Elevated expression of v-mos is correlated with altered differentiation of carcinoma cells

Permanent alterations of the epithelial differentiation pattern were investigated after infection of HH-16 cl. 4 adenocarcinoma cells with Moloney murine sarcoma virus (MoMuSV). Transformed cell clones with fibroblastoid morphology were isolated and compared with clones of unchanged epithelioid phenotype. Southern blot analyses showed intact MoMuSV proviral genomes in copy numbers between 4 and 9 in the DNA of the morphologically transformed cell clones as well as in the clones with unaltered morphology. The fibroblastoid cells produced sarcomas after inoculation of newborn rats, whereas MoMuSV-infected cell clones with unaltered epithelioid morphology yielded adenocarcinomas. Immunocytochemical analyses revealed that morphological transformation into the fibroblastoid phenotype was accompanied by loss of cytokeratin expression and appearance of the mesenchymal marker protein vimentin. Proviral DNA was transcribed in the infected cell clones irrespective of their phenotype; however, transcription was significantly higher in cells with fibroblastoid morphology than in epithelioid cells.