乳腺导管内增生病变中p53表达与外显子突变的研究

目的 肿瘤抑制基因p53异常是浸润性乳腺癌发生发展中常见事件,而其与包括普通型增生(usual ductal hyperplasia,UDH)、不典型增生 (atypical ductal hyperplasia,ADH)及导管内原位癌 (ductal carcinoma in situ,DCIS)的乳腺导管内增生性病变关系不明.本研究旨在探讨乳腺导管内增生性病变中p53外显子突变及突变型p53蛋白表达情况,以期了解p53突变及蛋白表达在乳腺癌发生发展中的作用.方法 用高分辨率熔解曲线(high-resolution melting,HRM)结合测序研究140例乳腺导管内增生性病变中p53外显子5-8的突变情况.用免疫组化研究240例乳腺导管内增生性病变中突变型p53蛋白表达情况.结果 经过HRM分析,共17例患者DNA熔解曲线与野生型标准品熔解曲线大于阈值结合测序分析结果发现,其中16例出现p53外显子突变.p53在UDH、ADH及DCIS中的突变率为0.0%(0/40),12.7%(8/63)和21.6%(8/37),三者间差异显著(P<0.05).40例UDH中未出现突变型p53蛋白阳性表达,在14.6%(19/130)的ADH出现阳性表达,在31.4%(22/70)的DCIS中出现阳性表达,三者间差异显著(P<0.05).Spearman相关性分析示突变型p53蛋白表达与p53外显子突变呈正相关(r=0.792,P<0.01).结论 p53外显子突变及突变型p53蛋白表达发生于乳腺导管内增生性病变中的ADH与DCIS,其可能为乳腺癌发生发展中的早期事件.

Genetic mutations and expression of p53 in breast intraductal proliferative lesions

Objective:Although the abnormality of tumor suppressor gene p53 is one of the most common alterations identified in invasive breast carcinomas,it is not clear whether its alterations frequently occur in intraductal proliferative lesions including usual ductal hyperplasia(UDH),atypical ductal hyperplasia(ADH) and ductal carcinoma in situ(DCIS).The aim of this study is to investigate the p53 mutations and exprssion in intraductal proliferative lesions,and explore their significance in breast carcinogenesis.Methods: p53 mutation was examined in 140 cases of intraductal proliferative lesions including UDH,ADH and DCIS by high-resolution melting(HRM),followed by DNA sequence analysis.240 cases of intraductal proliferative lesions were subjected to the immunohistochemical staining of mutant p53 protein.Results: The HRM and sequencing analysis demonstrated that the positive rates of p53 mutation were 0.0%(0/40),12.7(8/63)and 21.6%(8/37) in UDH,ADH and DCIS respectively.The p53 protein expression was detected in none of the UDH,14.6%(19/130) of ADH and 31.4%(22/70) of DCIS samples.Statistically,p53 mutation and protein accumulation were gradually increased from UDH,ADH to DCIS(P<0.05).There was significantly positive association between p53 mutation and expression in these samples by Spearman chi-square test(r=0.792,P<0.01).Conclusion: p53 mutation and mutant p53 expression occur in intraductal proliferative lesions including ADH and DCIS,and they may represent early events in breast carcinogenesis.