Free fatty acids receptors 2 and 3 control cell proliferation by regulating cellular glucose uptake

BACKGROUND Colorectal cancer(CRC)is a worldwide problem,which has been associated with changes in diet and lifestyle pattern.As a result of colonic fermentation of dietary fibres,short chain free fatty acids are generated which activate free fatty acid receptors(FFAR)2 and 3.FFAR2 and FFAR3 genes are abundantly expressed in colonic epithelium and play an important role in the metabolic homeostasis of colonic epithelial cells.Earlier studies point to the involvement of FFAR2 in colorectal carcinogenesis.AIM To understand the role of short chain FFARs in CRC.METHODS Transcriptome analysis console software was used to analyse microarray data from CRC patients and cell lines.We employed short-hairpin RNA mediated down regulation of FFAR2 and FFAR3 genes,which was validated using quantitative real time polymerase chain reaction.Assays for glucose uptake and cyclic adenosine monophosphate(cAMP)generation was done along with immunofluorescence studies to study the effects of FFAR2/FFAR3 knockdown.For measuring cell proliferation,we employed real time electrical impedancebased assay available from xCELLigence.RESULTS Microarray data analysis of CRC patient samples showed a significant down regulation of FFAR2 gene expression.This prompted us to study the FFAR2 in CRC.Since,FFAR3 shares significant structural and functional homology with FFAR2,we knocked down both these receptors in CRC cell line HCT 116.These modified cell lines exhibited higher proliferation rate and were found to have increased glucose uptake as well as increased level of glucose transporter 1.Since,FFAR2 and FFAR3 signal through G protein subunit(Gαi),knockdown of these receptors was associated with increased cAMP.Inhibition of protein kinase A(PKA)did not alter the growth and proliferation of these cells indicating a mechanism independent of cAMP/PKA pathway.CONCLUSION Our results suggest role of FFAR2/FFAR3 genes in increased proliferation of colon cancer cells via enhanced glucose uptake and exclude the role of PKA mediated cAMP signalling.Alternate pathways could be involved that would ultimately result in increased cell proliferation as a result of down regulated FFAR2/FFAR3 genes.This study paves the way to understand the mechanism of action of short chain FFARs in CRC.

Role of short chain fatty acids in gut health and possible therapeutic approaches in inflammatory bowel diseases

Inflammatory bowel diseases(IBDs) are characterized by inflammation in the gastrointestinal tract and include Ulcerative Colitis and Crohn’s Disease.These diseases are costly to health services,substantially reduce patients’ quality of life,and can lead to complications such as cancer and even death.Symptoms include abdominal pain,stool bleeding,diarrhea,and weight loss.The treatment of these diseases is symptomatic,seeking disease remission.The intestine is colonized by several microorganisms,such as fungi,viruses,and bacteria,which constitute the intestinal microbiota(IM).IM bacteria promotes dietary fibers fermentation and produces short-chain fatty acids(SCFAs) that exert several beneficial effects on intestinal health.SCFAs can bind to G protein-coupled receptors,such as GPR41 and GPR43,promoting improvements in the intestinal barrier,anti-inflammatory,and antioxidant effects.Thus,SCFAs could be a therapeutic tool for IBDs.However,the mechanisms involved in these beneficial effects of SCFAs remain poorly understood.Therefore,this paper aims to provide a review addressing the main aspects of IBDs,and a more detailed sight of SCFAs,focusing on the main effects on different aspects of the intestine with an emphasis on IBDs.