胰岛素瘤中p16基因甲基化和表达下降与临床病理特征的关系

Methylation of p16 gene and reduced expression of p16 protein in insulinoma associated with clinicopathological features

目的探索胰岛素瘤中p16基因甲基化和表达下降与临床病理特征关系。方法纳入2003年10月至2017年12月在北京协和医院手术切除胰岛素瘤的72例患者的资料,用免疫组织化学染色测定72例患者胰岛素瘤组织和49例对照胰腺组织中p16蛋白的表达。从组织中提取基因组DNA并且用亚硫酸氢盐修饰,用甲基化特异PCR的方法检测32例肿瘤组织和17例配对瘤旁组织p16基因启动子区甲基化;将肿瘤组织中p16基因表达以及p16基因甲基化和临床病理进行关联分析。结果72例患者中,男30例,女42例;年龄(46.5±14.0)岁。胰岛素瘤中58.3%(42/72)的肿瘤p16蛋白表达丢失或下降,正常或瘤旁胰腺组织34.7%(17/49)p16蛋白表达丢失或下降(χ^(2)=6.52,P=0.011)。32例胰岛素瘤中有13例(40.6%)发生p16基因启动子甲基化,而瘤旁对照组织仅有2例(11.8%)发生基因甲基化(χ^(2)=4.35,P=0.037)。胰岛素瘤患者性别、年龄、肿瘤大小和肿瘤病理分级等临床特征与p16蛋白表达均无关(均P>0.05)。结论胰岛素瘤中p16蛋白表达丢失或下降并且和p16基因启动子甲基化相关。

Objective To study the alterations of p16 gene and its expression in insulinoma and to correlate the findings with clinicopathological characteristics.Methods Expression of p16 protein was detected in 72 insulinomas and 49 para-tumoral or normal pancreatic tissues by immunohistochemical staining.Genomic DNA was isolated from 32 tumor tissue and 17 paired pancreatic tissues and bisulfite-modified.Promoter methylation status of p16 gene was detected in 32 tumor tissue and 17 paired pancreatic tissues by methylation specific PCR.The findings were correlated with the clinicopathological features.Results There were 30 males and 42 females in all 72 patients,aged(46.5±14.0)years.Loss or reduced expression of p16 protein was found in 42 of 72 insulinomas(58.3%)while loss or reduced expression of p16 was seen in only 34.7%(17/49)of para-tumoral or normal pancreatic tissues(χ^(2)=6.52,P=0.011).Promoter methylation of p16 gene was found in 13 of 32 insulinomas(40.6%)and only 2 of 17(11.8%)para-tumoral tissues(χ^(2)=4.35,P=0.037).The expression of p16 protein in insulinoma was not associated with clinicopathological features such as gender,age,tumor size and tumor grade.Conclusions Loss or reduced expression of p16 protein was found in insulinomas,and associated with p16 gene promoter methylation.