Correlation between expression of cadherin and gap junctional communication in human lung carcinoma cells

The correlation between expression of Ca 2+ dependent cell adhesion molecule, cadherin, and gap junctional intercellular communication (GJIC) in human lung carcinoma PG cell line and connexin43 (Cx43) cDNA transfected PG cell clones was investigated. Results from immunoblotting and immunofluorescent staining revealed that cultured normal human lung cells (RF) expressed N cadherin. However, the expression level of N cadherin in PG cells was very low in comparison with normal RF cells. The Cx43 transfected PG clones exhibited comparable levels of Cx43 protein, but varied in the level of N cadherin expression and in the function of GJIC as measured by scrape loading and dye transfer (SLDT) method. Positive correlation between N cadherin and GJIC was demonstrated. The in vitro and in vivo growth examination results suggest that N cadherin mediated cell cell adhesions and Cx43 functional expression, the GJIC, may work coordinately with each other in regulation of cell growth and differentiation. Deficiency in both GJIC and cell adhesion may be crucial for cell transformation.