Relationship between reduced folate carrier gene methylation and methotrexate resistance / 国际儿科学杂志

Tumor recurrence and drug resistance impact patients'therapeutic effect and prognosis seriously.In recent years,it has been found that epigenetic changes are involved in drug resistance.DNA methylation is one of the ways of epigenetic.DNA methylation of drug metabolism enzyme gene can affect gene's expression,leading to drug resistance.Methotrexate(MTX),a folic acid antagonist,is the most widely used drug in the treatment of malignant tumors,such as leukemia,osteosarcoma,head and neck cancer,and so on.Reduced folate carrier(RFC) is the main transporter cartier of MTX,and gene methylation is related to tumor cells'resistance to MTX.This paper reviews the role of RFC,relation of RFC methylation and methotrexate resistance and the factors of RFC methylation.

Role of serum folate, polymorphisms related reduced folate carrier gene and methionine synthase reductase gene in cervical cancer / 肿瘤研究与临床

Objective To evaluate the possible association among serum folate,polymorphisms related reduced folate carrier gene (RFC-1) AS0G,methionine synthase reductase gene (MTRR) A66G,and cervical cancer,and to provide clues for the etiology of cervical cancer.Methods Based on a hospital-based case-control study,107 cases diagnosed as cervical cancer pathematologically and 107 controls with hysteromyoma,were selected by frequency,matched with age and habitation.Serum folate concentration was detected by RIA and polymorphism RFC-1 A80G and MTRR A66G was examed by RFLP-PCR.Results Serum folate concentration in patient group [(1.86±0.60) ng/rml] was significantly lower than that in control group [(2.30 ± 1.14) ng/ml],and risk of cervical cancer increased with the decreased serum folate levels (x2trend =12.57,P =0.001).Risks to catch cervical cancer for women with RFC-1 80 GG were 2.42 times (95 ％ CI 1.01-5.81) as much as for those with RFC-1 80 AA,and 1.65 times (95 ％ CI 0.77-3.53) for those with RFC-1 80 AA and RFC-1 80 AG,risks to catch cervical cancer for women with MTRR 66 GG were 1.35 times (95 ％ CI 0.40-4.56) as much as for those with MTRR 66 AA and 1.26 times (95 ％ CI 0.38-4.16) for those with RFC-1 80 AA and RFC-1 80 AG.Conclusion Serum folate deficiency to a certain degree can increase the risk of cervical cancer.RFC-1 A80G mutation may be a risk factor for cervical cancer and homozygous (GG) gene may increase the susceptibility of cervical cancer.MTRR A66G gene mutation may have nothing to do with cervical cancer.

Inlfuence of transport protein gene polymorphisms on the effects and toxicity of high-dose methotrexate in child-hood acute lymphoblastic leukemia / 临床儿科杂志

Objectives To investigate the inlfuence of polymorphisms of SLC19A1 80G>A, MDR1 exon26C>T and MDR1 exon21G>T/A on curative effect and adverse reaction of high-dose methotrexate in patients with acute lymphoblastic leukemia. Methods MALDI-TOF-MS technique was used to detect the polymorphisms of SLC19A1 80G>A, MDR1 exon 26C>T and MDR1 exon21G>T/A in 108 patients with acute lymphoblastic leukemia (ALL). The relationship of genetic polymorphism, survival rate and toxicity was analyzed. Results The 36-month event-free survival was not related to any polymorphisms of MDR1 and SLC19A1. Patients with mutant types of MDR1 exon26C>T and MDR1 exon21G>T/A showed a much higher MTX plasma levels at 24 hours and higher incidence of hepatic injury (PT, MDR1 exon21G>T/A has a large inlfuence on hepatic toxicity and plasma concentra-tions of MTX.

Influence of Reduced Folate Carrier and Dihydrofolate Reductase Genes on Methotrexate-Induced Cytotoxicity / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The aim of this study is to investigate the effect of genetic variations and the expression of the reduced folate carrier (RFC) and dihydrofolate reductase (DHFR) on the drug sensitivity to methotrexate (MTX) in different cancer cell lines. MATERIALS AND METHODS: We examined the six human cancer cell lines (MCF-7, AGS, A549, NCI-H23, HCT-116 and Saos-2). The cytotoxicity of MTX was measured by sulforhodamine B (SRB) assay. The expressions of the DHFR and RFC were evaluated by real-time PCR and western blotting. Four single nucleotide polymorphisms (SNPs) of the DHFR and two SNPs of the RFC were genotyped. RESULTS: The IC50s of MTX was in an extensively broad range from 6.05+/-0.81 nM to>1,000 nM in the cell lines. The Saos-2 (>1,000 nM) and MCF-7 (114.31+/-5.34 nM) cells were most resistant to MTX; in contrast, the AGS and HCT-116 cells were highly sensitive to MTX with an IC50 of 6.05+/-0.81 nM and 13.56+/-3.76 nM, respectively. A reciprocal change of the RFC and DHFR mRNA expression was found between the MTX-sensitive AGS and MTX-resistant Saos-2 cells. There was no significant difference in the expression levels of RFC protein in both the AGS and Saos-2 cells, whereas DHFR protein was more increased in the MTX-resistant Saos-2 cells treated with MTX. The genotype of the MTX-sensitive AGS cells were mutant variants of the DHFR; in contrast, the Saos-2 cells had the wild-type of the DHFR. CONCLUSION: In conclusion, this study showed that inverse change of the RFC and DHFR mRNA and protein expression was associated with RFC and DHFR polymorphisms and it is postulated that this phenomenon might play an important role in sensitivity of certain cancers to MTX.

The relationship between the polymorphisms of RFC and methotrexate resistance / 国际儿科学杂志

The best characterized methotrexate (MTX) transporter is the reduced folate carrier (RFC),whose gene polymorphism is one of the reasons causing MTX resistance. Based on the studies in rencent years,we have known that synthesis of mutant RFC or loss of RFC transcripts and proteins results in antifolate resistance due to incomplete inhibition of cellular enzyme targets and insufficient substrate for polyglutamate synthesis. So additional human RFC structural and mechanistic studies are absolutely essential. This paper summarizes an association between the polymorphisms of RFC and MTX resistance, which can provide a basis for clinical treatment.

Reduced folate carrier 1 (RFC1) is associated with cleft of the lip only

In this report, we have reanalyzed genotyping data in a collection of families from South America based on maternal origin. Genotyping analysis was performed at the Craniofacial Anomalies Research Center at the University of Iowa. These genotypes were derived from genomic DNA samples obtained from blood spots from children born with isolated orofacial clefts in 45 hospitals located in eight countries (Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay, Uruguay, and Venezuela) collaborating with ECLAMC (Latin American Collaborative Studies of Congenital Malformations) between January 1998 and December 1999. Dried blood samples were sent by regular mail to the Laboratory of Congenital Malformations, Federal University of Rio de Janeiro. Previous findings suggested that mitochondrial haplotype D is more commonly found among cleft cases born in South America. We hypothesized that association of certain genes may depend upon the ethnic origin, as defined by population-specific markers. Therefore, we tested if markers in MTHFR (5,10-methylenetetrahydrofolate reductase) and RFC1 (reduced folate carrier 1) were associated with oral clefts, depending on the maternal origin defined by the mitochondrial haplotype. Transmission distortion of alleles in MTHFR C677T and RFC1 G80A polymorphic variants was tested in 200 mother/affected child pairs taking into consideration maternal origin. RFC1 variation was over-transmitted to children born with cleft lip only (P = 0.017) carrying mitochondrial DNA haplotypes other than haplotype D. Our results provide a new indication that variation in RFC1 may contribute to cleft lip only. Future studies should investigate the association between oral clefts and RFC1 based on more discrete phenotypes.

Detection of RFC,DHFR and GST-? expression in human osteosarcoma cell line with MTX-resistence by FQ-PCR / 中国矫形外科杂志

[Objective]To study the difference in expression of RFC, GST-?, DHFRmRNA between human osteosarcoma U2-OS cell line and the MTX-resisitant variants U2-OS/R1-R3, and to investigate the significance in MTX resistance for human osteosarcoma. [Methods]Three resistant MTX human osteosarcoma cell lines were established by pulse exposure parental cell line(U2-OS) in gradually increased dose of MTX . The expression of RFC,GST-?,DHFRmRNA were assayed by real-time fluorescence quantitative polymerase chain reaction(FQ-PCR).[Results]Three MTX-resistant variants(U2-OS/R1-R3) were successfully established , the results of the FQ-PCR revealed that the MTX resistance was associated with the decreased expression of the RFC mRNA and increased expression of DHFR mRNA and GST-? mRNA.[Conclusion]The author investigated the MTX resistant mechanism of human osteosarcoma cell line at a gene level. The decreased expression of RFC mRNA and the increased expression of DHFR mRNA and GST-? mRNA participate in the MTX resistance in human osteosarcoma cell lines U-2 OS. This provides the evidence for exploring the MTX resistance mechanism in clinical osteosarcoma patients ,and helps to screen the patients who are insensitive to MTX chemotherapy.