DHFR

Gene Summary

Gene:DHFR; dihydrofolate reductase
Aliases: DYR, DHFRP1
Location:5q14.1
Summary:Dihydrofolate reductase converts dihydrofolate into tetrahydrofolate, a methyl group shuttle required for the de novo synthesis of purines, thymidylic acid, and certain amino acids. While the functional dihydrofolate reductase gene has been mapped to chromosome 5, multiple intronless processed pseudogenes or dihydrofolate reductase-like genes have been identified on separate chromosomes. Dihydrofolate reductase deficiency has been linked to megaloblastic anemia. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2014]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:dihydrofolate reductase
Source:NCBIAccessed: 16 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 16 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 16 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: DHFR (cancer-related)

Selhub J, Rosenberg IH
Excessive folic acid intake and relation to adverse health outcome.
Biochimie. 2016; 126:71-8 [PubMed] Related Publications
The recent increase in the intake of folic acid by the general public through fortified foods and supplements, has raised safety concern based on early reports of adverse health outcome in elderly with low B12 status who took high doses of folic acid. These safety concerns are contrary to the 2015 WHO statement that "high folic acid intake has not reliably been shown to be associated with negative healeffects". In the folic acid post-fortification era, we have shown that in elderly participants in NHANES 1999-2002, high plasma folate level is associated with exacerbation of both clinical (anemia and cognitive impairment) and biochemical (high MMA and high Hcy plasma levels) signs of vitamin B12 deficiency. Adverse clinical outcomes in association with high folate intake were also seen among elderly with low plasma B12 levels from the Framingham Original Cohort and in a study from Australia which combined three elderly cohorts. Relation between high folate and adverse biochemical outcomes were also seen in the Sacramento Area Latino Study on Aging (High Hcy, high MMA and lower TC2) and at an outpatient clinic at Yale University where high folate is associated with higher MMA in the elderly but not in the young. Potential detrimental effects of high folic acid intake may not be limited to the elderly nor to those with B12 deficiency. A study from India linked maternal high RBC folate to increased insulin resistance in offspring. Our study suggested that excessive folic acid intake is associated with lower natural killer cells activity in elderly women. In a recent study we found that the risk for unilateral retinoblastoma in offspring is 4 fold higher in women that are homozygotes for the 19 bp deletion in the DHFR gene and took folic acid supplement during pregnancy. In the elderly this polymorphism is associated with lower memory and executive scores, both being significantly worse in those with high plasma folate. These and other data strongly imply that excessive intake of folic acid is not always safe in certain populations of different age and ethnical/genetic background.

Choi JH, Yates Z, Martin C, et al.
Gene-Nutrient Interaction between Folate and Dihydrofolate Reductase in Risk for Adenomatous Polyp Occurrence: A Preliminary Report.
J Nutr Sci Vitaminol (Tokyo). 2015; 61(6):455-9 [PubMed] Related Publications
Folate and related gene variants are significant risk factors in the aetiology of colorectal cancer. Dihydrofolate reductase (DHFR) is critical in the metabolism of synthetic folic acid (pteroylmonoglutamatamic, PteGlu) to tetrahydrofolate following absorption. Therefore, the 19bp deletion variant of DHFR may lead to the alteration of folate-related colorectal disease susceptibility. This study examined the association between PteGlu and 19bp del-DHFR, and adenomatous polyp (AP) occurrence, an antecedent of colorectal cancer. A total of 199 subjects (162 controls and 37 AP cases) were analysed to determine dietary intake of total folate, natural methylfolate and synthetic PteGlu, level of erythrocyte folate and plasma homocysteine (tHcy), and genotype of 19bp del-DHFR. Dietary folate intake, erythrocyte folate, tHcy and 19bp del-DHFR variants did not independently predict the occurrence of AP. However, a gene-nutrient interaction was observed when subjects were stratified according to dietary folate intake. In subjects with a folate intake above the median value due to significant dietary PteGlu content, the presence of the 19bp-deletion allele decreased the risk for AP (OR=0.35, 95% CI: 0.13-0.97). However, such association was not evident in individuals with a folate intake below the median value. In conclusion, the finding suggests that folate nutrition and 19bp del-DHFR variation may interact to modify AP risk.

Shimamoto Y, Nukatsuka M, Takechi T, Fukushima M
Association between mRNA expression of chemotherapy-related genes and clinicopathological features in colorectal cancer: A large-scale population analysis.
Int J Mol Med. 2016; 37(2):319-28 [PubMed] Free Access to Full Article Related Publications
To establish the individualized treatment of patients with colorectal cancer, factors associated with chemotherapeutic effects should be identified. However, to the best of our knowledge, few studies are available on this topic, although it is known that the prognosis of patients and sensitivity to chemotherapy depend on the location of the tumor and that the tumor location is important for individualized treatment. In this study, primary tumors obtained from 1,129 patients with colorectal cancer were used to measure the mRNA expression levels of the following genes associated with the effects of standard chemotherapy for colorectal cancer: 5-fluorouracil (5-FU)-related thymidylate synthase (TYMS), dihydropyrimidine dehydrogenase (DPYD) and thymidine phosphorylase (TYMP); folate-related dihydrofolate reductase (DHFR), folylpolyglutamate synthase (FPGS) and gamma-glutamyl hydrolase (GGH); irinotecan-related topoisomerase I (TOP1); oxaliplatin-related excision repair cross-complementing 1 (ERCC1); biologic agent-related vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR). Large-scale population analysis was performed to determine the association of gene expression with the clinicopathological features, in particular, the location of the colorectal cancer. From the results of our analysis of the mRNA expression of these 10 genes, we noted the strongest correlation between DPYD and TYMP, followed by TYMS and DHFR. The location of the colorectal cancer was classified into 4 regions (the right‑ and left-sided colon, rectosigmoid and rectum) and was compared with gene expression. A significant difference in all genes, apart from VEGF, was noted. Of the remaining 9 genes, the highest expression of TYMS and DPYD was observed in the right‑sided colon; the highest expression of GGH and EGFR was noted in the left-sided colon; the highest expression of DHFR, FPGS, TOP1 and ERCC1 was noted in the rectosigmoid, whereas TYMP expression was approximately equivalent in the right-sided colon and rectum, and higher than that in other locations. The data generated from this study may prove to be useful for the development of individualized chemotherapeutic treatments for patients with colorectal cancer, and will mean that the tumor location is taken into account.

Ravegnini G, Zolezzi Moraga JM, Maffei F, et al.
Simultaneous Analysis of SEPT9 Promoter Methylation Status, Micronuclei Frequency, and Folate-Related Gene Polymorphisms: The Potential for a Novel Blood-Based Colorectal Cancer Biomarker.
Int J Mol Sci. 2015; 16(12):28486-97 [PubMed] Free Access to Full Article Related Publications
One challenge in colorectal cancer (CRC) is identifying novel biomarkers to be introduced in screening programs. The present study investigated the promoter methylation status of the SEPT9 gene in peripheral blood samples of subjects' positive fecal occult blood test (FOBT). In order to add new insights, we investigated the association between SEPT9 promoter methylation and micronuclei frequency, and polymorphisms in the folate-related pathway genes. SEPT9 promoter methylation, micronuclei frequency, and genotypes were evaluated on 74 individuals' FOBT positive. Individuals were subjected to a colonoscopy that provided written informed consent for study participation. SEPT9 promoter methylation status was significantly lower in the CRC group than controls (p = 0.0006). In contrast, the CaCo2 cell-line, analyzed as a tissue specific model of colon adenocarcinoma, showed a significantly higher percentage of SEPT9 promoter methylation compared to the CRC group (p < 0.0001). Linear regression analysis showed an inverse correlation between micronuclei frequency and the decrease in the methylation levels of SEPT9 promoter region among CRC patients (β = -0.926, p = 0.0001). With regard to genotype analysis, we showed the involvement of the DHFR polymorphism (rs70991108) in SEPT9 promoter methylation level in CRC patients only. In particular, the presence of at least one 19 bp del allele significantly correlates with decreased SEPT9 promoter methylation, compared to the 19 bp ins/ins genotype (p = 0.007). While remaining aware of the strengths and limitations of the study, this represents the first evidence of a novel approach for the early detection of CRC, using SEPT9 promoter methylation, micronuclei frequency and genotypes, with the potential to improve CRC risk assessment.

Yang SY, Choi SA, Lee JY, et al.
miR-192 suppresses leptomeningeal dissemination of medulloblastoma by modulating cell proliferation and anchoring through the regulation of DHFR, integrins, and CD47.
Oncotarget. 2015; 6(41):43712-30 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The main cause of death in medulloblastoma is recurrence associated with leptomeningeal dissemination. During this process, the role of microRNAs (miRs) in the acquisition of metastatic phenotype remains poorly understood. This study aimed to identify the miR involved in leptomeningeal dissemination and to elucidate its biological functional mechanisms.
MATERIALS AND METHODS: We analyzed the miR expression profiles of 29 medulloblastomas according to the presence of cerebrospinal fluid (CSF) seeding. Differentially expressed miRs (DEmiRs) were validated in 29 medulloblastoma tissues and three medulloblastoma cell lines. The biological functions of the selected miRs were evaluated using in vitro and in vivo studies.
RESULTS: A total of 12 DEmiRs were identified in medulloblastoma with seeding, including miR-192. The reduced expression of miR-192 was confirmed in the tumor seeding group and in the medulloblastoma cells. Overexpression of miR-192 inhibited cellular proliferation by binding DHFR. miR-192 decreased cellular anchoring via the repression of ITGAV, ITGB1, ITGB3, and CD47. Animals in the miR-192-treated group demonstrated a reduction of spinal seeding (P < 0.05) and a significant survival benefit (P < 0.05).
CONCLUSIONS: Medulloblastoma with seeding showed specific DEmiRs compared with those without. miR-192 suppresses leptomeningeal dissemination of medulloblastoma by modulating cell proliferation and anchoring ability.

Kodidela S, Pradhan SC, Dubashi B, Basu D
Influence of dihydrofolate reductase gene polymorphisms rs408626 (-317A>G) and rs442767 (-680C>A) on the outcome of methotrexate-based maintenance therapy in South Indian patients with acute lymphoblastic leukemia.
Eur J Clin Pharmacol. 2015; 71(11):1349-58 [PubMed] Related Publications
PURPOSE: The most common cause of treatment failure in acute lymphoblastic leukaemia (ALL) is the relapse. Genetic polymorphisms of dihydrofolate reductase (DHFR) enzyme affect the response to methotrexate (MTX) treatment. Inter-individual variability exists in the distribution of DHFR variants, and they influence MTX treatment outcome. To the best of our knowledge, there are no genetic studies reported from India, which have explored the influence of DHFR variants on the outcome of MTX treatment. Therefore, we aim to study the influence of DHFR rs408626 (-317A>G) and rs442767 (-680C>A) variants on ALL outcome in South Indian patients.
METHODS: A total of 70 ALL patients who were on MTX-based maintenance therapy were recruited for the study. DNA was extracted from leukocytes, and genotyping was done by real-time PCR.
RESULTS: The DHFR-317GG genotype was associated with the increased risk of relapse in patients with ALL (relative risk 2.25, 95% confidence interval (CI) 1.38 to 3.6, p = 0.02). DHFR-317AA and -680CA genotypes were found to be associated with severe leucopenia (p < 0.05). In Cox regression model, -317GG genotype was found to have lower relapse-free survival (hazard ratio (HR) 2.56, 95% CI 1.06 to 6.19, p = 0.03) and overall survival (HR 3.72, 95% CI 1.44 to 9.65, p = 0.007). Similarly, patients with white blood cell (WBC) count >50,000 cells/mm(3) were also found to have lower relapse-free survival (HR 2.20, 95% CI 1.10 to 4.79, p = 0.04) and overall survival (HR 3.30, 95% CI 1.45 to 7.53, p = 0.004).
CONCLUSION: The GG genotype of DHFR-317A>G variant is associated with increased risk of ALL relapse and lower overall survival in South Indian population. Both variants of DHFR (-317 AA and -680 CA) are found to be associated with severe leucopenia caused by MTX.

Kucharczyk T, Krawczyk P, Powrózek T, et al.
The Effectiveness of Pemetrexed Monotherapy Depending on Polymorphisms in TS and MTHFR Genes as Well as Clinical Factors in Advanced NSCLC Patients.
Pathol Oncol Res. 2016; 22(1):49-56 [PubMed] Free Access to Full Article Related Publications
In NSCLC, second-line chemotherapy using pemetrexed or docetaxel has limited efficacy and should be dedicated to selected groups of patients. Pemetrexed is an antifolate compound with the ability to inhibit enzymes (TS, DHFR and GARFT) involved in pyrimidine and purine synthesis. The objective of this study was to evaluate the association between polymorphisms of TS and MHFR genes and clinical outcomes in NSCLC patients treated with pemetrexed monotherapy. DNA was isolated from peripheral blood of 72 non-squamous NSCLC patients treated with pemetrexed. Using PCR and RFLP methods, the variable number of tandem repeats (VNTR), the G > C SNP in these repeats and insertion/deletion polymorphism of TS gene as well as 677C > T SNP in MTHFR gene were analyzed and correlated with disease control rate, progression-free survival and overall survival (OS) of NSCLC patients. Carriers of 2R/3R(G), 3R(C)/3R(G), 3R(G)/3R(G) genotypes showed significantly more frequent early progression than carriers of 2R/2R, 2R/3R(C), 3R(C)/3R(C) genotypes of TS gene (p < 0.05). Among carriers of triple 28 bp tandem repeats (3R) in TS gene and C/C genotype of MTHFR gene a significantly shorter OS was observed (HR = 3.07; p = 0.003). In multivariate analysis, significantly higher risk of death was observed in carriers of both 3R/3R genotype in TS and C/C genotype in 677C > T SNP in MTHFR (HR = 3.85; p < 0.005) as well as in patients with short duration of response to first-line chemotherapy (HR = 2.09; p < 0.005). Results of our study suggested that genetic factors may have a high predictive and prognostic value (even greater than clinical factors) for patients treated with pemetrexed monotherapy.

Wang L, Wang YM, Xu S, et al.
MicroRNA-215 is upregulated by treatment with Adriamycin and leads to the chemoresistance of hepatocellular carcinoma cells and tissues.
Mol Med Rep. 2015; 12(4):5274-80 [PubMed] Related Publications
Non-coding microRNAs (miRNAs), involved in post-transcriptional control, are widely involved in the mechanism of cellular resistance to antitumor chemotherapy. Ectopic expression of one of these miRNAs, miRNA‑215 (miR‑215), leads to chemoresistance by directly targeting dihydrofolate reductase (DHFR) and thymidylate synthase (TS), which are two of the most important targets of chemotherapeutic agents. This indicates the possible upregulation of endogenous miR‑215 in the process of chemoresistance by interfering with important transcripts. In the present study, the upregulation of miR‑215 was examined in hepatocellular carcinoma (HCC) subcell lines, Adriamycin (ADM)‑resistant HepG2 (HepG2/AR), Hep3B (Hep3B/AR) cell lines, and in ADM‑treated patients with HCC. Upregulated miR‑215 directly targeted DHFR and TS mRNA and reduced their protein expression levels, without altering mRNA levels. The ectopic expression of miR‑215 anti‑sense oligo‑nucleotides in HepG2/AR and Hep3B/AR cells enhanced chemosensitivity, whereas the expression of the miR‑215 mimics led to chemoresistance. Notably, the upregulation of miR‑215 indirectly increased the protein levels of P53 and P21 levels in the HepG2 cells, which contain functional P53, which is expected to result in the inhibition of proliferation and colony formation. Taken together, the present study demonstrated that the upregulation of miR‑215 resulting from ADM treatment in HCC cells leads to the development of insensitivity to ADM and worsens the prognosis of patients with HCC exhibiting mutated P53.

Cheng TY, Makar KW, Neuhouser ML, et al.
Folate-mediated one-carbon metabolism genes and interactions with nutritional factors on colorectal cancer risk: Women's Health Initiative Observational Study.
Cancer. 2015; 121(20):3684-91 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Investigations of folate-mediated one-carbon metabolism (FOCM) genes and gene-nutrient interactions with respect to colorectal cancer (CRC) risk are limited to candidate polymorphisms and dietary folate. This study comprehensively investigated associations between genetic variants in FOCM and CRC risk and whether the FOCM nutrient status modified these associations.
METHODS: Two hundred eighty-eight candidate and tagging single-nucleotide polymorphisms (SNPs) in 30 FOCM genes were genotyped for 821 incident CRC case-control matched pairs in the Women's Health Initiative Observational Study cohort. FOCM biomarkers (red blood cell [RBC] folate, plasma folate, pyridoxal-5'-phosphate [PLP], vitamin B12, and homocysteine) and self-reported alcohol consumption were measured at the baseline. Conditional logistic regression was implemented; effect modification was examined on the basis of known enzyme-nutrient relations.
RESULTS: Statistically significant associations were observed between CRC risk and functionally defined candidate SNPs of methylenetetrahydrofolate dehydrogenase 1 (MTHFD1; K134R), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR; P450R), and PR domain containing 2 with ZNF domain (PRDM2; S450N) and a literature candidate SNP of thymidylate synthase (TYMS; g.676789A>T; nominal P < .05). In addition, suggestive associations were noted for tagging SNPs in cystathionine-β-synthase (CBS), dihydrofolate reductase (DHFR), DNA (cytosine-5-)-methyltransferase 3β (DNMT3B), methionine adenosyltransferase I α (MAT1A), MTHFD1, and MTRR (nominal P < .05; adjusted P, not significant). Significant interactions between nutrient biomarkers and candidate polymorphisms were observed for 1) plasma/RBC folate and folate hydrolase 1 (FOLH1), paraoxonase 1 (PON1), transcobalamin II (TCN2), DNMT1, and DNMT3B; 2) plasma PLP and TYMS TS3; 3) plasma B12 and betaine-homocysteine S-methyltransferase 2 (BHMT2); and 4) homocysteine and methylenetetrahydrofolate reductase (MTHFR) and alanyl-transfer RNA synthetase (AARS).
CONCLUSIONS: Genetic variants in FOCM genes are associated with CRC risk among postmenopausal women. FOCM nutrients continue to emerge as effect modifiers of genetic influences on CRC risk.

Jabeen S, Holmboe L, Alnæs GI, et al.
Impact of genetic variants of RFC1, DHFR and MTHFR in osteosarcoma patients treated with high-dose methotrexate.
Pharmacogenomics J. 2015; 15(5):385-90 [PubMed] Related Publications
Osteosarcoma patients are commonly treated with high doses of methotrexate (MTX). MTX is an analog of folate, which is essential for DNA synthesis. Genetic polymorphism at single nucleotide can be indicative to the prognostic outcome in patients. Germ-line variants in candidate genes, coding for enzymes active in the metabolism of MTX, were studied in 62 osteosarcoma patients. Patients harboring the GG genotype in reduced folate carrier 1 (RFC1) rs1051266 had significantly better survival in comparison with patients having the AA genotype (P=0.046). These patients also had a lower frequency of metastasis (15%, P=0.029). Also patients homozygous for the G allele of rs1053129 in the dihydrofolate reductase (DHFR) gene were more likely to have a metastasis (45%, P= 0.005), and the methylenetetetrahydrofolate reductase (MTHFR) 677C allele was associated with higher degree of liver toxicity (88%, P=0.007). The study suggests that germ-line variants in the MTX metabolic pathway are associated with survival and side effects in patients treated with MTX.

Neradil J, Pavlasova G, Sramek M, et al.
DHFR-mediated effects of methotrexate in medulloblastoma and osteosarcoma cells: the same outcome of treatment with different doses in sensitive cell lines.
Oncol Rep. 2015; 33(5):2169-75 [PubMed] Free Access to Full Article Related Publications
Although methotrexate (MTX) is the most well-known antifolate included in many standard therapeutic regimens, substantial toxicity limits its wider use, particularly in pediatric oncology. Our study focused on a detailed analysis of MTX effects in cell lines derived from two types of pediatric solid tumors: medulloblastoma and osteosarcoma. The main aim of this study was to analyze the effects of treatment with MTX at concentrations comparable to MTX plasma levels in patients treated with high-dose or low-dose MTX. The results showed that treatment with MTX significantly decreased proliferation activity, inhibited the cell cycle at S-phase and induced apoptosis in Daoy and Saos-2 reference cell lines, which were found to be MTX-sensitive. Furthermore, no difference in these effects was observed following treatment with various doses of MTX ranging from 1 to 40 µM. These findings suggest the possibility of achieving the same outcome with the application of low-dose MTX, an extremely important result, particularly for clinical practice. Another important aspect of treatment with high-dose MTX in clinical practice is the administration of leucovorin (LV) as an antidote to reduce MTX toxicity in normal cells. For this reason, the combined application of MTX and LV was also included in our experiments; however, this application of MTX together with LV did not elicit any detectable effect. The expression analysis of genes involved in the mechanisms of resistance to MTX was a final component of our study, and the results helped us to elucidate the mechanisms of the various responses to MTX among the cell lines included in our study.

Meng X, Qi X, Guo H, et al.
Novel role for non-homologous end joining in the formation of double minutes in methotrexate-resistant colon cancer cells.
J Med Genet. 2015; 52(2):135-44 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Gene amplification is a frequent manifestation of genomic instability that plays a role in tumour progression and development of drug resistance. It is manifested cytogenetically as extrachromosomal double minutes (DMs) or intrachromosomal homogeneously staining regions (HSRs). To better understand the molecular mechanism by which HSRs and DMs are formed and how they relate to the development of methotrexate (MTX) resistance, we used two model systems of MTX-resistant HT-29 colon cancer cell lines harbouring amplified DHFR primarily in (i) HSRs and (ii) DMs.
RESULTS: In DM-containing cells, we found increased expression of non-homologous end joining (NHEJ) proteins. Depletion or inhibition of DNA-PKcs, a key NHEJ protein, caused decreased DHFR amplification, disappearance of DMs, increased formation of micronuclei or nuclear buds, which correlated with the elimination of DHFR, and increased sensitivity to MTX. These findings indicate for the first time that NHEJ plays a specific role in DM formation, and that increased MTX sensitivity of DM-containing cells depleted of DNA-PKcs results from DHFR elimination. Conversely, in HSR-containing cells, we found no significant change in the expression of NHEJ proteins. Depletion of DNA-PKcs had no effect on DHFR amplification and resulted in only a modest increase in sensitivity to MTX. Interestingly, both DM-containing and HSR-containing cells exhibited decreased proliferation upon DNA-PKcs depletion.
CONCLUSIONS: We demonstrate a novel specific role for NHEJ in the formation of DMs, but not HSRs, in MTX-resistant cells, and that NHEJ may be targeted for the treatment of MTX-resistant colon cancer.

Oberst MD, Fuhrmann S, Mulgrew K, et al.
CEA/CD3 bispecific antibody MEDI-565/AMG 211 activation of T cells and subsequent killing of human tumors is independent of mutations commonly found in colorectal adenocarcinomas.
MAbs. 2014; 6(6):1571-84 [PubMed] Free Access to Full Article Related Publications
Individual or combinations of somatic mutations found in genes from colorectal cancers can redirect the effects of chemotherapy and targeted agents on cancer cell survival and, consequently, on clinical outcome. Novel therapeutics with mechanisms of action that are independent of mutational status would therefore fulfill a current unmet clinical need. Here the CEA and CD3 bispecific single-chain antibody MEDI-565 (also known as MT111 and AMG 211) was evaluated for its ability to activate T cells both in vitro and in vivo and to kill human tumor cell lines harboring various somatic mutations commonly found in colorectal cancers. MEDI-565 specifically bound to normal and malignant tissues in a CEA-specific manner, and only killed CEA positive cells. The BiTE® antibody construct mediated T cell-directed killing of CEA positive tumor cells within 6 hours, at low effector-to-target ratios which were independent of high concentrations of soluble CEA. The potency of in vitro lysis was dependent on CEA antigen density but independent of the mutational status in cancer cell lines. Importantly, individual or combinations of mutated KRAS and BRAF oncogenes, activating PI3KCA mutations, loss of PTEN expression, and loss-of-function mutations in TP53 did not reduce the activity in vitro. MEDI-565 also prevented growth of human xenograft tumors which harbored various mutations. These findings suggest that MEDI-565 represents a potential treatment option for patients with CEA positive tumors of diverse origin, including those with individual or combinations of somatic mutations that may be less responsive to chemotherapy and other targeted agents.

Ulrich CM, Rankin C, Toriola AT, et al.
Polymorphisms in folate-metabolizing enzymes and response to 5-fluorouracil among patients with stage II or III rectal cancer (INT-0144; SWOG 9304).
Cancer. 2014; 120(21):3329-37 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Recurrence and toxicity occur commonly among patients with rectal cancer who are treated with 5-fluorouracil (5-FU). The authors hypothesized that genetic variation in folate-metabolizing genes could play a role in interindividual variability. The objective of the current study was to evaluate the associations between genetic variants in folate-metabolizing genes and clinical outcomes among patients with rectal cancer treated with 5-FU.
METHODS: The authors investigated 8 functionally significant polymorphisms in 6 genes (methylenetetrahydrofolate reductase [MTHFR] [C677T, A1298C], SLC19A1 [G80A], SHMT1 [C1420T], dihydrofolate reductase [DHFR] [Del19bp], TS 1494del,and TSER) involved in folate metabolism in 745 patients with TNM stage II or III rectal cancer enrolled in a phase 3 adjuvant clinical trial of 3 regimens of 5-FU and radiotherapy (INT-0144 and SWOG 9304).
RESULTS: There were no statistically significant associations noted between polymorphisms in any of the genes and overall survival, disease-free survival (DFS), and toxicity in the overall analyses. Nevertheless, there was a trend toward worse DFS among patients with the variant allele of MTHFR C677T compared with wild-type, particularly in treatment arm 2, in which patients with the MTHFR C677T TT genotype had worse overall survival (hazards ratio, 1.76; 95% confidence interval, 1.06-2.93 [P = .03]) and DFS (hazards ratio, 1.84; 95% confidence interval, 1.12-3.03 [P = .02]) compared with those with homozygous wild-type. In addition, there was a trend toward reduced hematological toxicity among patients with variants of SLC19A1 G80A in treatment arm 1 (P for trend, .06) and reduced esophagitis/stomatitis noted among patients with variants of TSER in treatment arm 3 (P for trend, .06).
CONCLUSIONS: Genetic variability in folate-metabolizing enzymes was found to be associated only to a limited degree with clinical outcomes among patients with rectal cancer treated with 5-FU.

Salvi S, Calistri D, Gurioli G, et al.
Copy number analysis of 24 oncogenes: MDM4 identified as a putative marker for low recurrence risk in non muscle invasive bladder cancer.
Int J Mol Sci. 2014; 15(7):12458-68 [PubMed] Free Access to Full Article Related Publications
Patients with non-muscle invasive bladder cancer (NMIBC) generally have a high risk of relapsing locally after primary tumor resection. The search for new predictive markers of local recurrence thus represents an important goal for the management of this disease. We studied the copy number variations (CNVs) of 24 oncogenes (MDM4, MYCN, ALK, PDGFRA, KIT, KDR, DHFR, EGFR, MET, SMO, FGFR1, MYC, ABL1, RET, CCND1, CCND2, CDK4, MDM2, AURKB, ERBB2, TOP2A, AURKA, AR and BRAF) using multiplex ligation probe amplification technique to verify their role as predictive markers of recurrence. Formalin-fixed paraffin-embedded tissue samples from 43 patients who underwent transurethral resection of the bladder (TURB) were used; 23 patients had relapsed and 20 were disease-free after 5 years. Amplification frequencies were analyzed for all genes and MDM4 was the only gene that showed significantly higher amplification in non recurrent patients than in recurrent ones (0.65 vs. 0.3; Fisher's test p=0.023). Recurrence-free survival analysis confirmed the predictive role of MDM4 (log-rank test p=0.041). Our preliminary results indicate a putative role for the MDM4 gene in predicting local recurrence of bladder cancer. Confirmation of this hypothesis is needed in a larger cohort of NMIBC patients.

Arozarena I, Goicoechea I, Erice O, et al.
Differential chemosensitivity to antifolate drugs between RAS and BRAF melanoma cells.
Mol Cancer. 2014; 13:154 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: The importance of the genetic background of cancer cells for the individual susceptibility to cancer treatments is increasingly apparent. In melanoma, the existence of a BRAF mutation is a main predictor for successful BRAF-targeted therapy. However, despite initial successes with these therapies, patients relapse within a year and have to move on to other therapies. Moreover, patients harbouring a wild type BRAF gene (including 25% with NRAS mutations) still require alternative treatment such as chemotherapy. Multiple genetic parameters have been associated with response to chemotherapy, but despite their high frequency in melanoma nothing is known about the impact of BRAF or NRAS mutations on the response to chemotherapeutic agents.
METHODS: Using cell proliferation and DNA methylation assays, FACS analysis and quantitative-RT-PCR we have characterised the response of a panel of NRAS and BRAF mutant melanoma cell lines to various chemotherapy drugs, amongst them dacarbazine (DTIC) and temozolomide (TMZ) and DNA synthesis inhibitors.
RESULTS: Although both, DTIC and TMZ act as alkylating agents through the same intermediate, NRAS and BRAF mutant cells responded differentially only to DTIC. Further analysis revealed that the growth-inhibitory effects mediated by DTIC were rather due to interference with nucleotide salvaging, and that NRAS mutant melanoma cells exhibit higher activity of the nucleotide synthesis enzymes IMPDH and TK1. Importantly, the enhanced ability of RAS mutant cells to use nucleotide salvaging resulted in resistance to DHFR inhibitors.
CONCLUSION: In summary, our data suggest that the genetic background in melanoma cells influences the response to inhibitors blocking de novo DNA synthesis, and that defining the RAS mutation status could be used to stratify patients for the use of antifolate drugs.

Galbiatti AL, Caldas HC, Maniglia JV, et al.
Gene expression profile of 5-fluorouracil metabolic enzymes in laryngeal cancer cell line: predictive parameters for response to 5-fluorouracil-based chemotherapy.
Biomed Pharmacother. 2014; 68(5):515-9 [PubMed] Related Publications
BACKGROUND: 5-fluorouracil (5-FU) is an antifolate chemotherapeutic that has become established in many therapeutic regimes, but sensitivity variations and development of resistance are common problems that limit the efficiency of the treatments. Inter-individual variations to 5-FU outcome have been attributed to different expression profiles of genes related to folate metabolism.
METHODS: To elucidate the mechanisms of variations to 5-FU outcome, the authors investigated MTHFR, DHFR, TYMS and SLC19A1 folate genes expression for 5-FU response in laryngeal cancer cell line (Hep-2). Concentrations of 10, 50, and 100 ng/mL of 5-FU chemotherapeutic were added separately in Hep-2 cell line for 24 hours at 37 °C. Cell sensibility was evaluated with fluorescein isothiocyanate (FITC) label Bcl-2 by flow cytometry. The real-time quantitative PCR (qPCR) technique was performed for quantification of gene expression using TaqMan(®) Gene Expression Assay. ANOVA and Bonferroni's post hoc tests were utilized to statistical analysis.
RESULTS: The numbers of viable Hep-2 cells with 10, 50, and 100 ng/mL concentrations of 5-FU chemotherapy were 15.87, 28.3 and 68.9%, respectively. Statistical analysis showed significant association between control group and increased expression for TYMS gene in cells treated with 100 ng/mL/5-FU chemotherapy (P<0.05).
CONCLUSIONS: The authors found association between the highest 5-FU dose chemotherapy and increased expression levels for TYMS folate gene in laryngeal cancer cell line. Although these experiments were performed in vitro, the results suggest that genetic factors are thought to play an important role in drug metabolism and may be useful for predicting treatment outcomes.

Corrigan A, Walker JL, Wickramasinghe S, et al.
Pharmacogenetics of pemetrexed combination therapy in lung cancer: pathway analysis reveals novel toxicity associations.
Pharmacogenomics J. 2014; 14(5):411-7 [PubMed] Related Publications
Identification of polymorphisms that influence pemetrexed tolerability could lead to individualised treatment regimens and improve quality of life. Twenty-eight polymorphisms within eleven candidate genes were genotyped using the Illumina Human Exome v1.1 BeadChip and tested for their association with the clinical outcomes of non-small cell lung cancer and mesothelioma patients receiving pemetrexed/platinum doublet chemotherapy (n=136). GGH rs11545078 was associated with a reduced incidence of grade ⩾3 toxicity within the first four cycles of therapy (odds ratio (OR) 0.25, P=0.018), as well as reduced grade ⩾3 haematological toxicity (OR 0.13, P=0.048). DHFR rs1650697 conferred an increased risk of grade ⩾3 toxicity (OR 2.14, P=0.034). Furthermore, FOLR3 rs61734430 was associated with an increased likelihood of disease progression at mid-treatment radiological evaluation (OR 4.05, P=0.023). Polymorphisms within SLC19A1 (rs3788189, rs1051298 and rs914232) were associated with overall survival. This study confirms previous pharmacogenetic associations and identifies novel markers of pemetrexed toxicity.

Lladó V, López DJ, Ibarguren M, et al.
Regulation of the cancer cell membrane lipid composition by NaCHOleate: effects on cell signaling and therapeutical relevance in glioma.
Biochim Biophys Acta. 2014; 1838(6):1619-27 [PubMed] Related Publications
This review summarizes the cellular bases of the effects of NaCHOleate (2-hydroxyoleic acid; 2OHOA; Minerval) against glioma and other types of tumors. NaCHOleate, activates sphingomyelin synthase (SGMS) increasing the levels of cell membrane sphingomyelin (SM) and diacylglycerol (DAG) together with reductions of phosphatidylethanolamine (PE) and phosphatidylcholine (PC). The increases in the membrane levels of NaCHOleate itself and of DAG induce a translocation and overexpression of protein kinase C (PKC) and subsequent reductions of Cyclin D, cyclin-dependent kinases 4 and 6 (CDKs 4 and 6), hypophosphorylation of the retinoblastoma protein, inhibition of E2F1 and knockdown of dihydrofolate reductase (DHFR) impairing DNA synthesis. In addition in some cancer cells, the increases in SM are associated with Fas receptor (FasR) capping and ligand-free induction of apoptosis. In glioma cell lines, the increases in SM are associated with the inhibition of the Ras/MAPK and PI3K/Akt pathways, in association with p27Kip1 overexpression. Finally, an analysis of the Repository of Molecular Brain Neoplasia Data (REMBRANDT) database for glioma patient survival shows that the weight of SM-related metabolism gene expression in glioma patients' survival is similar to glioma-related genes. Due to its low toxicity and anti-tumoral effect in cell and animal models its status as an orphan drug for glioma treatment by the European Medicines Agency (EMA) was recently acknowledged and a phase 1/2A open label, non-randomized study was started in patients with advanced solid tumors including malignant glioma. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Nazki FH, Sameer AS, Ganaie BA
Folate: metabolism, genes, polymorphisms and the associated diseases.
Gene. 2014; 533(1):11-20 [PubMed] Related Publications
Folate being an important vitamin of B Complex group in our diet plays an important role not only in the synthesis of DNA but also in the maintenance of methylation reactions in the cells. Folate metabolism is influenced by several processes especially its dietary intake and the polymorphisms of the associated genes involved. Aberrant folate metabolism, therefore, affects both methylation as well as the DNA synthesis processes, both of which have been implicated in the development of various diseases. This paper reviews the current knowledge of the processes involved in folate metabolism and consequences of deviant folate metabolism, particular emphasis is given to the polymorphic genes which have been implicated in the development of various diseases in humans, like vascular diseases, Down's syndrome, neural tube defects, psychiatric disorders and cancers.

Lautner-Csorba O, Gézsi A, Erdélyi DJ, et al.
Roles of genetic polymorphisms in the folate pathway in childhood acute lymphoblastic leukemia evaluated by Bayesian relevance and effect size analysis.
PLoS One. 2013; 8(8):e69843 [PubMed] Free Access to Full Article Related Publications
In this study we investigated whether polymorphisms in the folate pathway influenced the risk of childhood acute lymphoblastic leukemia (ALL) or the survival rate of the patients. For this we selected and genotyped 67 SNPs in 15 genes in the folate pathway in 543 children with ALL and 529 controls. The results were evaluated by gender adjusted logistic regression and by the Bayesian network based Bayesian multilevel analysis of relevance (BN-BMLA) methods. Bayesian structure based odds ratios for the relevant variables and interactions were also calculated. Altogether 9 SNPs in 8 genes were associated with altered susceptibility to ALL. After correction for multiple testing, two associations remained significant. The genotype distribution of the MTHFD1 rs1076991 differed significantly between the ALL and control population. Analyzing the subtypes of the disease the GG genotype increased only the risk of B-cell ALL (p = 3.52×10(-4); OR = 2.00). The GG genotype of the rs3776455 SNP in the MTRR gene was associated with a significantly reduced risk to ALL (p = 1.21×10(-3); OR = 0.55), which resulted mainly from the reduced risk to B-cell and hyperdiploid-ALL. The TC genotype of the rs9909104 SNP in the SHMT1 gene was associated with a lower survival rate comparing it to the TT genotype (80.2% vs. 88.8%; p = 0.01). The BN-BMLA confirmed the main findings of the frequentist-based analysis and showed structural interactional maps and the probabilities of the different structural association types of the relevant SNPs especially in the hyperdiploid-ALL, involving additional SNPs in genes like TYMS, DHFR and GGH. We also investigated the statistical interactions and redundancies using structural model properties. These results gave further evidence that polymorphisms in the folate pathway could influence the ALL risk and the effectiveness of the therapy. It was also shown that in gene association studies the BN-BMLA could be a useful supplementary to the traditional frequentist-based statistical method.

Marverti G, Ligabue A, Lombardi P, et al.
Modulation of the expression of folate cycle enzymes and polyamine metabolism by berberine in cisplatin-sensitive and -resistant human ovarian cancer cells.
Int J Oncol. 2013; 43(4):1269-80 [PubMed] Related Publications
Berberine is a natural isoquinoline alkaloid with significant antitumor activity against many types of cancer cells, including ovarian tumors. This study investigated the molecular mechanisms by which berberine differently affects cell growth of cisplatin (cDDP)-sensitive and -resistant and polyamine analogue cross-resistant human ovarian cancer cells. The results show that berberine suppresses the growth of cDDP-resistant cells more than the sensitive counterparts, by interfering with the expression of folate cycle enzymes, dihydrofolate reductase (DHFR) and thymidylate synthase (TS). In addition, the impairment of the folate cycle also seems partly ascribable to a reduced accumulation of folate, a vitamin which plays an essential role in the biosynthesis of nucleic acids and amino acids. This effect was observed in both lines, but especially in the resistant cells, correlating again with the reduced tolerance to this isoquinoline alkaloid. The data also indicate that berberine inhibits cellular growth by affecting polyamine metabolism, in particular through the upregulation of the key catabolic enzyme, spermidine/spermine N1-acetyltransferase (SSAT). In this regard, berberine is shown to stimulate the SSAT induction by the spermine analogue N1, N12 bisethylspermine (BESpm), which alone was also able to downregulate DHFR mRNA more than TS mRNA. We report that the sensitivity of resistant cells to cisplatin or to BESpm is reverted to the levels of sensitive cells by the co-treatment with berberine. These data confirm the intimate inter-relationships between folate cycle and polyamine pathways and suggest that this isoquinoline plant alkaloid could be a useful adjuvant therapeutic agent in the treatment of ovarian carcinoma.

Galbiatti AL, Castro R, Caldas HC, et al.
Alterations in the expression pattern of MTHFR, DHFR, TYMS, and SLC19A1 genes after treatment of laryngeal cancer cells with high and low doses of methotrexate.
Tumour Biol. 2013; 34(6):3765-71 [PubMed] Related Publications
Inter-individual variations to methotrexate (MTX) outcome have been attributed to different expression profiles of genes related to folate metabolism. To elucidate the mechanisms of variations to MTX outcome, we investigated MTHFR, DHFR, TYMS, and SLC19A1 gene expression profiles by quantifying the mRNA level of the genes involved in folate metabolism to MTX response in laryngeal cancer cell line (HEP-2). For this, three different concentrations of MTX (0.25, 25, and 75 μmol) were added separately in HEP-2 cell line for 24 h at 37 °C. Apoptotis quantification was evaluated with fluorescein isothiocyanate-labeled Bcl-2 by flow cytometry. Real-time quantitative PCR technique was performed by quantification of gene expression with TaqMan® Gene Expression Assay. ANOVA and Bonferroni's post hoc tests were utilized for statistical analysis. The results showed that the numbers of apoptotic HEP-2 cells with 0.25, 25.0, and 75.0 μmol of MTX were 14.57, 77.54, and 91.58%, respectively. We found that the expression levels for MTHFR, DHFR, TYMS, and SLC19A1 genes were increased in cells with 75.0 μmol of MTX (p < 0.05). Moreover, SLC19A1 gene presented lower expression in cells treated with 0.25 μmol of MTX (p < 0.05). In conclusion, our data suggest that MTHFR, DHFR, TYMS, and SLC19A1 genes present increased expression after the highest application of MTX dose in laryngeal cancer cell line. Furthermore, SLC19A1 gene also presents decreased expression after the lowest application of MTX dose in laryngeal cancer cell line. Significant alterations of expression of these studied genes in cell culture model may give support for studies in clinical practice and predict interesting and often novel mechanisms of resistance of MTX chemotherapy.

Sáez-Ayala M, Montenegro MF, Sánchez-Del-Campo L, et al.
Directed phenotype switching as an effective antimelanoma strategy.
Cancer Cell. 2013; 24(1):105-19 [PubMed] Related Publications
Therapeutic resistance in melanoma and other cancers arises via irreversible genetic, and dynamic phenotypic, heterogeneity. Here, we use directed phenotype switching in melanoma to sensitize melanoma cells to lineage-specific therapy. We show that methotrexate (MTX) induces microphthalmia-associated transcription factor (MITF) expression to inhibit invasiveness and promote differentiation-associated expression of the melanocyte-specific Tyrosinase gene. Consequently, MTX sensitizes melanomas to a tyrosinase-processed antifolate prodrug 3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG), that inhibits the essential enzyme DHFR with high affinity. The combination of MTX and TMECG leads to depletion of thymidine pools, double-strand DNA breaks, and highly efficient E2F1-mediated apoptosis in culture and in vivo. Importantly, this drug combination delivers an effective and tissue-restricted antimelanoma therapy in vitro and in vivo irrespective of BRAF, MEK, or p53 status.

Shi X, Sun M, Liu H, et al.
Long non-coding RNAs: a new frontier in the study of human diseases.
Cancer Lett. 2013; 339(2):159-66 [PubMed] Related Publications
With the development of whole genome and transcriptome sequencing technologies, long noncoding RNAs (lncRNAs) have received increased attention. Multiple studies indicate that lncRNAs act not only as the intermediary between DNA and protein but also as important protagonists of cellular functions. LncRNAs can regulate gene expression in many ways, including chromosome remodeling, transcription and post-transcriptional processing. Moreover, the dysregulation of lncRNAs has increasingly been linked to many human diseases, especially in cancers. Here, we reviewed the rapidly advancing field of lncRNAs and described the relationship between the dysregulation of lncRNAs and human diseases, highlighting the specific roles of lncRNAs in human diseases.

Jung M, Lee CH, Park HS, et al.
Pharmacogenomic assessment of outcomes of pemetrexed-treated patients with adenocarcinoma of the lung.
Yonsei Med J. 2013; 54(4):854-64 [PubMed] Free Access to Full Article Related Publications
PURPOSE: The main objective of this study was to evaluate the association between polymorphisms of the target genes of pemetrexed and clinical outcomes in non-small cell lung cancer (NSCLC) patients treated with pemetrexed.
MATERIALS AND METHODS: We assessed polymorphisms at 8 sites in 4 genes [thymidylate synthase (TS), dihydrofolate reductase (DHFR; 1610, 680, 317, intron 1), methylenetetrahydrofolate reductase (MTHFR; 677, 1298), glycinamide ribonucleotide formyl transferase (GARFT; 2255)] associated with pemetrexed metabolism using polymerase chain reaction, gene scanning, and restriction fragment length polymorphism analysis in 90 patients with adenocarcinoma of the lung.
RESULTS: Survival was significantly longer with pemetrexed in patients with TS 3RGCC/3RGCC or 3RGGC/3RGGC compared with the other groups (PFS; 5.2 months vs. 3.7 months, p=0.03: OS; 31.8 months vs. 18.5 months, p=0.001). Patients with DHFR 680CC experienced fatigue more frequently (50% vs. 8.6%, p=0.008). Polymorphisms of MTHFR and GARFT were not significantly associated with clinical outcomes of pemetrexed.
CONCLUSION: The TS genotype was associated with survival and one DHFR polymorphism was associated with fatigue in NSCLC patients treated with pemetrexed. Further large prospective studies are required to identify other biomarkers that affect patients being treated with pemetrexed for adenocarcinoma of the lung.

Ito K, Maruyama Z, Sakai A, et al.
Overexpression of Cdk6 and Ccnd1 in chondrocytes inhibited chondrocyte maturation and caused p53-dependent apoptosis without enhancing proliferation.
Oncogene. 2014; 33(14):1862-71 [PubMed] Related Publications
Cell proliferation and differentiation are closely coupled. However, we previously showed that overexpression of cyclin-dependent kinase (Cdk6) blocks chondrocyte differentiation without affecting cell-cycle progression in vitro. To investigate whether Cdk6 inhibits chondrocyte differentiation in vivo, we generated chondrocyte-specific Cdk6 transgenic mice using Col2a1 promoter. Unexpectedly, differentiation and cell-cycle progression of chondrocytes in the Cdk6 transgenic mice were similar to those in wild-type mice. Then, we generated chondrocyte-specific Ccnd1 transgenic mice and Cdk6/Ccnd1 double transgenic mice to investigate the possibility that Cdk6 inhibits chondrocyte differentiation through E2f activation. Bromodeoxyuridine (BrdU)-positive chondrocytes and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive chondrocytes were increased in number, and chondrocyte maturation was inhibited only in Cdk6/Ccnd1 transgenic mice (K6(H)/D1(H) mice), which showed dwarfism. Retinoblastoma protein (pRb) was highly phosphorylated but p107 was upregulated, and the expression of E2f target genes was dysregulated as shown by upregulation of Cdc6 but downregulation of cyclin E, dihydrofolate reductase (dhfr), Cdc25a and B-Myb in chondrocytes of K6(H)/D1(H) mice. Similarly, overexpression of Cdk6/Ccnd1 in a chondrogenic cell line ATDC5 highly phosphorylated pRb, upregulated p107, induced apoptosis, upregulated Cdc6 and downregulated cyclin E, dhfr and B-Myb and p107 small interfering RNA reversed the expression of downregulated genes. Further, introduction of kinase-negative Cdk6 and cyclin D1 abolished all effects by Cdk6/cyclin D1 in ATDC5 cells, indicating the requirement of the kinase activity on these effects. p53 deletion partially restored the size of the skeleton and almost completely rescued chondrocyte apoptosis, but failed to enhance chondrocyte proliferation in K6(H)/D1(H) mice. These findings indicated that Cdk6/Ccnd1 overexpression inhibited chondrocyte maturation and enhanced G1/S cell-cycle transition by phosphorylating pRb, but the chondrocytes failed to accomplish the cell cycle, and underwent p53-dependent apoptosis probably due to the dysregulation of E2f target genes. Our findings also indicated that p53 deletion in addition to the inactivation of Rb was not sufficient to accelerate chondrocyte proliferation, suggesting the resistance of chondrocytes to sarcomagenesis.

Babyshkina N, Malinovskaya E, Nazarenko M, et al.
The effect of folate-related SNPs on clinicopathological features, response to neoadjuvant treatment and survival in pre- and postmenopausal breast cancer patients.
Gene. 2013; 518(2):397-404 [PubMed] Related Publications
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.

Zee RY, Rose L, Chasman DI, Ridker PM
Genetic variation of fifteen folate metabolic pathway associated gene loci and the risk of incident head and neck carcinoma: the Women's Genome Health Study.
Clin Chim Acta. 2013; 418:33-6 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: Recent studies have demonstrated the importance of folate metabolic pathway (FMP) in the pathogenesis of head and neck carcinoma (HNC). Whether the genetic variation within the FMP associated genes modulates HNC remains elusive. To date, prospective, epidemiological data on the relationship of FMP gene variation with the risk of HNC are sparse.
METHODS: The association between 203 tag-SNPs (tSNPs) of 15 FMP associated genes (CBS, BHMT, DHFR, FOLR1, FOLR2, FOLR3, MTHFR, MTR, MTRR, MTHFD1, RFC1, SHMT1, SLC19A1, TCN2, and TYMS) and incident HNC was investigated in 23,294 Caucasian female participants of the prospective Women's Genome Health Study. All were free of known cancer at baseline. During a 15-year follow-up period, 55 participants developed a first ever HNC. Multivariable Cox regression analysis was performed to investigate the relationship between genotypes and HNC risk assuming an additive genetic model. Haplotype-block analysis was also performed.
RESULTS: A total of 11 tSNPs within DHFR, MTHFR, RFC1, and TYMS were associated with HNC risk (all p-uncorrected <0.050). Further investigation using the haplotype-block analysis revealed an association of several prespecified haplotypes of RFC1 with HNC risk (all p-uncorrected <0.050).
CONCLUSION: If corroborated in other large prospective studies, the present findings suggest that genetic variation within the folate metabolic pathway gene loci examined, in particular, the replication factor C-1 (RFC1) gene variation may influence HNC risk.

Deschatrette J, Ng-Bonaventure K, Philippe L, Wolfrom C
Interaction between Gambogic acid and dihydrofolate reductase and synergistic lethal effects with methotrexate on hepatoma cells.
Anticancer Res. 2013; 33(1):133-42 [PubMed] Related Publications
Gambogic acid (GA), a natural xanthone, has a wide spectrum of pharmacological activities, including repression of telomerase expression and induction of apoptosis of cancer cells. GA has also been reported to reduce the steady-state level of thymidylate synthetase mRNA in a gastric carcinoma cell line. Therefore, it has recently emerged as a candidate for use in cancer treatment. Using hepatoma cells with a dihydrofolate reductase (DHFR) gene amplification and cells transfected with an inducible DHFR transgene, we observed a negative relationship between DHFR expression and resistance to GA. Furthermore, DHFR assays in vitro indicated that in the presence of GA, DHFR activity was slightly inhibited and the affinity of the enzyme for dihydrofolate was markedly decreased. Treatment of rat hepatoma and other human and murine cancer cell lines with methotrexate and GA revealed that the two drugs displayed a marked synergistic lethal effect.

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