Antisense gene constructs have been very useful in the functional analysis of genes and their products. In this report we used a connexin 43 (Cx43) antisense gene construct to study the role that heterologous gap-junctional intracellular communication (GJIC) plays in the ability of untransformed fibroblasts to suppress the foci-forming ability of src oncogene-transformed cells. Untransformed Rat-1 fibroblasts transfected with the Cx43 antisense DNA construct showed marked decreases in Cx43 RNA and protein, which were accompanied by a corresponding decrease in GJIC. These Cx43 antisense-transfected cells maintained normal cell morphology, growth rates, and saturation densities and did not grow in soft-agar suspension. However, in coculture experiments, the Cx43 antisense cells were less effective than vector-alone-transfected, sense-transfected, and untransfected cells at inhibiting foci formation of pp60(v-src)-transformed cells. These effects of junctionally competent, normal cells were associated with the existence of heterologous GJIC with the transformed cells and did not appear to result from the elaboration of a stable, diffusible inhibitory factor. Thus, gap-junction-mediated transfer of putative regulatory molecules may play a role in the ability of untransformed cells to suppress the expression of certain properties of transformed cells. (C) 1994 Wiley-Liss, Inc.
