Neal R. Patel

Matrix Metalloproteinase-9 Functions as a Tumor Suppressor in Colitis-Associated Cancer

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.

Constitutive expression of MMP9 in intestinal epithelium worsens murine acute colitis and is associated with increased levels of proinflammatory cytokine Kc

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohns disease, is a chronic inflammatory disease associated with an increased risk for colon cancer. Matrix metalloproteinases (MMPs) are the predominant proteinases expressed in the gut mucosa during active IBD. Our laboratory has previously demonstrated that epithelial-derived MMP9 is absent in normal colonic tissue but is upregulated during IBD. In this study MMP9 transgenic mice (Tg-villin-MMP9) are generated specifically to overexpress MMP9 in intestinal epithelium to examine the role and underlying mechanism by which it modulates the pathogenesis of acute colitis. Dextran sodium sulfate (3% DSS)- and Salmonella typhimurium (S.T.)-induced colitis models were used to study gut inflammation in Tg-villin-MMP9 and wild-type littermates (WT). Colonic tissue was analyzed via Western blot, histology, myeloperoxidase (MPO) assay, and quantitative PCR. Tg-villin-MMP9 mice expressed significantly increased MMP9 mRNA and protein expression at basal level. There was a significant decrease in the goblet cells, but a significant increase in proliferation and apoptosis were observed among Tg-villin-MMP9 mice compared with WT mice. There was also a significant increase in the proinflammatory chemokine Kc among Tg-villin-MMP9 compared with WT mice. Tg-villin-MMP9 exhibited a severe inflammatory response than WT mice in both DSS- and S.T.-induced colitis models as evident by greater weight loss and higher clinical score, histological score, and MPO activity, which correlated with relative levels of Kc mRNA. MMP9 expressed by intestinal epithelial cells mediates inflammation in colitis with simultaneous increase in proinflammatory cytokine Kc.

HIGH-SENSITIVITY TROPONIN-I LEVELS PREDICT LONG-TERM MORTALITY INDEPENDENT OF CORONARY ARTERY DISEASE SEVERITY

High-sensitivity Troponin-I (hs-TnI) as a marker of myocardial injury is predictive of adverse outcomes in patients with coronary artery disease (CAD). Whether the relationship between hs-TnI and outcomes is dependent on underlying CAD severity is unknown. 2826 patients without AMI (mean age 62, 64

M2004 Deletion of Matrix Metalloproteinase-9 (MMP-9) Increases the Susceptibility for Colon Cancer

tumor progression and the development of inflammation. Inflammation and tumor grade were evaluated histologically and colonic levels of IL-12p40 and TNFαmRNAwere measured by real-time PCR. Nuclear β-catenin levels and NF-kB phosphorylation were determined by immunohistochemistry. Results: AOM-treated (6 weekly injections) IL-10-/mice developed colitis and displayed highly penetrant tumor formation under SPF conditions, while WT mice showed no evidence of intestinal inflammation and had minimal tumor formation. AOM-treated IL10-/mice showed a dramatic increase in colon tumor multiplicity and progression compared to WT mice. Tumor multiplicity increased 20-fold while progression from low to high-grade/invasive carcinoma increased by ~70% in IL10-/compared to WT mice. These tumors showed increased nuclear β-catenin accumulation and the presence of phosphorylated RelA. B. vulgatus mono-associated IL10-/mice failed to develop significant intestinal inflammation and showed greatly reduced tumor formation. AOM-treated IL10-/; MyD88-/mice showed reduced colonic expression of TNFα and IL12p40 mRNA and were devoid of neoplastic lesions compared to AOM-treated IL10-/mice. Conclusions: Bacterial-induced intestinal inflammation correlates with the progression of colon cancer in AOM-treated IL-10-/mice. The TLR/MyD88 signaling pathway is essential for the development of CAC.