结直肠癌组织中KRAS、NRAS、BRAF、PIK3CA基因突变与临床病理特征及MMR蛋白、p53蛋白表达的相关性研究

Relationship between mutations of KRAS,NRAS,BRAF and PIK3CA genes and clinicopathological parameters and MMR and p53 protein expression in colorectal cancer

目的分析结直肠癌组织中KRAS、NRAS、BRAF、PIK3CA基因突变情况,探讨其与临床病理参数及MMR蛋白、p53蛋白表达的关系。方法回顾性分析140例结直肠癌组织的临床病理特征,应用扩增阻碍突变系统(ARMS)进行实时荧光定量PCR检测140例结直肠癌组织KRAS、NRAS、BRAF、PIK3CA基因突变情况;应用免疫组化方法分析MMR蛋白、p53蛋白表达情况;应用统计学方法分析KRAS、NRAS、BRAF、PIK3CA基因突变情况与临床病理特征、MMR蛋白、p53蛋白表达之间的关系。结果140例结直肠癌患者中,检测出KRAS基因突变者64例(45.7%),NRAS基因突变者6例(4.3%),BRAF基因突变者13例(9.3%),PIK3CA基因突变者5例(3.6%)。KRAS/BRAF基因双突变者6例,KRAS/PIK3CA基因双突变者4例,NRAS/KRAS基因双突变者1例。KRAS基因在右半结肠、左半结肠、直肠的突变率分别为54.5%、78.4%、24.2%(P=0.0000),在PMS2缺失者中的突变率显著低于无PMS2缺失者中(0 vs 49.6%,P=0.0043)。高分化腺癌、年龄≤30岁者中PIK3CA基因突变率高于中、低分化腺癌、30~60岁及>60岁者(P<0.05);在p53野生型中PIK3CA的突变率显著高于p53突变型(12.9%vs 0.9%,P=0.0087)。NRAS、BRAF基因突变在不同性别、年龄、直径、肿瘤原发部位、肿瘤分化程度、区域淋巴结转移、TNM分期、组织学类型、p53突变及MMR蛋白表达中的差异均无统计学意义(P<0.05)。结论结直肠癌患者中,KRAS基因突变率最高。KRAS、NRAS、PIK3CA与临床病理参数存在相关性。

Objective To analyze KRAS,NRAS,BRAF and PIK3 CA gene mutations in colorectal cancer(CRC),and to explore their relationship with clinicopathological parameters,and the expression of MMR protein and p53 protein.Methods A total of 140 cases of CRC were clinicopathologically reviewed and immunohistochemical staining was performed and the gene mutation status was determined by ARMS.Results Among the 140 CRC cases,KRAS was the most common gene mutation that occurred in all cases(64 cases,45.7%),followed by BRAF(13 cases,9.3%),NRAS(6 cases,4.3%)and PIK3 CA(5 cases,3.6%).There were 6 cases carried both KRAS/BRAF mutation,4 cases carried KRAS/PIK3 CA mutation and 1 case carried NRAS/KRAS mutation.The KRAS mutation was associated with more leftsided tumors,and fewer PMS2 deficiency(P<0.05).The PIK3 CA mutation was associated with the younger age,higher well differentiated tumor and P53 wild-type(P<0.05).There was no significant difference in NRAS mutation and BRAF gene mutation with gender,age,diameter,primary site,differentiation,lymph node metastasis,TNM stage,histological type,p53 mutation and MMR protein expression(P<0.05).Conclusion Among colorectal cancer patients,the rate of KRAS gene mutation is most frequently detected.KRAS,NRAS and PIK3 CA gene mutations are correlated with clinicopathological parameters.