J. Hakkola et al., EXPRESSION OF XENOBIOTIC-METABOLIZING CYTOCHROME-P450 FORMS IN HUMAN FULL-TERM PLACENTA, Biochemical pharmacology, 51(4), 1996, pp. 403-411
The expression of individual xenobiotic-metabolizing cytochrome P450 (
CYP) genes in human placenta was studied at the mRNA level by reverse
transcriptase-polymerase chain reaction (RT-PCR). mRNAs of CYP1A1, CYP
2E1, CYP2F1, CYP3A3/4, CYP3A5, and CYP4B1 were detected by RT-PCR, and
CYP1A2, CYP2A6/7, CYP2B6/7, CYP2C8-19, CYP2D6, and CYP3A7 were not de
tected. Several enzyme activity assays and immunoblots were used to fu
rther characterize expression of forms producing detectable mRNA trans
cripts. The catalytic activities of 7-ethoxycoumarin O-deethylase (ECO
D), 7-ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxy
lase (AHH) were substantially increased in response to maternal cigare
tte smoking, and paralleled the amount of CYP1A1 mRNA and protein. Aro
matase activities were slightly lower in placentas exposed to cigarett
e smoke compared with nonexposed placentas. These data show that sever
al xenobiotic-metabolizing CYP genes are expressed in human placenta a
t a low level. The significance of such low-level expression is unknow
n, but it may have local physiological or toxic consequences.