2002 Fiscal Year Final Research Report Summary
Real time PCR analysis of transporter and metabolism enzyme expression level in human alimentary canal epidermic cell
| Project/Area Number |
13672387
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
応用薬理学・医療系薬学
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| Research Institution | KOBE UNIVERSITY |
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Principal Investigator |
SAKAEDA Toshiyuki Kobe Univ.University Hospital Associate Professor, 医学部附属病院, 助教授 (00304098)
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| Co-Investigator(Kenkyū-buntansha) |
AOYAMA Nobuo Kobe Univ.University Hospital Associate Professor, 医学部附属病院, 助教授 (30243299)
OKUMURA Katsuhiko Kobe Univ.University Hospital Professor, 医学部附属病院, 教授 (60025707)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Caco-2 / Human duodenal enterocytes / Real time PCR / mRNA / MDR1 / MRP1 / CYP3A |
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| Research Abstract |
The expression levels of mRNAs for transporters and a metabolic enzyme related to oral absorption in Caco-2 cells were quantitatively compared with those in human duodenal enterocytes using real time PCR method. Alteration in mRNA expression levels of these proteins was also evaluated in Caco-2 cells during culture and passage. Furthermore, the effect of the C3435T mutation in exon 26 of MDR1 gene on the expression levels of MDR1 mRNA was evaluated in human duodenal enterocytes.
The study results are shown in the following.
1. Relative concentrations of mRNAs for transporters (MDR1, MRP1 and MRP2) and a metabolic enzyme (CYP3A) in human enterocytes were about 12-, 3-, 7- and 8000-fold higher than in Caco-2 cells, respectively. Three of five Caco-2 cell lines had no detectable CYP3A mRNA.
2. MDR1, MRP1 and CYP3A mRNA levels in Caco-2 cells were comparable with those in normal colorectal tissues and colorectal adenocarcinomas. MRP2 mRNA was detected in Caco-2 cells, whereas those in normal colorectal tissues and colorectal adenocarcinomas were barely detectable.
3. The duodenal mRNA level of MDR1 in the subject with the homozygote of the mutant allele (T/T) was higher than that in those with homozygote of wild-type allele (C/C). A good correlation (r=0.797 ; P<0.01) was also observed between the mRNA expression levels of MDR1 and CYP3A4 in the individual duodenal biopsies.
In conclusion, Caco-2 cell lines showed the gene expression profiles of oral absorption related proteins closer to those of human normal colorectal tissue and colorectal adenocarcinoma, rather than human duodenal enterocytes. The mutant C3435T at exon 26 of the MDR1 gene associated with the higher level of MDR1-mRNA in the duodenum. Lower plasma concentrations of the substrates for CYP3A4 may be observed in subjects harboring the mutant C3435T of the MDR1 gene.
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