Induction of the transcription factor AP-1 in cultured human colon adenocarcinoma cells following exposure to bile acids.
We studied the effects of bile acids on inducibility of the transcription factor AP-1 in human colon carcinoma LoVo cells. Firstly, cells were treated with chenodeoxycholic acid and the nuclear extracts from those cells were processed by electrophoretic mobility shift assays to analyze nuclear AP-1 DNA-binding activity. We demonstrated that chenodeoxycholic acid induced AP-1 DNA-binding activity in a dose- and time-dependent fashion. Antibody supershift experiments clearly revealed that the majority of protein components in induced AP-1 DNA-binding activity were the products of oncogenes c-fos and c-jun. On the other hand, DNA-binding activity in the nuclear extracts for either NF kappa B, Sp1, or ATF/CREB was not affected by bile acids, suggesting that the effect of bile acids was rather specific for AP-1. Transient transfection experiments supported this notion: expression of the AP-1-luciferase reporter construct was induced by bile acids in a dose-dependent manner, and expression of either reporter construct for NF kappa B, Sp1, or ATF/CREB was not influenced by treatment of the cells with bile acids. We also demonstrated that those bile acids efficiently activated AP-1-dependent promoter in DLD-1 cells, which (as well as LoVo cells), are derived from colon adenocarcinoma, but not in COLO320DM cells which are from colon carcinoid tumor. Thus, we may indicate that bile acids exclusively induce nuclear AP-1 activity in colon adenocarcinoma cells.
Hirano
F
F
Second Department of Internal Medicine, Asahikawa Medical College, Japan.
Tanada
H
H
Makino
Y
Y
Okamoto
K
K
Hiramoto
M
M
Handa
H
H
Makino
I
I
D051697:Activating Transcription Factor 1; D000230:Adenocarcinoma / Q000378:metabolism*; D001483:Base Sequence; D001647:Bile Acids and Salts / Q000494:pharmacology*; D002635:Chenodeoxycholic Acid / Q000494:pharmacology; D002756:Cholagogues and Choleretics / Q000494:pharmacology*; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004273:DNA, Neoplasm / Q000187:drug effects* / Q000378:metabolism; D004268:DNA-Binding Proteins; D003840:Deoxycholic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008095:Lithocholic Acid / Q000494:pharmacology; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D011033:Podophyllin / Q000031:analogs & derivatives / Q000378:metabolism; D011034:Podophyllotoxin / Q000031:analogs & derivatives; D011493:Protein Kinase C / Q000096:biosynthesis*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014580:Ursodeoxycholic Acid / Q000494:pharmacology
D051697:Activating Transcription Factor 1; D001647:Bile Acids and Salts; D002756:Cholagogues and Choleretics; D002793:Cholic Acids; D017931:DNA Primers; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D003840:Deoxycholic Acid; D002635:Chenodeoxycholic Acid; D008095:Lithocholic Acid; C003170:mitopodozide; D014580:Ursodeoxycholic Acid; D011033:Podophyllin; D011493:Protein Kinase C; D019826:Cholic Acid; D011034:Podophyllotoxin; D013755:Tetradecanoylphorbol Acetate