Estrogen-inducible pS2 protein is not the key regulatory component in the proliferation of human breast cancer cells (MCF-7).
Exposure of human breast cancer cells (MCF-7) to tumor promoters such as 12-O-tetradecanoyl phorbol 13-acetate (TPA) for 24 h at concentrations of 1-100 nM resulted in marked inhibition of DNA synthesis but a 3-5-fold increase in the amount of pS2 protein in the medium. These results support our previous suggestion that pS2 protein is not involved in the mechanism controlling proliferation of MCF-7 cells. During treatment with TPA, the intracellular content of pS2 protein was constant, suggesting that TPA did not induce secretion of pS2 protein but rather de novo synthesis of the protein. The increase in the pS2 protein content of the medium by TPA was inhibited by simultaneous addition of cycloheximide, but not by that of actinomycin D. Northern-blot hybridization analysis showed that the amount of pS2 mRNA was unchanged by treatment of the cells with TPA. These results indicate that TPA does not induce transcription of the pS2 gene, and suggest that the main effect of TPA results from the induction of translation of pS2 mRNA.
Kida
N
N
Department of Molecular Biology, Gifu Pharmaceutical University, Japan.
Yoshimura
T
T
Takahashi
H
H
Nagao
S
S
Nozawa
Y
Y
Furukawa
Y
Y
Mori
K
K
Hayashi
K
K
D001692:Biological Transport; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002455:Cell Division / Q000502:physiology; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000187:drug effects; D003609:Dactinomycin / Q000494:pharmacology; D004967:Estrogens / Q000502:physiology*; D016762:Genes, fos; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D000071163:Trefoil Factor-1; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D004273:DNA, Neoplasm; D004967:Estrogens; D009363:Neoplasm Proteins; D011506:Proteins; D012334:RNA, Neoplasm; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D003609:Dactinomycin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate