Bahadur Namrata, Leathart Julian B S, Mutch Elaine, Steimel-Crespi Dorothy, Dunn Stuart A, Gilissen Ron, Houdt Jos Van, Hendrickx Jan, Mannens Geert, Bohets Hilde, Williams Faith M, Armstrong Martin, Crespi Charles L, Daly Ann K
Department of Pharmacological Sciences, University of Newcastle Medical School, Framlington Place, NE2 4HH, Newcastle upon Tyne, UK.
Biochem Pharmacol. 2002 Dec 1;64(11):1579-89. doi: 10.1016/s0006-2952(02)01354-0.
Published cDNA sequences suggest the existence of non-synonymous single nucleotide polymorphisms in the cytochrome P450 CYP2C8. To determine whether these polymorphisms could be confirmed in a Caucasian population and to investigate whether additional polymorphisms occur in the coding and upstream regions of this gene, we screened for previously described and for novel polymorphisms using PCR-RFLP and SSCP analysis. We confirmed the existence of two of the previously detected polymorphisms which give rise to the amino acid substitutions I264M and K399R, respectively, but failed to detect three others in our population. We also confirmed that a recently identified polymorphism (R139K) is linked to K399R (CYP2C83) in our study population. The allele frequencies for the I264M (CYP2C84 allele) and the CYP2C83 allele were 0.075 and 0.15, respectively. Three novel polymorphisms (T-370G, C-271A and T1196C/L390S) were also detected with the upstream polymorphisms showing allele frequencies of 0.061 and 0.196, respectively, but the L390S polymorphism detected only in a single subject. An additional single subject was heterozygous for a polymorphism recently described in African-Americans (A805T; CYP2C82 allele). The functional significance of the two upstream polymorphisms and the CYP2C83 and CYP2C84 alleles was investigated in human liver microsomes. Samples heterozygous for CYP2C83 showed significantly lower paclitaxel 6alpha-hydroxylase activity compared with wild-type samples. Median activity associated with CYP2C84 also appeared lower than the wild-type but the difference was not significant. There was no evidence that either upstream polymorphism gave rise to altered CYP2C8 expression.
已发表的cDNA序列表明细胞色素P450 CYP2C8存在非同义单核苷酸多态性。为了确定这些多态性是否能在白种人群中得到证实，并研究该基因的编码区和上游区域是否存在其他多态性，我们采用聚合酶链反应-限制性片段长度多态性分析（PCR-RFLP）和单链构象多态性分析（SSCP）筛选先前描述的和新的多态性。我们证实了先前检测到的两种多态性的存在，它们分别导致氨基酸替换I264M和K399R，但在我们的人群中未检测到其他三种多态性。我们还证实，在我们的研究人群中，最近鉴定出的一种多态性（R139K）与K399R（CYP2C83）连锁。I264M（CYP2C84等位基因）和CYP2C83等位基因的等位基因频率分别为0.075和0.15。还检测到三种新的多态性（T-370G、C-271A和T1196C/L390S），上游多态性的等位基因频率分别为0.061和0.196，但L390S多态性仅在一名受试者中检测到。另外一名受试者对最近在非裔美国人中描述的一种多态性（A805T；CYP2C82等位基因）呈杂合状态。在人肝微粒体中研究了两种上游多态性以及CYP2C83和CYP2C84等位基因的功能意义。与野生型样本相比，CYP2C83杂合的样本显示紫杉醇6α-羟化酶活性显著降低。与CYP2C84相关的中位活性似乎也低于野生型，但差异不显著。没有证据表明任何一种上游多态性会导致CYP2C8表达改变。
