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KMID : 0617220000110010085
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Duksung Bulletin Phamaceutical Sciences
2000 Volume.11 No. 1 p.85 ~ p.90
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Human CYP1A2 Promoter Fused-Luciferase Gene Constructs Hardly Respond to Polycyclic Hydrocarbons in Transient Transfection Study in HepG2 Cells
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Chung Injae
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Abstract
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In previous study. both constitutive expression and 3-methylcholanthrene (3MC)-mediated elevation of CYP1A2 mRNA were demonstrated in human hepatoma HepG2 cells by reverse transcription-polymerase chain reaction (RT-PCR), suggesting that HepG2 cells would be appropriate for the study of human CYP1A2 regulation(Chung and Bresnick. 1994). Further studies were conducted to detemine the basis of this induction phenomenon that is observed in HepG2 cells. Since CYP1A1 gene. another polycyclic hydrocarbon(PH)-inducible gene. is regulated by PHs through their interactions via receptors with cis-elements, the 5-flanking region of human CYP1A2 gene was analyzed to search such responsive elements. The promoter activity of various lengths of CYP1A2 gene sequence (-3203/+58 bp) was measured in transiently-transfected HepG2 cells by fusion constructs containing the CAT,hGH or luciferase genes as a reporter. This region of the CYP1A2 gene,although containing a XRE, was only weakly responsive (less than 2 fold induction) to 10 nM of TCDD or 1 uM 3 MC treatment. This small enhancement of promoter activity is inconsistent with the previous observation, i.e.. 12 to 14 fold-enhanced CYP1A2 mRNA from 1 uM 3 MC treated HepG2 cells, suggesting that additional mechanisms would exist for PH-mediated induction of CYP1A2 in these cells.
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