腮腺癌在多形性腺瘤中p16基因的表达及甲基化改变

目的研究腮腺癌在多形性腺瘤中（carcinoma ex pleomorphic adenoma,CXPA）p16基因的蛋白表达和甲基化改变,并评价其在该肿瘤癌变中的意义。方法收集40例腮腺CXPA标本及10例正常腮腺标本,应用免疫组织化学技术和甲基化特异性PCR技术,检测p16基因的蛋白表达和甲基化改变。结果正常腺体p16蛋白表达均为阳性,21例 (21/40,52.5%)CXPA标本表现为表达降低或表达缺失,二者存在统计学差异(P＜0.05)。正常腺体p16基因启动子未见高甲基化,16例(16/40, 40%)CXPA出现启动子高甲基化,二者存在统计学差异(P＜0.05)。结论p16基因表达降低或表达缺失、启动子高甲基化对于腮腺CXPA的癌变具有重要意义,后者可能是p16基因在CXPA中的重要失活机制。

Expression and methylation of p16 in carcinoma ex pleomorphic adenoma of the parotid gland

Objective To study the changes of p16 gene protein expression and promoter methylation in carcinoma ex pleomor-phic adenoma (CXPA) of the parotid gland, and to evaluate their significance for carcinogenesis of CXPA. Methods p16 gene protein expression and promoter methylation were determined in 40 samples of CXPAs of the parotid glands and 10 normal samples of the parotid gland(NM) using immunohistochemistry (IHC) and methylation specific PCR (MSP). Results In normal parotid glands, the p16 protein was positively expressed. In the CXPAs group, 21 cases (52.5%) showed a decreased (in different de-grees) or absence ofpl6 protein expression. There was significant statistical difference (P<0.05) between the two groups. Hyper-methylation of the p16 gene promoter was found in 16 cases (16/40, 40%) of CXPAs, but was not found in normal salivary glands (P<0.05). Conclusion The decreased or absence of p16 protein expression and promoter hypermethylation play an important role in the carcinogenesis of CXPA. And hypermethylation may be the important inactivation mechanism of the p16 gene in CXPA.