喉鳞状细胞癌中p16^(INK4a)基因甲基化状况及表达

Methylation and expression of p16^(INK4a) gene in laryngeal squamous cell carcinomas

目的研究喉鳞状细胞癌p16INK4a基因启动子区域5′CpG岛的甲基化状况,探讨基因异常甲基化与蛋白表达及其临床病理指标的关系。方法采用甲基化特异性PCR检测30例喉鳞状细胞癌及15例远离肿瘤的正常喉黏膜中p16INK4a基因启动子区域5′CpG岛的甲基化状况,并应用免疫组化EnVision法检测p16INK4a蛋白的表达情况。结果30例喉鳞状细胞癌中p16INK4a基因启动子区5′CpG岛甲基化率76.7%(23/30);p16INK4a蛋白缺失率为93.3%(28/30)。15例正常喉黏膜中未检测到p16INK4a基因异常甲基化,而且其相应蛋白表达均为阳性。p16INK4a基因甲基化状况与其蛋白表达和临床分期密切相关。结论p16INK4a基因5′CpG岛异常甲基化在喉鳞状细胞癌中频率很高,可能在喉癌发生、发展中扮演重要角色;而且这可能是一个早期事件,其临床早期诊断和基因治疗意义均值得进一步深入探讨。

Objective To investigate the methylation status of p16^（INK4a） gene promoter 5′CpG islands in laryngeal squamous cell carcinoma （LSCC） and to elucidate the relationship among aberrant methylation, protein expression and clinicopathological parameters. Methods Methylation-specific PCR （MSP） was adopted to determine the methylation status of p16^（INK4a） gene promoter 5′CpG islands in 30 cases of LSCC and 15 cases of normal laryngeal tissue. The expression of p16^（INK4a） gene was detected by immunohistochemistry （EnVision）. Results Among 30 LSCC tissues, 23 cases （76.7 % ）showed abnormal methylation in the promoter area of gene p16^（INK4a） ; 28 cases （93.3 % ） lost p16^（INK4a） expression. Fifteen specimen of normal tissue displayed no methylation and showed normal p16^（INK4a） expression. The methylation status of p16^（INK4a） gene was closely related to p16^（INK4a） protein loss. There were significant differences between the methylation rates of four clinical stages. Conclusion There is a high frequency of aberrant methylation of CpG island in the 5′-promoter region of p16^（INK4a） gene, which might be an early event and play a vital role in the carcinogenesis of LSCC. It is also of high value to conduct further research on the significance of aberrant p16^（INK4a） gene methylation for early diagnosis and gene therapy.