A novel splice-site variant of the base excision repair gene MYH is associated with production of an aberrant mRNA transcript encoding a truncated MYH protein not localized in the nucleus
A novel splice-site variant of the base excision repair gene MYH is associated with production of an aberrant mRNA transcript encoding a truncated MYH protein not localized in the nucleus
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DOI：
10.1093/carcin/bgh206
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发表时间：
2004-10-01
期刊：
影响因子：
4.7
通讯作者：
Tsugane, S
中科院分区：
文献类型：
--
作者：
Tao, H;Shinmura, K;Tsugane, S
MYH基因编码一种DNA糖基化酶，参与腺嘌呤与8-羟基鸟嘌呤配对的切除修复，这是氧化DNA损伤的主要成分，据报道，双等位基因种系MYH突变使个体易患多发性结直肠腺瘤和癌。为了确定MYH基因是否参与胃癌的发生，我们通过聚合酶链反应-单链构象多态性（PCR-SSCP）分析，然后直接测序，检测了20例日本家族性胃癌（GC）患者的血液标本中MYH突变。在所有标本中均未发现双等位基因生殖系MYH突变，但除了4种已知的突变体外，在2例患者中发现了一种新的剪接位点突变体IVS 10 -2A > G（c.892-2A > G）作为其杂合子。逆转录-PCR分析显示，IVS 10 -2A > G变体引起编码截短MYH蛋白的异常mRNA转录物的产生。免疫荧光分析表明，野生型MYH蛋白，而不是变异型，定位于细胞核。然后，我们用反向双引物PCR在128例消化道癌患者中寻找IVS 10 -2A > G变异，并从6例患者中鉴定出8例具有IVS 10 -2A/G基因型的癌症。然而，没有检测到其他生殖系MYH突变或其余野生型等位基因的失活。接下来，我们在148例GC病例和292例对照的病例对照研究中检验了IVS 10 -2G等位基因与GC风险的假定相关性，但在病例和对照之间没有发现IVS 10 -2A > G变异体的分布有显著差异。有趣的是，IVS 10 -2G等位基因的纯合子被发现在一个GC的情况下，但没有在任何控制。这些结果表明，由于基于MYH IVS 10 -2A > G变异体的剪接异常，修复核DNA中8-羟基鸟嘌呤的能力在日本个体之间可能存在差异，并且双等位基因IVS 10 -2A > G变异可能是GC发生的原因。
The MYH gene encodes a DNA glycosylase involved in the excision repair of adenines paired with 8-hydroxyguanines, a major component of oxidative DNA damage, and bi-allelic germline MYH mutations have been reported to predispose individuals to multiple colorectal adenomas and carcinoma. To determine whether the MYH gene is involved in gastric carcinogenesis, we examined blood specimens from 20 Japanese familial gastric cancer (GC) patients for MYH mutations by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis followed by direct sequencing. Bi-allelic germline MYH mutations were not found in any of the specimens, but in addition to four known variants, a novel splice-site variant, IVS10-2A > G (c.892-2A > G), was found in two patients as its heterozygote. Reverse transcription-PCR analysis revealed that the IVS10-2A > G variant caused the production of an aberrant mRNA transcript encoding a truncated MYH protein. Immunofluorescence analysis showed that the wild-type MYH protein, but not the variant-type, is localized in the nucleus. We then searched for the IVS10-2A > G variant in 128 digestive tract cancer patients by PCR with confronting two-pair primers, and eight cancers from six patients with the IVS10-2A/G genotype were identified. However, no other germline MYH mutations or inactivation of the remaining wild-type allele was detected. We next tested the presumed correlation of the IVS10-2G allele with GC risk in a case-control study of 148 GC cases and 292 controls, but no significant difference in the distribution of the IVS10-2A > G variant was found between the cases and controls. Interestingly, the homozygote for the IVS10-2G allele was found in one GC case, but not in any controls. These results suggested that the ability to repair 8-hydroxyguanine in nuclear DNA may differ among Japanese individuals due to the splicing abnormality based on the MYH IVS10-2A > G variant, and that the bi-allelic IVS10-2A > G variation may be responsible for the occurrence of GC.