Abstract
Influence of intestinal microbiota on autophagy in colorectal cancer.
Author
Rashad Nawfal
Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut., Beirut, Lebanon
info_outline
Rashad Nawfal, Mohamed Noureldein, Sara Bitar, Sarah Al Moussawi, Batoul Dia, Assam El-Osta, Fadlo Raja Khuri, Assaad Antoine Eid
Full text
Authors
Rashad Nawfal
Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut., Beirut, Lebanon
info_outline
Rashad Nawfal, Mohamed Noureldein, Sara Bitar, Sarah Al Moussawi, Batoul Dia, Assam El-Osta, Fadlo Raja Khuri, Assaad Antoine Eid
Organizations
Department of Anatomy, Cell Biology and Physiological Sciences, Faculty of Medicine and Medical Center, American University of Beirut., Beirut, Lebanon, Epigenetics in Human Health and Disease, Department of Diabetes, Central Clinical School, Monash University, Melbourne, Australia, American University of Beirut/Emory University Winship Cancer Institute, Beyrouth, GA, Lebanon
Abstract Disclosures
Research Funding
Other Foundation
Qatar National Research Foundation, American University of Beirut Medical Research Plan
Background:
Gut microbiota favors butyrate-forming bacteria and maintains homeostatic balance which is revoked during the development of colorectal cancer (CRC)-associated dysbiosis. Butyrate is a short chain fatty acid that acts as a lysine deacetylase inhibitor and is known to activate the AMPK pathway as well as inhibiting inflammation and ROS production. The role of AMPK activation in diabetes-associated complications including colorectal cancer is poorly understood. This project examines the role of dysbiosis and butyrate on CRC onset and disease progression.
Methods:
C57BL/6-
Apc
tm1Tyj
/J (
APC
)
mice that spontaneously develop CRC were used and the study included four groups of mice (n = 3 for each): (1) Control C57BL/6, (2)
APC
, (3)
APC
treated with probiotics rich in butyrate forming bacteria and (4)
APC
treated with butyrate. Probiotics and butyrate were administered by oral gavage and intraperitoneally, respectively. Feces were collected at early (when CRC is developed at 8 weeks of age) and late (at 16 weeks of age, day of sacrifice) timepoints, and microbial composition was identified by 16S rRNA sequencing. Mice colons following sacrifice were also harvested for molecular, anatomical, and histological analyses.
Results:
The butyrate kinase gene was assessed in fecal samples. Butyrate forming bacteria were significantly reduced in
APC
mice but elevated in
AP
C receiving probiotics when compared to control mice. Anatomically, polyp number was reduced in groups receiving probiotics and butyrate when compared to
APC
mice without treatment (p < 0.01 for each). Histologically, butyrate and probiotics ameliorated the histological changes observed in in
APC
mice as assessed by PAS staining. Furthermore, we observed a decrease in goblet cells, and increased number of crypts on distal colon histology. The expression of NADPH Oxidase 4 (NOX4) and TIGAR, a P53 target protein expression were significantly increased in
APC
mice and restored following the administration of probiotics or butyrate. ROS production assessed by HPLC showed similar pattern across our 4 groups. The expression of the autophagy markers Beclin-1, ATG-12 and LC3-β were restored to control levels after probiotics and butyrate administration. 16S rRNA sequencing of fecal samples revealed significant differences in microbial composition between groups, most significantly at 16 weeks with Lachnospiraceae (ASV 175), Muribaculaceae (ASV 53) and Muribaculaceae (ASV 584) were decreased in
APC
when compared to control mice ( < -7 Log2 fold change each).
Conclusions:
Collectively, our data suggests colorectal cancer is associated with dysbiosis characterized by lower abundance of butyrate-forming bacteria. This disruption leads to over-expression of NOX4, and ROS production associated with alteration in autophagy, thus worsening gastrointestinal complications and CRC. Restoring butyrate forming bacteria might serve as an effective adjuvant to therapy in CRC.
Clinical status
Pre-clinical
3 organizations
2 drugs
14 targets
Organization
American University of Beirut/Emory University Winship Cancer Institute, Beyrouth, GA, LebanonDrug
probioticsDrug
butyrateTarget
Beclin-1Target
ATG-12Target
ROS productionTarget
InflammationTarget
colorectal cancerTarget
LC3-βTarget
gut microbiotaTarget
lysine deacetylaseTarget
AMPK pathwayTarget
Autophagy markersTarget
NADPH Oxidase 4 (NOX4)Target
TIGARTarget
NOX4