Expression of cell adhesion molecules and connexins in gap junctional intercellular communication deficient human mesothelioma tumour cell lines and communication competent primary mesothelial cells

Gap junctional intercellular communication (GJIC) has been reportedto be markedly reduced in human mesothelloma tumour cell linescompared with primary mesothelial cells. Iminunofluorescencestainings have shown that the gap junction protein connexin43(Cx43) is expressed In both malignant and normal mesothelialcells. In this study the mRNA expression of Cx43 and three differentconnexlns—Cx37, Cx40 and Cx45, which are highly expressedin lung tissue—was investigated in eight human mesotheliomacell lines, and in human primary mesothellal cells from severaldonors. The expression of the intercellular adhesion moleculesA-CAM (N-cadherln) and L-CAM (E-cadherin) was studied at theprotein level. No mRNA expression of Cx37, Cx40 or Cx45 in eithermesothelioma tumour cells or the primary mesothelial cells wasdetected. Cx43 was expressed at both the mRNA and the proteinlevel, in seven out of eight mesothelloma cell lines, as wellas in all the primary mesothellal cell cultures. The intercellularadhesion molecule A-CAM was expressed at the cell—cellborders In six out of seven mesothelioma cell lines, as wellas in normal mesothellal cells. No expression of L-CAM was observedin these cells. The results suggest that Cx43 and A-CAM arethe major proteins in gap and adherens Junctions respectivelyin human mesothellal cells. Most mesothelioma tumour cell lineswith markedly reduced GJIC still express both Cx43 and A-CAM.Only one of our mesothelloma tumour cell lines severely deficientin GJIC lacks both the gap junction protein Cx43 and the celladhesion molecule A-CAM.