P-164 YI Epithelial Derived-Matrix Metalloproteinase (MMP9) Has a Defensive Role in Inflammation Associated Colorectal Cancer by Activating MMP9-ARF-p53 Axis. (March 2016)

• Record Type: Journal Article
• Authors: Walter, Lewins; Garg, Pallavi
• Is Part Of: Inflammatory bowel diseases. Volume 22(2016:Mar.)Supplement 1
• Publication Date: 2016-03
• Subjects: Inflammatory bowel diseases -- Periodicals; Colitis, Ulcerative -- Periodicals; Crohn Disease -- Periodicals; Inflammatory Bowel Diseases -- Periodicals; 616.344
• DOI: 10.1097/01.MIB.0000480282.46656.91
• Languages: English
• ISSNs: 1078-0998

Abstract

Abstract : Background: Individuals with inflammatory bowel disease, have increased risk of developing colon cancer. The pathogenesis of colitis-associated cancer (CAC) is incompletely understood and the lack of understanding of CAC pathogenesis is the main barrier to design specific therapeutic strategies against it. CAC is a subtype of colorectal cancer (CRC), but being a chronic inflammation driven carcinoma, it is distinctively different from CRC. Matrix metalloproteinases (MMPs) are neutral endopeptidases that participate in degradation of extra-cellular matrix proteins during normal tissue remodeling and a variety of pathological processes including inflammation and cancer. Among 25 known mammalian MMPs, MMP9 is very unique. It is absent in normal tissues however is highly expressed during acute inflammation. MMP9 protein expression and activity is undetectable in healthy adult tissues including intestine but is highly expressed during inflammation. We have observed that MMP9 has a protective role in CAC, which is exclusive and contrary to its traditional role of a facilitator in acute inflammation and CRC. Knowing the fact that both epithelial cells and neutrophil cells are the 2 most important sources of MMP9 secretion, it is important to know which MMP9 (epithelial derived or neutrophil derived) has the protective function in CAC. Methods: In the present study we have used homozygous transgenic mice that overexpress MMP9 in intestinal epithelium (TgM9) and wild-type (WT) littermates for in vivo experiments. CAC was induced by using 3 cycles of dextran sodium sulfate (a chemical widely used to induce colonic inflammation). Stably transfected HCT116 with/without p-EGFP-MMP9 plasmid and embryonic-fibroblasts (isolated from WT and MMP9 −/− mice, MEFs) were used for in vitro experiments. Results: TgM9 mice exhibited less tumor burden, increased apoptosis, protein expressions of active-Notch1, p53, p21WAF1/Cip1, caspase-3 and cyclinE in CAC compared to WTs. This data was also supported by our in vitro model of MEFs. HCT116-cells overexpressing MMP9 indicated decreased cell proliferation. FACS analysis indicated S-phase cell-cycle arrest and analysis of phosphorylated gamma-H2AX expressions indicated less double-strand-breaks (DSBs) compared to vector. MMP9 −/− mice also showed attenuation of MMP9 was directly associated with p19ARF, which is an upstream regulator of p53. Conclusions: Our study highlights 2 novel findings (1) MMP9 regulates p14ARF expression and thereby activates MMP9-ARF-p53 axis in CAC and (2) MMP9 activates apoptosis, cell-cycle arrest and suppresses DNA double strand breaks. Outcome of this study highlights the paradox of using MMP9 inhibitors in current therapies to treat CAC patients and explains the failure of such treatments, implying that MMP9 expression might be a natural/biological way to suppress ulceration due to chronic inflammation