血浆游离FHIT基因杂合性缺失在非小细胞肺癌中的临床意义

Loss of Heterozygosity on FHIT Gene in Plasma of Patients with Non-Small Cell Lung Cancer

目的探讨脆性组氨酸三联体(fragile histidine triad,FHIT)基因在非小细胞肺癌(non-small cell lung canc-er,NSCLC)患者血浆及组织中杂合性缺失(loss of heterozygosity,LOH)的特点,检测血浆游离FHIT基因的LOH在NSCLC研究中的临床意义。方法通过聚合酶链式反应(polymerase chain reaction,PCR)-银染法检测69例NSCLC患者(手术前、后)血浆和新鲜癌组织标本中FHIT基因的3个微卫星位点D3S1300、D3S1234、D3S4103的LOH,并进行比较;15例肺良性病变患者静脉血、组织标本及5例健康志愿者的静脉血标本作对照。对应的组织病理切片进行FHIT蛋白的免疫组化染色。结果NSCLC患者术前血浆和组织FHIT基因的3个微卫星位点上LOH阳性率分别为53.6%(37/69例)、72.5%(50/69例),其共同检出率达74.0%(37/50例)。肺良性病变及健康人血浆中未检出该基因突变,两组相比差异有显著性意义(P<0.05)。不同病理类型的肺癌患者手术前后血浆FHIT基因LOH之间差异无统计学意义(P>0.05);有淋巴结转移的肺癌患者与无淋巴结转移者相比,血浆更易检测到FHIT基因的LOH,差异有统计学意义(P<0.05);不同临床分期患者术前血浆FHIT基因LOH之间差异无统计学意义(P>0.05),而术后同一患者血浆FHIT基因的LOH的检出率差异有统计学意义(P<0.05);免疫组化染色发现在78.3%(54/69)NSCLC患者肿瘤组织中检测出FHIT蛋白表达缺失,而在FHIT蛋白表达缺失的54例肿瘤组织中,有39例患者血浆FHIT基因存在1个或2个上述微卫星位点的LOH。结论NSCLC患者血浆与肿瘤组织中FHIT基因LOH有较高的一致性变化;LOH可能是NSCLC肿瘤组织FHIT蛋白表达下调的重要机制之一,血浆FHIT基因的LOH检测对于评估肺癌的预后、转移具有潜在的价值和广阔的应用前景。

Objective To explore the characteristics of loss of heterozygosity（LOH） on fragile histidine triad（FHIT） gene in plasma and matched primary tumor tissues of 69 patients with non-small cell lung cancer（NSCLC） and the clinical implication of LOH detection of plasma free FHIT gene in the study on NSCLC.Methods Polymerase chain reaction and silver staining were performed to examine the LOH in 3 micro-satellite loci D3S1300,D3S1234 and D3S4103 on FHIT gene in plasma（pre-and post-operation） and matched primary tumor tissues of 69 patients with NSCLC.Whole blood and tissues in 15 cases of benign lung diseases and whole blood in 5 healthy people were taken as control.Immunohistochemical staining was used to detect the expression of the FHIT protein in the tumor tissues.Results The positive rate of 3 micro-satellite loci LOH at FHIT gene was 53.6%（37/69 cases）,72.5%（50/69 cases） in preoperative plasma and tissues in NSCLC,respectively,and their accordant rate was 74.0%（37/50 cases）,but in the controls,that was not detected.No significant difference was found among different stages and pathological types（P0.05）.The LOH at FHIT gene in plasma with lymph node metastasis in NSCLC was easier to be detected than in the patients without metastasis（P0.05）.There was significant difference in the LOH at FHIT gene among different stages in the blood extracted after operation（P0.05）.The expression of FHIT protein was down-regulated in the tumor tissues in 54 out of the 69 cases（78.3%）.Among the 54 samples,LOH at the FHIT gene was detected in 39 cases,at one or two of the micro-satellite loci tested.Conclusion LOH at FHIT gene shows a high concordant pattern between the tissue and plasma in NSCLC;LOH may be an important mechanism for down-regulation of the FHIT protein expresison in the NSCLC.Monitoring the LOH at the FHIT gene in plasma of patients with NSCLC may be a clinical potential role to assess the prognosis and metastasis with broadly application prospects.