O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkyl...O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkylating agent therapy such as temozolomide （TMZ） and carmustine. It has been shown that epigenetic silencing of the MGMT gene by promoter methylation shuts down gene transcription and reflects a common alteration in primary human tumors leading to MGMT deficiency. Epigenetic silencing of the MGMT gene has been shown to correlate with improved survival in several studies of glioma patients treated with the alkylating agent therapy and has been substantiated in two clinical trials.展开更多
目的观察甲基化抑制剂5-氮杂-2′-脱氧胞苷(5-aza-2′-deoxycytidine,5-Aza-CdR)对肺癌SPC-A1细胞增殖、细胞划痕和凋亡的影响,探讨抑癌基因分泌型卷曲相关蛋白1(secreted frizzled related protein 1,SFRP1)和O6-甲基鸟嘌呤-DNA甲基转...目的观察甲基化抑制剂5-氮杂-2′-脱氧胞苷(5-aza-2′-deoxycytidine,5-Aza-CdR)对肺癌SPC-A1细胞增殖、细胞划痕和凋亡的影响,探讨抑癌基因分泌型卷曲相关蛋白1(secreted frizzled related protein 1,SFRP1)和O6-甲基鸟嘌呤-DNA甲基转移酶(O6-methylguanine-DNA-methyltransferase,MGMT)基因启动子区DNA甲基化mRNA和蛋白在其中的表达和意义。方法CCK-8法检测不同浓度的5-Aza-CdR对人肺癌SPC-A1细胞增殖影响,划痕实验测定5-Aza-CdR对SPC-A1细胞迁移能力的影响,Hoechst 33258染色检测(0、3、10、30μmol·L^(-1))5-Aza-CdR处理肺癌SPC-A1细胞24h后细胞凋亡情况,RT-PCR、Western blot法检测SPC-A1细胞中SFRP1和MGMT的mRNA、蛋白表达。结果5-Aza-CdR可以浓度梯度的抑制肺癌SPC-A1细胞增殖,IC 50为21.2μmol·L^(-1);5-Aza-CdR(3、10、30μmol·L^(-1))作用48 h后,肺癌SPC-A1细胞划痕愈合分别为对照组的(92.4±2.6)%、(83.6±4.2)%、(76.7±4.5)%;5-Aza-CdR处理肺癌SPC-A1细胞后,出现典型的细胞凋亡形态学改变;不同浓度5-Aza-CdR(3、10、30μmol·L^(-1))处理SPC-A1细胞24 h后,SFRP1、MGMT mRNA和蛋白表达增加(P<0.05)。结论5-Aza-CdR可抑制肺癌SPC-A1细胞增殖,抑制肺癌细胞划痕修复和促进凋亡,可能与升高MGMT和SFRPl的甲基化表达有关。展开更多
目的分析外周血P16、死亡相关蛋白激酶(death-associated protein kinase,DAPK)、RAS相关区域家族1A(RAS association domain family protein 1A,RASSF1A)、脆性组氨酸三联体(fragile histidine traid,FHIT)、肠腺瘤性息肉病基因(adenom...目的分析外周血P16、死亡相关蛋白激酶(death-associated protein kinase,DAPK)、RAS相关区域家族1A(RAS association domain family protein 1A,RASSF1A)、脆性组氨酸三联体(fragile histidine traid,FHIT)、肠腺瘤性息肉病基因(adenomatous polyposis coii,APC)、人类O6-甲基鸟嘌呤-DNA-甲基转移酶(human O6 methylguanine DNA methyltransfer ase,MGMT)、表皮生长因子受体(epidermal growth factor receptor,EGFR)及周期素依赖性激酶10(cyclin-dependent kinase 10,CDK10)基因启动子区CpG岛甲基化水平,探讨基于上述8个抑癌基因构建人工神经网络(artificial neural network,ANN)模型在肺癌筛查中的意义。方法选取2015-03-31-2018-11-30河南省胸科医院和郑州大学第二附属医院呼吸内科与胸外科原发性肺癌患者84例,同时选取2个医院体检健康者84例为对照组。采用实时荧光定量甲基化特异PCR(real-timefluorescent quantitative methylation-specific PCR,qMSP)法检测基因启动子区CpG岛甲基化水平。建立ANN筛查模型,Fisher判别分析模型,数据分组与ANN模型分组相同采用ROC曲线评估模型预测效果。结果小细胞肺癌组FHIT(P=0.357)、CDK10(P=0.199)、P16(P=0.275)、MGMT(P=0.887)、RASSF1A(P=0.137)、APC(P=0.248)、EGFR(P=0.083)、DAPK(P=0.993);非小细胞肺癌组FHIT(P=0.248)、CDK10(P=0.301)、P16(P=0.587)、MGMT(P=0.638)、RASSF1A(P=0.169)、APC(P=0.136)、EGFR(P=0.426)、DAPK(P=0.861)基因启动子甲基化水平高于对照组,均P<0.001。二元logistic回归分析显示年龄(OR=0.697,95%CI:0.235~2.065,P=0.315)、吸烟(OR=2.049,95%CI:1.367~3.071,P=0.031)、性别(OR=1.100,95%CI:0.568~2.131,P=0.623)、肿瘤家族史(OR=1.283,95%CI:0.759~2.168,P=0.435)、FHIT甲基化(OR=2.878,95%CI:1.921~4.313,P=0.016)、CDK10甲基化(OR=1.680,95%CI:1.241~2.273,P=0.005)、P16甲基化(OR=1.784,95%CI:1.335~2.385,P=0.010)、MGMT甲基化(OR=1.780,95%CI:1.356~2.336,P=0.013)、RASSF1A甲基化(OR=2.539,95%CI:1.427~4.517,P=0.028)、APC甲基化(OR=2.478,95%CI:1.513~4.059,P=0.001)�展开更多
文摘目的 探讨基于多序列MRI的卷积神经网络模型预测脑胶质瘤O6-甲基鸟嘌呤-DNA-甲基转移酶(O6-methylguanine-DNA methyltransferase, MGMT)启动子甲基化状态的价值。材料与方法 回顾性分析宁夏医科大学总医院2015年11月至2022年6月经手术病理证实的161例胶质瘤患者的临床及MRI影像资料,其中MGMT启动子甲基化型80例,未甲基化型81例。收集术前MRI的T2WI、T2液体衰减反转恢复(T2 fluid attenuated inversion recovery, T2-FLAIR)及对比增强T1WI (contrast enhanced T1WI, CE-T1WI)序列,对所有图像预处理后,勾画感兴趣区(region of interest, ROI)。对图像进行标注后按照7∶3随机分为训练集和验证集。使用34层残差神经网络(34-layer-residual convolutional neural network, ResNet34)分别建立基于T2WI、T2-FLAIR、CE-T1WI的单序列模型T2-net、T2f-net、TC-net和多序列融合模型TS-net,预测MGMT启动子甲基化状态。采用受试者工作特征曲线下面积(area under the receiver operating characteristic, AUROC)、精确度-召回率曲线下面积(area under the precision-recall curve, AUPRC)、准确度、特异度和敏感度评估模型效能,通过DeLong检验比较模型间的预测效能。结果 四个预测模型T2-net、T2f-net、TC-net、TS-net均有良好的预测效能,TS-net的AUROC值均高于T2-net、T2f-net、TC-net(训练集:0.930 vs. 0.859、0.877、0.920;验证集:0.910 vs. 0.812、0.840、0.854),TS-net的AUPRC值均高于T2-net、T2f-net、TC-net(训练集:0.912 vs. 0.860、0.864、0.908;验证集:0.896 vs. 0.796、0.826、0.839)。验证集中TS-net的AUROC值均高于T2-net、T2f-net、TC-net,差异均有统计学意义,训练集中与T2-net、T2f-net相比差异有统计学意义(DeLong检验,P<0.05)。结论 基于多序列MRI融合的卷积神经网络模型,可以准确、无创地预测胶质瘤MGMT甲基化状态,优于单一序列模型,为指导临床治疗决策和评估胶质瘤患者预后提供可靠依据。
文摘O6-Methylguanine-DNA methyltransferase （MGMT） is a cellular DNA repair protein that rapidly reverses alkylation （e.g. methylation） at the O6 position of guanine, thereby neutralizing the cytotoxic effects of alkylating agent therapy such as temozolomide （TMZ） and carmustine. It has been shown that epigenetic silencing of the MGMT gene by promoter methylation shuts down gene transcription and reflects a common alteration in primary human tumors leading to MGMT deficiency. Epigenetic silencing of the MGMT gene has been shown to correlate with improved survival in several studies of glioma patients treated with the alkylating agent therapy and has been substantiated in two clinical trials.
