title: Bile acid: a potential inducer of colon cancer stem cells.
abstract: Although the unconjugated secondary bile acids, specifically deoxycholic acid (DCA) and lithocholic acid (LCA), are considered to be risk factors for colorectal cancer, the precise mechanism(s) by which they regulate carcinogenesis is poorly understood. We hypothesize that the cytotoxic bile acids may promote stemness in colonic epithelial cells leading to generation of cancer stem cells (CSCs) that play a role in the development and progression of colon cancer.
  
  
  
  Normal human colonic epithelial cells (HCoEpiC) were used to study bile acid DCA/LCA-mediated induction of CSCs. The expression of CSC markers was measured by real-time qPCR. Flow cytometry was used to isolate CSCs. T-cell factor/lymphoid-enhancing factor (TCF/LEF) luciferase assay was employed to examine the transcriptional activity of β-catenin. Downregulation of muscarinic 3 receptor (M3R) was achieved through transfection of corresponding siRNA.
  
  
  
  We found DCA/LCA to induce CSCs in normal human colonic epithelial cells, as evidenced by the increased proportion of CSCs, elevated levels of several CSC markers, as well as a number of epithelial-mesenchymal transition markers together with increased colonosphere formation, drug exclusion, ABCB1 and ABCG2 expression, and induction of M3R, p-EGFR, matrix metallopeptidases, and c-Myc. Inhibition of M3R signaling greatly suppressed DCA/LCA induction of the CSC marker ALDHA1 and also c-Myc mRNA expression as well as transcriptional activation of TCF/LEF.
  
  
  
  Our results suggest that bile acids, specifically DCA and LCA, induce cancer stemness in colonic epithelial cells by modulating M3R and Wnt/β-catenin signaling and thus could be considered promoters of colon cancer.
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.|Department of Internal Medicine, Wayne State University, Detroit, MI, 48201, USA.
authors.forename: Lulu
authors.initials: L
authors.lastname: Farhana
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.|Karmanos Cancer Institute, Detroit, MI, 48201, USA.|Department of Internal Medicine, Wayne State University, Detroit, MI, 48201, USA.
authors.forename: Pratima
authors.initials: P
authors.lastname: Nangia-Makker
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.
authors.forename: Evan
authors.initials: E
authors.lastname: Arbit
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.
authors.forename: Kathren
authors.initials: K
authors.lastname: Shango
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.
authors.forename: Hamidah
authors.initials: H
authors.lastname: Mahmud
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.|Department of Internal Medicine, Wayne State University, Detroit, MI, 48201, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Hadden
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA.|Department of Internal Medicine, Wayne State University, Detroit, MI, 48201, USA.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Veterans' Affairs Medical Center, 4646 John R, Detroit, MI, 48201, USA. a.majumdar@wayne.edu.|Karmanos Cancer Institute, Detroit, MI, 48201, USA. a.majumdar@wayne.edu.|Department of Internal Medicine, Wayne State University, Detroit, MI, 48201, USA. a.majumdar@wayne.edu.
authors.forename: Adhip P N
authors.initials: AP
authors.lastname: Majumdar
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2 / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D003106:Colon / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects* / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006801:Humans; D008095:Lithocholic Acid / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051822:T Cell Transcription Factor 1 / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D014408:Biomarkers, Tumor; C495270:CTNNB1 protein, human; C489427:MYC protein, human; D009363:Neoplasm Proteins; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering; D043587:Receptor, Muscarinic M3; D051822:T Cell Transcription Factor 1; C497576:TCF7 protein, human; D051176:beta Catenin; D003840:Deoxycholic Acid; D008095:Lithocholic Acid; D008156:Luciferases; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: ABCCB1; ABCG2; Cancer stem cells; Colonic epithelial cell; Colonospheres; Deoxycholic acid; Lithocholic acid; Wnt/β-catenin signaling; matrix metallopeptidases