Race-dependent association of sulfidogenic bacteria with colorectal cancer.
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.



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.



AAs harboured a greater abundance of sulfidogenic bacteria compared with NHWs regardless of disease status.Bilophila wadsworthia-specificdsrAwas 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.



These results implicate sulfidogenic bacteria as a potential environmental risk factor contributing to CRC development in AAs.
Division of Gastroenterology and Hepatology, University of Illinois College of Medicine at Chicago, Chicago, Illinois, USA.
Cemal
C
Yazici
Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Patricia G
PG
Wolf
Center for Clinical and Translational Science, University of Illinois at Chicago, Chicago, Illinois, USA.
Hajwa
H
Kim
Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Tzu-Wen L
TL
Cross
Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Karin
K
Vermillion
Division of Gastroenterology and Hepatology, University of Illinois College of Medicine at Chicago, Chicago, Illinois, USA.
Timothy
T
Carroll
Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA.
Gaius J
GJ
Augustus
Division of Digestive Diseases and Nutrition, Rush University Medical Center, Chicago, Illinois, USA.
Ece
E
Mutlu
Division of Academic Internal Medicine and Geriatrics, University of Illinois College of Medicine at Chicago, Chicago, Illinois, USA.
Lisa
L
Tussing-Humphreys
Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, USA.
Carol
C
Braunschweig
Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA.
Rosa M
RM
Xicola
Division of Gastroenterology and Hepatology, University of Illinois College of Medicine at Chicago, Chicago, Illinois, USA.
Barbara
B
Jung
Section of Digestive Diseases, Yale University, New Haven, Connecticut, USA.
Xavier
X
Llor
Department of Cellular and Molecular Medicine, University of Arizona, Tucson, Arizona, USA.
Nathan A
NA
Ellis
Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
H Rex
HR
Gaskins
D000230:Adenocarcinoma / Q000208:ethnology / Q000209:etiology / Q000382:microbiology*; D000328:Adult; D001741:Black or African American; D000368:Aged; D016022:Case-Control Studies; D002641:Chicago; D003106:Colon / Q000382:microbiology*; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000209:etiology / Q000382:microbiology*; D004032:Diet / Q000009:adverse effects; D004041:Dietary Fats / Q000009:adverse effects; D004044:Dietary Proteins / Q000009:adverse effects; D005260:Female; D054624:Health Status Disparities; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D016999:Sulfur-Reducing Bacteria / Q000302:isolation & purification*; D044465:White People
D004041:Dietary Fats; D004044:Dietary Proteins
COLONIC MICROFLORA; COLORECTAL CANCER; HYDROGEN SULPHIDE