Elsevier

Leukemia Research

Volume 32, Issue 1, January 2008, Pages 19-24
Leukemia Research

Methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase promoter (TSER) polymorphisms in Indonesian children with and without leukemia

https://doi.org/10.1016/j.leukres.2007.02.011Get rights and content

Abstract

Genetic variations in the polymorphic tandem repeat sequence of the enhancer region of the thymidylate synthase promoter (TSER), as well as in methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, influence methotrexate sensitivity. We studied these polymorphisms in children with acute lymphoblastic leukaemia (ALL) and in subjects without malignancy in Indonesia and Holland.

The frequencies of TT and CT genotypes were two-fold higher in Dutch children. The TSER 3R/3R repeat was three-fold more frequent in the Indonesian children, while the 2R/2R repeat was only 1% compared to 21% in the Dutch children. No differences of these polymorphisms were found between ALL cells and normal blood cells, indicating an ethnic rather than leukemic origin. These results may have implications for treatment of Indonesian children with ALL.

Introduction

Acute lymphoblastic leukemia (ALL) is the most common malignancy that affects children, representing nearly one-third of all paediatric cancers. Annual incidence of ALL is about 30 cases per million people, with a peak incidence in patients aged 2–5 years [1]. The optimisation of the use of antileukemic agents that were developed from the 1950s through the 1980s, has resulted in a substantial reduction in death rates from ALL, particularly in children [2]. An important drug in the treatment of ALL is methotrexate (MTX), which inhibits several enzymes involved in folate homeostasis. MTX is an inhibitor of dihydrofolate reductase and decreases intracellular levels of reduced folates, such as 5,10-methylenetetrahydrofolate (CH2-THF), which is required for DNA synthesis and for maintaining the balance of the deoxynucleotide pool [3]. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-CH2-THF to 5-CH3-THF, the predominant circulatory form of folate and carbon donor for the remethylation of homocysteine to methionine (Fig. 1). MTHFR is located on the short (p) arm of chromosome 1, at position 36.3 (1p36.3). Up to 12–15% of Caucasian individuals are homozygous for a C  T polymorphism located at nucleotide 677 (referred to as the TT genotype). The resulting substitution of alanine to valine increases thermolability and reduces the activity of MTHFR [4]. Accumulation of 5,10-CH2-THF resulting from the MTHFR C677T polymorphism may have an effect on the response to MTX, and recent studies have suggested that the TT genotype may be associated with an increased toxicity of MTX in leukemia patients [5], [6]. The risk of cardiovascular disease, neural tube defects and several cancers, including ALL, may also be increased, although the evidence to support these relationships is controversial [4], [7], [8].

Thymidylate synthase (TS) is a key-enzyme in de novo DNA synthesis, which catalyses the conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP), and is another critical target for MTX [3]. Inhibition of this enzyme results in deoxythymidine triphosphate (dTTP) depletion, chromosome breaks and cell death [9]. The TYMS gene is located on chromosome 18p11.32 and has a unique tandem repeat sequence in the enhancer region (TSER) that has been shown to be polymorphic [10], containing either two (2R) or three (3R) 28-bp repeats. The presence of the 3R versus 2R was shown to influence gene expression in vitro and in vivo[10], and in childhood ALL, homozygosity for the 3R, was reported to be associated with poorer outcome compared to the presence of at least one 2R allele [10].

The prevalence of the MTHFR C677T and TSER polymorphisms may be different among various populations and may affect the efficacy of MTX, a chemotherapeutic agent that is extensively used for the treatment of paediatric ALL. Therefore, identification of these polymorphisms may be an important pharmacogenetic determinant to predict response or toxicity to chemotherapy in children affected by leukaemia. Ethnic variations in the frequency of both the C677T MTHFR and the TSER polymorphic tandem repeat sequences have been described earlier [11], [12]. However, to our knowledge, identification of the MTHFR C677T and TSER polymorphisms in Indonesian ALL patients has not been performed before. ALL treatment protocols in Indonesia are analogous to the Dutch protocols (DCLSG ALL-6 and ALL-9), which are based on tolerability and efficacy in this Caucasian population. Since ethnic differences may exist between Dutch and Indonesian children, which may affect drug sensitivity, we determined the ethnic variations in TSER and MTHFR polymorphisms in Dutch and Indonesian children with ALL, in Dutch adult controls, and in Indonesian children without malignancies.

Section snippets

Patient and control samples

The patients of Indonesian origin included in this study were 71 children diagnosed with ALL treated at Dr. Sarjito Hospital, Yogyakarta, Indonesia and Dr. Soetomo Hospital, Surabaya, Indonesia with the Wijaya Kusuma ALL 2000 protocol. Control samples were from 44 patients without any malignancy selected within the range of 3–8 years of age, while the mean age of the children affected by ALL was 6.1 years (Table 1). For DNA isolation we used isolated mononuclear cells frozen on DMSO and stored

Results

We analyzed the TSER genotype in 71 samples of Indonesian origin from leukemia cells and compared the results to the 157 samples of Caucasian origin that were published earlier [13]. In addition, blood samples of 44 Indonesian paediatric children without any malignancies were analysed to evaluate whether the difference in genotype would be due to ethnicity and not to a characteristic of the leukaemia cells. This has for instance been described for colon cancer where occasionally only one allele

Discussion

In this paper we demonstrate that large differences exist between Indonesian and Dutch children, both in polymorphisms of TSER and MTHFR. In Indonesian children a much higher proportion of the 3R allele, and specifically of the TSER 3R/3R group, was present, while for MTHFR, the frequency of TT genotype was very low. There is no difference for TSER between Caucasian childhood ALL [13] and adult controls [12], while the genotype distribution in the Indonesian ALL samples was slightly different

Conflicts of interest

All the authors do not have any commercial or other associations that might pose a conflict of interest.

Acknowledgement

This study was supported by a grant (KWF-IN-2006-22) from the Dutch Cancer Society.

Contributions. E. Giovannetti contributed to the analysis and interpretation of data, writing the article. D.G. Ugrasena and E. Supriyadi contributed to the study conception and analysis of data. L. Vroling, A. Azzarello and D. de Lange contributed to the analysis and interpretation of data. G.J. Peters contributed to the study conception, interpretation of data, writing and revising the article. A.J.P. Veerman

References (27)

  • N. Rosenberg et al.

    The frequent 5,10-methylenetetrahydrofolate reductase C677T polymorphism is associated with a common haplotype in whites, Japanese, and Africans

    Am J Hum Genet

    (2002)
  • A. Jemal et al.

    Cancer statistics, 2006

    CA Cancer J Clin

    (2006)
  • C.H. Pui et al.

    Treatment of acute lymphoblastic leukemia

    N Engl J Med

    (2006)
  • Cited by (41)

    • The association between MTHFR gene C677T polymorphism and ALL risk based on a meta-analysis involving 17,469 subjects

      2017, Clinica Chimica Acta
      Citation Excerpt :

      The version 12.0 STATA software, was used for all the analyses in the present studies (Stata Corporation, USA). Totally thirty-nine studies were included in the present study concerning the relationship between C677T polymorphism of MTHFR gene and ALL [4,12,20–55]. There are 6551 patients and 10,918 controls totally in these studies, containing thirteen Caucasian population studies, seventeen Asian population studies, and nine mixed population studies.

    • Variants of the MTHFR gene and susceptibility to acute lymphoblastic leukemia in children: A synthesis of genetic association studies

      2012, Cancer Epidemiology
      Citation Excerpt :

      The studies used validated genotyping methods for the determination of the genetic variants [6,7]. Studies were conducted in various populations of different ethnicity: 10 involved Whites [27,30,31,36,40–45], six East Asians [33–35,39,46,47], three Indians [29,34,35], two mixed populations [48,49], one Turks [28] and one Arabs [50]. Fig. 2 shows the individual studies’ results for the association between the allele contrast and the risk of developing ALL.

    View all citing articles on Scopus
    View full text