Association of extracellular cleavage of E-cadherin mediated by MMP-7 with HGF-induced in vitro invasion in human stomach cancer cells

BACKGROUND

Proteolytic shedding of the ectodomain of a variety of transmembrane proteins, including cell-to-cell adhesion molecules, has been observed in solid cancers. We have investigated whether extracellular cleavage of E-cadherin mediated by matrix metalloproteinase-7 (MMP-7) is involved in hepatocyte growth factor (HGF) induced in vitro invasion in stomach cancer cells.

METHODS

The effects of HGF on the expression of E-cadherin/beta-catenin and MMP-7 at both the protein and mRNA levels were assessed in stomach cancer cells, NUGC-3 and MKN-28, and in cells in which the expression of MMP-7 was downregulated by transfection with a MMP-7 short hairpin RNA plasmid.

RESULTS

Treatment with HGF increased the extracellular cleavage of E-cadherin and the release of MMP-7 and reduced the level of E-cadherin in a dose- and time-dependent manner. HGF treatment repressed the phosphorylation of beta-catenin in a Triton-soluble fraction, but enhanced this phosphorylation in a Triton-insoluble fraction. The association of E-cadherin with beta-catenin was decreased by HGF treatment in the Triton-soluble fraction. In addition, treatment of MMP-7 short hairpin RNA transfected NUGC-3 cells with HGF resulted in no extracellular cleavage of E-cadherin and also decreased the in vitro cell invasion.

CONCLUSIONS

These results suggest that incubation with HGF mediated the release of MMP-7, resulting in extracellular cleavage of E-cadherin from stomach cancer cells. This might be a key mechanism in HGF-induced in vitro invasion and metastasis.

Dissimilatory Fe(III) reduction by an electrochemically active lactic acid bacterium phylogenetically related to Enterococcus gallinarum isolated from submerged soil

AIMS

The isolation and identification of a glucose-oxidizing Fe(III)-reducing bacteria (FRB) with electrochemical activity from an anoxic environment, and characterization of the role of Fe(III) in its metabolism.

METHODS AND RESULTS

A Gram-positive (Firmicutes), nonmotile, coccoid and facultative anaerobic FRB was isolated based on its ability to reduce Fe(III). Using the Vitek Gram-positive identification card kit and 16S rRNA gene sequence analysis, the isolate was identified as Enterococcus gallinarum, designated strain MG25. On glucose this isolate produced lactate plus small amounts of acetate, formate and CO2 and its growth rates were similar in the presence and absence of Fe(O)OH. These results suggest that MG25 can couple glucose oxidation to Fe(III) reduction, but without conservation of energy to support growth. Cyclic voltammetry showed that strain MG25 was electrochemically active.

CONCLUSIONS

An electrochemically active and FRB, E. gallinarum MG25, was isolated from submerged soil. Fe(III) is used in the bacterial metabolism as an electron sink.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report concerning the electrochemical activity of glucose-oxidizing FRB, E. gallinarum. This organism and others like it could be used as new biocatalysts to improve the performance of a mediator-less microbial fuel cell.

Involvement of phospholipase D in oxidative stress-induced necrosis of vascular smooth muscle cells

Phospholipase D (PLD) has been associated with necrosis. However, it is not clear whether PLD plays a causative role in this cellular process. We investigated the role of PLD in oxidative stress-induced necrosis of vascular smooth muscle cells (VSMCs). Pervanadate (hydrogen peroxide plus orthovanadate) but not hydrogen peroxide alone activated PLD in a dose- and time-dependent manner. Exposure of VSMCs to pervanadate resulted in necrosis. Pretreatment with butan-1-ol, a PLD inhibitor, attenuated both pervanadate-induced necrosis and increase of intracellular Ca(2+). Removal of extracellular Ca(2+) inhibited pervanadate-induced necrosis by 50%. These results suggest that PLD activation mediates pervanadate-induced necrosis of VSMCs, which is at least partly due to Ca(2+) toxicity.

Comparison of Tc-99m sestamibi and TI-201 uptake in multiple myeloma

The authors report abnormal Tc-99m sestamibi (MIBI) and TI-201 uptake in a 62-year-old patient with histologically and biochemically proved myeloma. TI-201 imaging was undertaken for tumor evaluation, and 3 days later a Tc-99m MIBI study showed diffuse and focal marrow uptake with focal skull lesions, whereas TI-201 did not show skull lesions. After treatment, follow-up Tc-99m MIBI whole-body imaging was performed and the marrow uptake was decreased.

Tumor angiogenesis as a prognostic predictor in colorectal carcinoma with special reference to mode of metastasis and recurrence

Tumor angiogenesis has proved to be a useful prognostic determinant for patients with various solid tumors. In this study, we investigated the quantitative expression of angiogenesis in colorectal carcinoma to determine how angiogenesis correlates with clinicopathologic factors and prognosis. One hundred twenty-seven specimens resected from patients with primary colorectal carcinoma were investigated immunohistochemically using a polyclonal antibody against factor-VIII-related antigen, and areas with the highest vascular density at the invasive tumor margin were counted at 200 times magnification. The microvessel count, defined as angiogenesis density (AD), became significantly higher with increase in histologic grade (p = 0.02) and Dukes stage (p = 0.001). AD was also significantly higher in patients with lymph node metastasis (p = 0. 005), lymphatic invasion (p = 0.042), vascular invasion (p < 0.001), and liver metastasis (p = 0.0004) than in those without. In addition, patients with synchronous distant hematogenous metastasis in stage D disease showed significantly higher AD than patients with nonhematogenous metastasis (p = 0.006). When 27 cases of disease recurrence after surgical resection with curative intent were stratified according to mode of spread, AD in cases with a hematogenous pattern of relapse proved to be significantly higher than in cases with nonhematogenous spread (p < 0.001). No significant differences were, however, found in AD when they were subdivided as to operative nodal status (p = 0.39 and 0.08 in the node-negative and the node-positive group, respectively). Multivariate analysis indicated that AD was an independent prognostic factor (p = 0.0004) in colorectal carcinoma. Quantitative evaluation of tumor angiogenesis at the invasive tumor margin is suggested to be a good prognostic indicator and a useful predictor for hematogenous spread and recurrence in patients with colorectal carcinoma.