Conditions for hormone-stimulated expression of endogenous C57Bl strain-associated mammary tumor virus genome.

Full MMTV-Y gene expression can occur in dexamethasone-insulin-prolactin-stimulated cell cultured derived from C57Bl/10 mammary adenocarcinomas induced by syncarcinogenic action of chemical carcinogens (dimethylbenzanthracene), and mammotropic hormones (estrogen and prolactin). The rate of the hormone-stimulated virus production, as determined by biochemical, immunological and electron microscopical methods, was comparable to the level of spontaneous MMTV production by cells of established mouse mammary cancer cultures (CCL-51 and Mm5mt/cl). On the contrary, no virus production has been detected in hormone-stimulated cultures derived from C57Bl/10 mammary tumors induced by chemical carcinogen alone (urethan).