Selective lack of intercellular communication between transformed and nontransformed cells as a common property of chemical and oncogene transformation of BALB/c 3T3 cells.

BALB/c 3T3 cells can be transformed by transfection of an activated cellular oncogene as well as by chemicals. When the cells were transformed by pEJ-ras transfection, a marked increase in Mr 21,000 protein expression was found by Western blotting and immunohistochemical staining, whereas no such increase was detected in cells transformed by methylcholanthrene, suggesting two different molecular mechanisms. By directly microinjecting a fluorescent dye (Lucifer Yellow CH) into individual cells, we measured junctional intercellular communication among and between transformed and surrounding nontransformed cells. In both chemical and oncogene transformation studies, transformed cells and surrounding normal cells have similar capacities for gap-junctional communication, but there was complete lack of communication between transformed and nontransformed cells. When BALB/c 3T3 cells were transformed by methylcholanthrene initiation followed by phorbol ester promotion, again we saw no intercellular communication between transformed and nontransformed cells, suggesting that the observed selective communication block between transformed and nontransformed cells may be a general phenomenon in BALB/c 3T3 cells. These results indicate that selective lack of intercellular communication between transformed and surrounding normal cells may be an important phenomenon that separates transformed cells and nontransformed cells, permitting transformed cells to maintain autonomous growth.