title: Matrix metalloproteinase-9 functions as a tumor suppressor in colitis-associated cancer.
abstract: There is a well-documented association of matrix metalloproteinase-9 (MMP-9) and receptor Notch-1 overexpression in colon cancer. We recently showed that MMP-9 is also upregulated in colitis, where it modulates tissue damage and goblet cell differentiation via proteolytic cleavage of Notch-1. In this study, we investigated whether MMP-9 is critical for colitis-associated colon cancer (CAC). Mice that are wild type (WT) or MMP-9 nullizygous (MMP-9(-/-)) were used for in vivo studies and the human enterocyte cell line Caco2-BBE was used for in vitro studies. CAC was induced in mice using an established carcinogenesis protocol that involves exposure to azoxymethane followed by treatment with dextran sodium sulfate. MMP-9(-/-) mice exhibited increased susceptibility to CAC relative to WT mice. Elevations in tumor multiplicity, size, and mortality were associated with increased proliferation and decreased apoptosis. Tumors formed in MMP-9(-/-) mice exhibited expression of p21(WAF1/Cip1) and increased expression of beta-catenin relative to WT mice. In vitro studies of MMP-9 overexpression showed increased Notch-1 activation with a reciprocal decrease in beta-catenin. Notch and beta-catenin/Wnt signaling have crucial roles in determining differentiation and carcinogenesis in gut epithelia. Despite being a mediator of proinflammatory responses in colitis, MMP-9 plays a protective role and acts as a tumor suppressor in CAC by modulating Notch-1 activation, thereby resulting in activation of p21(WAF1/Cip1) and suppression of beta-catenin.
authors.affiliation: Division of Digestive Diseases and Department of Pathology, Emory University, Atlanta, Georgia 30322, USA. pgarg6@emory.edu
authors.forename: Pallavi
authors.initials: P
authors.lastname: Garg
authors.forename: Dittakavi
authors.initials: D
authors.lastname: Sarma
authors.forename: Sabrina
authors.initials: S
authors.lastname: Jeppsson
authors.forename: Neal R
authors.initials: NR
authors.lastname: Patel
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Gewirtz
authors.forename: Didier
authors.initials: D
authors.lastname: Merlin
authors.forename: Shanthi V
authors.initials: SV
authors.lastname: Sitaraman
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D018938:Caco-2 Cells; D048708:Cell Growth Processes / Q000502:physiology; D003092:Colitis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D014162:Transfection; D051176:beta Catenin / Q000378:metabolism
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016328:NF-kappa B; D051176:beta Catenin; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051546:Cyclooxygenase 2; D020780:Matrix Metalloproteinase 9