Development of Caco-2 cells expressing high levels of cDNA-derived cytochrome P4503A4.
OBJECTIVE
To develop Caco-2 cell derivatives expressing high levels of human cytochrome P450 drug metabolizing enzymes.


METHODS
The cDNAs for two cytochrome P450 forms, CYP2A6 and CYP3A4, were introduced into an extrachromosomal vector under control of the cytomegalovirus early intermediate promoter. Vector-bearing cells were selected via resistance to hygromycin B.


RESULTS
Transfected cells exhibited high levels of cDNA-derived protein as measured by Western blot, spectrophotometric P450 determination and/or cytochrome P450 form-selective enzyme assay. CYP3A4 and CYP2A6 catalytic activities were about 100 fold higher than in control cells. cDNA-expressing cells were found to form tight monolayers and were suitable for study of xenobiotic transport and metabolism. The permeabilities of cephalexin, phenylalanine, mannitol and propranolol across transfected monolayers were found to be similar to those across untransfected monolayers. The appropriate transfected monolayers metabolized the CYP2A6 substrate coumarin and the CYP3A4 substrates testosterone and nifedipine.


CONCLUSIONS
A Caco-2 cell system to simultaneously study drug transport and metabolism has been developed.
Crespi
C L
CL
GENTEST Corporation, Woburn, Massachusetts 01801, USA.
Penman
B W
BW
Hu
M
M
D001189:Aryl Hydrocarbon Hydroxylases; D001692:Biological Transport; D018938:Caco-2 Cells / Q000201:enzymology*; D065637:Cytochrome P-450 CYP2A6; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics* / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection; D015262:Xenobiotics / Q000493:pharmacokinetics
D018076:DNA, Complementary; D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; C104464:CYP3A protein, human; D065637:Cytochrome P-450 CYP2A6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human