Open Access

Enhanced levels of asymmetric dimethylarginine in a serum of middle age patients with myelodysplastic syndrome

  • Jana Štikarová1,
  • Jiří Suttnar1Email author,
  • Kristýna Pimková1,
  • Leona Chrastinová-Mášová1,
  • Jaroslav Čermák1 and
  • Jan E Dyr1
Journal of Hematology & Oncology20136:58

DOI: 10.1186/1756-8722-6-58

Received: 17 July 2013

Accepted: 17 August 2013

Published: 19 August 2013

Abstract

Myelodysplastic syndromes (MDS) are hematological malignancies of unclear etiology where oxidative stress may contribute to the pathogenesis. Methylarginines, naturally occurring inhibitors of NO synthase, can increase superoxide generation from uncoupled NO synthase. We found significant increase in concentrations of asymmetric dimethylarginine (0.84 ± 0.32 μmol/L, p = 0.0022) and malondialdehyde (0.77 ± 0.11 μmol/L, p < 0.001) in sera of MDS patients vs controls (asymmetric dimethylarginine: 0.56 ± 0.16 μmol/L, malondialdehyde: 0.52 ± 0.07 μmol/L). On the contrary, nitrites concentrations were significantly decreased in MDS patients (1.71 ± 0.46 μmol/L, p = 0.0028) vs controls (2.16 ± 0.38 μmol/L). We suppose that the oxidative stress in MDS is enhanced due to methylated arginines influence on NO synthase activity impairment.

To the editor

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematological disorders, characterized by ineffective hematopoiesis and a high risk of transformation into acute myeloid leukemia. It has been determined that oxidative stress plays a role in the initialization and disease progression [1]. The reactive oxygen species may oxidize tetrahydrobiopterin resulting into nitric oxide synthase (NOS) uncoupling and preferential formation to superoxide anion radical. It was found that methylarginines (asymmetric dimethylarginine - ADMA, NG-monomethyl-L-arginine - MMA and symmetric dimethylarginine - SDMA), naturally occurring inhibitors of NOS [2], can profoundly increase superoxide generation from uncoupled NOS [3]. Free methylated arginines, capable of inhibiting NOS [4], are formed exclusively by the sequence of methylation of arginine residues of proteins, followed by proteolysis of these proteins. Protein arginine methylation is in mammalian cells carried out by protein arginine methyltransferases (PRMTs); many of them show links to cancer [5].

The subjects of the study are characterized in Table 1. Ethics approval (Ethics Committee of the Institute of Hematology and Blood Transfusion) and informed consent from all subjects were obtained. Serum concentration of oxidative stress marker malondialdehyde (MDA) was estimated using liquid chromatography (Shimadzu, Tokyo, Japan) of its thiobarbituric acid derivative [6]. Methylated arginines were analyzed using HILIC chromatography with MS/MS detection (ABSciex, Framingham, USA) [7]. Nitrites were assayed by chromatography using the fluorescent reaction product with 2,3-diaminonaphthalene [8].
Table 1

Baseline characteristics of MDS patients and healthy controls

 

MDS

Controls

aAge (years)

43.7 (33–59)

44.3 (37–67)

Male/Female

11/9

8/8

aSerum iron [μmol/L]

22.3 (11.4-43.3)

b8.5-28

aSerum ferritin [μg/L]

641.2 (8.9-1907.3)

b15-150

aThe data are depicted as averages with ranges. bReference interval.

The concentrations of methylated arginine derivatives, malondialdehyde and nitrites are summarized in the Table 2. We found significantly increased serum concentrations of ADMA, SDMA, MMA, and MDA in sera of MDS patients as compared with healthy donors. The nitrites concentrations were significantly decreased in sera of MDS patients as compared with controls. The concentration of ADMA strongly positively correlated with concentration of MMA (r = 0.87, p < 0.001) and SDMA (r = 0.70, p < 0.001). ADMA concentration moderately positively correlated with MDA concentration (r = 0.50, p = 0.006).
Table 2

Concentrations of methylated arginines in sera of MDS patients and healthy controls

 

MDS

Controls

ap

ADMA [μmol/L]

0.84 ± 0.32

0.56 ± 0.16

0.0022**

SDMA [μmol/L]

0.54 ± 0.18

0.42 ± 0.14

0.0361*

MMA [μmol/L]

0.14 ± 0.05

0.10 ± 0.03

0.033*

Homoarginine [μmol/L]

1.77 ± 1.06

2.32 ± 1.26

0.1777

Citrulline [μmol/L]

46.68 ± 14.96

42.19 ± 12.31

0.3298

MDA [μmol/L]

0.77 ± 0.11

0.52 ± 0.07

<0.001***

Nitrites [μmol/L]

1.71 ± 0.46

2.16 ± 0.38

0.0028**

The data are represented as averages ± SD. ADMA, NG, NG-dimethyl-L-arginine; MMA, NG-monomethyl-L-arginine; SDMA, NG,NG’-dimethyl-L-arginine; MDA, malondialdehyde. aTwo-tailed t-test was used to compare measured concentrations of analytes in MDS patients with healthy donors. Statistical significance coding: * p < 0.05, ** p < 0.01 and *** p < 0.001.

Our results showed significantly increased oxidative stress even in MDS patients characterized by moderately enhanced iron and serum transferrin concentrations. Resulting shift of overexpressed [9] NO synthase activity in favour of superoxide production at the expense of nitric oxide synthesis (reflected by nitrites concentrations [10]) was further augmented at the presence of methylated arginines. Therefore, oxidative stress in MDS patients could be explained by a positive feedback of both superoxide and methylated arginines on original NOS activity impairment. Moreover, recently proposed PRMT-specific inhibitors [11] might have a therapeutic effect on leukemia also by oxidative stress reduction.

Abbreviations

MDS: 

Myelodysplastic syndromes

NOS: 

Nitric oxide synthase

ADMA: 

NG,NG-dimethyl-L-arginine

MMA: 

NG-monomethyl-L-arginine

SDMA: 

NG,NG’-dimethyl-L-arginine

MDA: 

Malondialdehyde

PRMT: 

protein arginine methyltransferase.

Declarations

Acknowledgement

This work was supported by Grant CZ.2.16/3.1.00/24001 of the EU ERDF OPPK, by P205/12/G118 of Centrum Excellence, by Grant KAN200670701 from the Academy of Sciences, Czech Republic and by the Ministry of Health, Czech Republic project for the conceptual development of research organization, VZ MZ 00002373601 IHBT.

Authors’ Affiliations

(1)
Institute of Hematology and Blood Transfusion

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Copyright

© Štikarová et al.; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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