Rap1GAP1在人胰腺癌组织中的表达及意义

目的通过检测Rap1GAP1在人胰腺癌中的表达情况及rap1GAP1在三种人胰腺癌细胞系中的突变情况,探讨其在人胰腺癌发生发展过程中的作用。方法(1)采用免疫组织化学Envision两步法,检测73例人胰腺癌组织及其癌旁胰腺组织中Rap1GAP1的表达情况,并分析其与胰腺癌临床病理特征之间的关系;(2)采用RT-PCR和测序法检测三种人胰腺癌细胞系中rap1GAP1的突变情况。结果(1)Rap1GAP1在癌旁胰腺组织、胰腺上皮内肿瘤(pancreatic intraepithelialneoplasia,PanIN)1a、1b、2及3级和浸润性胰腺癌中的阳性率分别为100%、93.8%、92.3%、70.0%、57.9%和13.7%。癌旁胰腺组织、各级PanIN与浸润性癌之间的表达差异有统计学意义(P<0.01);Rap1GAP1在高、中和低分化胰腺癌中阳性率分别为26.9%、7.1%和0,显示Rap1GAP1的表达与胰腺癌的分化程度有关(P<0.05)。而Rap1GAP1的表达与患者的年龄、性别、淋巴结转移情况和临床分期无关。(2)Panc-1、MiaPaCa-2细胞系中存在rap1GAP1关键区域(催化结构域)的大片段缺失,而Aspc-1细胞系含有完整的编码rap1GAP催化结构域的外显子。结论相比于癌旁胰腺组织和各级PanIN,浸润性胰腺癌中 Rap1GAP1的表达显著降低。另外,Rap1GAP1在低分化胰腺癌中的表达显著降低。提示Rap1GAP1可能是胰腺癌发生发展过程中的一个晚期事件。三种人胰腺癌细胞系中的突变分析结果提示其表达降低可能与遗传学上的大片段缺失有关。

Expression and Significance of Rap1GAP1 in Human Pancreatic Ductal Adenocarcinomas

Objective To detect the protein expression of Rap1GAP1 in human pancreatic ductal adenocarcinomas(PDACs) and rap1GAP1 mutational status in three pancreatic cancer cell lines,and to explore its roles in the pathogenesis of PDAC.Methods(1)The protein expression of Rap1GAP1 was detected by immunohistochemistry in 73 specimens of PDAC cases and normal pancreatic tissues adjacent to PDACs.The relation of Rap1GAP1 with the clinicopathological characteristics of HDACs was analyzed.(2)rap1GAP1 mutational status was detected by RT-PCR and then DNA sequencing.Results(1)The positive rates of Rap1GAP1 expression in normal pancreatic tissues adjacent to PDACs,pancreatic intraepithelial neoplasia(PanIN 1a,1b,2,3) and invasive PDACs were 100%,93.8%,92.3%,70.0%,57.9% and 13.7%,respectively.Rap1GAP1 expression was significantly decreased in invasive PDACs(P<0.01),compared with those in the normal pancreatic tissues adjacent to PDACs and PanIN 1-3.The positive rate of Rap1GAP1 expressions in histologically well,moderate and poor differentiated PDACs were 26.9%,7.1% and %,respectively.Rap1GAP1 expression was significantly decreased in poor differentiated PDACs(P<0.05).However,Rap1GAP1 expression was not related to age,gender,status of metastasis of lymph nodes and clinical stage.(2) Panc-1 and MiaPaCa-2 cells had large fragment lost of rap1GAP1,while Aspc-1 cells had full catalytic domain of rap1GAP1.Conclusion Rap1GAP1 expression was significantly decreased in invasive PDACs and related to tumor cell differentiation,suggesting that loss of Rap1GAP1 happens at a later stage of PDAC progression.Mutational status in three pancreatic cancer cell lines suggested that loss of Rap1GAP1 might be due to large fragment lost of rap1GAP1.