title: Utility of a bacterial infection model to study epithelial-mesenchymal transition, mesenchymal-epithelial transition or tumorigenesis.
abstract: DCLK1 and Lgr5 have recently been identified as markers of quiescent and cycling stem cells in the small intestinal crypts, respectively. Epithelial-mesenchymal transition (EMT) is a key development program that is often activated during cancer invasion and metastasis, and also imparts a self-renewal capability to disseminating cancer cells. Utilizing the Citrobacter rodentium (CR)-induced transmissible murine colonic hyperplasia (TMCH) model, we observed a relative decrease in DCLK1 expression in the colonic crypts, with significant shift towards stromal staining at peak (12 days post infection) hyperplasia, whereas staining for Lgr5 and Msi-1 increased several fold. When hyperplasia was regressing (days 20-34), an expansion of DCLK1+ve cells in the CR-infected crypts compared with that seen in uninfected control was recorded. Purified colonic crypt cells exhibiting epigenetic modulation of the transforming growth factor-β (TGFβ), Wnt and Notch pathways on 12 or 34 days post infection formed monolayers in vitro, and underwent trans-differentiation into fibroblast-like cells that stained positive for vimentin, fibronectin and DCLK1. These cells when trypsinized and regrown in soft agar, formed colonospheres/organoids that developed into crypt-like structures (colonoids) in Matrigel and stained positive for DCLK1. Mice exhibiting 12 or 34 days of TMCH were given azoxymethane once for 8 h (Gp1) or weekly for 3 weeks (Gp2), and subjected to crypt isolation. Crypt cells from Gp1 animals formed monolayers as well as colonospheres in soft agar and nodules/tumors in nude mice. Crypt cells isolated from Gp2 animals failed to form the monolayers, but developed into colonospheres in soft agar and nodules/tumors in nude mice. Thus, both hyperplasia and increased presence of DCLK1+ve cells promote cellular transformation in response to a second hit. The TMCH model, therefore, provides an excellent template to study how alterations in intestinal stem cells promote trans-differentiation, crypt regeneration or colon carcinogenesis following bacterial infection.
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Oklahoma City, OK, USA.
authors.forename: P
authors.initials: P
authors.lastname: Chandrakesan
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: B
authors.initials: B
authors.lastname: Roy
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: L U M R
authors.initials: LU
authors.lastname: Jakkula
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: I
authors.initials: I
authors.lastname: Ahmed
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: P
authors.initials: P
authors.lastname: Ramamoorthy
authors.affiliation: Department of Anatomic and Surgical Pathology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: O
authors.initials: O
authors.lastname: Tawfik
authors.affiliation: Carestream Molecular Imaging, Woodbridge, CT, USA.
authors.forename: R
authors.initials: R
authors.lastname: Papineni
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Oklahoma City, OK, USA.
authors.forename: C
authors.initials: C
authors.lastname: Houchen
authors.affiliation: 1] Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA [2] The University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: S
authors.initials: S
authors.lastname: Anant
authors.affiliation: 1] Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA [2] The University of Kansas Cancer Center, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: S
authors.initials: S
authors.lastname: Umar
mesh_terms: D000818:Animals; D001397:Azoxymethane / Q000633:toxicity; D001424:Bacterial Infections / Q000473:pathology*; D063646:Carcinogenesis; D002454:Cell Differentiation; D003106:Colon / Q000187:drug effects / Q000473:pathology; D004195:Disease Models, Animal; D044127:Epigenesis, Genetic; D058750:Epithelial-Mesenchymal Transition; D051379:Mice; D008819:Mice, Nude; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000473:pathology; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D051880:Receptors, Notch; D051153:Wnt Proteins; D001397:Azoxymethane