The inflammatory milieu plays an important role in colon cancer development and progression. Previously, we have shown that tumor-associated macrophages (TAMs), an important component of the tumor microenvironment, are enriched in tumors compared with normal tissue and confer a poorer prognosis. In the present study, we found that matrix metallopeptidase-9 (MMP-9), which degrades extracellular matrix proteins, was increased in biopsies from colon cancer patients and in mouse xenografts with SW480 cell-derived tumors. SW480 colon cancer cells exposed to M2-like macrophage-conditioned medium (M2-medium) exhibited increased MMP-9 mRNA, protein expression and gelatinase activity. A similar effect was obtained by the addition of tumor necrosis factor-α (TNFα) and leukotriene D (LTD ). MMP-9 expression and activity were reduced by a TNFα blocking antibody adalimumab and a cysteinyl leukotriene receptor 1 (CysLTR1, the receptor for LTD ) antagonist montelukast. M2-medium also induced changes in the epithelial-mesenchymal transition (EMT) markers E-cadherin, β-catenin, vimentin, and snail in SW480 cells. We also found that both M2-medium and TNFα and LTD induced stabilization/nuclear translocation of β-catenin. Furthermore, we also observed an elongated phenotype that may indicate increased invasiveness, as confirmed in a collagen I invasion assay. M2-medium increased the invasive ability, and a similar effect was also obtained by the addition of TNFα and LTD . The specific MMP inhibitor I or adalimumab and montelukast reduced the number of invasive cells. In conclusion, our findings show that M2-medium enriched in TNFα and LTD promote colon cancer cell invasion via MMP-9 expression and activation and the induction of EMT.

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Dysregulation of Wnt/b-catenin signaling is a hallmark of colon cancer. Glycogen synthase kinase-3b (GSK-3b) can be a positive regulator of survival and proliferation of cultured colon cancer cell but its role in clinical colon cancer is unknown. Our objectives were to evaluate the role of GSK-3b in colon cancer. A tumor tissue microarray of primary colon cancers and metastases was used to evaluate expression and subcellular localization of GSK-3b and b-catenin. In total, 85 primary colon cancer samples were evaluated by immunohistochemistry. Immunoreactivity was correlated to known markers of adverse prognosis. Overall survival was the primary end-point. We found nuclear accumulation of GSK-3b in 39% (33/85) of evaluated tumors. Nuclear GSK-3b was significantly associated with shorter overall survival (p 5 0.008), larger tumor size (p 5 0.015), distant metastasis (p 5 0.029) and loss of membranous b-catenin (p 5 0.007). Loss of membranous b-catenin occurred in 37% (30/82) of the tumors and was associated with poor survival (p 5 0.016). The combination of nuclear GSK-3b and lack of membrane b-catenin occurred in a total of 26% of the studied tumors (21/61) and was significantly and independently associated with poor prognosis. Our results suggest that nuclear expression of GSK-3b and loss of membrane b-catenin identify a subset of colon carcinomas with worse prognosis.Colorectal cancer (CRC) is the third most common cancer worldwide, with over one million cases occurring every year. The mortality rate for CRC is approximately half of its global incidence. Five-year survival estimate for CRC exceeds 50%, but is highly variable depending on the stage of the disease. 1 The etiological factors and pathogenic mechanisms underlying the development of CRC are complex and heterogeneous and include inflammation, with inflammatory bowel disease being associated with an increased risk of CRC; dietary and life style factors, such as diets rich in red meat and unsaturated fat, excessive alcohol consumption and reduced physical activity. 2 Further, it is estimated that 15-30% of patients have a major hereditary component, only a quarter of which can be attributed to hereditary nonpolyposis colorectal cancer or familial adenomatous polyposis. 3 Wnt signaling is one of the key signaling pathways controlling proliferation, differentiation and morphogenesis of cells during development. In all, >90% of CRCs have a mutation in a key regulatory factor of the Wnt/b-catenin pathway, most often in APC or b-catenin, resulting in activation of the pathway. 4 Wnt signaling is initiated by the binding of Wnt family members to a receptor complex consisting of the Frizzled family of transmembrane receptors, together with the coreceptors LRP5/6. Wnt signaling inactivates GSK-3b and prevents it from phosphorylating b-catenin, and thus stabilizing b-catenin in the cytoplasm. As b-catenin accumulates, it translocates into the nucleus where it binds to T-cell-specific transcription factor (TCF)/LEF and increases transcription of proto-oncogenes s...