Epithelial derived-matrix metalloproteinase (MMP9) exhibits a novel defensive role of tumor suppressor in colitis associated cancer by activating MMP9-Notch1-ARF-p53 axis

// Lewins Walter 1 , Adani Pujada 1 , Noopur Bhatnagar 2 , Agnieszka B Bialkowska 3 , Vincent W. Yang 3 , Hamed Laroui 4 , Pallavi Garg 1 1 Institute for Biomedical Sciences, Georgia State University, Atlanta, GA, USA 2 Department of Biology, Georgia State University, Atlanta, GA, USA 3 Stony Brook University, Department of Medicine, Stony Brook, NY, USA 4 Center for Diagnostics and Therapeutics, Department of Chemistry/ Biology, Georgia State University, Atlanta, GA, USA Correspondence to: Pallavi Garg, email: pgarg@gsu.edu Keywords: MMP9, tumor suppressor, colitis associated cancer, Notch1, γH2AX Received: June 02, 2016 Accepted: November 11, 2016 Published: November 16, 2016 ABSTRACT Colitis associated cancer (CAC) is chronic inflammation driven colon cancer, prevalent among individuals with Inflammatory Bowel Disease. Matrix-metalloproteinase (MMP9) is one of the essential regulators of extra cellular matrix components. We have shown that MMP9 is protective in CAC contrary to its inflammatory role in acute-colitis. Aim of our study is to identify the mechanism of the protective role of epithelial derived-MMP9 in CAC. We used homozygous transgenic mice constitutively-expressing MMP9 in colonic-epithelium (TgM9) and wild-type (WT) littermates for in vivo experiments. Stably-transfected HCT116 with/without MMP9, and mouse embryonic-fibroblasts (WT and MMP9 –/– , MEFs) were used for in vitro experiments. TgM9 mice exhibited less tumor burden, increased apoptosis, and increased expressions of active-Notch1, p53, p21 WAF1/Cip1 , caspase-3 and cyclin E in CAC compared to WTs. These results were supported by MEFs data. HCT116-cells overexpressing MMP9 indicated decreased cell proliferation, S-phase cell-cycle arrest and less DNA damage compared to vector. MMP9 –/– mice showed attenuation of MMP9 was directly associated with p19ARF. Our study identifies the tumor suppressor role of epithelial derived-MMP9 in CAC via novel mechanistic pathway “MMP9-Notch1-ARF-p53 axis” regulating apoptosis, cell-cycle arrest and DNA damage implying, that MMP9 expression might be a natural/biological way to suppress colonic ulceration due to chronic inflammation.