in beneficial bacteria. This Lactobacillus strain has many commercial applications with its cultures found in yogurt, kefir, kombucha and sauerkraut.
Next, the team used mice that were bred with an ATM gene mutation. This made them susceptible to ataxia telangiectasia (AT), a neurological disorder associated with a high incidence of leukaemia, lymphomas and other cancers.
The mice were then placed into one of two groups. One group were given only anti-inflammatory bacteria and the other received a mix of inflammatory and anti-inflammatory microbes that normally co-exist in the intestines.
In an analysis of the mice's urine and faeces, the scientists found that mice receiving only the beneficial microbiota produced metabolites that are known to prevent cancer.
Those mice also had more efficient fat and oxidative metabolism, which the researchers believe might also lower the risk for cancer.
The mice receiving only the beneficial bacteria formed lymphomas half as quickly as other mice. These mice also lived four times longer and had less DNA damage and inflammation.
Gut instinct
"Together, these findings lend credence to the notion that manipulating microbial composition could be used as an effective strategy to prevent or alleviate cancer susceptibility," the researchers write.
In the future, it is our hope that the use of probiotics-containing [supplements] would be a potential chemopreventive for normal humans, while the same type of microbiota would decrease tumour incidence in cancer susceptible populations."
Despite efforts in the field of AT research, the mechanisms that microbiota follow that cause lymphoma formation remain difficult to define.
It is known that ATM regulates the protective cellular response to oxidative stress by sensing double-stranded DNA breaks, thus inhibiting cell cycle progression.
As much as intestinal microbiota can exert a protective effect, its makeup can induce cancer development, for example Helicobacter pylori, inducing gastric cancer and lymphoma in WT mice and humans, as well as potentially influencing the response of cancer to therapies.
ATM-deficient mice have provided a suitable subject to investigate the progression of certain cancers. These subjects have been the focus of previous studies that demonstrated these mice developed lymphomas and died between 2 and 5 months of age.
In attempting to explain how the metabolic changes in mice were as a result of their gut microbiome composition, the UCLA team looked to the analysis of urine and faecal sample results.
The data suggested that certain microbiota caused a metabolic shift towards the upregulation of metabolites including kyneurenic acid, methyladenine and 3-methybutyrolactone.
These metabolites could weaken cancer-promoting signalling pathways, and have been previously shown protective abilities from certain cancer types, independent of the subject’s genetic make-up.
Source: PLOS One
Published online ahead of print, doi.org/10.1371/journal.pone.0151190
“Chemopreventive Metabolites Are Correlated with a Change in Intestinal Microbiota Measured in A-T Mice and Decreased Carcinogenesis.”
Authors: Amrita K. Cheema , Irene Maier , Tyrone Dowdy, Yiwen Wang, Rajbir Singh, Paul M. Ruegger, James Borneman, Albert J. Fornace Jr, Robert H. Schiestl