Gut microbiome research questions established cancer biomarkers and identifies novel bacterial links to colorectal cancer

In a recent study published in the journal natural medicine, a team of European researchers quantitatively characterized the microbiome profile to study the association between gut microbiota and malignant changes in the colon in colorectal cancer. They also aimed to identify microbiome-related covariates that may obscure the biological phenomena involved in the association between the gut microbiome and colorectal cancer.

Research: Microbiome confounders and quantitative profiling question predicted microbial targets in colorectal cancer development. Image credit: FOTOGRIN / Shutterstock

background

The incidence of colorectal cancer is increasing, especially among people under the age of 50. It is the third most prevalent cancer and has the second highest cancer-related mortality rate. However, early detection and treatment can effectively slow the progression of colorectal cancer and reduce the risk of death. Timely detection and removal of adenomas and polyps through colonoscopy is known to reduce the risk of colorectal cancer by 90%.

Recent studies on the gut microbiota have revealed that changes in the gut microbiota are associated with various disease phenotypes. Studies have also reported associations between bacterial markers. Fusobacterium It is present in the stool and lesions of colorectal cancer patients. However, it remains a challenge to identify risk factors for colorectal cancer and the role of confounding variables that can improve screening across populations.

About research

In this study, we quantitatively characterized the microbiota profile to determine its association with malignant changes in the colon. Researchers examined the microbial profiles of nearly 600 patients whose clinical symptoms required colonoscopies. This included patients with colorectal cancer. We then compared these microbial profiles with profiles from previous studies and existing datasets including colorectal cancer patients and controls.

Researchers also identified covariates that could potentially obscure or confound the biological phenomena underlying the association between the gut microbiome and colorectal cancer risk. purpose. They believe that although it is known that multiple variables can influence the gut microbiome profile, control for these covariates is not standardized. Factors such as water content are known to significantly influence overall variation in the gut microbiota, but are not controlled for in many studies.

Furthermore, the relative microbiome profiling approach, which expresses taxon abundance as a percentage and is the method primarily used in microbiome studies, raises various issues related to the interpretation of microbial composition and relative profiles. Therefore, quantitative microbiome profiling approaches that use normalized comparisons of profiles across different conditions or samples can help reduce the rate of false negatives and false positives.

In the current study, researchers used clinical assessment and colonoscopy to classify participants into three groups. Patients with no evidence of colonic involvement, patients with precancerous lesions or polyps with a size of 6 mm to 10 mm and fewer than 10, and patients with various stages of colorectal cancer. Flow cytometry was used to measure the microbial burden in stool samples collected from participants.

In addition, the mass loss after lyophilization of the fecal samples was used to determine the water content and the fecal concentration of calprotectin was also determined. For microbial profiling, deoxyribonucleic acid (DNA) was extracted from fecal samples, and 16S ribosomal ribonucleic acid (RNA) sequences were amplified using polymerase chain reaction (PCR).

result

The results showed that the following biomarkers for colorectal cancer have been established. FusobacteriumAfter adjusting for covariates such as body mass index (BMI), fecal calprotectin (an indicator of intestinal inflammation), and transit time (measured as a proxy for water content), there was no significant association with colorectal cancer diagnosis. There was no.

However, this study found a strong association between colorectal cancer risk and the following bacterial species: Prevotella intermedia, Porphyromonas asacharolitica, Peptostreptococcus anaerobius, Parvimonas micula, Diary Star Pneumosintesand vagina anaerococcus. Researchers believe these bacteria should be targeted as potential biomarkers of colorectal cancer risk.

Furthermore, those who had no lesions in the colon but whose fecal immunochemistry test justified the need for colonoscopy had higher Bacteroides 2 enterotype abundance, lower microbial abundance, and cell counts. It exhibits all the hallmarks of an imbalance of the gut microbiota, including a decrease in gut microbiota and a decrease in gut microbiota. Increased abundance of butyrate-producing bacteria, pro-inflammatory bacteria, and increased concentration of calprotectin in feces. These findings also highlight the uncertainties involved in determining sound controls for studies related to the cancer microbiome.

conclusion

Overall, quantitative characterization of the microbial profile of patients with colorectal cancer, precancerous polyps, or lesions reveals that established biomarkers of colorectal cancer risk include water content, BMI, and fecal calculus. It was found that the results were not significant when adjusting for covariates such as protectin. However, strong associations have been found between many other bacterial species and colorectal cancer, and these may be targeted as biomarkers.

Additionally, this finding reveals that individuals without colonic lesions but with positive fecal immunochemical tests have an enrichment of dysbiosis enterotypes in their microbiome, indicating that dysbiosis enterotypes are enriched in the cancer microbiome. character has been revealed.