非小细胞肺癌中窖蛋白1基因的蛋白表达和甲基化及其意义

Study on expression and methylation of caveolin 1 gene in non-small cell lung cancers

目的 检测窖蛋白1（Cav-1）在非小细胞肺癌（NSCLC）中的蛋白表达以及启动子的甲基化状况，探讨Cav-1基因在NSCLC中的作用及其临床意义。方法 应用免疫组织化学（SP法）和量子点Qd600染色检测123例NSCLC组织、17例良性病变肺组织中Cav-1蛋白表达和亚细胞定位。亚硫酸氢钠处理DNA，甲基化特异性PCR（MSP）检测Cav-1基因启动子区域的甲基化水平。结果 Cav-1蛋白在肺支气管黏膜上皮细胞、肺泡上皮细胞、毛细血管内皮细胞、成纤维细胞、平滑肌细胞的胞质和胞膜高表达。癌旁组织（对照）组和肺癌组中Cav-1蛋白的阳性率分别为17／17、43．1％（53／123），两组间差异有统计学意义（P=0．001）；Cav-1蛋白在NSCLC不同的组织学类型（P=0．552）和分化程度（P＝0．160）中差异均无统计学意义。Cav-1蛋白阳性率与NSCLC的TNM分期（P=0．001）以及淋巴结转移（P=0．001）均相关。在40例Cav-1蛋白表达为阴性的肺癌组织和12例癌旁肺组织，MSP法均未检测到Cav-1基因启动子区域的甲基化。结论 Cav-1蛋白失表达的机制可能与启动子区是否甲基化无关。Cav-1蛋白高表达预示NSCLC恶化进展和高侵袭性。

Objective To study the methylation of CpG islands in the promoter region, expression of caveolin 1 （Cav-1） gene and their clinical significance in non-small cell lung cancers （NSCLC）. Methods Immunohistochemistry and quanta Qd600 staining were used to detect the expression of Cav-1 in tissues from benign lung lesions （ n = 17 ） and NSCLC （ n = 123）. DNA was treated with sodium bisulfite and the Cav-1 promoter region was screened using methylation-specific polymerase chain reaction for the possible methylation sites. Results Cav-1 protein was highly expressed in cytoplasm and cell membrane of normal bronchial epithelium, alveolar epithelium, endothelial cells, fibroblasts and smooth muscle cells. The expression rates of Cav-1 protein were 100% （17/17） in the control group and 43.1% （53/123） in the NSCLC group （P =0. 001）. Amongst the NSCLC group, there was no statistically significant difference in Cav-1 protein expression in different histologic types （P =0. 552） and tumor grades （P =0. 160）. On the other hand, Cav-1 protein immunoreactivity was remarkably higher in advanced tumor stage： 72. 7% in stage ⅢA ＋ⅢB, compared with 9.4% in stage I A ＋ I B and 38. 3% in stage ⅡA ＋ ⅡB （P =0. 001 ）. The expression rate of Cav-1 protein in the NSCLC cases with lymph node metastasis was 53. 6%, compared with 20.5% in those without nodal involvement （P =0. 001 ）. DNA from 40 NSCLC cases with negative Cav-1 protein expression and 12 cases of peritumoral lung tissues were extracted. Methylation in the promoter region of Cav-1 gene was not detected in lung cancer or peritumoral tissues. Conclusions High expression of Cav- 1 protein is respected of the aggressive clinical behavior and advanced tumor stage. Loss of Cav-1 protein expression seems not correlated to the methylation status in the promoter region of Cav-1 gene.