[Deoxycholic acid-induced signal transduction in HT-29 cells: role of NF-kappa B and interleukin-8].
OBJECTIVE
Deoxycholic acid (DCA) has been appeared to be an endogenous colon tumor promoter. In this study, we investigated whether DCA induces nuclear factor-kappa B (NF-kappa B) activation and IL-8 expression, and tauroursodeoxycholic acid (TUDC) inhibits this signaling in HT-29 cells.


METHODS
After DCA treatments, time courses of NF-kappa B binding activity were determined by electrophoretic mobility shift assay (EMSA). Also, we performed Western blotting of I kappa B alpha to confirm NF-kappa B activation. Time and concentration courses of DCA-induced secretion of IL-8 were measured with ELISA in supernatants of cultured media from the cells. To evaluate the role of NF-kappa B, IL-8 levels were assessed after pretreatment with using phosphorothioate-modified anti-sense oligonucleotides (ODN). Moreover, DCA-induced secretions of IL-8 were measured after pretreatment with TUDC.


RESULTS
DCA dose-dependently induced prominent NF-kappa B binding complexes from 30 min to 8 hr and degradation of I kappa B alpha. The secretions of IL-8 were increased with DCA (50-200 micro M) treatment in a time and dose-dependent manner. Pre-incubation of the cells with TUDC (0.1-10 micro M) for 2 hours caused significant decreases in DCA induced IL-8 secretion. However, transient transfection using p50 or p65 AS-ODN showed no effect on IL-8 secretion.


CONCLUSIONS
DCA may play as a colonic tumor promoter through anti-apoptotic effect of NF-kappa B activation and IL-8 expression, and DCA-induced NF-kappa B independent IL-8 expression is inhibited by TUDC.
Lee
Dong Ki
DK
Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
Park
Sun Young
SY
Baik
Soon Koo
SK
Kwon
Sang Ok
SO
Chung
Jun Mo
JM
Oh
Eok-Soo
ES
Kim
Hyun Soo
HS
D015153:Blotting, Western; D003110:Colonic Neoplasms; D003840:Deoxycholic Acid / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D019073:HT29 Cells; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013655:Taurochenodeoxycholic Acid / Q000494:pharmacology*; D015533:Transcriptional Activation / Q000187:drug effects
D016209:Interleukin-8; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D003840:Deoxycholic Acid; D013655:Taurochenodeoxycholic Acid; C031655:ursodoxicoltaurine