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Aberrant activation and upregulation of the Wnt pathway is a key feature of many cancers. Wnt antagonists have recently attracted wide attention. Wnt inhibitory factor-1 (WIF-1) is a secreted antagonist that can bind to Wnt proteins directly and inhibit Wnt signaling pathway. It has been reported that WIF-1 expression is down regulated in several solid tumors and that WIF-1 is silenced by promoter hypermethylation in lung and colorectal cancer. By using RT–PCR, bisulfite sequence analysis, and methylation-specific PCR, we analysed expression and methylation of WIF-1 in cancer cell lines and freshly resected cancer tissues of the esophagus, stomach, colorectum, and pancreas. Downregulation of WIF-1 mRNA expression was observed in 61 (91.0%) of 67 cancer cell lines, 16 (80.0%) of 20 esophageal, 23 (74.2%) of 31 gastric, 41 (82.0%) of 50 colorectal, and six (75.0%) of eight pancreatic cancer tissues. Downregulation of WIF-1 expression was also observed at protein level. No significant association between WIF-1 downregulation and clinicopathological characteristics was found, suggesting that downregulation of WIF-1 expression is an early event in carcinogenesis of these cancers. Indeed, downregulation of WIF-1 expression was observed in 32 (72.7%) of 44 colorectal adenoma tissues and 18 (78.2%) of 23 early mucosal or submucosal colorectal carcinoma tissues. CpG island hypermethylation in the WIF-1 promoter region correlated with downregulation of WIF-1 expression in cancer cell lines and tissues. Treatment with demethylating agent, 5-aza-2′-deoxycytidine (5-aza-dC), restored WIF-1 expression in cancer cell lines. A combined treatment of 5-aza-dC and a histone deacetylase inhibitor, trichostatinA, restored WIF-1 expression synergistically, indicating the role of cytosine methylation and histone deacetylation in the silencing of the WIF-1 gene. Transfection of the WIF-1 gene construct into TE-1 esophageal cancer cell lines or SW48 colon cancer cell lines lacking WIF-1 expression resulted in a significant inhibition on colony formation, cell proliferation, anchorage-independent growth in soft agar. TOPflash assay showed WIF-1 inhibits Wnt canonical signaling in these cell lines. These results suggest tumor suppressive function of WIF-1, due to its ability to inhibit Wnt signaling. Our results suggest that WIF-1 silencing due to promoter hypermethylation is an important mechanism underlying aberrant activation of the Wnt signaling pathway in carcinogenesis of the digestive organs. Modulation of the Wnt pathway, through reversal of WIF-1 silencing by demethylating agents, is a potential target for treatment and/or prevention of gastrointestinal cancers.Oncogene (2005) 24, 7946–7952. doi:10.1038/sj.onc.1208910; published online 11 July 2005 [ABSTRACT FROM AUTHOR]

Expression of matrilysin-2, matrix metalloproteinase (MMP)-26, has been implicated in the progression of several types of human cancer. Matrilysin-2 has been reported to be a physiological and pathological activator of pro-MMP-9. The aim of this study was to examine matrilysin-2 expression and determine whether it is correlated with progression of human esophageal squamous cell carcinoma (ESCC). Semi-quantitative reverse transcriptasepolymerase chain reaction, immunohistochemical analysis, zymography and an in vitro invasion assay were performed. Matrilysin-2 mRNA expression was undetectable or only faintly detected in non-tumor tissues, but its overexpression was detected in 24 of the 50 ESCC tissues. Matrilysin-2 overexpression was significantly correlated with depth of invasion, lymph node metastasis and an advance in pathological tumor node metastasis (pTNM) stage. Sections with immunostaining signals in >10% of carcinoma cells at the invasive front, which were observed in 46 of 100 cases, were judged to be positive for matrilysin-2 expression. Matrilysin-2 expression was significantly correlated with depth of invasion, lymph node and distant metastasis, advance in pTNM stage and recurrence. Expression of matrilysin-2 was significantly correlated with nuclear -catenin expression and MMP-9 expression. Patients with matrilysin-2-positive cancer had significantly shorter overall and disease-free survival periods than did those with matrilysin-2-negative cancer. Matrilysin-2 expression retained its significant predictive value for overall and disease-free survival in multivariate analysis. Moreover, patients with concomitant expression of matrilysin-2 and MMP-9 had the worst prognosis. Zymography revealed that matrilysin-2 expression was significantly correlated with expression of active MMP-9 in ESCC tissues. Matrilysin-2-transfected TE-1 ESCC cells showed active MMP-9 activity and were more invasive in vitro compared with mock-transfected TE-1 cells. The results of this study suggest that matrilysin-2, the expression of which is closely correlated with nuclear -catenin expression and active MMP-9 activity, plays a key role in the progression of ESCC. [ABSTRACT FROM AUTHOR]

Morphologically, early colorectal tumors are divided into two groups, protruded-type tumors and flat-type tumors. Although some studies have shown genetic alterations in protruded-type tumors, little is known about genetic and epigenetic alterations in flat-type tumors, as well as pT1 (early invasive) colorectal cancers (CRCs). In the current study, we compared the frequencies of genetic and epigenetic alterations of the RAS–RAF and Wnt signaling pathways in flat-type and protruded-type tumors. In addition, we investigated the relationship between those alterations and invasive potential of pT1 CRCs. Methylations of RASSF2, O-6-methylguanine-DNA methyltransferase (MGMT), Wnt inhibitory factor-1 (WIF-1), EPHB2, CDKN2A and MLH1 were detected in 44.3, 30.3, 81.4, 7.5, 43.6 and 13.4% of the 307 early colorectal tumors, respectively. Mutations of KRAS, BRAF, catalytic subunit alpha of phosphatidylinositol 3′-kinase (PIK3CA) and β-catenin were detected in 25.4, 4.6, 1.6 and 9.4% of those tumors, respectively. Methylations of MGMT, WIF-1 and CDKN2A were detected in significantly higher percentages of protruded-type tumors than in flat-type tumors. Mutation of at least one gene was detected in a significantly higher percentage of flat-type tumors than in protruded-type tumors. RASSF2 methylation was correlated significantly with KRAS, BRAF or PIK3CA mutation. Multiple logistic analysis showed that lymphatic invasion and RASSF2 methylation with KRAS, BRAF or PIK3CA mutation were independent risk factors for venous invasion in pT1 CRCs. In conclusion, since genetic alterations of these pathways have frequently occurred in flat-type tumors, flat-type tumors seem to have a distinct genetic profile different from that of protruded-type tumors. RASSF2 methylation with oncogenic activation is a promising biomarker for predicting invasive potential of pT1 CRCs. [ABSTRACT FROM AUTHOR]