title: Synergy between bacterial infection and genetic predisposition in intestinal dysplasia.
abstract: Accumulating evidence suggests that hyperproliferating intestinal stem cells (SCs) and progenitors drive cancer initiation, maintenance, and metastasis. In addition, chronic inflammation and infection have been increasingly recognized for their roles in cancer. Nevertheless, the mechanisms by which bacterial infections can initiate SC-mediated tumorigenesis remain elusive. Using a Drosophila model of gut pathogenesis, we show that intestinal infection with Pseudomonas aeruginosa, a human opportunistic bacterial pathogen, activates the c-Jun N-terminal kinase (JNK) pathway, a hallmark of the host stress response. This, in turn, causes apoptosis of enterocytes, the largest class of differentiated intestinal cells, and promotes a dramatic proliferation of SCs and progenitors that serves as a homeostatic compensatory mechanism to replenish the apoptotic enterocytes. However, we find that this homeostatic mechanism can lead to massive over-proliferation of intestinal cells when infection occurs in animals with a latent oncogenic form of the Ras1 oncogene. The affected intestines develop excess layers of cells with altered apicobasal polarity reminiscent of dysplasia, suggesting that infection can directly synergize with the genetic background in predisposed individuals to initiate SC-mediated tumorigenesis. Our results provide a framework for the study of intestinal bacterial infections and their effects on undifferentiated and mature enteric epithelial cells in the initial stages of intestinal cancer. Assessment of progenitor cell responses to pathogenic intestinal bacteria could provide a measure of predisposition for apoptotic enterocyte-assisted intestinal dysplasias in humans.
authors.affiliation: Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Yiorgos
authors.initials: Y
authors.lastname: Apidianakis
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Pitsouli
authors.forename: Norbert
authors.initials: N
authors.lastname: Perrimon
authors.forename: Laurence
authors.initials: L
authors.lastname: Rahme
mesh_terms: D000818:Animals; D017209:Apoptosis; D002452:Cell Count; D002454:Cell Differentiation; D002455:Cell Division; D049109:Cell Proliferation; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000201:enzymology / Q000382:microbiology; D020895:Enterocytes / Q000382:microbiology / Q000473:pathology; D004789:Enzyme Activation; D041981:Gastrointestinal Tract / Q000382:microbiology / Q000473:pathology; D011905:Genes, ras; D020022:Genetic Predisposition to Disease; D006706:Homeostasis; D006965:Hyperplasia; D007414:Intestinal Neoplasms / Q000382:microbiology / Q000473:pathology; D007422:Intestines / Q000382:microbiology* / Q000473:pathology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D011552:Pseudomonas Infections / Q000150:complications* / Q000201:enzymology / Q000473:pathology*; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D013234:Stem Cells / Q000382:microbiology / Q000473:pathology
chemical_list: D029721:Drosophila Proteins; C467520:esg protein, Drosophila; D048031:JNK Mitogen-Activated Protein Kinases