HETEROLOGOUS GAP JUNCTIONAL INTERCELLULAR COMMUNICATION IN NORMAL ANDMORPHOLOGICALLY TRANSFORMED COLONIES OF SYRIAN-HAMSTER EMBRYO CELLS

A study was made of whether normal and morphologically transformed col onies in the Syrian hamster embryo (SHE) cell transformation assay per formed heterologous gap junctional intercellular communication (GJIC). Two compounds, 12-O-tetradecanoylphorbol-13-acetate (TPA) and Na-orth ovanadate (vanadate), which induce high frequencies of morphological t ransformation in SHE cells, have been employed. Three approaches were used to study the possibility of heterologous GJIC. (i) Morphologicall y transformed colonies (induced by TPA) partially overlapping with nor mal colonies were selected. Cells in the border area were micro-inject ed with the fluorescent dye Lucifer yellow to determine whether the dy e spread to cells belonging to the other colony. This approach proved to be unsuccessful due to an inability to pinpoint which cells belonge d to which colony. (ii) X-irradiated, non-dividing feeder cells are ea sily recognized by their large size. Feeder cells in contact with norm al or TPA-transformed colonies were injected with Lucifer yellow. The dye was found to spread to most of the contacting cells, irrespective of whether they belonged to a normal or morphologically transformed co lony. (iii) TPA- and vanadate-exposed colonies were labelled by endocy tosis of Lucifer yellow overnight. This resulted in a punctate fluores cent pattern. Unlabelled, previously unexposed cells were seeded onto the dishes and incubated for 3.5-7 h. The ability to perform heterolog ous GJIC between the newly seeded cells and labelled colony cells was investigated. Both normal and transformed colonies were found to be ab le to communicate with the newly seeded cells. Thus, the present resul ts indicate that selective communication is not a general property of morphologically transformed SHE cell colonies.