东北地区亚甲基四氢叶酸还原酶基因C677T单核苷酸多态性与乳腺癌易感性的相关性研究

目的::研究亚甲基四氢叶酸还原酶(MTHFR)基因单核苷酸多态性与乳腺癌易感性的关系.方法:采用以人群为基础的病例对照研究方法,聚合酶链反应-限制性片段长度多态性法检测MTHFR基因型在东北地区乳腺癌患者和正常人群中的分布.结果:MTHFR基因677位点在乳腺癌组和对照组中等位基因频率及基因型分布有显著差异性(P<0.05).进一步分析表明,纯合突变G/G基因型、杂合突变C/G基因型与野生C/C基因型相比,患乳腺癌的危险度分别提高了2.23倍和2.00倍.结论:MTHFR基因C677T突变基因型与乳腺癌的易感性有关.     

亚甲基四氢叶酸还原酶基因多态性与肺癌易感性的关系

目的研究亚甲基四氢叶酸还原酶(MTHFR)基因多态性与肺癌易感性的关系。方法采用PCRRFLP方法检测MTHFR基因型在广东地区肺癌患者和正常人群中的分布。结果肺癌组和对照组中MTHFR各基因型的分布有显著性差异(P=0.030),在男女两种性别之间,非小细胞肺癌和小细胞肺癌之间,非小细胞肺癌各个病理类型之间,肺癌病例各个临床分期之间MTHFRC677T多态性的分布没有显著性差异。结论MTHFR基因C677T突变在肺癌病例中的分布与正常人群中的分布有明显的差异。     

5,10-亚甲基四氢叶酸还原酶基因多态性与肺癌的相关性研究

叶酸代谢在肺癌发生过程中占有重要的地位,因为叶酸的代谢同时影响了DNA与核苷酸的合成。5,10-亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR）是一种非常重要的叶酸还原酶,它不可逆地将5,10-亚甲基四氢叶酸催化生成5-甲基四氢叶酸,而后者正是同型半胱氨酸甲基化生成蛋氨酸反应的甲基供体。MTHFR基因的多态性（C677T,A1298C）会造成酶的活性降低,从而影响疾病的发病率。已有研究表明MTHFR的基因多态性与肺癌的发病率显著相关,文章对MTHFR基因多态性与肺癌的关系作一综述。     

亚甲基四氢叶酸还原酶基因多态性与乳腺癌相关性的研究进展

乳腺癌是一种复杂的全身性的疾病,其发病机制尚未完全清楚,但受基因及环境相互作用的影响。亚甲基四氢叶酸还原酶（MTHFR）基因位于1号染色体短臂的末端（1p36.6）,是叶酸代谢途径的关键酶,参与DNA合成、修复及甲基化过程。MTHFR基因多态性的分布在不同的种族及区域存在差异,其基因的单核苷酸突变会使该酶的生物活性及热稳定性下降,参与肿瘤的发生及发展过程,多项研究显示 MTHFR基因多态性与乳腺癌发生、发展及预后密切相关。     

云南人亚甲基四氢叶酸还原酶基因型多态性与乳腺癌易感性的关联

 目的亚甲基四氢叶酸还原酶(MTHFR)是叶酸代谢的关键性酶,其催化作用决定了DNA甲基化与DNA合成之间的平衡。MTHFR基因多态性可能会影响叶酸代谢结局,从而构成肿瘤风险因子。研究分析了MTHFR各基因型在云南籍乳腺癌人群和正常人群中的分布差异,初步探索了MTH-FR多态性与乳腺癌易感性之间的关系。方法以多重PCR-RFLP技术,对125例云南籍乳腺癌患者和103例正常人群MTHFR677位点1298位点多态性进行筛查。结果未发现MTHFRC677T和A1298C基因型频率在乳腺癌和对照样本之间存在显著差异。结论在目前样本条件下,上述两个MTHFR位点基因型多态性与云南籍人群的乳腺癌易感性之间无明显相关性。     

亚甲基四氢叶酸还原酶基因多态性与中国人群食管癌易感性的Meta分析

目的运用Meta分析的方法综合评价中国人群中亚甲基四氢叶酸还原酶（MTHFR）基因多态性与食管癌发病的相关性。方法通过计算机文献检索中国生物医学文献数据库(CBM) 和PubMed数据库,并结合文献追溯、网上查询(www.baidu.com; www.google.cn)的方法,收集所有关于MTHFR基因多态性与食管癌易感性的病例对照研究或队列研究。以食管癌组与对照组人群基因型分布的OR值为效应指标,各资料间进行一致性检验,以确定采用固定或随机效应模型进行合并分析。发表偏倚用漏斗图和Egger’s线性回归检验来评估。结果共有在国内外发表的相关文献10篇纳入分析,Meta分析结果表明：MTHFR C677T基因多态和MTHFR A1298C基因多态合并OR值及其95%CI分别为1.97（1.69,2.30）,0.84(0.66,1.08)。按是否吸烟进行分层发现吸烟组中MTHFR 677CT/TT基因型与食管癌有关(OR=2.57,95%CI:1.73~3.80),而不吸烟组中未见MTHFR 677CT/TT基因型与食管癌存在关联（OR=1.33,95%CI:0.94~1.88)。结论中国人群MTHFR C677T基因多态性与食管癌易感性有关,MTHFR A1298C基因多态性与食管癌易感性无统计学关联。吸烟可能会增加MTHFR C677T基因型个体患食管癌的危险性。     

亚甲基四氢叶酸还原酶基因单核苷酸多态与乳腺癌风险

目的 内研究亚甲基四氢叶酸还原酶(MTHFR)基因单核苷酸多态与女性乳腺癌风险的关系。方法 以聚合酶链反应(PCR)和限制性片段长度多态性(RFLF)分析方法,检测了217例乳腺癌患者和218例配对的正常对照者MTHFR因C677T和A1298C基因型,并比较不同基因型与乳腺癌风险的关系。结果 677TT基因型频率在乳腺癌患者和正常对照中的分布差异有显著性(32．7％比24．8％,P=0．02)。携带MTHFR 677TT基因犁者与携带MTHFR 677CC基因型者比较,前者罹患乳腺癌的风险增加1,84倍(95％ C：1．09～3．14)。MTHFR 677CT基因型以及MTHFR A1298C多态与乳腺癌风险不相关。结论 MTHFR基因677C→T突变是女性乳腺癌的遗传易感因素。     

亚甲基四氢叶酸还原酶基因单核苷酸多态性与儿童急性淋巴细胞白血病的相关性

 【摘要】　目的　探讨亚甲基四氢叶酸还原酶基因（MTHFR）单核甘酸多态性与儿童急性淋巴细胞白血病（ALL）发病风险的关系。方法　分别收集45例ALL患儿（ALL组）及45名健康儿童（对照组）外周血各2 ml,提取基因组DNA,应用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）法,检测MTHFR C677T和A1298C基因型,比较不同基因型对儿童ALL发病风险的影响。采用Logistic回归模型计算比值比（OR）和95 %可信区间（95 % CI）。结果　对照组MTHFR 677CC、CT和TT基因型基因分布频率分别为31.1 %（14／45）、51.1 %（23／45）和17.7 %（8／45）,ALL组3种基因型分布频率分别为51.1 %（23／45）、40.0 %（18／45）和8.9 %（4／45）,两者比较差异有统计学意义（χ2＝7.48,P＝0.04）;MTHFR 677 T等位基因在ALL组中的检出率为48.8 %（22／45）,在对照组中的检出率为69.9 %（31／45）;T等位基因携带者发生ALL的风险是CC基因型的0.4倍（95 % CI 0.21～0.83）。对照组MTHFR 1298AA、AC和CC基因型基因分布频率分别为57.8 %、40.0 %和2.2 %,ALL组中3种基因型分布频率分别为18.8 %、44.4 %和6.8 %,两者比较差异无统计学意义（χ2＝11.23,P＝0.23）;MTHFR 1298 C等位基因ALL组中的检出率为42.2 %（19／45）,对照组中的检出率为51.1 %（23／45）;C等位基因的存在并不会提高儿童ALL发生的风险（OR＝1.3,95 % CI 0.21～0.83）。结论　MTHFR 677 T等位基因的存在会显著降低儿童发生ALL的风险,而MTHFR 1298各基因型与儿童ALL的发生均无明显相关性。     

亚甲基四氢叶酸还原酶多态性与乳腺癌化疗敏感性的相关研究

目的:观察叶酸代谢的关键酶亚甲基四氢叶酸还原酶(MTHFR)基因C677T、A1298C多态性与乳腺癌FEC方案化疗敏感性的关系。方法:收集经病理学确诊的初治乳腺癌患者104例,所有病例化疗前抽静脉血,提取DNA,用PCR-RFLP技术检测MTHFR基因型,所有患者行FEC方案新辅助或姑息性化疗2~6周期,比较疗效和基因型之间的关系。结果:104例乳腺癌患者中,MTHFR C677T T/T基因型39例(37.5%)、C/C基因型55例(52.9%)、C/T基因型 10例(9.6%);T/T基因型化疗有效率79.5%(31/39)高于C/C基因型52.7%(29/55)和C/T基因型20.0%(2/10)（P＜0.05）。MTHFR A1298C A/A基因型41例(39.4%),A/C基因型56例(53.8%),C/C基因型7例(6.7%);各基因型化疗有效率之间无统计学关系（P＞0.05）。结论:本研究初步显示MTHFR C677T基因多态性对预测乳腺癌化疗效果具有较好的临床应用价值。     

亚甲基四氢叶酸还原酶基因多态性检测在肿瘤患者中的临床价值

摘 要：亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase MTHFR)是叶酸代谢、DNA甲基化的关键酶。MTHFR的单核苷酸多态性(single nucleotide polymorphism,SNP),包括677 C→T和1298A→C突变,可使MTHFR酶活性下降,从而影响细胞内叶酸的正常代谢。全文分析MTHFR 基因多态性对叶酸代谢和DNA合成的影响及其在恶性肿瘤发生、诊治和预后的研究进展,阐述恶性肿瘤患者中检测MTHFR基因多态性的价值及存在争议。     

Genetic polymorphisms of methylenetetrahydrofolate reductase and susceptibility to colorectal cancer

Objectives: To study the relation between genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T or A1298C and the susceptibility of colorectal cancer. Methods: We conducted a case-control study with 315 cases of colorectal cancer and 371 population-based controls in Jiangsu province, China. The epidemiological data were collected, and DNA of peripheral blood leukocytes was obtained from all of the subjects. MTHFR C677T and A1298C genotypes were detected by the PCR-RFLP method. Results: (1) When men and women were assessed together, the frequencies of the MTHFR C677T and A1298 genotypes or their alleles were not significantly different between controls and colon cancer or rectal cancer cases. No significant relation was observed between MTHFR C677T or A1298C polymorphisms and colon or rectal cancer susceptibility. (2) Among males, individuals who had MTHFR C677T T/T genotype were at a significantly higher risk of developing colon cancer (age-, residence-, smoking-, alcohol drinking-, tea consumption-adjusted OR=2.15, 95%CI: 1.07-4.33) compared with those who had C677T C allele. Individuals who had C677T T/T and A1298C A/A genotypes were at an increased risk of developing colon cancer (adjusted OR=2.64, 95%CI: 1.20-5.81) compared with those with C677T C allele and A1298C A/A genotypes among males. On the contrary, individuals who had C677T T/T and A1298C A/A genotypes were at an decreased risk of developing rectal cancer (adjusted OR=0.47, 95%CI: 0.22-1.03). Conclusions: These results in the present study suggested that polymorphisms of the MTHFR C677T could influence susceptibility to colon or rectal cancer and that there was a coordinated effect between MTHFR A1298C A/A and C677T T/T genotypes among males.     

磁性纳米颗粒载ABCG2-siRNA逆转乳腺癌细胞对阿霉素耐药性的研究

目的：研究抑制乳腺癌耐药蛋白（ABCG2）表达对乳腺癌细胞耐药性的逆转作用,为乳腺癌基因靶向治疗提供新思路。方法：通过透射电镜和纳米粒度电位分析仪对磁性纳米颗粒（polyMAG）的粒径、电位进行表征,利用凝胶电泳阻滞实验检测polyMAG 与siRNA的结合情况,并用polyMAG携载不同浓度（5、10、20、50、100 nmol/L）ABCG2-siRNA,将其转染入乳腺癌细胞耐药株（MCF-7/ADR）后,采用CCK-8检测siRNA转染后细胞的存活率,荧光定量PCR和Western blotting分别检测ABCG2 mRNA和蛋白表达水平,Calcein-AM/PI染色观察细胞凋亡。结果：polyMAG粒径约100 nm,呈正电荷,表面电位29.6 mV。当polyMAG与ABCG2-siRNA的比为1：1和1：2时ABCG2-siRNA可完全结合。当20~100 nmol/L polyMAG-siRNA干扰ABCG2表达后,细胞存活率较未转染组明显降低（P < 0.05）。20 nmol/L polyMAG-siRNA转染组ABCG2 mRNA表达显著下调,约为未转染组的1/8（P < 0.05）,且凋亡细胞较其他组明显增多;50 nmol/L polyMAG-siRNA转染后可明显干扰ABCG2蛋白表达（P < 0.05）。结论：polyMAG-siRNA能高效干扰ABCG2表达,增加MCF-7/ADR细胞对阿霉素敏感性,逆转细胞耐药。     

亚甲基四氢叶酸还原酶基因多态性与结直肠癌易感性的关系

目的:研究亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因C677T、A1298C多态性与结直肠癌易感性的关系。方法:在江苏省进行了一个病例-对照研究(结直肠癌患者315例,人群对照371例),调查研究对象的生活习惯,抽取静脉血,提取白细胞DNA,采用PCR-RFLP检测研究对象的MTHFR C677T、A1298C基因型。结果:1)男女合计的结直肠癌组、结肠癌组和直肠癌组与对照组之间的MTHFR C677T、A1298C基因型分布频度和等位基因频度差异无统计学意义,MTHFR C677T、A1298C基因多态与结直肠癌、结肠癌和直肠癌的易感性无显著相关。2)在男性中,结肠癌组MTHFR C677T T/T基因型的频度为24.6%,明显高于对照组的14.8%,但差异无统计学意义,χ2=3.42,P=0.064。与C677T C等位基因携带者相比,T/T基因型者发生结肠癌的危险性显著升高,其性别、年龄、居住地区及吸烟、饮酒和饮茶习惯调整后的OR为2.15(95%CI:1.07~4.33)。与同时携带MTHFR C677T C等位基因和A1298C A/A基因型者相比,男性的MTHFR C677T T/T和A1298C A/A基因型携带者发生结肠癌的危险性显著升高,其调整OR为2.64(95%CI:1.20~5.81),而他们发生直肠癌的危险性则明显降低,(调整OR=0.47,95%CI:0.22~1.03)。结论:MTHFR C677T基因多态可以影响男性结、直肠癌的易感性,MTHFR A1298C多态与C677T多态在对男性结、直肠癌易感性的影响中有协同作用。     

Monitoring the chemosensitizing effects of toremifene with flow cytometry in estrogen receptor negative multidrug resistant human breast cancer cells

Summary The clinical study of compounds that modulate multidrug resistance in cancer cells has been hindered by both the toxicities of these agents and the inability to monitor their effectiveness at a cellular level. The non-steroidal triphenylethylene toremifene is well tolerated clinically and can sensitize multidrug resistant cells to the effects of doxorubicin in vitro. The chemosensitizing properties of toremifene in estrogen receptor negative, multidrug resistant MDA-A1 human breast cancer cells were studied using flow cytometric analysis. Cell cycle kinetics of MDA-A1 cells were not significantly affected by treatment with either toremifene or doxorubicin alone, as the majority of cells remained in G₀/G₁. However, preincubation with toremifene for 70 hours followed by treatment with doxorubicin caused a marked shift of cells to G₂, as cells appeared to be blocked in that phase of the cell cycle. This result was nearly identical to the effect of doxorubicin alone on doxorubicin-sensitive MDA-MB-231 breast cancer cells and can be interpreted as a "resensitization" by toremifene of MDA-A1 cells to doxorubicin. This chemosensitizing effect of toremifene was accompanied by an enhanced accumulation of doxorubicin in MDA-A1 cells (+110% after 70 hours pre-incubation with toremifene), and by a depression in protein kinase C activity in MDA-A1 cells that was maximal following 70 hours incubation with toremifene. Flow cytometry is a widely available technique that might be applied clinically to monitor at the cellular level the chemosensitizing effects of toremifene and other modulators of multidrug resistance.     

Thymidylate synthase and methylenetetrahydrofolate reductase gene polymorphisms: relationships with 5-fluorouracil sensitivity

The relationship of thymidylate synthase (TS) and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms on 5-fluorouracil (FU) sensitivity was tested on 19 human cancer cell lines (head and neck, breast, digestive tract) in the absence and presence of folinic acid (FA) supplementation. Thymidylate synthase polymorphisms in the 5' promoter region (double or triple tandem repeats) and 3' untranslated region (6-bp deletion) were analysed by PCR. The C677T and A1298C MTHFR polymorphisms were determined by melting curve analyses (LightCycler). Thymidylate synthase activity and intracellular concentration of the reduced folate 5-10 methylenetetrahydrofolate (CH(2)FH(4)) were measured (biochemical assays). Thymidylate synthase activity was significantly different according to 5' TS genotype, heterozygous cell lines (2R/3R) exhibiting higher TS activities than homozygous ones (P=0.05). However, whether in the absence or presence of FA, FU sensitivity was not statistically associated with either 5' or 3' TS polymorphism. Basal CH(2)FH(4) cellular concentrations were lowest in C677T homozygous wild-type (wt) (C/C) cell lines. FU sensitivity was not linked to C677T polymorphism. In contrast, there was a marked trend for a greater FU efficacy in mutated A1298C variants (C/C+A/C) as compared to wt homozygous cell lines (A/A) (P=0.055 and 0.085 without and with FA supplementation, respectively). These results suggest for the first time a potential role of A1298C MTHFR polymorphism on fluoropyrimidine sensitivity.     

耐药相关基因二氢叶酸还原酶在人胰腺癌细胞株中的表达

目的探讨耐药相关基因二氢叶酸还原酶（DHFR）在胰腺癌细胞株中的表达。方法通过RT—PCR和Western-blot方法分别测定六株人胰腺癌细胞（SW1990,Capan-1,AsPC-1,MiAPaCa-2,PANC-1,P3）中的DHFR在基因和蛋白水平上表达。结果在六株人胰腺癌细胞株中,DHFR在基因水平上的表达各细胞株之间没有显著性差异（P〈0．05）;DI-IFR蛋白的表达水平以AsPC-1和P3较高,与其余四株细胞之间均存在着显著性差异（P〈0．05）,而SW1990、Capan-1、MiAPaCa-2、PANC-1之间及AsPC-1、P3之间则无显著性差异（P〉0．05）。结论结合本组先前研究结果提示胰腺癌细胞株对DHFR抑制剂的低敏感性与DHFR蛋白的高水平表达有关,DHFR参与了胰腺癌对化疗的耐药。     

Folate intake, methylenetetrahydrofolate reductase polymorphisms, and risk of esophageal cancer

Aim: Genetic and environmental factors may play roles in the pathogenesis of esophageal cancer and susceptibility may be modified by functional polymorphisms in folate metabolic genes, such as methylenetetrahydrofolate reductase (MTHFR). We here evaluated associations of the MTHFR C677T polymorphism and folate intake with esophageal cancer. Methods: A matched hospital-based case-control study with 155 esophageal cancer and 310 non-cancer controls was conducted in a Chinese population with gene-environment interactions evaluated between the MTHFR C667T polymorphism and drinking and smoking, as well as folate intake. Results: Individuals carrying MTHFR 667CT [adjusted odds ratio (OR), 1.95; 95% confidence interval (CI), 1.23-2.62] and TT [adjusted odds ratio (OR), 3.36; 95% confidence interval (CI), 1.46-8.74] had significantly increased esophageal cancer risk compared with those with MTHFR 667CC genotype. Folate intake was seen to have non-significant preventive effect. In former, moderate and heavy drinkers, a high esophageal cancer risk was observed for those with an MTHFR 677T allele genotype [ORs: 5.0(1.29-18.88), 3.70(1.83-7.66) and 5.77(2.11-15.72), respectively]. Significant interaction was found for moderate-heavy drinking and the MTHFR 677T allele genotype for esophageal cancer risk (p<0.05). Significant increased risk was also found in moderate and heavy smokers with the two genotypes [ORs: 3.58(1.64-7.80) and 4.51(1.15-17.78), respectively]. High folate intake and MTHFR 677TT was associated with a non-significant tendency for decreased esophageal cancer risk. Conclusion: Our finding supports the hypothesis that MTHFR C667T polymorphisms play a role in pathogenesis of esophageal cancer in the Chinese population.     

Anxa2和P-gp蛋白相互作用对多药耐药乳腺癌细胞迁移与侵袭影响的研究

目的:探讨Anxa2和P-gp蛋白相互作用对多药耐药乳腺癌细胞迁移与侵袭的影响.方法:采用小干扰RNA技术下调人多药耐药乳腺癌细胞MCF-7/ADR中P-gp的表达,并筛选稳定的单克隆细胞株;利用噻唑蓝(MTT)比色法和Transwell实验研究P-gp的表达对MCF-7及其耐药细胞MCF-7/ADR的增殖、迁移和侵袭能力的影响;利用免疫沉淀和免疫荧光分析多药耐药细胞中Anxa2和P-gp的相互关系.结果:蛋白印迹法检测发现,Anxa2和P-gp在耐药乳腺癌细胞中均高表达;MCF-7/ADR与其亲本细胞MCF-7相比,迁移和侵袭能力明显增强;MCF-7/ADR细胞中P-gp的表达被抑制后,其迁移和侵袭能力显著下降,并且差异有统计学意义,P＜0.05.免疫沉淀证实,Anxa2和P-gp之间存在相互作用;免疫荧光发现,Anxa2和P-gp在细胞膜上存在很好的共定位.结论:降低P-gp的表达可以明显抑制耐药乳腺癌细胞MCF-7/ADR的迁移和侵袭能力,Anxa2和P-gp之间存在较好的共定位和相互作用.提示Anxa2和P-gp的相互作用有可能对增强多药耐药乳腺癌细胞的侵袭转移能力起到一个重要的作用.