Interleukin-18 Down-Regulates Multidrug Resistance-Associated Protein 2 Expression through Farnesoid X Receptor Associated with Nuclear Factor Kappa B and Yin Yang 1 in Human Hepatoma HepG2 Cells.
Multidrug resistance-associated protein 2 (MRP2) plays an important role in bile acid metabolism by transporting toxic organic anion conjugates, including conjugated bilirubin, glutathione, sulfate, and multifarious drugs. MRP2 expression is reduced in cholestatic patients and rodents. However, the molecular mechanism of MRP2 down-regulation remains elusive. In this report, we treated human hepatoma HepG2 cells with interleukin-18 (IL-18) and measured the expression of MRP2, nuclear factor kappa B (NF-κB), farnesoid X receptor (FXR), and the transcription factor Yin Yang 1 (YY1) by quantitative real-time quantitative polymerase chain reaction (PCR) and western blotting. We found that expression of MRP2 was repressed by IL-18 at both the mRNA and protein levels in a dose- and time-dependent manner. Furthermore, the activated NF-κB pathway increased YY1 and reduced FXR. These changes were all attenuated in HepG2 cells with knockdown of the NF-κB subunit, p65. The reduced expression of FXR and MRP2 in HepG2 cells that had been caused by IL-18 treatment was also attenuated by YY1 knockdown. We further observed significantly elevated IL-18, NF-κB, and YY1 expression and decreased FXR and MRP2 expression in bile duct-ligated Sprague Dawley rat livers. Chromatin immunoprecipitation assays also showed that FXR bound to the promoter region in MRP2 was less abundant in liver extracts from bile duct-ligated rats than sham-operated rats. Our findings indicate that IL-18 down-regulates MRP2 expression through the nuclear receptor FXR in HepG2 cells, and may be mediated by NF-κB and YY1.
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China; Department of Gastroenterology, Chengdu Military General Hospital, Chengdu, Sichuan, People's Republic of China.
Xiao-cong
XC
Liu
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Wei
W
Lian
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Liang-jun
LJ
Zhang
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Xin-chan
XC
Feng
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Yu
Y
Gao
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Shao-xue
SX
Li
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Chang
C
Liu
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Ying
Y
Cheng
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Long
L
Yang
Department of Burn and Plastic Surgery, Chengdu Military General Hospital, Chengdu, Sichuan, People's Republic of China.
Xiao-Juan
XJ
Wang
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Lei
L
Chen
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Rong-quan
RQ
Wang
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Jin
J
Chai
Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing, People's Republic of China.
Wen-sheng
WS
Chen
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006801:Humans; D020382:Interleukin-18 / Q000276:immunology*; D008099:Liver / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D008297:Male; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000276:immunology; D016328:NF-kappa B / Q000235:genetics* / Q000276:immunology; D017207:Rats, Sprague-Dawley; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics* / Q000276:immunology; D015398:Signal Transduction; D050986:YY1 Transcription Factor / Q000235:genetics* / Q000276:immunology; D000099150:Receptor, Farnesoid X-Activated
D020382:Interleukin-18; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D016328:NF-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D050986:YY1 Transcription Factor; D000099150:Receptor, Farnesoid X-Activated; C000715087:ABCC2 protein, human; C494698:YY1 protein, human