Tumor cell invasion and gap junctional communication. I. Normal and malignant cells confronted in monolayer cultures

Mammary tumor cells of the rat (BICR/M1Rk) and mouse (EMT6/Ro) as well as rat glioma cells (C6) are electrically coupled and show intercellular dye spreading. Monolayer cultures of synchronously beating chicken heart cells were also electrically coupled, dye spreading, however, was significantly restricted to only one or two adjacent cells. In all coupled cells, gap junctions were found in both freeze-fracture replicas and ultrathin sections. Heterologous gap junctional coupling between these tumor cells and heart cells was regularly established. The human cervix carcinoma line HeLa and the mouse L sarcoma line were electrically not coupled and did not reveal gap junctions, consequently they showed no coupling to heart cells.