A relationship between methylenetetrahydrofolate reductase variants and the development of invasive cervical cancer

OBJECTIVE: Low red blood cell folate levels have been associated with hypomethylation of DNA in dysplastic tissue and an increased risk for cervical intraepithelial neoplasia in human papillomavirus (HPV)-infected women. Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme regulating the metabolism of folate and methionine, the important components of DNA synthesis and methylation. Two common genetic polymorphisms, causing reduced MTHFR activity, have been identified. Therefore, the goal of this study was to evaluate these MTHFR variations as risk factors for invasive cervical cancer. METHODS: To overcome the failure to properly match cases and controls that can cause false-positive inferences due to population stratification and unrecognized variables in a traditional case-control study, a family-based transmission/disequilibrium test (TDT) was used. We obtained samples from nuclear families of 102 women with invasive cervical cancer (ICC). One polymorphism was typed by a PCR-RFLP method, while a template-directed dye-terminator assay was developed for the other. RESULTS AND CONCLUSIONS: We were unable to confirm a strong association of MTHFR polymorphisms and ICC using family-based controls and a transmission/disequilibrium test. The overall results of the TDT showed chi(2) (1 df) of 0.28 (P = 0.60) for exon 4, chi(2) (1 df) of 0.81(P = 0.37) for exon 7, and chi(2) (3 df) of 2.56 (P = 0.46) for the haplotype, meaning that there was no transmission of those alleles significantly in excess of Mendelian expectations to affected women. In addition, there was no effect of these variants with increased parity or infection with high-risk-type human papillomavirus.     

Glutathione-S-transferase and p53 polymorphisms in cervical carcinogenesis

OBJECTIVE: To investigate the clinical significance of glutathione-S-transferase GSTM1, GSTT1 and p53 codon 72 polymorphisms in cervical carcinogenesis. METHODS: GSTM1, GSTT1 and p53 codon 72 polymorphisms together with human papillomavirus (HPV) types were examined in a total of 198 cervical smear samples using multiplex polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism (RFLP) techniques. RESULTS: Forty-two patients with high-grade squamous intraepithelial lesion (HSIL) had higher frequency of high-risk HPV and null GSTT1 genotype than 102 with low-grade SIL (LSIL) and 54 controls. Thirty-one patients with HSIL had also statistically higher frequency of null GSTT1 genotype than 28 with LSIL among 69 patients with high-risk HPV. There was no statistical difference in p53 Arg, Arg/Pro and Pro genotypes between SILs and controls with or without high-risk HPV. CONCLUSION: GSTT1 null genotype in cervical cell samples may be associated with more severe precancerous lesions of the cervix in a Japanese population. The p53 codon 72 polymorphism is unlikely to be related to HPV status and the onset of cervical cancer.     

A pilot case-control association study of cytokine polymorphisms in Brazilian women presenting with HPV-related cervical lesions

OBJECTIVE AND STUDY DESIGN: A case-control study was conducted on 42 Brazilian women presenting with human papilloma virus (HPV) infection and cervical lesion and 87 HPV-negative women to evaluate single nucleotide polymorphisms observed in TNF-alpha, TGF-beta, IL-10, IL-6, and IFN-gamma genes. RESULTS AND CONCLUSION: No significant association was observed on the cytokine polymorphisms analyzed in this series. Larger studies using cytokine polymorphisms may be useful for providing further information regarding their influence or not in HPV-related cervical lesions.     

Polycystic ovary syndrome and the single nucleotide polymorphisms of methylenetetrahydrofolate reductase: a pilot observational study

Polycystic ovary syndrome (PCOS), insulin resistance and overall mortality due to diabetes and coronary artery disease are higher in South Asians than in Caucasians. Aims: We compared the prevalence of the C677T and A1298C single nucleotide polymorphisms in the methylenetetrahydrofolate reductase gene in South Asian and Caucasian women, its association with folate and homocysteine (Hcy) metabolism, and its relevance to future atherogenic events. Methods and results: 71 women were recruited for the study: South Asian PCOS (21) plus controls (9) and Caucasian PCOS (25) plus controls (16). Anthropometric and laboratory parameters were compared. South Asian PCOS women were significantly hyperandrogenic and exhibited a greater degree of insulin resistance. Caucasian PCOS women had higher plasma Hcy concentrations with a 1.9 times higher frequency of the T allele than the South Asian PCOS group. In the presence of this variant allele, plasma Hcy levels appear to be higher in both PCOS groups. The South Asians had a 1.8 times higher frequency of the C allele than the Caucasians; however, the overall frequency was comparable in the two PCOS groups. The frequency of homozygosity, i.e. TT677 and CC1298, was 7.2% and 4.9% in the Caucasians and 0% and 16.6% in the South Asian recruits, respectively.

Dietary inadequacies in the South Asian women can influence their plasma folate and B12 concentrations resulting in hyperhomocysteinemia which, in combination with dyslipidaemia and insulin resistance, can lead to long-term atherogenic consequences. Conclusions: Current data suggests that the mechanisms of atherothrombosis have separate pathways in the two ethnic groups. Larger studies exploring the current theme need to be carried out in the PCOS groups to obtain adequate insight.     

Polycystic ovary syndrome and the single nucleotide polymorphisms of methylenetetrahydrofolate reductase: a pilot observational study

Polycystic ovary syndrome (PCOS), insulin resistance and overall mortality due to diabetes and coronary artery disease are higher in South Asians than in Caucasians. Aims: We compared the prevalence of the C677T and A1298C single nucleotide polymorphisms in the methylenetetrahydrofolate reductase gene in South Asian and Caucasian women, its association with folate and homocysteine (Hcy) metabolism, and its relevance to future atherogenic events. Methods and results: 71 women were recruited for the study: South Asian PCOS (21) plus controls (9) and Caucasian PCOS (25) plus controls (16). Anthropometric and laboratory parameters were compared. South Asian PCOS women were significantly hyperandrogenic and exhibited a greater degree of insulin resistance. Caucasian PCOS women had higher plasma Hcy concentrations with a 1.9 times higher frequency of the T allele than the South Asian PCOS group. In the presence of this variant allele, plasma Hcy levels appear to be higher in both PCOS groups. The South Asians had a 1.8 times higher frequency of the C allele than the Caucasians; however, the overall frequency was comparable in the two PCOS groups. The frequency of homozygosity, i.e. TT677 and CC1298, was 7.2% and 4.9% in the Caucasians and 0% and 16.6% in the South Asian recruits, respectively. Dietary inadequacies in the South Asian women can influence their plasma folate and B12 concentrations resulting in hyperhomocysteinemia which, in combination with dyslipidaemia and insulin resistance, can lead to long-term atherogenic consequences. CONCLUSIONS: Current data suggests that the mechanisms of atherothrombosis have separate pathways in the two ethnic groups. Larger studies exploring the current theme need to be carried out in the PCOS groups to obtain adequate insight.     

思南县女性5,10-亚甲基四氢叶酸还原酶基因多态性调查及其与血清同型半胱氨酸水平相关性的研究

目的:研究叶酸代谢障碍关键酶基因5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T、A1298C位点基因多态性与血清同型半胱氨酸(HCY)的相关性。方法:随机以贵州省思南县2 188例女性为研究对象,检测其MTHFR C677T、A1298C基因位点多态性,采用统计学方法分析该地区基因的多态性分布特征,并与其他同等级区域人群既有数据比对分析;对其中276例孕期女性,测定血清HCY浓度,分析该指标与遗传因素的相关性。结果:本县的汉族、苗族、土家族女性MTHFR C677T、A1298C位点基因型及等位基因分布情况差异无统计学意义(P0.05)。本地区汉族女性MTHFR 677TT基因型频率(14.9%)显著低于尚志、三河、寿光、张家港等地人群(P0.05),显著高于陵水县人群(P0.05);与郫县人群数据差异无统计学意义(P0.05)。MTHFR 1298CC基因型频率(4.2%)与郫县人群无统计学差异(P0.05),与其他各地区人群均有统计学差异(P0.05)。血清HCY水平在C677T位点3种基因型间有统计学差异(P0.05),而A1298C位点3种基因型间无统计学差异(P0.05)。结论:本县汉族女性MTHFR基因C677T、A1298C位点多态性分布特征有其自身的特点;C677T位点的多态性变化对血清HCY水平有显著影响。     

亚甲基四氢叶酸还原酶基因C677T单核苷酸多态性与卵巢癌易感性的关系

目的:研究亚甲基四氢叶酸还原酶(MTHFR)基因第4外显子677位点单核苷酸多态性与卵巢癌易感性的关系。方法:采用聚合酶链反应-限制性片段长度多态性方法,检测81例卵巢癌患者和80例正常对照者的亚甲基四氢叶酸还原酶基因C677T位点突变。结果:卵巢癌组和对照组中MTHFR基因677等位基因位点C和T的分布差异有统计学意义(P<0.05),其中等位基因T使卵巢癌发病风险增加1.93倍。MTHFR基因677C/T各基因型分布差异有统计学意义(P<0.05),纯合突变(T/T)基因型、杂合突变(C/T)基因型与野生(C/C)基因型相比,患卵巢癌的危险度分别提高了3.48倍和2.15倍。结论:MTHFR基因677位点等位基因突变与卵巢癌发生有一定关系,突变基因型增加了卵巢癌的发病风险。     

HLA-DQB1 polymorphisms and risk for cervical cancer: a case-control study in a southern Chinese population

OBJECTIVES AND METHODS: HLA II DQB1 polymorphisms have been shown to associate with cervical cancer risk, but results varied among different populations. In this study, the HLA DQB1 alleles among 221 southern Chinese women with cervical intraepithelial neoplasia grade III (CIN III)/invasive cervical carcinoma (ICC) were compared to 191 controls. RESULTS: The frequency of DQB1*03 was significantly lower among ICC overall as compared to controls (65.4% vs. 79.1%, odds ratio [95% confidence interval]: 0.50 [0.28-0.88], corrected p-value: 0.04). The protective association of DQB1*03 remained significant for human papillomavirus (HPV) 16-positive ICC, but not for HPV16-negative cases. This is in contrast to studies on European populations where DQB1*03 was associated with an increased risk for ICC. In the current study, 70.1% of the HPV16 isolates were Asian variants, and 28.0% were European variants. However, no significant association between HPV16 variant and DQB1*03 distribution was observed. HPV52 and HPV58 were found respectively in 16.3% and 10.0% of CIN III/ICC, which were higher compared to that of Europe and North America. Further analyses revealed a positive risk association between DQB1*06 and HPV58-positive CIN III/ICC (3.68 [1.37-9.92], corrected p-value: 0.012). CONCLUSION: The host genetics and the distribution of HPV types/variants may account for the observed differences among southern Chinese and other populations.     

血管紧张素Ⅰ转换酶基因和N5,N10-亚甲基四氢叶酸还原酶基因多态性与妊娠高血压综合征发病的关系

目的探讨血管紧张素Ⅰ转换酶(ACE)基因和N5,N10-亚甲基四氢叶酸还原酶(MTHFR)基因多态性与妊娠高血压综合征(妊高征)发病的关系.方法应用PCR技术检测99例妊高征患者(妊高征组,其中轻度21例、中度24例、重度54例)及54例正常孕妇(对照组)的ACE基因多态性,应用多聚酶链反应-限制性内切酶片段长度多态性(PCR-RFLP) 技术,检测两组孕妇的MTHFR基因多态性.结果妊高征组孕妇ACE基因Ⅱ、ID、DD基因型频率分别为20.2%、37.4%、42.4%,MTHFR基因CC、CT、TT基因型频率分别为53.5%、31.3%、15.2%.对照组孕妇ACE基因中Ⅱ、ID、DD基因型频率分别为44.4%、29.6%、25.9%, MTHFR基因CC、CT、TT基因型频率分别为46.3%、44.4%、9.3%,两组孕妇的DD、CT基因型及D等位基因频率比较,差异有显著性(P<0.05).妊高征组轻度与重度患者的DD和CT基因型比较,差异有显著性(P<0.05).回归分析表明,DD基因型、D等位基因与妊高征发病相关;CT基因型与重度妊高征相关.结论 (1)CC+DD基因型者易患妊高征;CC+Ⅱ或CT+Ⅱ基因型者不易患妊高征.(2)ACE基因中DD基因型、MTHFR基因中CT基因型是妊高征的易感基因,ACE基因中Ⅱ基因型是妊高征的保护基因.(3)ACE基因与MTHFR基因在妊高征发病中可能有协同作用.     

Death receptors and ligands in cervical carcinogenesis: an immunohistochemical study

OBJECTIVE: Increasing imbalance between proliferation and apoptosis is important in cervical carcinogenesis. The death ligands FasL and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induce apoptosis by binding to their cognate cell-surface death receptors Fas or death receptor (DR) 4 and DR5. This study aims to examine if changes in death ligand and death receptor expression during different stages of cervical carcinogenesis are related to an imbalance between proliferation and apoptosis. METHODS: The immunohistochemical expression and localization of Fas/FasL and DR4/DR5/TRAIL were assessed in 11 normal cervices, 15 cervical intraepithelial neoplasia (CIN) grade I, 15 CIN II, 13 CIN III, and 25 (microinvasive) squamous cell cervical cancers. The number of apoptotic cells was determined by morphological criteria and the number of proliferating cells by counting Ki-67-positive cells. RESULTS: A marked increase in proliferation as well as apoptosis percentage was found with increasing severity of neoplasia. In normal cervix and CIN I samples, FasL, DR4, DR5, and TRAIL staining was mainly observed in the basal/parabasal layer, whereas Fas staining was localized in the superficial, more differentiated epithelial layer. Frequency of Fas-positive staining decreased with increasing severity of CIN. In contrast, homogeneous FasL, DR4, DR5, and TRAIL expression throughout the lesions was more frequently observed in CIN III and cervical cancer. FasL, DR4, DR5, and TRAIL staining patterns were correlated, although TRAIL expression was more intense in low-grade lesions. No association was found between death receptor or ligand expression with the percentage of apoptosis or proliferation. CONCLUSION: The loss of Fas and the deregulation of FasL, DR4, DR5, and TRAIL in the CIN-cervical cancer sequence suggest a possible functional role of these death ligands and receptors during cervical carcinogenesis. The frequent expression of DR4 and DR5 presents these receptors as promising targets for innovative therapy modalities in cervical cancer.     

MTHFR (methylenetetrahydrofolate reductase: EC 1.5.1.20) SNPs (single-nucleotide polymorphisms) and homocysteine in patients referred for investigation of fertility

Journal of Assisted Reproduction and Genetics - MTHFR, one of the major enzymes in the folate cycle, is known to acquire single-nucleotide polymorphisms that significantly reduce its activity,...     

Risk factors for cervical cancer in China: a case-control study

OBJECTIVES: To determine the prevalence of human papillomavirus types and investigate the risk factors for cervical cancer in Hubei, China. METHODS: We conducted a case-control study to investigate risk factors. RESULTS: HPV DNA was detected in 94.55% of patients with cervical carcinoma, and 23.64% of control subjects. The most common HPV type in cervical cancer was HPV type 16 (81.82%), followed by HPV 58 (6.36%). HPV infected patients have a higher risk of developing cervical carcinoma, which is 75.79 times more than non-infected people. The other risks were age at first intercourse (p = 0.017) and number of live births (p = 0.032). A history of previous cytologic screening was associated with a substantial reduction in risk (p = 0.001). CONCLUSIONS: The three principal reasons that Hubei has a high rate of women developing cervical carcinoma are HPV infection, age at first sexual intercourse and number of live births. Cervical cytology screening provides efficacious protection.     

Viral agents in two-stage cervical carcinogenesis: an experimental study in mice

The role of chemical and viral agents in the development of cervical cancer in mice was studied by repeated carcinogen applications, repeated intravaginal instillations of HSV type II virus, and single carcinogen application as initiating agent followed by repeated instillations of virus as promoter. In all the animals studied, repeated applications of 9,10-dimethylbenzanthracene (DMBA) induced dysplastic conditions of the cervix and vagina, mild, moderate, and severe, as well as a large number of invasive squamous cell carcinomas. DMBA alone as initiating agent did not induce tumors or marked dysplasia; when followed by repeated applications of HSV2 virus only mild dysplastic lesions occurred. Repeated applications of HSV2 alone produced inflammatory changes of the cervix and vagina. It is concluded that repeated intravaginal instillation of HSV2 virus as done in this study does not induce cervical cancer or its precursors, and in a two-stage system is only weakly a promoter of carcinogen-induced latent tumor cells.     

5,10 methylenetetrahydrofolate reductase polymorphism in black South African women with pre-eclampsia

The polymorphic C677T mutation in the gene encoding 5,10 methylenetetrahydrofolate reductase has been shown to be a risk factor for pre-eclampsia in Japanese and European women when inherited as a homozygous trait. We attempted to verify these findings in a black African population with a high incidence of pre-eclampsia. No difference in frequency of the T-allele was observed in 105 women with pre-eclampsia, compared with 110 healthy pregnant normotensive women. Only one woman with pre-eclampsia was TT homozygous, suggesting that methylenetetrahydrofolate reductase polymorphism is not an important factor in the pathogenesis of pre-eclampsia in black South African women.     

淄博市汉族女性亚甲基四氢叶酸还原酶和甲硫氨酸合成酶还原酶基因多态性分布研究

目的:分析淄博市汉族女性亚甲基四氢叶酸还原酶(MTHFR)C677T、A1298C及甲硫氨酸合成酶还原酶(MTRR)A66G基因多态性的分布特征。方法:采用横断面调查研究方法,以淄博市1041例汉族女性为研究对象,采集口腔黏膜上皮细胞,提取基因组DNA,采用Taqman-MGB技术检测MTHFR和MTRR基因多态性。统计分析基因多态性的分布特征,并与已报道的其他地区数据进行比较。结果:淄博市汉族女性的MTHFR 677TT纯合突变基因型频率为43.6%,显著高于郑州、德阳、海南地区(P<0.01);MTHFR 1298CC纯合突变基因型频率为1.4%,显著低于德阳和海南地区(P<0.01)。MTRR 66GG纯合突变基因型频率为4.8%,显著低于海南地区(P<0.01)。结论:淄博市汉族女性有不同于其他地区的MTHFR和MTRR基因多态性分布特征。