肝细胞癌患者血浆循环DNA微卫星变异的研究

Microsatellite alterations of circulating DNA in the plasma of patients with hepatocellular carcinoma

目的探讨肝细胞癌(HCC)患者血浆循环DNA微卫星变异的特点及其与肿瘤组织的一致性。方法选择位于染色体8p上3个具有高度多态性的微卫星标记,对62例肝细胞癌血浆、组织标本的DNA进行了杂合性缺失(LOH)和微卫星不稳定(MSI)检测。结果在联合检测的3个微卫星位点上,39例发生了LOH的组织标本其对应的血浆标本中有33例在相应位点检测到了相同的改变,一致性为84.6%;在19例MSI阳性的组织标本中,其对应的血浆中有14例检测到了相同的MSI,一致性为73.7%;62例HCC血浆DNA在至少一个位点的LOH阳性率(58.1%,36/62)明显高于MSI(29.0%,18/62)(P<0.01);HCC组织、血浆DNA在D8S277位点的MSI阳性率皆明显高于其他两个位点(P均<0.05)。结论HCC血浆循环DNA与肿瘤组织微卫星变异有较高的一致性变化,血浆循环DNA可以用来反映肿瘤组织的微卫星变异;LOH方式在HCC的发生发展过程中起着重要作用,MSI的作用次之;D8S277是HCC中对MSI敏感的一个检测位点。

Objective To explore the features of microsatellite alterations of circulating DNA in the plasma of patients with hepatocellular carcinoma （HCC） and whether they are in concordance with those in the carcinoma tissues. Methods Peripheral blood samples were collected from 62 HCC patients and the corresponding tumor tissues were obtained during operation. Three high-polymorphic microsatellite markers located at chromosome 8p, D8S277, D8S298, and D8S1771, were selected to be used to detect the loss heterozygosity （LOH） and microsatellite instability （MSI） by PCR and sequencing. Results Joint detection showed that 39 out of the 62 tissue samples showed LOH at all the 3 loci, and the same alterations at the same loci were seen in 33 matched plasma samples with a concordance rate of 84.6%. Nineteen tissue samples showed MSI at all 3 loci, and the same alterations were shown in 14 matched plasma samples with a concordance rate of 73.3%. The rate of LOH for at least one locus in the plasma DNA was 58.1% （36/ 62）, significantly higher than the rate of MSI at at least one locus in the plasma samples （29.0%, 18/62, P 〈0.01 ）. The MSI positive rate in the loci D8S277 of the plasma DNA was 22.6%, significantly higher than those of the other 2 loci （4.8% and 4.8% respectively, both P 〈0.05）. The MSI positive rate at the loci D8S277 of the cancer tissue was 46.8%, significantly higher than those of the other 2 loci （38.7% for D8S298 and 37.1% for D8S1771, beth P 〈 0.05）. Conclnsion Microsatellite alterations show a high concordant pattern between the tissue and plasma DNA in HCC, which indicates that the microsatellite alterations of tumor tissue are reflected by plasma DNA, LOH may play an important role in hepatocarcinogenesis whereas MSI may also contribute to this progress in a less significant way, and D8S277 is a sensitive locus to MSI in HCC.