Race-dependent association of sulfidogenic bacteria with colorectal cancer

Abstract

Objective Colorectal cancer (CRC) incidence is higher in African Americans (AAs) compared with non-Hispanic whites (NHWs). A diet high in animal protein and fat is an environmental risk factor for CRC development. The intestinal microbiota is postulated to modulate the effects of diet in promoting or preventing CRC. Hydrogen sulfide, produced by autochthonous sulfidogenic bacteria, triggers proinflammatory pathways and hyperproliferation, and is genotoxic. We hypothesised that sulfidogenic bacterial abundance in colonic mucosa may be an environmental CRC risk factor that distinguishes AA and NHW. Design Colonic biopsies from uninvolved or healthy mucosa from CRC cases and tumour-free controls were collected prospectively from five medical centres in Chicago for association studies. Sulfidogenic bacterial abundance in uninvolved colonic mucosa of AA and NHW CRC cases was compared with normal mucosa of AA and NHW controls. In addition, 16S rDNA sequencing was performed in AA cases and controls. Correlations were examined among bacterial targets, race, disease status and dietary intake. Results AAs harboured a greater abundance of sulfidogenic bacteria compared with NHWs regardless of disease status. Bilophila wadsworthia-specific dsrA was more abundant in AA cases than controls. Linear discriminant analysis of 16S rRNA gene sequences revealed five sulfidogenic genera that were more abundant in AA cases. Fat and protein intake and daily servings of meat were significantly higher in AAs compared with NHWs, and multiple dietary components correlated with a higher abundance of sulfidogenic bacteria. Conclusions These results implicate sulfidogenic bacteria as a potential environmental risk factor contributing to CRC development in AAs.

Largest brain cancer study offers clues to inherited risk

“…In a Journal of Clinical Oncology study published in 2013, they showed that depending on the disease risk, comorbidities, and graft-versus-host disease, lasting remissions were seen in 45% to 75% of allogeneic transplant patients with advanced hematologic malignancies who were treated with minimal-intensity conditioning regimens for allogeneic transplant patients with advanced hematologic malignancies. 1 The 5-year survival rates ranged from 25% to 60%.…”

“…The research, published in Nature Genetics, uncovered 13 new genetic errors associated with an increased risk of glioma, the most common form of brain cancer. 1 One of these changes increases the risk by as much a third, whereas the other errors increase the risk by at least 15% each. The new information can assist physicians in identifying people who are at significantly increased risk of developing the disease.…”

“…The new information can assist physicians in identifying people who are at significantly increased risk of developing the disease. 1 The study, led by researchers at the Institute for Cancer Research, London, along with colleagues in Europe and the United States, included more than 30,000 people with and without glioma. The disease, which accounts for 40% of all brain tumors, presents challenges to health care providers on a number of fronts; this is mainly related to the fact that there are no reliable means of early detection, and current treatments are not very effective.…”

Race-specific differences in mucosal sulfidogenic bacteria modify colon cancer risk

“…The study by Yazici et al 5 is important because it provides compelling evidence that the gut microbiome plays a significant part in defining cancer risk in AAs by modifying sulfur metabolism. Hydrogen sulfide (H2S) is a regulator of gut health linked with multiple GI diseases, and its inflammatory, cytotoxic and genotoxic effects have been well described 6 7.…”

“…Yazici et al 5 systematically analysed mucosal biopsies from a large cohort of AA and non-Hispanic white (NHW) subjects after routine bowel preparation during endosocopy and surgery (n=329). The study employed a quantitative analysis of SRBs using quantitative PCR and a taxonomic examination of the mucosal ecology based on 16S rRNA analysis of on and off cancer biopsies in both cohorts to provide a comprehensive map of microbiome biology.…”