NONCOMMUNICATING HUMAN AND MURINE CARCINOMA-CELLS PRODUCE ALPHA(1) GAP JUNCTION MESSENGER-RNA

The gap junctional communication capacity of six human carcinoma-deriv ed tumorigenic cell lines (pancreatic, pharyngeal and cervical), two m urine carcinoma-derived tumorigenic cell lines (bladder-derived and Eh rlich ascites) and one monkey non-tumorigenic cell line (kidney epithe lium) have been compared by the dye-transfer technique. All the tumori genic cell lines were communication defective, while the non-tumorigen ic cell line was not. Moreover, six of the eight tumorigenic cell line s expressed a gap junction transcript coding for the connexin 43 (alph a(1)). Finally, gap junction plaques were not detected between tumorig enic cells by immunofluorescence staining. Consequently, these data su ggest that communication defects in tumorigenic cells may result from either abnormally low levels of translation of junction mRNA or altera tions in the assembly of junction protein into cell surface plaques, a nd not from failure to produce junction transcripts. Furthermore, sinc e induction of alpha(1) expression has been associated with dedifferen tiation processes, the presence of alpha(1) mRNA might be a characteri stic property of certain tumorigenic cells that originate from cells t hat do not normally express alpha(1) mRNA.