Co-treatment with deoxycholic acid and azoxymethane accelerates secretion of HMGB1 in IEC6 intestinal epithelial cells.
OBJECTIVE
High-mobility group box 1 (HMGB1) is a nuclear protein that acts as a ligand of the receptor for advanced glycation end products (RAGE) and its expression enhances progression of cancer. However, the mechanism underlying HMGB1 secretion is still unclear. In this study, we examined the effect of deoxycholic acid (DCA), a promoter of colon carcinogenesis, on HMGB1 secretion.


METHODS
We used an in vitro transformation model comprised of IEC6 intestinal epithelial cells treated with azoxymethane (AOM) and/or DCA. HMGB1 expression and secretion were examined by Western and Northern blot analyses, and ELISA. Intracellular translocation of HMGB1 was examined by protein fractionation.


RESULTS
AOM + DCA-treated IEC6 cells showed upregulation of HMGB1 mRNA expression and increased level of HMGB1 protein in culture medium, but decreased level of HMGB1 protein in the nucleus. AOM + DCA treatment increased level of histone H4 acetylation, which induced translocation of HMGB1 from the nucleus to the cytoplasm and increased HMGB1 secretion. Leptomycin B inhibited extranuclear translocation and secretion of the HMGB1 protein.


CONCLUSIONS
These findings suggest that DCA affects intracellular localization and secretion of HMGB1.
Fujii
K
K
Department of Molecular Pathology, Nara Medical University, Kashihara, Nara, Japan.
Luo
Y
Y
Sasahira
T
T
Denda
A
A
Ohmori
H
H
Kuniyasu
H
H
D000107:Acetylation / Q000187:drug effects; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001397:Azoxymethane / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000187:drug effects; D002756:Cholagogues and Choleretics / Q000494:pharmacology*; D003106:Colon / Q000166:cytology; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006877:Hydroxamic Acids / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D015854:Up-Regulation / Q000187:drug effects
D000903:Antibiotics, Antineoplastic; D002273:Carcinogens; D002756:Cholagogues and Choleretics; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D024243:HMGB1 Protein; D006657:Histones; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D003840:Deoxycholic Acid; C012589:trichostatin A; D001397:Azoxymethane; C038753:leptomycin B