Gap junctional communication in cultured human lung carcinoma cells

Animal tumor models have demonstrated a close correlation between gap junctional, intercellular communication (GJIC) and tumor metastasis. To examine GJIC levels in human lung carcinoma cells, a novel technique was developed: cells were grown on a glass slide, half of which was coated with electrically conductive, optically transparent, indium-tin oxide. An electric pulse which opens transient pores on the plasma membrane was applied in the presence of the fluorescent dye, Lucifer yellow, causing the dye's penetration into the cells growing on the conductive part of the slide. The migration of the dye through gap junctions to the non-electroporated cells growing on the non-conductive area was then observed microscopically under fluorescence illumination. The results show that this is a rapid, precise and highly reproducible assay for GJIC assessment in lines established from lung carcinomas or freshly explanted lung tumor cells. Out of 17 established lines only two had extensive junctional communication, while out of 16 fresh tumor specimens none displayed GJIC. On the other hand, fibroblasts isolated from the same tumors had extensive junctional permeability. The examination of GJIC in a large number of samples could establish a correlation between GJIC and metastasis which might have prognostic value.