Specific viral oncogenes cause differential effects on cell-to-cell communication, relevant to the suppression of the transformed phenotype by normal cells

✍ Scribed by Margherita Bignami; Silvia Rosa; Germana Falcone; Franco Tató; Fumitaka Katoh; Hiroshi Yamasaki

• Publisher: John Wiley and Sons
• Year: 1988
• Tongue: English
• Weight: 863 KB
• Volume: 1
• Category: Article
• ISSN: 0899-1987
• DOI: 10.1002/mc.2940010113

✦ Synopsis

We have studied growth regulation in mixed cultures of normal and oncogene-transformed 3T3 cells. The NIH 3T3 cells transformed by myc, src, and ras showed comparable cloning efficiency in semisolid medium. However, when they were plated on plastic with an excess o f normal mouse embryo fibroblasts, BALBlc 3T3 CIA31-1-1, rasand src-transformed cells were able to form distinct foci on the layer of density-arrested normal cells, whereas myc-transformed cells lacked this ability. In order to determine whether suppression or expression of the transformed phenotype could be correlated with the ability of the different cell populations to communicate, gap-junctional intercellular communication (IC) was measured by the Lucifer yellow dye transfer assay in coculture of normal and transformed cells. The dye was observed t o spread from BALBlc 3T3 to myc-NIH 3T3 cells, indicating the presence of IC between these t w o cell types. In contrast no passage o f Lucifer yellow was observed between src-NIH 3T3 or ras-NIH 3T3 and BALBlc 3T3. Addition of a phorbol ester tumor promoter, phorbol-12,13-didecanoate, efficiently rescued proliferation and focus formation by myc-transformed cells. The tumor promoter was able to inhibit IC in BALBlc 3T3 cells, although this response greatly varied among the different oncogene transformed clones. Tumorigenicity in nude mice strongly correlated with growth behavior in vitro: myc-transformed cells were either nontumorigenic or slowly tumorigenk, and src-and ras-transformed cells were highly tumorigenic. These data suggest an important role of IC in modulating abnormal growth behavior in vitro and in vivo.