寡核苷酸芯片技术检测中国肝细胞癌p53基因点突变

目的探讨寡核苷酸芯片技术在我国肝细胞癌p53基因点突变发生频率及形式,并以DNA测序法进行验证。方法参照国际p53突变公共数据库资料,以发生频率最高的7个点突变序列设计探针,制备p53基因点突变专用寡核苷酸芯片,应用该技术检测我国肝细胞癌p53基因7个常见突变位点的突变频率及形式,以DNA测序法验证结果,比较不同分组时p53基因点突变差异。结果共检测肝细胞癌石蜡包埋标本54例,p53基因突变率为38.9%(21/54)。54例中广西肝癌高发病区组17例,广西低发病区组(低发区组)19例,区(省)外组18例,三组突变率分别为47%、21%、50%。p53突变主要发生在249编码区,主要突变形式为249ser突变(由AGG→AGT,第三碱基G→T颠换);以DNA测序法对结果进行验证,两种技术检测结果重合率100%。结论寡核苷酸芯片技术可作为检测肝癌p53基因突变的一种新的、可靠和便捷的手段;我国肝癌不同地区之间p53基因突变在频率及形式上既有差异性又有类似性,可能预示不同地区肝细胞癌的病因学异同性。

p53基因点突变的发生与非小细胞肺癌患者病理生理特征的相关性分析

目的:分析p53基因点突变的发生与非小细胞肺癌患者病理生理特征的相关性。方法:将2018年4月至2019年4月期间吉林大学附属第一医院收治的53例非小细胞肺癌患者作为研究对象。采用聚合酶链反应单链构象多态性分析法对这53例患者进行p53基因点突变检测。然后,观察这53例患者发生p53基因点突变的情况,并分析p53基因点突变的发生与其病理生理特征的相关性。结果:在这53例患者中,有27例患者发生p53基因点突变,发生p53基因点突变患者的占比为50.9%;有26例未发生p53基因点突变,未发生p53基因点突变患者的占比为49.1%。这53例患者中病理分期为Ⅰ~Ⅱ期的非小细胞肺癌患者p53基因点突变的发生率低于这53例患者中病理分期为Ⅲ~Ⅳ期的非小细胞肺癌患者,P<0.05;发生淋巴结转移的非小细胞肺癌患者p53基因点突变的发生率高于未发生淋巴结转移的非小细胞肺癌患者,P<0.05。结论:p53基因点突变的发生与非小细胞肺癌患者的病理分期及淋巴结转移的情况具有相关性。

p53反义RNA对人肺癌细胞表型和顺铂敏感性的影响

目的 研究外源p53反义RNA对有p53基因 2 4 8密码点突变的人肺癌细胞系恶性表型和顺铂敏感性的影响。方法 构建p53反义RNA真核细胞表达载体PEGFP p53(AS) ,经酶切图证明反向联结质粒。Lipofectin介导转染有p53基因 2 4 8密码点突变的人肺癌细胞系 80 1D ,经G41 8筛选获耐受克隆。稀释法建立单细胞克隆系 ,应用PCR检测外源基因 ,荧光显微镜检测细胞绿色荧光蛋白表达 ,p53单抗免疫组化染色检测p53突变蛋白表达 ,体外集落形成实验检测细胞生长 ,流式细胞仪检测细胞周期 ,MTT法检测细胞对顺铂药物敏感性。结果 酶切图证明了p53 cDNA反向联结于质粒 ,构建了PEGFP p53(AS) ,并建立了转染单细胞克隆系PEGFP p53(AS) 80 1D及空载细胞系PEGFP 80 1D。PCR检测外源p53基因和neo基因存在于转染细胞系 ,而荧光显微镜下发现其胞浆有绿荧光蛋白表达。免疫组化染色p53突变蛋白在 80 1D细胞系为阳性 ,而PEGFP p53(AS) 80 1D为阴性 ,证明外源反义p53在转染细胞稳定表达并封闭内源突变蛋白表达。与母系相比 ,PEG FP p53(AS) 80 1D集落形成抑制率为 61 % (P <0 .0 1 ) ,流式细胞仪检测该细胞系G1期细胞数明显增加 ,出现G1期阻滞的表现。MTT检测PEGFP p53(AS) 80 1D对顺铂比母系更为敏感。结论 有p53基因 2 4 8密码点?

Overexpression and mutations of tumor suppressor gene p53 in hepatocellular carcinoma

AIMS To examine the prevalance of p53 mutations in hepatocellular carcinoma (HCC) from Chongqing area and the relationship between the p53 mutations and clinicopathological features of HCC,as well as the risk factors. METHODS The overexpression and point mutations of tumor suppressor gene p53 in 38 cases of HCC were detected by a sensitive antigen retrieval fluid (ARF) immunohistochemical method and polymerase chain re- action(PCR)-restriction fragment length polymorphism (RFLP),and single strand conformation polymorphism (SSCP)-silver staining analysis. RESULTS The results showed that 16 of 38 HCCs had positive p53 protein (42.1%),7 HCCs had p53 mutation at 249 (18.4 % ) and 2 HCCS had point muta- tion within exon 7 other than 249. Among 9 cases of HCC with mutations,8 cases demonstrated positive p53 protein,its coincidental rate was 88.9%. The overexpression and mutations of p53 were significantly related to the differentiation and metastasis of HCCs. The frequency of p53 mutations was consistent with high prevalence of HBV and a moderate aflatoxin B1 (AFB1) exposure in our area. CONCLUSIONS The results suggest that AFB1 acts synergistically with HBV in the generation of p53 mutations. Furthermore,dietary exposure to AFB1 may mainly contribute to the tumor specific mutation at codon 249,while HBV may account for other scattered mutations in HCC.

Checkpoint with forkhead-associated and ring finger promoter hypermethylation correlates with microsatellite instability in gastric cancer

AIM:To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring fi nger(CHFR) and microsatellite mutator status in 59 primary gastric cancers.METHODS:We investigated the promoter methylation of CHFR in 59 cases of gastric cancer using methylation-specifi c PCR.Five microsatellite loci were analyzed using high-intensity microsatellite analysis reported previously, and p53 gene mutations were investigated by direct sequencing.RESULTS:Twenty cases(33.9%) showed promoter methylation and no relation was observed with the clinicopathological factors.We found that the promoter methylation of CHFR was frequently accompanied with microsatellite instability(MIN).Seven of 20(35.0%) cases showed MIN in hypermethylation of the CHFR tumor, while three of 39(7.7%) cases showed MIN in the non-methylated CHFR tumor(P < 0.01).However, we failed to fi nd any relationship between CHFR methylation and p53 mutation status.CONCLUSION:The coordinated loss of both the mitotic check point function and mismatch repair system suggests the potential to overcome the cell cycle check point, which may lead to an accumulation of mutations.However, the p53 mutation was not related to hypermethylation of the CHFR promoter and MIN, which indicates that an abnormality in p53 occurs as an independent process from the mismatch repair deficiency in carcinogenesis.