Association of MTHFR gene polymorphisms with breast cancer survival

MTHFR polymorphism as a predictive biomarker for gastrointestinal and hematological toxicity in North Indian adenocarcinoma patients

In the present study, we investigated the relationship between the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms and overall survival, toxicity and treatment response for North Indian adenocarcinoma patients. The polymorphisms of MTHFR gene in north Indian adenocarcinoma patients were assessed by PCR-RFLP. Our data observed that patients with mutant genotype (C/C) for 1298 A>C) polymorphism showed higher trend of median survival time compared to patients bearing the wild type genotype (A/A) (MST= 13.93 vs. 7.97, p=0.12). Further, we observed patients with the heterozygous genotype for A1298C polymorphism had 12-fold risk of diarrhea (AOR =12.54, 95% CI = 1.54-101.86, p=0.018). The patients with heterozygous genotype (CT) of the C677T polymorphism had 5.34-fold increased risk of developing neutropenia (AOR=5.34, 95% CI=1.49-19.06, p=0.009). Our results suggest that MTHFR polymorphisms are associated with hematological toxicity. MTHFR polymorphism might impact the development of pemetrexed and platinum-related toxicities but not as a clinical predictor of efficiency.

Association of Intake Folate and Related Gene Polymorphisms with Breast Cancer

Breast cancer is one of the most common malignancies in women worldwide and is associated with a variety of risk factors. Folate and vitamin B₁₂ are key elements of the one-carbon metabolism pathway where methylenetetrahydrofolate reductase (MTHFR) plays a significant role. Though many molecular and epidemiological studies have been performed to explore the relationship between intake folate, vitamin B₁₂, MTHFR gene polymorphism and breast cancer risk, there is no consensus to date. By reviewing the relevant literatures and summarizing the potential effect of dietary folate intake on MTHFR genes polymorphism and breast cancer risk, we conclude that MTHFR C677T gene polymorphism is associated with breast cancer risk among Asian, but not Caucasians, and the MTHFR A1298C gene polymorphism is not a susceptibility factor of breast cancers. Concomitant low activity of MTHFR enzyme resulted from C677T gene polymorphism and low dietary folate intake is associated with increased breast cancer risk.

Lack of association between MTHFR C677T Gene polymorphism with alcohol dependence: A meta-analysis of case-control studies

Many studies have reported that MTHFR C677T (rs 1801133) polymorphism is associated with the risk of alcohol dependence(AD). However, there are conflicting results regarding this relationship. In this article, we performed a meta-analysis of case-control studies to assess synthetically the influence of MTHFR C677T polymorphism on the risk of AD. All relevant studies were searched from Cochrane Library, EmBase, PubMed, and Web of science. 7 studies were included to evaluate the strength of associations between the MTHFR C677T polymorphism and AD by pooled odds ratios (ORs) and 95% confidence intervals (CIs). The present meta-analysis evaluated a total of 1066 AD patients and 1049 controls and showed that MTHFR C677T polymorphism was not significantly associated with AD susceptibility in all five genetic models (Allelic, T vs C: OR = 1.04,95% CI: 0.83-1.31, P = 0.73; Homozygous, TT vs CC: OR = 0.98,95% CI: 0.57-1.68, P = 0.94; Heterozygous, TT vs CT: OR = 0.87,95% CI: 0.64-1.19, P = 0.39; Dominant, TT + CT vs CC: OR = 1.12,95% CI: 0.92-1.35, P = 0.26; Recessive, TT vs CT + CC: OR = 0.93,95% CI: 0.58-1.47, P = 0.74). On subgroup analysis by ethnicity, there was still insignificant association was detected in the Caucasians and Asians under the five genetic models respectively. In conclusion, the present data revealed that MTHFR C677T polymorphism may not be associated with AD susceptibility. Further well designed studies in a larger population and biological functional analysis of MTHFR are needed to elucidate the role of MTHFR C677T Gene polymorphism in AD.

Correlation Between Methylenetetrahydrofolate Reductase (MTHFR) C677T Polymorphisms and Pemetrexed Chemotherapy Efficacy/Toxicity in Non-Squamous Non-Small Cell Lung Cancer

Background

In the present study, we aimed to retrospectively analyze the correlation between toxicity of pemetrexed (PEM) chemotherapy and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms in patients with advanced non-squamous non-small cell lung cancer (non-sq NSCLC).

Material/Methods

We used polymerase chain reaction, gene scanning, and restriction fragment length polymorphism to analyze MTHFR C677T in 51 patients with advanced non-sq NSCLC. The patients received chemotherapies with single-agent PEM (monotherapy group) or with PEM combined with cisplatin (joint group). The correlation between MTHFR C677T polymorphisms and chemotherapy efficacy/toxicity was also assessed.

Results

There were 40 patients in the monotherapy group and 11 patients in the joint group. Among the 40 patients received single-agent PEM chemotherapy, those with the CT/TT genotype had higher incidence of leukopenia, neutropenia, nausea, and fatigue compared to patients with the with wild-type genotype CC (all P<0.05). However, polymorphisms of MTHFR C677T were not significantly associated with other adverse events and clinical outcomes.

Conclusions

Compared with genotype CC (the wild type), patients with the CT/TT genotype had higher incidence of leukopenia, neutropenia, nausea, and fatigue. Therefore, the MTHFR C677T polymorphism could be a predictive factor for leukopenia, neutropenia, nausea, and fatigue toxicities in non-sq NSCLC patients treated with single-agent PEM.

MTHFR C677T and A1298C polymorphisms may contribute to the risk of Parkinson's disease: A meta-analysis of 19 studies

The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been reported to be a candidate gene for susceptibility to Parkinson's disease (PD), but results of different studies are conflicting. Here, we conducted a meta-analysis of published case-control studies to evaluate the association between MTHFR C677T and A1298C gene polymorphisms with the risk of PD. Electronic search through PubMed, EmBase, ScienceDirect and Cochrane Library was conducted to identify all relevant studies. A total of 19 studies with 2746 cases and 8967 controls were included. No significant association between MTHFR C677T polymorphism and PD risk was found in the overall population in all five genetic models. In the subgroup analysis stratified by ethnicity, a significant association between MTHFR C677T and PD risk was observed in the dominant model in Caucasians (OR=1.175, 95%CI: 1.008-1.369, P=0.040), but not in Asians. Significant association was found between MTHFR A1298C polymorphism and PD risk in the overall population in the dominant (OR=1.168, 95%CI: 1.008-1.353, P=0.039) and heterozygous model (OR=1.172, 95%CI: 1.004-1.367, P=0.044). But in the subgroup analysis, no association was found between MTHFR A1298C and PD neither in Caucasians nor in Asians. Our meta-analysis suggests that MTHFR C677T polymorphism may be associated with increased PD risk in Caucasians and MTHFR A1298C polymorphism may also increase susceptibility to PD.

Can MTHFR C677T and A1298C Polymorphisms Alter the Risk and Severity of Sporadic Breast Cancer in Brazilian Women?

INTRODUCTION

Polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR) modify the risk and severity of sporadic breast cancer (BC). In this context, the MTHFR C677T and A1298C polymorphisms have been associated with risk and severity of sporadic BC.

PATIENTS AND METHODS

In total, 253 women with BC and 257 controls were enrolled in this study. Polymorphisms were analyzed using restriction fragment length polymorphism - polymerase chain reaction. Epidemiology, tumor characteristics, and reproductive factors were considered in the analysis. Statistical tests included the χ² test, the Fisher exact test, and the Mann-Whitney and Kruskal-Wallis tests, or parametric equivalents.

RESULTS

MTHFR polymorphisms were not a risk factor for BC. The 677CC genotype was associated with distant metastasis (odds ratio [OR] = 5.311; 95% confidence interval [CI] = 1.124-25.09) and lower estrogen receptor expression, whereas the 1298AA genotype was associated with stage 0 (OR = 0.244; 95% CI = 0.077-0.771) and increased estrogen receptor expression. In haplotype analysis, 677CC/1298AA was associated with hypertension (OR = 1.979; 95% CI = 1.036-3.782), and 677CT/1298AC was associated with invasive carcinoma of no special type (OR = 0.472; 95% CI = 0.243-0.918) and stage 0 (OR = 3.476; 95% CI = 1.341-10.47).

CONCLUSION

The MTHFR C677T and A1298C polymorphisms do not alter the risk of BC, but are associated with the clinical severity of BC.

Polymorphisms in the MTHFR gene are associated with recurrence risk in lymph node-positive breast cancer patients

Purpose

The aim of this study is to clarify the relationship between recurrence risk of breast cancer and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms.

Patients and methods

Breast cancer patients who had undergone surgery in Gaziantep University Oncology Hospital between June 2005 and June 2012 were followed-up and retrospectively enrolled in this study. Blood samples were collected from all patients to assess MTHFR C677T polymorphisms. Stage according to tumor–node–metastasis system, estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 status, grade of disease, menopausal status, and administered chemotherapy or hormonal therapy were recorded. Effects of these parameters on recurrence risk were evaluated using univariate analysis and multivariate binary logistic regression model.

Results

Association of MTHFR C677T polymorphisms with recurrence risk was evaluated in 298 patients whose median age was 47 years (range: 21–79 years). In all patients, age (odds ratio [OR] =0.953, P=0.005) and N3 lymph node status (OR =6.293, P=0.001) were found to affect the recurrence risk. While MTHFR homozygote genotype did not have an effect on recurrence risk in all patients, increased risk was observed in lymph node-positive subgroup (OR =4.271; 95% CI 1.515–12.023; P=0.006). Adjusting for age, tumor size (T), and node status (N), MTHFR homozygote genotype had more statistically significant risk for recurrence (OR =3.255; 95% CI 1.047–10.125; P=0.041).

Conclusion

MTHFR TT genotype was found to be associated with increased recurrence risk in patients with lymph node-positive breast cancer.

Association of MTHFR (C677T) Gene Polymorphism With Breast Cancer in North India

BACKGROUND

Breast cancer is one of the most common malignancies in women and is associated with a variety of risk factors. The functional single-nucleotide polymorphism (SNP) C677T in the gene encoding 5,10-methylenetetrahydrofolate reductase (MTHFR) may lead to decreased enzyme activity and affect the chemosensitivity of tumor cells. This study was designed to investigate the association of MTHFR gene polymorphism (SNP) in the pathogenesis of breast cancer among the North Indian women population.

MATERIALS AND METHODS

Genotyping was performed by polymerase chain reaction (PCR) using genomic DNA, extracted from the peripheral blood of subjects with (275 cases) or without (275 controls) breast cancer. Restriction fragment length polymorphism was used to study C677T polymorphism in the study groups.

RESULTS

The distribution of MTHFR (C677T) genotype frequencies, ie, CC, TT, and CT, among the patients was 64.7%, 2.18%, and 33.09%, respectively. In the healthy control group, the CC, TT, and CT frequencies were 78.91%, 1.09%, and 20.1%, respectively. The frequencies of C and T alleles were 81.2% and 18.7%, respectively, in the patient subjects, while they were 88.9% and 11.09%, respectively, among the healthy control group. Frequencies of the CT genotype and the T allele were significantly different (P = 0.007 and P = 0.005, respectively) between the control and the case subjects.

CONCLUSION

This study shows an association of the CT genotype and the T allele of the MTHFR (C667T) gene with increased genetic risk for breast cancer among Indian women.

Common germline polymorphisms associated with breast cancer-specific survival

INTRODUCTION

Previous studies have identified common germline variants nominally associated with breast cancer survival. These associations have not been widely replicated in further studies. The purpose of this study was to evaluate the association of previously reported SNPs with breast cancer-specific survival using data from a pooled analysis of eight breast cancer survival genome-wide association studies (GWAS) from the Breast Cancer Association Consortium.

METHODS

A literature review was conducted of all previously published associations between common germline variants and three survival outcomes: breast cancer-specific survival, overall survival and disease-free survival. All associations that reached the nominal significance level of P value <0.05 were included. Single nucleotide polymorphisms that had been previously reported as nominally associated with at least one survival outcome were evaluated in the pooled analysis of over 37,000 breast cancer cases for association with breast cancer-specific survival. Previous associations were evaluated using a one-sided test based on the reported direction of effect.

RESULTS

Fifty-six variants from 45 previous publications were evaluated in the meta-analysis. Fifty-four of these were evaluated in the full set of 37,954 breast cancer cases with 2,900 events and the two additional variants were evaluated in a reduced sample size of 30,000 samples in order to ensure independence from the previously published studies. Five variants reached nominal significance (P <0.05) in the pooled GWAS data compared to 2.8 expected under the null hypothesis. Seven additional variants were associated (P <0.05) with ER-positive disease.

CONCLUSIONS

Although no variants reached genome-wide significance (P <5 x 10(-8)), these results suggest that there is some evidence of association between candidate common germline variants and breast cancer prognosis. Larger studies from multinational collaborations are necessary to increase the power to detect associations, between common variants and prognosis, at more stringent significance levels.

Prediction of breast cancer survival using clinical and genetic markers by tumor subtypes

PURPOSE

To identify the genetic variants associated with breast cancer survival, a genome-wide association study (GWAS) was conducted of Korean breast cancer patients.

METHODS

From the Seoul Breast Cancer Study (SEBCS), 3,226 patients with breast cancer (1,732 in the discovery and 1,494 in the replication set) were included in a two-stage GWAS on disease-free survival (DFS) by tumor subtypes based on hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2). The associations of the re-classified combined prognostic markers through recursive partitioning analysis (RPA) of DFS for breast cancer were assessed with the Cox proportional hazard model. The prognostic predictive values of the clinical and genetic models were evaluated by Harrell's C.

RESULTS

In the two-stage GWAS stratified by tumor subtypes, rs166870 and rs10825036 were consistently associated with DFS in the HR+ HER2- and HR- HER2- breast cancer subtypes, respectively (Prs166870 = 2.88 × 10(-7) and Prs10825036 = 3.54 × 10(-7) in the combined set). When patients were classified by the RPA in each subtype, genetic factors contributed significantly to differentiating the high risk group associated with DFS inbreast cancer, specifically the HR+ HER2- (P discovery=1.18 × 10(-8) and P replication = 2.08 × 10(-5)) and HR- HRE2- subtypes (P discovery = 2.35 × 10(-4) and P replication = 2.60 × 10(-2)). The inclusion of the SNPs tended to improve the performance of the prognostic models consisting of age, TNM stage and tumor subtypes based on ER, PR, and HER2 status.

CONCLUSION

Combined prognostic markers that include clinical and genetic factors by tumor subtypes could improve the prediction of survival in breast cancer.

Dietary folate and related micronutrients, folate-metabolising genes, and ovarian cancer survival

OBJECTIVE

Folate is essential for DNA synthesis and methylation and is implicated in tumour progression. Few studies have examined its role in ovarian cancer survival. Our objective was to determine relationships between intake of folate, related one-carbon nutrients, single nucleotide polymorphisms (SNPs) in folate-metabolising genes and survival following ovarian cancer diagnosis.

METHODS

This analysis included 1270 women with invasive epithelial ovarian cancer diagnosed in 2002-2006. Pre-diagnostic and some post-diagnostic lifestyle, dietary, and sociodemographic information was collected via self-administered questionnaires. DNA samples were genotyped for SNPs in methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and methionine synthase reductase (MTRR) genes. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox regression.

RESULTS

Multivariate analyses did not identify associations between higher pre-diagnostic intake of folate, folic acid, vitamins B2, B6, and B12, methionine, betaine or choline and survival overall. In stratified analyses, higher folic acid and folate intake was associated with significantly worse survival among women with mucinous tumours (HRs per 100 μg 1.30 and 1.43, respectively) and smokers (HRs per 100 μg 1.23 and 1.16 respectively). There was also a suggestion that higher supplemental folic acid use post-diagnosis was associated with worse survival (HR per 100 μg 1.03, 95%CI 1.00-1.05). MTHFR SNP rs2066470 was significantly associated with survival (per allele HR 0.81, 95%CI 0.67-0.98).

CONCLUSIONS

Our data provide little evidence that folate intake affects ovarian cancer survival. However, combined effects with smoking, and findings within the mucinous subtype and for post-diagnosis folic acid, warrant further investigation.

Genetic variations in radiation and chemotherapy drug action pathways and survival in locoregionally advanced nasopharyngeal carcinoma treated with chemoradiotherapy

Background and Purpose

Treatment outcomes vary greatly in patients with nasopharyngeal carcinoma (NPC). The purpose of this study is to evaluate the influence of radiation and chemotherapy drug action pathway gene polymorphisms on the survival of patients with locoregionally advanced NPC treated with cisplatin- and fluorouracil-based chemoradiotherapy.

Material and Methods

Four hundred twenty-one consecutive patients with locoregionally advanced NPC were prospectively recruited. We utilized a pathway approach and examined 18 polymorphisms in 13 major genes. Polymorphisms were detected using the LDR-PCR technique. Multifactor dimensionality reduction (MDR) analysis was performed to detect potential gene-gene interaction.

Results

After adjustment for clinicopathological characteristics, overall survival was significantly decreased in patients with the MPO rs2243828 CT/CC genotype (HR=2.453, 95% CI, 1.687-3.566, P<0.001). The ERCC1 rs3212986 CC (HR=1.711, 95% CI, 1.135-2.579, P=0.010), MDM2 rs2279744 GT/GG (HR=1.743, 95% CI, 1.086-2.798, P=0.021), MPO rs2243828 CT/CC (HR=3.184, 95% CI, 2.261-4.483, P<0.001) and ABCB1 rs2032582 AT/AA (HR=1.997, 95% CI, 1.086-3.670, P=0.026) genotypes were associated with poor progression-free survival. Prognostic score models based on independent prognostic factors successfully classified patients into low-, intermediate-, and high-risk groups. Furthermore, MDR analysis showed no significant interaction between polymorphisms.

Conclusions

Four single nucleotide polymorphisms were associated with survival in patients with locoregionally advanced NPC treated with cisplatin- and fluorouracil-based chemoradiotherapy. Combining clinical prognostic factors with genetic information was valuable in identifying patients with different risk.

Phytochemicals targeting genes relevant for type 2 diabetes

Nutrigenomic approaches based on ethnopharmacology and phytotherapy concepts have revealed that type 2 diabetes mellitus (T2DM) may be susceptible to dietary intervention. Interaction between bioactive food components and the genome may influence cell processes and modulate the onset and progression of the disease. T2DM, characterized by insulin resistance and beta cell dysfunction, is one of the leading causes of death and disability. Despite the great advances that have been made in the understanding and management of this complex, multifactorial disease, T2DM has become a worldwide epidemic in the 21st century. Population and family studies have revealed a strong genetic component of T2DM, and a number of candidate genes have been identified in humans. Variations in the gene sequences such as single nucleotide polymorphisms, explain the individual differences in traits like disease susceptibility and response to treatment. A clear understanding of how nutrients affect the expression of genes should facilitate the development of individualized intervention and, eventually, treatment strategies for T2DM. Review of the literature identified many phytochemicals/extracts from traditional medicinal plants that can target diabetogenic genes. This review focuses on the genetic aspects of T2DM, nutrient modification of genes relevant for diabetes, and future prospects of nutritional therapy of T2DM.

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms and promoter methylation in cervical oncogenic lesions and cancer

The aim of this study was to investigate the role of methylenetetrahydrofolate reductase (MTHFR) polymorphisms and MTHFR methylation pattern in cervical lesions development among women from Romania, a country with high prevalence of human papillomavirus (HPV) cervical infections. To achieve this goal, blood samples and cervical cytology specimens (n = 77)/tumour tissue specimens (n = 23) were investigated. As control, blood and negative cytological smears (n = 50) were used. A statistically significant association was found between T allele of C677T polymorphism and cervical lesions, heterozygote women presenting a threefold increased risk (normal/cervical lesions and tumours: wild homozygote 34/41 (0.68/0.41), heterozygote 14/51 (0.28/0.51), mutant homozygote 2/8 (0.04/0.08); OR = 3.081, P = 0.0035). Using χ square test for the control group, the HPV-negative and HPV-positive patients with cervix lesions, a significant correlation between viral infection and T allele of C677T polymorphism (P = 0.0287) was found. The MTHFR promoter was methylated in all HGSIL and tumour samples, significant differences being noted between HPV-positive samples, control group and cases of cervical dysplastic lesions without HPV DNA (P < 0. 0001) and between samples from patients with high-risk (hr)HPV versus low-risk (lr)HPV (P = 0.0026). No correlations between polymorphisms and methylation were observed. In Romania, individuals carrying T allele are susceptible for cervical lesions. MTHFR promoter methylation is associated with cervical severity lesions and with hrHPV.

Germline DNA copy number aberrations identified as potential prognostic factors for breast cancer recurrence

Breast cancer recurrence (BCR) is a common treatment outcome despite curative-intent primary treatment of non-metastatic breast cancer. Currently used prognostic and predictive factors utilize tumor-based markers, and are not optimal determinants of risk of BCR. Germline-based copy number aberrations (CNAs) have not been evaluated as determinants of predisposition to experience BCR. In this study, we accessed germline DNA from 369 female breast cancer subjects who received curative-intent primary treatment following diagnosis. Of these, 155 experienced BCR and 214 did not, after a median duration of follow up after breast cancer diagnosis of 6.35 years (range = 0.60–21.78) and 8.60 years (range = 3.08–13.57), respectively. Whole genome CNA genotyping was performed on the Affymetrix SNP array 6.0 platform. CNAs were identified using the SNP-Fast Adaptive States Segmentation Technique 2 algorithm implemented in Nexus Copy Number 6.0. Six samples were removed due to poor quality scores, leaving 363 samples for further analysis. We identified 18,561 CNAs with ≥1 kb as a predefined cut-off for observed aberrations. Univariate survival analyses (log-rank tests) identified seven CNAs (two copy number gains and five copy neutral-loss of heterozygosities, CN-LOHs) showing significant differences (P<2.01×10⁻⁵) in recurrence-free survival (RFS) probabilities with and without CNAs.We also observed three additional but distinct CN-LOHs showing significant differences in RFS probabilities (P<2.86×10⁻⁵) when analyses were restricted to stratified cases (luminal A, n = 208) only. After adjusting for tumor stage and grade in multivariate analyses (Cox proportional hazards models), all the CNAs remained strongly associated with the phenotype of BCR. Of these, we confirmed three CNAs at 17q11.2, 11q13.1 and 6q24.1 in representative samples using independent genotyping platforms. Our results suggest further investigations on the potential use of germline DNA variations as prognostic markers in cancer-associated phenotypes.

The effect of folate-related SNPs on clinicopathological features, response to neoadjuvant treatment and survival in pre- and postmenopausal breast cancer patients

This study aimed to investigate the relationship of ten single nucleotide polymorphisms (SNPs) in the MTHFR, MTR, MTRR, DHFR, MTHFD1, TS, RFC1 and DNMT3b genes with cancer survival, therapeutic response to neoadjuvant chemotherapy and clinicopathological characteristics in 300 pre- and postmenopausal breast cancer patients of a Russian Western Siberian population. We found that the MTHFR 677CT genotype as well as combination of MTHFR 677CT and 677TT genotype was related to tumor size and estrogen-positive status in postmenopausal group. The RFC1 80А allele was associated with an increased risk of lymph node metastases among postmenopausal women. The MTHFR 677TT genotype was significantly correlated with a better progression-free survival in premenopausal patients. In contrast, a worse outcome was observed in this group patient with MTHFD1 1958AA genotype. In the multivariate analysis, the MTHFD1 1958AA genotype was identified as an independent prognostic factor for premenopausal breast cancer survival. Our findings provide evidence for associations of breast cancer survival with folate-related SNPs in a population of Western Siberian region of Russia and the MTHFD1 (1958G>A) may have additional prognostic value especially among premenopausal patients.

A literature review of MTHFR (C677T and A1298C polymorphisms) and cancer risk

5,10-Methlenetetrahydrofolate reductase (MTHFR) is one of the most important enzymes for folate metabolism. This enzyme is mapped on chromosome 1, which is located at the end of the short arm (1p36.3). The C677T and A1298C are MTHFR polymorphisms that decrease in vitro MTHFR enzyme activity. Folate metabolism plays a key role in cell metabolism. These reactions are associated with purine-pyrimidine synthesis: DNA, RNA, and protein methylation. Polymorphism is also a factor in biodiversity, and be affected by ethnic heritage and geographic locale. In the case of unknown outcomes, not only should all geographical regions be investigated to ascertain biodiversity, but all populations as well to fully understand the variations in the effect. PUBMED was searched from January 2006 to December 2011 to develop an investigatory pursuit strategy. MTHFR, cancer, C677T, A1298C, and polymorphisms were key words used to focus the search. The literature review included all published relevant cancer types and MTHFR polymorphisms for that 5 years period. All selected polymorphisms data for cancer types was listed in tables for easy access and retrieval.

Phase II trial of pemetrexed and bevacizumab in patients with recurrent or metastatic head and neck cancer

PURPOSE

We hypothesized that bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), will potentiate the activity of pemetrexed, a multitargeted antifolate, in squamous cell carcinoma of the head and neck (SCCHN).

PATIENTS AND METHODS

Patients with previously untreated, recurrent, or metastatic SCCHN were treated with pemetrexed 500 mg/m(2) and bevacizumab 15 mg/kg given intravenously every 21 days with folic acid and B(12) supplementation until disease progression. Primary end point was time-to-progression (TTP). DNA was isolated from whole blood samples for the detection of polymorphisms in thymidylate synthase, methylenetetrahydrofolate reductase (MTHFR), and VEGF.

RESULTS

Forty patients were enrolled. The median TTP was 5 months, and the median overall survival (OS) was 11.3 months. In 37 evaluable patients, the overall response rate was 30%, including a complete response rate of 5%, and the disease control rate was 86%. Grade 3 to 5 bleeding events occurred in six patients (15%): four were grade 3, and two were fatal. Other serious toxicities in 10% or more of patients included neutropenia (10%) and infection (12.5%). One patient died of sepsis after receiving eight cycles of therapy. For the MTHFR A1298C (rs1801131) single nucleotide polymorphisms, homozygote patients with AA had worse OS (P = .034).

CONCLUSION

The addition of bevacizumab to pemetrexed resulted in promising efficacy outcomes in SCCHN. Bleeding events were frequent but some may have been due to natural history of disease. Polymorphisms in MTHFR may offer potential for treatment individualization.

MTHFR polymorphisms and breast cancer risk

INTRODUCTION

Two functional single nucleotide polymorphisms (SNPs) in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, C677T and A1298C, lead to decreased enzyme activity and affect chemosensitivity of tumour cells.

MATERIAL AND METHODS

We evaluated these two common polymorphisms and breast cancer risk association in an Iranian sporadic breast cancer population-based case-control study of 294 breast cancer cases and 306 controls using a PCR-RFLP-based assay.

RESULTS

Analyses of affected and controls show that homozygote genotype MTHFR 677CC has the highest frequency in both groups (28.3% in patients and 25.3% in control group). Genotype MTHFR 677CT and genotype MTHFR 1298AC were found to be statistically significant risk factors in our population (odds ratio: 1.6, 95% CI: 1.019-2.513, p = 0.041; and odds ratio: 2.575, 95% CI: 1.590-4.158, p = 0.001 respectively).

CONCLUSIONS

We can conclude based on the results of our study that a significant association between breast cancer and C677T and A1298C polymorphism might exist.

Pharmacogenetics in breast cancer: steps toward personalized medicine in breast cancer management

There is wide individual variability in the pharmacokinetics, pharmacodynamics, and tolerance to anticancer drugs within the same ethnic group and even greater variability among different ethnicities. Pharmacogenomics (PG) has the potential to provide personalized therapy based on individual genetic variability in an effort to maximize efficacy and reduce adverse effects. The benefits of PG include improved therapeutic index, improved dose regimen, and selection of optimal types of drug for an individual or set of individuals. Advanced or metastatic breast cancer is typically treated with single or multiple combinations of chemotherapy regimens including anthracyclines, taxanes, antimetabolites, alkylating agents, platinum drugs, vinca alkaloids, and others. In this review, the PG of breast cancer therapeutics, including tamoxifen, which is the most widely used therapeutic for the treatment of hormone-dependent breast cancer, is reviewed. The pharmacological activity of tamoxifen depends on its conversion by cytochrome P450 2D6 (CYP2D6) to its abundant active metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the coadministration of other drugs that inhibit CYP2D6 function, produce little endoxifen and hence derive limited therapeutic benefit from tamoxifen; the same can be said about the different classes of therapeutics in breast cancer. PG studies of breast cancer therapeutics should provide patients with breast cancer with optimal and personalized therapy.

TYMS, MTHFR, p53 and MDR1 gene polymorphisms in breast cancer patients treated with adjuvant therapy

PURPOSE

The distribution of TSER (TYMS), C677T (MTHFR), Arg72Pro (p53) and C3435T (MDR1) gene polymorphisms was investigated in 80 consecutive breast cancer patients treated with adjuvant chemotherapy.

RESULTS

Observed allelic frequencies were: TSER, (2) 0.55 and (3) 0.45; MTHFR C677T, (C) 0.65 and (T) 0.35; p53 Arg72Pro, (Arg) 0.76 and (Pro) 0.24; MDR1 C3435T, (C) 0.51 and (T) 0.49. MTHFR C677T was found to be a strong predictor of the presence of multifocal tumour (odds ratio, 4.1; 95% CI, 1.1-15.7; P=0.035).

CONCLUSION

Our data indicate that breast cancer patients with the C/C variant may present multifocal tumour most frequently.

Dietary folate and vitamin B12 intake before diagnosis decreases gastric cancer mortality risk among susceptible MTHFR 677TT carriers

OBJECTIVE

To assess gastric cancer survival in relation to dietary intake of methyl donors and the methylenetetrahydrofolate reductase 677C>T (MTHFR 677C>T) polymorphism.

METHODS

A prospective cohort of 257 incidental, histologically confirmed gastric cancer cases was assembled in January 2004 and followed until June 2006. Patients were recruited from the main oncology and/or gastroenterology units in Mexico City and were queried regarding their sociodemographic information, clinical history, and dietary habits 3 y before the onset of their symptoms. The intake of methyl donors was estimated with a food-frequency questionnaire and the MTHFR 677C>T polymorphisms were determined by polymerase chain reaction/restriction fragment length polymorphism analysis. Cox's multivariate regression models were used to estimate the mortality risk of gastric cancer.

RESULTS

MTHFR 677TT carriers with low folate and vitamin B12 intakes had the lowest survival rate in cases of gastric cancer. High intakes of folate and vitamin B12 before diagnosis was associated with decreased gastric cancer mortality risk in susceptible MTHFR 677TT carriers (mortality risk for folate 0.14, 95% confidence interval 0.04-0.46, P for trend=0.001; mortality risk for vitamin B12 0.23, 95% confidence interval 0.08-0.66, P for trend=0.008).

CONCLUSION

Folate and related B vitamins may be used as an intervention strategy to improve the survival outcome of gastric cancer.

One-carbon metabolism and breast cancer: an epidemiological perspective

One-carbon metabolism is a network of biological reactions that plays critical role in DNA methylation and DNA synthesis, and in turn, facilitates the cross-talk between genetic and epigenetic processes. Genetic polymorphisms and supplies of cofactors (e.g. folate, vitamins B) involved in this pathway have been shown to influence cancer risk and even survival. In this review, we summarized the epidemiological evidence for one-carbon metabolism, from both genetics and lifestyle aspects, in relation to breast cancer risk. We also discussed this pathway in relation to breast cancer survival and the modulation of one-carbon polymorphism in chemotherapy. Emerging evidence on modulation of DNA methylation by one-carbon metabolism suggests that disruption of epigenome might have been the underlying mechanism. More results are expected and will be translated to guidance to the general population for disease prevention as well as to clinicians for treatment and management of the disease.

A mitochondrial target sequence polymorphism in manganese superoxide dismutase predicts inferior survival in breast cancer patients treated with cyclophosphamide

PURPOSE

Manganese superoxide dismutase protects against oxidative damage and modulates the efficacy of chemotherapeutic drugs. A functional single-nucleotide polymorphism in codon 16 of SOD2 (rs4880), which encodes manganese superoxide dismutase, results in a substitution of valine by alanine (Val16Ala). We hypothesized that this single-nucleotide polymorphism affects breast cancer survival of patients receiving chemotherapy.

EXPERIMENTAL DESIGN

Two patient populations from the United States (n = 248) and Norway (n = 340) were genotyped for Val16Ala. Kaplan-Meier survival and Cox proportional hazards regression analyses were used to examine the relationship between Val16Ala and disease-specific survival.

RESULTS

Val16Ala was significantly associated with breast cancer outcome in both patient populations. Carriers of the Ala allele had inferior survival rates in the multivariate analysis [hazard ratio (HR), 2.44 and 95% confidence interval (95% CI), 1.11-5.37 in U.S. cohort; HR, 1.91 and 95% CI, 1.06-3.45 in Norway cohort for Ala/Ala versus Val/Val]. In an analysis of the combined cohorts, this association was significant for patients receiving adjuvant therapy (HR, 2.47; 95% CI, 1.46-4.19), but not for patients without it (HR, 1.47; 95% CI, 0.57-3.74). After further stratification by type of chemotherapy, the effect of the Ala allele was mostly restricted to cyclophosphamide-containing chemotherapy regimens (HR, 22.0; 95% CI, 5.22-92.9; Ala/Ala versus Val/Val).

CONCLUSION

The Val16Ala polymorphism affects survival of patients receiving cyclophosphamide-containing chemotherapy. The findings provide the first evidence pointing toward a mechanism for cyclophosphamide resistance in breast cancer patients.

Randomized Phase II and Pharmacogenetic Study of Pemetrexed Compared With Pemetrexed Plus Carboplatin in Pretreated Patients With Advanced Non–Small-Cell Lung Cancer

Purpose

We performed a randomized phase II trial comparing pemetrexed with pemetrexed plus carboplatin (PC) in patients experiencing relapse after platinum-based chemotherapy.

Patients and Methods

Main eligibility criteria were histologic or cytologic proof of advanced non–small-cell lung cancer (NSCLC), relapse more than 3 months after platinum-based chemotherapy, normal organ function, and Eastern Cooperative Oncology Group performance status 0 to 2. Patients were randomly assigned to pemetrexed 500 mg/m2(arm A) or carboplatin area under the curve 5 and pemetrexed 500 mg/m2(arm B), both administered intravenously every 3 weeks. Response assessment was performed every 6 weeks; toxicity assessment was performed every 3 weeks. Primary end point was time to progression (TTP); secondary end points were objective response rate (ORR), overall survival (OS), and toxicity. The study was designed to detect a 33% decrease in the hazard of disease progression in the combination arm (α = 0.05, two-sided log-rank test). Polymorphisms of thymidylate synthase, the reduced folate carrier, γ-glutamyl hydrolase, and methylenetetrahydrofolate reductase (MTHF) were investigated in peripheral WBCs of consenting patients.

Results

Two hundred forty patients were enrolled. Median TTP was 2.8 months for arm A versus 4.2 months for arm B (hazard ratio, 0.67; 95% CI, 0.51 to 0.89; P = .005). Median OS was 7.6 months and 8.0 months and ORR was 4% and 9% for arms A and B, respectively. Subgroup analyses found adenocarcinoma to be associated with favorable outcome. Toxicities in both arms was negligible, with one potential toxic death in arm A. Patients with MTHFR C677T homozygous mutation had increased progression-free survival compared with patients with wild-type or heterozygous mutations (P = .03).

Conclusion

PC as second-line treatment for relapsed NSCLC resulted in a significant 33% reduction of the hazard of disease progression as compared with pemetrexed alone.

Effect of the MTHFR C677T and A1298C polymorphisms on survival in patients with advanced CKD and ESRD: a prospective study

BACKGROUND

Abnormalities in the gene regulating methylenetetrahydrofolate reductase (MTHFR) are associated with increased homocysteine levels and increased mortality in normal and chronic kidney disease (CKD) populations.

STUDY DESIGN

Gene association study.

SETTING & PARTICIPANTS

This was a substudy of 677 patients from 21 Veterans Affairs medical centers participating in a randomized clinical trial (Homocysteinemia in Kidney and End-Stage Renal Disease [HOST]) of the effect on all-cause mortality of vitamin-induced lowering of plasma homocysteine levels. Of 677 patients, 213 (31%) were treated by using dialysis (end-stage renal disease [ESRD]) and 464 (69%) had a Cockcroft-Gault estimated creatinine clearance less than 30 mL/min (advanced CKD).

PREDICTOR

Polymorphisms C677T (rs1801133) and A1298C (rs1801131) of the MTHFR gene.

OUTCOMES

Unadjusted and adjusted all-cause mortality.

MEASUREMENTS

DNA was extracted from blood samples and amplified by means of polymerase chain reaction.

RESULTS

The adjusted hazard ratio in a recessive model of the relationship between the C677T polymorphism and all-cause mortality in all patients was 1.47 (95% confidence interval, 1.00 to 2.16; P = 0.05). In patients with ESRD with the mutant TT genotype, the adjusted hazard ratio for mortality in all patients was 2.27 (95% confidence interval, 1.07 to 4.84; P = 0.03); patients with advanced CKD showed a similar, although not significant, trend. The risk of myocardial infarction (P = 0.05) and composite risk of myocardial infarction, stroke, lower-extremity amputation, and mortality (P = 0.02) were greater in patients with ESRD with the mutant T allele at nucleotide 677. The overall relationship between the A1298C polymorphism and mortality was not significant (P = 0.6).

LIMITATIONS

Participants were 98% men; DNA samples were not obtained at enrollment in HOST; linkage disequilibrium with another causal polymorphism is a potential confounding factor; and power was reduced by the limited number of participants.

CONCLUSIONS

These findings provide additional support for the hypothesis that the mutant TT genotype at nucleotide 677 of the gene regulating MTHFR activity may increase the mortality risk in patients with ESRD.

B-vitamin intake, one-carbon metabolism, and survival in a population-based study of women with breast cancer

Breast cancer is the second leading cause of cancer mortality among women. Given its important role in DNA methylation and synthesis, one-carbon metabolism may affect breast cancer mortality. We used a population-based cohort of 1,508 women with breast cancer to investigate possible associations of dietary intake of B vitamins before diagnosis as well as nine polymorphisms of one-carbon metabolizing genes and subsequent survival. Women newly diagnosed with a first primary breast cancer in 1996 to 1997 were followed for vital status for an average of 5.6 years. Kaplan-Meier survival and Cox proportional hazard regression analyses were used to evaluate the association between dietary intakes of B vitamins (1,479 cases), genotypes ( approximately 1,065 cases), and all-cause as well as breast cancer-specific mortality. We found that higher dietary intake of vitamin B(1) and B(3) was associated with improved survival during the follow-up period (P(trend) = 0.01 and 0.04, respectively). Compared with the major genotype, the MTHFR 677 T allele carriers have reduced all-cause mortality and breast cancer-specific mortality in a dominant model [hazard ratio (95% confidence interval): 0.69 (0.49-0.98) and 0.58 (0.38-0.89), respectively]. The BHMT 742 A allele was also associated with reduced all-cause mortality [hazard ratio, 0.70 (0.50-1.00)]. Estrogen receptor/progesterone receptor status modified the association between the MTHFR C677T polymorphism and survival (P = 0.05). The survival associations with one-carbon polymorphisms did not differ with the use of chemotherapy, although study power was limited for examining such effect modification. Our results indicate that one-carbon metabolism may be an important pathway that could be targeted to improve breast cancer survival.

Folate pathway genetic polymorphisms and susceptibility of central nervous system tumors in Thai children

BACKGROUND

Folate is an important micronutrient molecule participating in DNA synthesis, methylation and repair mechanisms. Genetic polymorphisms in folate pathway related enzymes including methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, methionine synthase (MTR) A2756G, thymidylate synthase (TS) 28-bp tandem repeat, and reduced folate carrier (RFC) G80A have been shown to be associated with increased susceptibility for several cancers. The aim of the present study was to evaluate whether single nucleotide polymorphisms in the genes encoding enzymes of the folate pathway predispose to any CNS tumors in Thai children.

METHODS

In the present case-control study, we investigated these polymorphisms in genomic DNA from peripheral blood mononuclear cells in 73 Thai children with various types of central nervous system tumors and in 205 age and sex matched controls.

RESULTS

Thirty-one out of 73 patients were diagnosed with glial tumors (astrocytoma, oigodendroglioma and ependymoma), 28 with embryonal CNS tumors (medulloblastoma, pinealoblastoma and primitive neuroectodermal tumor), 13 with germ cell tumors and 1 with meningioma. We found that the homozygous CC allele of MTHFR A1298C conferred an increased risk of embryonal CNS tumors (OR: 3.9; 95% CI: 1.3-11.4, p=0.02).

CONCLUSION

Our findings thus suggest that folate metabolism may play a role in the pathogenesis of certain specific subtypes of pediatric brain tumor in Thai children, especially embryonal CNS tumors.