'MCC' protein interacts with E-cadherin and β-catenin strengthening cell-cell adhesion of HCT116 colon cancer cells

E-cadherin and β-catenin are key proteins that are essential in the formation of the epithelial cell layer in the colon but their regulatory pathways that are disrupted in cancer metastasis are not completely understood. Mutated in colorectal cancer (MCC) is a tumour suppressor gene that is silenced by promoter methylation in colorectal cancer and particularly in patients with increased lymph node metastasis. Here, we show that MCC methylation is found in 45% of colon and 24% of rectal cancers and is associated with proximal colon, poorly differentiated, circumferential and mucinous tumours as well as increasing T stage and larger tumour size. Knockdown of MCC in HCT116 colon cancer cells caused a reduction in E-cadherin protein level, which is a hallmark of epithelial-mesenchymal transition in cancer, and consequently diminished the E-cadherin/β-catenin complex. MCC knockdown disrupted cell-cell adhesive strength and integrity in the dispase and transepithelial electrical resistance assays, enhanced hepatocyte growth factor-induced cell scatter and increased tumour cell invasiveness in an organotypic assay. The Src/Abl inhibitor dasatinib, a candidate anti-invasive drug, abrogated the invasive properties induced by MCC deficiency. Mechanistically, we establish that MCC interacts with the E-cadherin/β-catenin complex. These data provide a significant advance in the current understanding of cell-cell adhesion in colon cancer cells.

Method for simultaneous determination of the distribution of capillary plasma flow and myocyte redox state (NADH-fluorescence) in the hypoperfused myocardium of the anesthetized rat

A method is described which allows to observe the pattern of capillary plasma filling simultaneously with the redox state (NADH-fluorescence) of the myocytes in the hypoperfused myocardium. In anesthetized rats the coronary perfusion pressure was reduced to a defined level, the blood plasma labeled with dye-conjugated albumin and a myocardial biopsy-sampled. Freeze-substitution of histological sections allowed to detect the intravascular plasma label as well as the myocyte NADH-fluorescence on a microscopic level. It was found that areas showing increased cellular NADH-fluorescence did not arise in a distribution congruent with zones of failing capillary plasma flow in the hypoperfused myocardium.

Structural relationships between hepatitis B surface antigen in human plasma and dimers from recombinant vaccine: a monoclonal antibody study

Ten monoclonal antibodies were obtained from mice immunized with a yeast recombinant hepatitis B vaccine. They were selected at an early stage for their ability to bind to native surface antigen particles (HBsAg) in human plasma. All antibodies recognized conformational epitopes which were destroyed completely or almost completely by reduction of disulphide bridges. They were divided into five epitope groups by their competition for binding to recombinant S protein, though epitopes within each group are not identical. Recombinant S protein migrated on SDS-PAGE in the absence of reducing agents as a mixture of monomers and dimers/oligomers. Sucrose gradient analysis suggests that all these forms are co-aggregated into HBsAg-like particles. On Western blots, all ten antibodies either bound only to dimers/oligomers or strongly preferred them over monomers. The results suggest that, of the antibodies produced in response to recombinant vaccine in mice, most of those which bind strongly to 'native' HBsAg particles in human plasma recognize surface structures created by interaction between two subunits.