Glycochenodeoxycholate plays a carcinogenic role in immortalized mouse cholangiocytes via oxidative DNA damage.
Bile acids have been suggested to be involved in biliary carcinogenesis, although the underlying mechanisms are yet to be established. The aim of this study was to investigate the carcinogenic effect of bile acids in the biliary tract in relation to oxidative stress. Immortalized mouse cholangiocytes were incubated with various bile acids, followed by measurement of reactive oxygen species (ROS) and the glutathione (GSH) level. As a marker of oxidative DNA damage, 8-hydroxydeoxyguanosine (8-OHdG) expression in cholangiocytes was analyzed by flow cytometry. Then the expression of oxidative DNA repair enzymes in cholangiocytes was examined by real-time PCR. In addition, the long-term effect of bile acid-induced oxidative DNA damage on cholangiocytes was investigated using a mouse oligo DNA microarray. It was found that glycochenodeoxycholate (GCDC) induced the generation of ROS and the depletion of GSH. In contrast, no marked changes were induced by the other bile acids. The percentage of 8-OHdG-positive cells was also increased by GCDC, but the expression of oxidative DNA repair enzymes was not up-regulated. DNA microarray analysis showed marked changes of various genes associated with carcinogenesis (genes related to cell proliferation, angiogenesis, invasion, and metastasis). In conclusion, the long-term effect of oxidative DNA damage due to GCDC may promote carcinogenesis in the biliary tract. Furthermore, accumulation of 8-OHdG due to GCDC might contribute to the dysfunction of oxidative DNA repair enzymes.
Komichi
Daisuke
D
Department of Medicine and Molecular Science, Graduate School of Biomedical Sciences, Hiroshima University, Japan.
Tazuma
Susumu
S
Nishioka
Tomoji
T
Hyogo
Hideyuki
H
Chayama
Kazuaki
K
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D001652:Bile Ducts / Q000166:cytology* / Q000187:drug effects; D001661:Biliary Tract Neoplasms / Q000139:chemically induced; D002273:Carcinogens / Q000494:pharmacology*; D002478:Cells, Cultured; D004249:DNA Damage; D045647:DNA Glycosylases / Q000378:metabolism; D004260:DNA Repair; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D015536:Down-Regulation; D020869:Gene Expression Profiling; D005999:Glycochenodeoxycholic Acid / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000502:physiology; D015854:Up-Regulation
D001647:Bile Acids and Salts; D002273:Carcinogens; D005999:Glycochenodeoxycholic Acid; D000080242:8-Hydroxy-2'-Deoxyguanosine; D045647:DNA Glycosylases; C485990:Ogg1 protein, mouse; D003849:Deoxyguanosine