EXPRESSION OF THE O^6－METHYLGUANINE－DNA METHYLTRANSFERASE GENE IN EIGHT HUMAN TUMOR CELL LINES

O6-methylguanine-DNA methyltransferase (MGMT) gene expression in 6 Mer+ (HeLa S3, SMMC-7721,SGC-7901, B-239, AGZY83-a, and Cc80 1) and 2 Mer- (SHG-44 , and HeLa MR) human tumor cell lines was examined. Southern blot analysis revealed no deletion, amplification, or rearrangement of the MGMT gene in these cell lines. However ,～ 1. 0 kb transcripts were detected in the 6 Mer+ cell lines but not in the 2 Mer-cell lines by Northern blot analysis. Furthermore,a rough correlation between MGMT activity and mRNA level in these cell lines was observed. These results suggest that transcriptional regulation of the MGMT gene is the molecular basis of the absence of MGMT activity in Mer-cell lines.

Amplification and function analysis of N6-adenine-specific DNA methyltransferase gene in Nilaparvata lugens

Methylation of the N6 position of adenine, termed N6-methyladenine, protects DNA from restriction endonucleases via the host-specific restriction-modification system. N6-methyladenine was discovered and has been well studied in bacteria. N6-adenine-specific DNA methyltransferase（N6AMT） is the main enzyme catalyzing the methylation of the adenine base and knowledge of this enzyme was mainly derived from work in prokaryotic models. However, large-scale gene discovery at the genome level in many model organisms indicated that the N6AMT gene also exists in eukaryotes, such as humans, mice, fruit flies and plants. Here, we cloned a N6AMT gene from Nilaparvata lugens（Nlu-N6AMT） and amplified its fulllength transcript. Then, we carried out a systematic investigation of N6AMT in 33 publically available insect genomes, indicating that all studied insects had N6AMT. Genomic structure analysis showed that insect N6AMT has short introns compared with the mammalian homologs. Domain and phylogenetic analysis indicated that insect N6AMT had a conserved N6-adenine Mlase domain that is specific to catalyze the adenine methylation. Nlu-N6AMT was highly expressed in the adult female. We knocked down Nlu-N6AMT by feeding ds RNA from the second instar nymph to adult female, inducing retard development of adult female. In all, we provide the first genome-wide analysis of N6AMT in insects and presented the experimental evidence that N6AMT might have important functions in reproductive development and ovary maturation.

RELATIONSHIP BETWEEN THE PATTERN OF METHYLATION OF CALCITONIN GENE AND ACTIVITY OF METHYLTRANSFERASEIN 8 TUMOR CELL LINES

Objective: The current study was designed to investigate the relationship between the pattern of methylation of calcitonin (CT) gene and the activity of DNA methyltranferase (MTase). Methods: The methylation rate of the 5′ region of the CT gene (CTMR) and the activity of MTase in 6 solid tumor cell lines and 2 leukemia cell lines were determined. CTMR was detected by polymerase chain reaction (PCR) with inter and external references in combination with restriction endonuclease and laser scan technique. MTase activity was examined by isotope labeled microassay. Results: Both CTMR and MTase activity in all tumor cell lines were significantly higher than that of control cells. The increased MTase activity was relative to elevated CTMR. Conclusion: There is prevalence of hypermethylation of CT gene and elevated activity of MTase in malignant cells. The increased MTase activity is one of the possible reasons for CT gene hypermethylation in tumor cells.

Influence of DNA methyltransferase 3b on FHIT expression and DNA methylation of the FHIT promoter region in hepatoma SMMC-7721 cells

BACKGROUND: Alterations in DNA methylation occur during the pathogenesis of human tumors. In this study, we investigated the influence of DNA methyltransferase 3b (DNMT3b) on fragile histidine trial (FHIT) expression and on DNA methylation of the FHIT promoter region in the hepatoma cell line SMMC-7721. METHODS: DNMT3b siRNA was used to down-regulate DNMT3b expression. DNMT3b and FHIT proteins were determined by Western blotting. Methylation-specific PCR was used to analyze the methylation status of the FHIT gene. RESULTS: After DNMT3b siRNA transfection, the expression of DNMT3b was inhibited in SMMC-7721 cells, and the expression of FHIT was significantly higher than that in the control group. There was no significant difference in methylation status between the DNMT3b siRNA transfected cells and control cells. CONCLUSION: DNMT3b may play an important role in regulation of FHIT expression in hepatoma SMMC-7721 cells, but not through methylation of the FHIT promoter. (Hepatobiliary Pancreat Dis Int 2009; 8: 273-277)

Isolation and Expression Analysis of MaPRMT1 Gene in Banana

[Objective] The aim of experiment was to lay molecular foundation for studying maturity mechanism of banana after harvest. [Method] The combined method of suppressing subtractive hybridization and cDNA micro-array were used to obtain cDNA segment of one PRMT gene in banana and the whole cDNA sequence of the gene was cloned.The bioinformatics analysis was operated on it,in addition, the expression profile analysis was conducted in different organs and different mature periods of banana.[Result] The whole length of cDNA in MaPRMT1 was 1 158 bp and possessed a complete open reading frame,which could encode 385 amino acids.It had high homology with PRMT in plant,containing one Methyltransf_1 domain.The MaPRMT1 gene was expressed in root,stem,leaf and fruit of banana and the expression levels in stem and leaf were relatively high.As the increase of days after harvest,the expression level declined gradually,however it reached maximum when ethylene release was biggest,then it declined.[Conclusion] MaPRMT1 belonged to the first kind of arginine methyltransferase and it was expressed differently in different organs and fruits at different mature periods.

Effects of 5-Aza-CdR on the Proliferation of Human Breast Cancer Cell Line MCF-7 and on the Expression of Apaf-1 Gene

Hypermethylation in the promoter region of tumor suppressor genes is a common mechanism of gene silencing, which tends to occur in cancer. The effects of 5-Aza-2＇-deoxycytidine （5-Aza-CdR）, a specific DNA methyltransferase inhibitor, on the cell proliferation of human breast cancer cell line MCF-7 and on the expression of Apaf-1 gene were investigated. Human MCF-7 cells were incubated with increasing concentrations of 5-Aza-CdR for 12 to 120 h. The growth inhibition rates of MCF-7 cells were detected by MTT assay. Changes of cell cycle distribution and apoptotic rates of MCF-7 cells were determined by flow cytometry. The expressions of DNA methyltransferase 3b mRNA and Apaf-1 mRNA were measured by reverse transcription polymerase chain reaction （RT-PCR）. Meanwhile, the expression of Apaf-1 protein was detected by Western blotting. The results showed that 5-Aza-CdR significantly inhibited the growth of MCF-7 cells and the growth inhibition rate of MCF-7 cells was significantly enhanced with the concentration of 5-Aza-CdR and the action time. Flow cytometry indicated that 5-Aza-CdR could significantly induce G1/S cell cycle arrest and increase the apoptosis rate of MCF-7 cells. The mRNA and protein expressions of Apaf-1 were up-regulated in MCF-7 cells treated with 5-Aza-CdR, which was accompanied by down-regulation of DNA methyltransferase 3b mRNA. It is concluded that 5-Aza-CdR might retard the growth of tumor ceils and promote the apoptosis of MCF-7 breast cancer cells by inhibiting the expression of DNA methyltransferase 3b and re-activating the Apaf-1 gene expression.

DNA methylation and carcinogenesis in digestive neoplasms

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Promoter Hypermethylation of DNA Repair Gene MGMT in Laryngeal Squamous Cell Carcinoma

The relationship between hypermethylation of CpG islands in the promoter regions of O^6- methylguanine DNA methyhransferase （MGMT） genes and laryngeal squamous cell carcinoma was explored. Methylation-specific PCR and semi-quantitative RT-PCR were used to study the promoter methylation and mRNA expression of the MGMT gene in laryngeal carcinoma tissues, tissues adjacent to the tumor and normal laryngeal tissues. Hypermethylation of MGMT gene was detected in 16 samples of 46 （34.8 %） laryngeal squamous cell carcinoma samples. However, the MGMT hypermethylation was not detected in all tissues adjacent to the tumors and normal tissues. No significant difference in MGMT gene hypermethylation was found in samples with different histological grades （χ^2= 3. 130, P=0. 077） or in samples from patients with different TNM status （χ^2= 3. 957, P=0. 138）. No expression of MGMT mRNA was detected in all hypermethylated laryngeal carcinoma tissues. The expression of MGMT mRNA was detected in all unmethylated laryngeal carcinoma tissues, tissues adjacent to the tumors and normal tissues. It suggests that MGMT gene promoter hypermethylation is associated with MGMT gene transcription loss in laryngeal carcinoma tissues and possibly plays an important role in carcinogenesis of laryngeal tissues.

The relationship between single nucleotide polymorphisms in estrogenmetabolizing genes CYP1A1,CYP17,COMT and estrogen receptor alpha and the risk of endometrial adenocarcinoma among the Chinese women

Objective:To explore whether polymorphisms of the genes responsible for catechol estrogen(CE)formation via estrogen biosynthesis(CYP17)and hydroxylation (CYP1A1)and CE inactivation(COMT)and ERa are associated with an elevated risk for en- dometrial adenocarcinoma in Chinese women.Methods:A multigenic case-control study was conducted,eighty-seven endometrial adenocarcinoma patients and ninety controls were recrui- ted.PCR-RFLP assays were used to determine the genotypes of estrogen-metabolizing genes and ERa gene.Results:The endometrial adenocarcinoma risk associated with individual susceptibili- ty genotypes varied among the six polymorphic sites and was the highest for CYP17,followed by CYP1 A1 Ile-Val,CYP1A1 MspI,COMT,ERa XhaI and ERa PvuII.Multivariate logistic regres- sion showed the CYP1A1 MspI genotype was the most significant determinant for endometrial adenocarcinoma development and was associated with a 3.61 fold increase in risk(95% confi- dence interval,1.73～7.55).Furthermore,a trend of increasing risk for developing endometrial adenocarcinoma was found in women harboring higher numbers of high-risk genotypes.Conclu- sion:The CYP1A1,CYP17 and ERa XbaI genotypes are related to the susceptibility of endome- trial adenocarcinoma,they may be useful markers for predicting endometrial adenocarcinoma susceptibility.The allele encoding for low acticity COMT,ERa PvuII may not be a genetic risk factor for endometrial adenocarcinoma.

Characterization of TaCOMT genes associated with stem lignin content in common wheat and development of a gene-specific marker

Stem lignin content(SLC) in common wheat(Triticum aestivum L.) contributes to lodging resistance. Caffeic acid 3-O-methyltransferase(COMT) is a key enzyme involved in lignin biosynthesis. Characterization of TaCOMT genes and development of gene-specific markers could enable marker-assisted selection in wheat breeding. In the present study, the full-length genomic DNA(gDNA) sequences of TaCOMT genes located on chromosomes 3 A, 3 B, and 3 D were cloned by homologous cloning. Two allelic variants, TaCOMT-3 Ba and TaCOMT-3 Bb, were identified and differed by a 222-bp insertion/deletion(InDel) in the 3′-untranslated region(3′-UTR). A co-dominant gene-specific marker based on this InDel was developed and designated as Ta COMT-3 BM. A total of 157 wheat cultivars and advanced lines grown in four environments were used to validate the associations between allelic patterns and SLC. The SLC of cultivars with TaCOMT-3 Ba was significantly(P<0.01) higher than that of those with TaCOMT-3 Bb, and the marker TaCOMT-3 BM could be effectively used in wheat breeding.

Effect of antisense DNMT3b gene eukaryotic expression plasmid on expression of the DNMT3b gene in human biliary tract carcinoma cells

BACKGROUND: Hypermethylation of the promoter region is one of the major mechanisms of tumor suppressor gene inactivation. DNA methyltransferase 3b (DNMT3b), an enzyme that participates in the establishment of de novo methylation patterns, is highly expressed in many tumor cells and tissues, and it is closely associated with hypermethylation of the promoter of tumor suppressor genes. The aim of this study was to explore the effect of transfection with antisense DNMT3b gene eukaryotic expression plasmid on the expression of the DNMT3b gene in human biliary tract carcinoma cell. METHODS: The constructed antisense DNMT3b gene eukaryotic expression plasmid was transfected into the human biliary tract carcinoma cell line QBC-939 with lipofectamine transfection reagent, and positive cell clones were formed using G418 selection after transfection. The constructed recombinant plasmid was transfected into QBC-939 cells successfully and was confirmed by amplification of the exogenous neo^R gene with the polymerase chain reaction method. The expression of DNMT3b gene mRNA and protein was detected by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and flow cytometry respectively. RESULTS: Following transfection, the mRNA level of the DNMT3b gene decreased from 0.956±0.053 to 0.209±0.023, and the protein level of the DNMT3b gene also decreased from (75.38±3.22)% to (29.87±3.46)%. Very significant differences were observed both at the transcription and posttranscription levels in the expression of the DNMT3b gene between the non-tranfection group and the antisense DN- MT3b gene eukaryotic expression plasmid transfection group (P<0.01). CONCLUSIONS: Transfection with the antisense DNMT3b gene eukaryotic expression plasmid can significantly reduce the expression level of the DNMT3b gene in the human biliary tract carcinoma cell line QBC-939. This study may provide a valid method to investigate the function of the DNMT3b gene and its role in biliary tract carcinoma.

Synergy of DNA methylation and histone deacetylase inhibitors in the re-expression of RASSF1A and P16 genes silenced in QBC cells

Objective: To investigate the effects of DNA methylation and histone deacetylase inhibitors in the re-expression of P16 and RASSIF1A of QBC939. Methods: The QBC939 cells were treated with hydralazine and valproate either alone or combined, and the control group was added with RPIM-1640 culture medium. After 48 h, the expression of P16 and RASSF1A genes were evaluated by reverse transcription-PCR, Western blot, and the methylation status of the two genes were detected with MSP (methylation specific PCR). Results: Hydralazine and valproate could induce demethylation of the promoter region of the two genes, and could make them re-active. The expressions of P16 and RASSF1A of cells treated with both drugs were higher than that of the cells treated with either hydralazine or valproate (P < 0.01). There was no RASSF1A gene, and few P16 gene expressing in the control group. The demethylation effect could be found in the groups treated with hydralazine or both drugs, whereas no demethylation effect happened in the valproate group. Conclusion: The two drugs could synergistically re-express P16 and RASSF1A genes silenced in QBC939, and they exerted a great anti-tumour effect on QBC cells.

Reduced non-CpG methylation is a potential epigenetic target after spinal cord injury

DNA methylation is a critical epigenetic regulator in the occurrence and development of diseases and is closely related to various functional responses in relation to spinal cord injury.To investigate the role of DNA methylation in spinal cord injury,we constructed a library with reduced-representation bisulfite sequencing data obtained at various time points(day 0-42)after spinal cord injury in mice.Global DNA methylation levels,specifically non-CpG(CHG and CHH)methylation levels,decreased modestly following spinal cord injury.Stages post-spinal cord injury were classified as early(day 0-3),intermediate(day7-14),and late(day 28-42)based on similarity and hie rarchical cluste ring of global DNA methylation patterns.The non-CpG methylation level,which included CHG and CHH methylation levels,was markedly reduced despite accounting for a minor proportion of total methylation abundance.At multiple genomic sites,including the 5’untranslated regions,promoter,exon,intron,and 3’untranslated regions,the non-CpG methylation level was markedly decreased following spinal cord injury,whereas the CpG methylation level remained unchanged at these locations.Approximately one-half of the differentially methylated regions were located in intergenic areas;the other differentially methylated regions in both CpG and non-CpG regions were cluste red in intron regions,where the DNA methylation level was highest.The function of genes associated with differentially methylated regions in promoter regions was also investigated.From Gene Ontology analysis results,DNA methylation was implicated in a number of essential functional responses to spinal cord injury,including neuronal synaptic connection creation and axon regeneration.Notably,neither CpG methylation nor non-CpG methylation was implicated in the functional response of glial or inflammatory cells.In summary,our work elucidated the dynamic pattern of DNA methylation in the spinal co rd following injury and identified reduced nonCpG methylation as an epigenetic target after spinal cord injury in mice.

钩藤UrLAMT基因及其启动子的克隆与分析

【目的】克隆钩藤(Uncaria rhynchophylla)中马钱苷酸甲基转移酶(loganic acid methyltransferase,LAMT)基因及其启动子,对UrLAMT基因的组织表达及其对生物和非生物胁迫的响应进行分析,并对UrLAMT及其启动子的生物信息学进行分析,为进一步研究UrLAMT转录调控奠定基础。【方法】基于钩藤的转录组数据设计引物,采用PCR从钩藤cDNA中克隆UrLAMT序列,并对其进行生物信息学分析;采用实时荧光定量PCR,分析UrLAMT在钩藤不同组织(根、茎、叶、花、果实、钩)中的表达,以及对外源茉莉酸甲酯(MeJA)、遮光/复光胁迫的响应;利用FPNI-PCR技术克隆UrLAMT上游启动子序列,并验证其活性,结合酵母单杂交试验,分析相应转录因子与UrLAMT启动子的调控关系。【结果】克隆得到钩藤UrLAMT序列,其长度为1137 bp,共编码378个氨基酸。UrLAMT蛋白质相对分子质量为42.64 ku,理论等电点为5.76,为亲水性蛋白,无信号肽,不含跨膜结构,定位在细胞质中;UrLAMT基因在钩藤叶中表达量最高,其次为根;UrLAMT均能响应MeJA和光;其与短小蛇根草和长春花的进化关系较近。UrLAMT启动子序列长度为1141 bp,除核心响应元件外还含有多个光响应元件,UrLAMT启动子在酵母中与光调控转录因子HY5存在相互作用。【结论】获得了UrLAMT基因及其启动子序列,其在钩藤叶中表达量最高,可能受光诱导。

通用转录因子2I在胶质母细胞瘤替莫唑胺化疗抵抗中的作用

目的:探讨通用转录因子2I(GTF2I)在胶质母细胞瘤(GBM)替莫唑胺化疗抵抗中的作用,并阐明其作用机制。方法:基于转录因子预测网站(PROMO网站),生物信息学分析GBM组织中甲基转移酶1(DNMT1)、损伤特异性DNA结合蛋白1(DDB1)、染色盒同源物5(CBX5)和着色性干皮病基因组C(XPC)的共同转录因子,并基于癌症基因组图谱(TCGA)数据库进行DDB1、CBX5、XPC和DNMT1与GTF2I和甲基鸟嘌呤甲基转移酶(MGMT)的相关性分析及生存分析。分别用小干扰序列(siRNA)转染并沉默人脑多形性成胶质细胞瘤T98细胞和人脑胶质瘤LN229细胞中MGMT及GTF2I的基因表达,采用实时荧光定量PCR(RT-qPCR)法检测上述基因的mRNA表达水平。沉默GTF2I基因后,平板克隆形成实验检测肿瘤细胞的集落形成能力,CCK-8法检测细胞对替莫唑胺的敏感性。结果:生物信息学分析,GBM组织中DDB1、CBX5、XPC和DNMT1表达水平与GTF2I表达水平呈显著正相关关系(P<0.05),与MGMT表达水平呈负相关关系(P<0.05);GTF2I表达水平与MGMT表达水平呈显著负相关关系(P<0.05)。剔除未接受替莫唑胺治疗的GBM患者的生存分析,GTF2I高表达的患者总体生存时间降低。沉默MGMT基因后,人脑胶质瘤T98细胞中GTF2I、DDB1、CBX5和XPC mRNA表达水平升高(P<0.001);沉默GTF2I基因后,人脑胶质瘤LN229细胞中MGMT mRNA表达水平升高(P<0.05),而DDB1、CBX5、XPC和DNMT1 mRNA表达水平明显降低(P<0.05或P<0.001)。平板克隆形成实验,沉默GTF2I基因前后,细胞集落形成能力比较差异无统计学意义(P=0.138);CCK-8法检测,与对照组比较,观察组细胞活力明显降低(P<0.05)。结论:转录因子GTF2I可以调控MGMT、DDB1、CBX5和XPC等关键DNA损伤修复蛋白的mRNA表达,参与GBM细胞替莫唑胺化疗抵抗,可能是GBM潜在的治疗新靶点。

一体化^(18)F-FET PET/MR术前评估成人胶质瘤患者MGMT基因启动子甲基化状态

目的 旨在研究一体化^(18)F-氟乙基酪氨酸(^(18)F-fluoroethyltyrosine, ^(18)F-FET)正电子发射断层成像(positron emission tomography, PET)/MR对成人胶质瘤的O6-甲基鸟嘌呤DNA甲基转移酶(O6-methylguanine DNA methyltransferase, MGMT)基因启动子甲基化状态的鉴别能力。材料与方法 回顾性分析未经活检或治疗的胶质瘤患者资料16例,均完成一体化PET/MR扫描,包括^(18)F-FET PET、常规MRI及体素内不相干运动(intravoxel incoherent motion, IVIM)成像。以靶本比(target-background ratio, TBR)=1.6为阈值对PET图像进行感兴趣体积(volume of interest, VOI)分割,通过刚性配准获得肿瘤VOI对应的IVIM图及其参数表观扩散系数(apparent diffusion coefficient, ADC)、真实扩散系数(true diffusion coefficient, D)、伪扩散系数(pseudo diffusion coefficient, D^(*))、灌注分数(perfusion fraction, f)、分布扩散系数(distributed diffusion coefficient, DDC)和异质性指数(heterogeneity index, α),使用pyradiomics对各参数进行特征提取,获得对应的一阶灰度直方图特征。计算每个IVIM参数图对应的特征值与^(18)F-FET PET参数的关系,并利用组间比较和受试者工作特征(receive operating characteristic, ROC)曲线分析探究PET和IVIM参数对MGMT启动子甲基化的区分能力。结果 IVIM-α的两个特征值90分位值(r=0.526,P<0.05)和最大值(r=0.520, P<0.05)与PET参数平均标准摄取值(meanstandarduptakevalue,SUVmean)呈正相关;IVIM-α和SUVmean在MGMT启动子甲基化状态阳性和阴性两组之间的差异有统计学意义(P<0.05),阳性组的IVIM-α均值和SUVmean显著高于阴性组;融合IVIM-α均值和SUVmean对MGMT启动子甲基化状态进行区分的曲线下面积(area under the curve, AUC)为0.77。结论 基于一体化PET/MR的^(18)F-FET PET和IVIM参数能够有效预测胶质瘤的MGMT启动子甲基化状态。

O^6-methylguanine-DNA methyltransferase gene expression confers alkylation resistance to tumor cells

The emergence of drug resistance is a major obstacle limiting the successful chemotherapy of malignant tumors. Our previous studies have demonstrated that O^6-methylguanine-DNA methyltransferase (MGMT, EC 2.1.1.63) is an important contributor to tumor cellular resistance toward mono- and bifunctional alkylating agents, such as 1- (4-amino-2-methyl-5-pyrimidinyl) methyl-3- (2-chloroethyl) -3-nitrosourea (ACNU) and N-methyl-N’-nitro-N-nitrosoguanidine (MNNG). Mechanistically, MGMT can specifically remove the induced alkyl groups at the O^6-position of guanine which finally would lead to a G→ A transition or a lethal DNA interstrand cross-link unless repaired. Cells

Gene amplification-driven RNA methyltransferase KIAA1429 promotes tumorigenesis by regulating BTG2 via m6A-YTHDF2-dependent in lung adenocarcinoma

Background:Epigenetic alterations have been shown to contribute immensely to human carcinogenesis.Dynamic and reversible N6-methyladenosine(m6A)RNA modification regulates gene expression and cell fate.However,the reasons for activation of KIAA1429(also known as VIRMA,an RNA methyltransferase)and its underlying mechanism in lung adenocarcinoma(LUAD)remain largely unexplored.In this study,we aimed to clarify the oncogenic role of KIAA1429 in the tumorigenesis of LUAD.Methods:Whole-genome sequencing and transcriptome sequencing of LUAD data were used to analyze the gene amplification of RNA methyltransferase.The in vitro and in vivo functions of KIAA1429 were investigated.Transcriptome sequencing,methylated RNA immunoprecipitation sequencing(MeRIP-seq),m6A dot blot assays and RNA immunoprecipitation(RIP)were performed to confirm the modified gene mediated by KIAA1429.RNA stability assays were used to detect the half-life of the target gene.Results:Copy number amplification drove higher expression of KIAA1429 in LUAD,whichwas correlatedwith poor overall survival.Manipulating the expression of KIAA1429 could regulate the proliferation and metastasis of LUAD.Mechanistically,the target genes of KIAA1429-mediated m6A modification were confirmed by transcriptome sequencing and MeRIP-seq assays.We also revealed that KIAA1429 could regulate BTG2 expression in an m6A-dependent manner.Knockdown of KIAA1429 significantly decreased the m6A levels of BTG2 mRNA,leading to enhanced YTH m6A RNA binding protein 2(YTHDF2,the m6A“reader”)-dependent BTG2 mRNA stability and promoted the expression of BTG2;thus,participating in the tumorigenesis of LUAD.Conclusions:Our data revealed the activation mechanism and important role of KIAA1429 in LUAD tumorigenesis,which may provide a novel view on the targeted molecular therapy of LUAD.

MGMT在双氧水诱导的氧化损伤模型中对晶状体上皮细胞DNA损伤和凋亡的影响

目的探讨DNA修复基因MGMT在氧化损伤环境中对晶状体上皮细胞(LECs)中DNA的损伤修复能力以及凋亡影响。方法采用不同浓度H_(2)O_(2)(0、200、400、600μmol·L^(-1))处理培养的晶状体上皮细胞(LECs),确认不同浓度H_(2)O_(2)对LECs的影响,将培养的LECs分为Control组(不做处理)、H_(2)O_(2)组(加入400μmol·L^(-1) H_(2)O_(2))、H_(2)O_(2)+HA组[加入400μmol·L^(-1) H_(2)O_(2)与对照质粒(HA)]及H_(2)O_(2)+OE-MGMT组[加入400μmol·L^(-1) H_(2)O_(2)与5μL pcDNA3.1-MGMT(过表达质粒)及12μL Lipofectamine8000(脂质体转染试剂)]。CCK-8实验检测各组细胞活力;Western blot实验检测年龄相关性白内障(ARC)患者晶状体前囊膜组织(ARC组)及各组细胞蛋白(DNA损伤标志蛋白γH2A与促凋亡蛋白Bax/Bcl2)表达水平;免疫荧光检测各组细胞DNA损伤修复能力(检测DNA损伤标志物15A3),TUNEL染色实验检测各组细胞凋亡情况。结果Western blot实验检测结果显示,Control组与ARC组患者细胞中MGMT蛋白相对表达水平分别为1.000±0.002与0.597±0.001,差异有统计学意义(P<0.0001)。LECs的MGMT蛋白相对表达水平随H_(2)O_(2)浓度上升呈下降趋势。Control组、H_(2)O_(2)组、H_(2)O_(2)+HA组及H_(2)O_(2)+OE-MGMT组γH2A相对表达水平分别为1.000±0.005、1.424±0.011、1.359±0.009、0.586±0.004,Bax/Bcl2表达水平分别为1.000±0.003、2.132±0.017、1.491±0.006、0.687±0.008,与H_(2)O_(2)+HA组比较,H_(2)O_(2)+OE-MGMT组表达均降低,差异均有统计学意义(均为P<0.001)。免疫荧光检测结果显示,Control组、H_(2)O_(2)组、H_(2)O_(2)+HA组及H_(2)O_(2)+OE-MGMT组15A3相对表达水平分别为1.000±0.128、1.842±0.207、2.104±0.267、0.723±0.073,与H_(2)O_(2)组相比,H_(2)O_(2)+OE-MGMT组15A3染色荧光强度下降,差异有统计学意义(P<0.001)。TUNEL染色检测结果显示,Control组、H_(2)O_(2)组、H_(2)O_(2)+HA组及H_(2)O_(2)+OE-MGMT组细胞凋亡的荧光强度分别为1.800±0.002、13.660±0.002、18.000±0.011、2.150±0.003,与H_(2)O_(2)组相比,H_(2)O_(2)+OE-MGMT组细胞凋亡的染色荧光强度下降,差异有统计学意义(P<0.0001)。CCK-8检测结果显示,Control组、H_(2)O_(2)组、H_(2)O_(2)+HA组及H_(2)O_(2)+OE-MGMT组细胞活力分别为100.09±1.54、57.09±2.09、60.39±3.87、74.16±1.96,与H_(2)O_(2)组比较,H_(2)O_(2)+OE-MGMT组细胞活力增加,差异有统计学意义(P<0.05)。结论MGMT在ARC患者前囊膜组织以及H_(2)O_(2)诱导的LECs氧化损伤模型中的表达均下降。MGMT过表达参与双链断裂修复通路和碱基切除修复通路促进LECs内损伤性DNA的修复,从而增加细胞的活力和减少凋亡的发生,调控ARC的发生发展。

AS3MT基因多态性与癫痫患儿临床特征、治疗效果的关系

目的探讨亚砷酸甲基转移酶([Arsenic(+3 oxidation state)methyltransferase,AS3MT])基因多态性与癫痫患儿临床特征、治疗效果的关系。方法将2019-07/2022-07月作者医院收治的164例癫痫患儿作为癫痫组,同时选取210例健康儿童作为健康组。癫痫组规律接受6个月及以上丙戊酸钠治疗,根据治疗效果不同分为有效组(n=129)和无效组(n=35)。采用聚合酶链反应-限制性内切酶片段长度多态性(polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)技术鉴定AS3MT rs7085104基因分型;采用Hardy-Weinberg遗传平衡度检验进行样本代表性评估;采用单因素及多因素Logistic回归分析探讨影响癫痫患儿治疗效果的因素。结果健康组与癫痫组AS3MT rs7085104 AA、GA、GG三种基因型均符合Hardy-Weinberg遗传平衡定律(P>0.05)。癫痫组AS3MT rs7085104 AA、GA、GG基因型频率分别为31.10%、48.17%、20.73%,健康组AA、GA、GG基因型频率分别为15.71%、38.10%、46.19%,两组比较差异有统计学意义(P<0.05)。癫痫每月发作频率>3次、有出生窒息史、有热性惊厥史患儿AS3MT rs7085104 AA、GA基因型分布频率分别高于癫痫每月发作频率≤3次、无出生窒息史、无热性惊厥史患儿,而GG基因型分布频率分别低于癫痫每月发作频率≤3次、无出生窒息史、无热性惊厥史患儿(P<0.05)。有效组AS3MT rs7085104 AA、GA、GG基因型频率分别为24.81%、52.71%、22.48%,无效组AA、GA、GG基因型频率分别为54.29%、31.43%、14.28%,两组比较差异有统计学意义(P<0.05)。多因素Logistic回归分析显示,癫痫每月发作频率>3次[OR=2.776,95%置信区间(confidence interval,CI):1.751~4.440]、有热性惊厥史(OR=2.375,95%CI:1.555~3.627)、AS3MT rs7085104 GA基因型(GA vs.AA,OR=0.397,95%CI:0.257~0.612)、AS3MT rs7085104 GG基因型(GG vs.AA,OR=0.322,95%CI:0.200~0.518)是癫痫患儿治疗无效的影响因素(P<0.05)。结论AS3MT rs7085104基因多态性与癫痫患儿每月发作频率、出生窒息史、热性惊厥史有关,同时影响丙戊酸钠的治疗效果,且携带AA基因型患儿的治疗效果更差。