人非小细胞肺癌中FHIT等位基因缺失和突变的研究

目的　探讨FHIT等位基因缺失、突变在肺癌发生、发展中的作用。方法　应用PCR SSCP和DNA序列分析方法对 3 5例人非小细胞肺癌和 4个肺癌细胞株中FHIT基因的 4个外显子 (外显子 3、4、5、8)和微卫星D3S13 0 0、D3S13 12、D3S13 13进行研究 ,并以远癌肺组织和 10例肺良性病变组织做对照。结果　在 3 5例肺癌中 ,2 2例肺癌发生了一个或两个以上的FHIT等位基因缺失 ,缺失率为 62 .86% ( 2 2 /3 5 )。在鳞癌中 ,FHIT等位基因缺失率 ( 88.2 4% ,15 /17)明显高于腺癌 ( 3 8.89% ,7/18) (P <0 .0 1) ;在吸烟患者中 ( 76.19% ,16/2 1)亦明显高于不吸烟患者 ( 4 2 .86% ,6/14 ) (P <0 .0 5 )。而FHIT等位基因缺失与肺癌的细胞分化程度、P TNM分期、原发肿瘤大小、部位、患者性别、年龄及有无转移均无明显关系 (P >0 .0 5 )。Lewis肺癌、A5 49细胞株亦有FHIT基因部分缺失。 4例肺癌组织具有微卫星灶D3S13 12点突变 ,经DNA序列分析显示均为D3S13 12微卫星灶基因的 87位点密码子发生了CT点突变。结论　FHIT基因异常主要以等位基因的缺失为主 ,而点突变发生率较低。FHIT等位基因缺失主要发生在肺鳞癌和吸烟患者中 ,且FHIT基因可能为烟草致肺癌的靶基因 ,其等位基因缺失可能是肺癌的早期分子事件。

A study on the allelic deletion and mutation of FHIT gene in human non-small cell lung cancer

Objective　To explore the role of the allelic deletion and mutation of FHIT gene on the carcinogenesis and development of lung cancer. Methods　The allelic alterations of FHIT gene and microsatellites D3S1300, D3S1312,D3S1313 were detected in 35 cancer samples of NSCLC, their corresponding normal tissues, and 4 lung cancer cell lines, and 10 lung tissues of benign pulmonary lesions as control by PCR-SSCP and DNA sequence. Results　Loss of heterozygosity (LOH) affecting at least one locus of FHIT gene was observed in 22 out of 35 tumors, with a LOH rate of 62.86％. LOH of FHIT gene in squamous cell carcinoma (88.24％) was significantly higher than that in adenocarcinoma (38.89％) (P＜0.01). The LOH rate of FHIT gene in smoking patients (76.19％) was also significantly higher than that in non-smoking patients (42.86％)(P＜0.05).No significant relationship was found among the LOH of FHIT and cell differentiation, P-TNM stages, size of primary tumor, location of cancer and age of the patients (P＞0.05). LOH of FHIT was also detected in Lewis lung cancer and A549 cell lines. Mutation of microsatellite D3S1312 was observed in 4 lung cancer tissues. DNA sequence showed that CT mutation occurred in the 87 codon of microsatellite D3S1312. Conclusion　The alteration of FHIT gene is mainly allelic loss and the frequency of allelic mutation is rare. FHIT gene alterations preferentially occur in squamous cell carcinoma patients and smokers, and FHIT gene may be a candidate molecular target of carcinogenesis in tobacco smoker. Allelic deletion of FHIT gene might be an early molecular event in smoking-related lung cancer.