TSH and cAMP enhance expression of the myc proto-oncogene in cultured thyroid cells.

The effect of TSH stimulation on cellular (c)-myc mRNA content in cultured thyroid cells was examined by Northern blot analysis. Polyadenylated mRNA was prepared from quiescent FRTL-5 rat thyroid cells and from cells stimulated by TSH for 8 h. A major 2.1 kilobase (kb) transcript was enhanced 5.5-fold by TSH. (Bu)2cAMP and forskolin each enhanced c-myc expression 2.7-fold. These data indicate that TSH, via cAMP as a second messenger, can regulate expression of a cellular oncogene in a non-neoplastic, specific target cell.