肺鳞癌、腺癌中p14 ARF基因启动子区甲基化及蛋白表达的研究

背景与目的 p14^ARF基因是新近发现的抑癌基因，其异常表达与多种人类肿瘤发生有关，启动子区异常甲基化作为p14^ARF基因失活的重要形式可能参与了肿瘤的发生。本研究通过检测肺鳞癌、腺癌中p14^ARF启动子区甲基化状态和蛋白表达，探讨p14^ARF启动子区甲基化与肺癌的关系。方法 通过免疫组织化学（IHC）、甲基化特异性PCR（MSP）和相关限制性内切酶PCR（RF-PCR）方法，检测40例肺鳞癌、腺癌组织中p14^ARF启动子区甲基化状态和蛋白表达水平。结果 癌组织及癌旁正常组织中p14^ARF启动子区甲基化阳性率分别为17．5％（7／40）和2．5％（1／40）（P-0．025）。RE-PCR检测结果相同。癌组织及癌旁正常组织中p14^ARF蛋白阳性率分别为70．0％（28／40）和95．0％（38／40）（P-0．003）。p14^ARF基因启动子区甲基化和蛋白表达均与肿瘤分期、组织类型、分化程度、淋巴结转移等临床病理特征无明显关系（P＜0．05）。p14^ARF启动子区甲基化与蛋白表达呈负相关（r=-0．56，P=0．001）。结论 启动子区甲基化是p14^ARF基因失活的重要机制。p14^ARF启动子区异常甲基化可能参与了非小细胞肺癌的发生，是肺癌发生过程的早期事件。

Promoter methylation status and protein expression of p14ARF gene in squamous cell carcinoma and adenocarcinoma of the lung

Background and objective Recently, the p14 ARF gene has emerged as a new putative tumor suppressor gene, and the alteration of p14 ARF gene is closely related to development of multiple human tumors. The aberrant promoter methylation as a mechanism of inactivation of p14 ARF gene might participate in tumorigenesis. The aim of this study is to investigate promoter methylation status and protein expression of p14 ARF gene in pulmonary squamous cell carcinoma and adenocarcinoma, and to value the role of p14 ARF promoter methylation in carcinogenesis of non-small cell lung cancer. Methods Promoter methylation status and protein expression of p14 ARF gene were analyzed in 40 cases of pulmonary squamous cell carcinoma and adenocarcinoma by methylation specific polymerase chain reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR) and immunohistochemistry (IHC). Results The positive rate of p14 ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer was 17.5% (7/40) and 2.5% (1/40) respectively (P= 0.025 ). The results of RE-PCR were consistent with the above. The positive rate of p14 ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer (P=0.003). Promoter methylation and protein expression of p14 ARF gene showed a significantly negative correlation (r=-0.56, P= 0.001 ), and both of them did not correlate statistically with the clinicopathologic characteristics of patients such as histological classification, TNM stages, differentiation grade and lymph node involvement. Conclusion Promoter methylation is a crucial mechanism of inactivation of p14 ARF gene. Promoter methylation of p14 ARF gene might be involved in carcinogenesis of non-small cell lung cancer, and it is an early event in development process of non-small cell lung cancer.