Transcriptional activity of the tandem repeat polymorphism in the 5'-flanking region of the human CYP2E1 gene.
BACKGROUND
There are remarkable interindividual differences in the expression of cytochrome P-4502E1(CYP2E1), which in turn may alter susceptibility to alcohol-related diseases and various cancers. We recently characterized the tandem repeat polymorphism in the 5'-flanking region of the human CYP2E1 gene and found that subjects with the homozygous mutant-type (A4/A4) may be at higher risk of developing esophageal cancer. In this study, we determined how this tandem repeat polymorphism alters transcriptional activities of the human CYP2E1 gene by transfection studies.


METHODS
The 5'-flanking region (-2,562 base pair to +9 base pair) of the CYP2E1 gene from three individuals of different genotypes (A2/A2, A2/A4, A4/A4) was amplified by polymerase chain reaction. The polymerase chain reaction products placed in front of a luciferase reporter gene were transfected into human hepatoblastoma cells, human esophageal cancer cells, and human uterus cancer cells. Transcriptional activities were determined by the dual-luciferase assay. When indicated, ethanol (50 mM) was included in the culture medium. CYP2E1 messenger RNA levels in peripheral lymphocytes were measured by the real-time reverse transcription-polymerase chain reaction using the LightCycler system.


RESULTS
The construct including the tandem repeat region exhibited luciferase activities in both A2 and A4 type. It was of note that the activity produced by the A4 allele was significantly greater than that by A2 allele in HeLa cells (p < 0.001). CYP2E1 messenger RNA levels in peripheral blood lymphocytes were comparable between the two genotypes.


CONCLUSIONS
Transcriptional activity of the mutant allele of the tandem repeat polymorphism in the 5'-flanking region of the CYP2E1 gene is greater than that of the wild type.
Nomura
Fumio
F
Department of Molecular Diagnosis, Graduate School of Medicine, Chiba University, Chiba City, Chiba, Japan. fnomura@ho.chiba-u.ac.jp
Itoga
Sakae
S
Uchimoto
Takayuki
T
Tomonaga
Takeshi
T
Nezu
Masahiko
M
Shimada
Hideaki
H
Ochiai
Takenori
T
D024506:5' Flanking Region / Q000235:genetics*; D000428:Alcohol Drinking / Q000009:adverse effects / Q000235:genetics*; D000483:Alleles; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics*; D004938:Esophageal Neoplasms / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006367:HeLa Cells; D006720:Homozygote; D006801:Humans; D062792:MARVEL Domain-Containing Proteins; D008565:Membrane Proteins / Q000235:genetics; D017354:Point Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D011510:Proteolipids; D012333:RNA, Messenger / Q000235:genetics; D020080:Tandem Repeat Sequences / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000378:metabolism
D062792:MARVEL Domain-Containing Proteins; D008565:Membrane Proteins; C094765:PLP2 protein, human; D011510:Proteolipids; D012333:RNA, Messenger; D019392:Cytochrome P-450 CYP2E1