Secretion of Mr 46,000 protein from human hepatoma cells treated with tumor promotors is regulated by c-myc gene expression.
Previously an Mr 46,000 protein (named p46) was shown to be induced in the culture medium of human hepatoblastoma cells, Huh-6 Cl-5, treated with 12-O-tetradecanoyl phorbol-13-acetate (TPA). For further characterization of p46, Huh-7 Cl-4, another line of well differentiated liver cells, was incubated in the presence and absence of TPA, and proteins were labeled with [35S]methionine, and the proteins secreted into the medium were analyzed by one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. A protein of Mr 46,000 was observed in the culture medium of Huh-7 Cl-4 cells treated by TPA or plated at low density, but only slightly in the culture medium of Huh-7 Cl-4 cells plated at high density. As these results suggested that the expression of p46 was regulated by a factor that was activated in the growth state and by TPA treatment, the effect of introduction of the competence gene c-myc into Huh-7 Cl-4 cells was examined. All 37 independent transfected colonies obtained showed enhanced expression of p46. As a control, the c-Ha-ras gene was introduced into Huh-7 Cl-4 cells and shown not to enhance expression of p46. These results strongly suggested that the expression of p46 was regulated by the competence gene c-myc.
Miwatani
H
H
Institute for Molecular and Cellular Biology, Osaka University, Japan.
Yoneda
Y
Y
Maki
H
H
Kaneda
Y
Y
Uchida
T
T
D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D011519:Proto-Oncogenes / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000473:pathology
D009363:Neoplasm Proteins; D013755:Tetradecanoylphorbol Acetate