RESUMO
Some studies show that alterations in DNA repair genes polymorphisms are associated with the pathogenesis and susceptibility of Myelodysplastic Syndrome (MDS). We genotyped 60 MDS patients for six DNA repair gene polymorphisms: BRCA1 rs4793191, BRCA2 rs9567623, RAD51 rs1801320, XRCC5 rs3835, XRCC6 rs2267437 and LIG4 rs1805388. The G/C heterozygote genotype of rs1801320 polymorphism was associated with a decreased chance of developing MDS (p = 0.05). Additionally, the G/G homozygous genotype was associated with the presence of one cytopenia in whole blood. The genotype C/G and CG + GG of the rs2267437 polymorphism was associated with normal karyotype (p = 0.010) and bone marrow cellularity normocellular + hypercellular (p = 0.023). We found that the A/G heterozygous genotype of the rs3835 polymorphism is associated with decreased chance of developing MDS (p < 0.001). These results support the importance of RAD51, XRCC5 and XRCC6 genes polymorphisms in the maintenance of genomic stability promoting a better understanding of the genesis and etiology of MDS.
Assuntos
Reparo do DNA/genética , Síndromes Mielodisplásicas/genética , Idoso , Idoso de 80 Anos ou mais , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/patologia , Fatores de RiscoRESUMO
Myelodysplastic syndrome (MDS) are a heterogeneous group of clonal disease characterized by insufficiency of bone marrow, increase of apoptosis and increased risk of acute leukemia progression. Proteins related to the mitotic spindle (AURKA, AURKB, TPX2), to the mitotic checkpoint (MAD2, CDC20) and the regulation of the cell cycle (p21) are directly related to chromosomal stability and tumor development. This study aimed to evaluate the mRNA expression levels of these genes in 101 MDS patients using a real-time PCR methodology. We identified that CDC20 expression are increased in patients with dysmegakaryopoiesis (p=0.024), thrombocytopenia (p=0.000) and high-risk patients (p=0.014, 0.018) MAD2 expression are decreased in patients with 2 or 3 cytopenias (p=0.000) and neutrophil below 800/mm3. TPX2 is also overexpressed in patients presenting dysmegakaryopoiesis (p=0.009). A decrease in AURKA and AURKB expression were observed in patients with altered karyotype (p=0.000), who presented dysplasia in 3 lineages (p=0.000; 0.017) and hemoglobin inferior to 8g/dL (p=0.024). The expression of AURKA, AURKB and MAD2 (p=0.000; 0.001; 0.025) were decreased in patients with hypoplastic MDS, associated with high frequency of chromosomal alterations and high mortality rate. This study reaffirms the importance of aurora kinases and mitotic spindle genes to the pathogenesis and clinical evolution of MDS.
Assuntos
Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Aurora Quinase A/genética , Aurora Quinase A/metabolismo , Aurora Quinase B/genética , Aurora Quinase B/metabolismo , Proteínas Cdc20/genética , Proteínas Cdc20/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Feminino , Humanos , Estimativa de Kaplan-Meier , Proteínas Mad2/genética , Proteínas Mad2/metabolismo , Masculino , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/mortalidade , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Prognóstico , Fuso Acromático/genética , Fuso Acromático/metabolismo , Transcriptoma , Adulto Jovem , Proteínas rho de Ligação ao GTP/genética , Proteínas rho de Ligação ao GTP/metabolismoRESUMO
Myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic stem cell (HSC) malignances characterized by peripheral cytopenias and predisposition to acute myeloid leukemia transformation. Several studies show that the MDS pathogenesis is a complex and heterogeneous process that involves multiple steps through a sequence of genetic lesions in the DNA which lead to functional changes in the cell and the emergence and subsequent evolution of pre-malignant clone. Double strand breaks (DSB) lesions are the most severe type of DNA damage in HSCs, which, if not properly repaired, might contribute to the development of chromosomal abnormalities, which in turn may lead to leukemia development. We assessed the mRNA expression levels of ATM, BRCA1, BRCA2, RAD51, XRCC5, XRCC6 and LIG4 genes in bone marrow samples of 47 MDS patients in order to evaluate the association with functional polymorphisms rs228593, rs4793191, rs9567623, rs1801320, rs3835, rs2267437 and rs1805388, respectively, and try to detect clinical associations. We found that the rs228593, rs2267437 and rs1805388 functional polymorphisms probably alter the level of expression of the ATM, XRCC6 and LIG4 genes, respectively, being important in the maintenance of genomic instability in MDS.
Assuntos
Reparo do DNA/genética , Leucemia Mieloide Aguda/genética , Síndromes Mielodisplásicas/genética , Polimorfismo Genético , Adulto , Proteínas Mutadas de Ataxia Telangiectasia/genética , Medula Óssea/metabolismo , Dano ao DNA , DNA Ligase Dependente de ATP/genética , Feminino , Instabilidade Genômica/genética , Células-Tronco Hematopoéticas/metabolismo , Humanos , Autoantígeno Ku/genética , Masculino , Pessoa de Meia-Idade , RNA Mensageiro/análiseRESUMO
OBJECTIVE: A relation between transfusional IOL (iron overload), HFE status and oxidative damage was evaluated. DESIGN, SETTING AND PARTICIPANTS: An observational cross-sectional study involving 87 healthy individuals and 78 patients with myelodysplastic syndromes (MDS) with and without IOL, seen at University Hospital of the Federal University of Ceará, Brazil, between May 2010 and September 2011. METHODS: IOL was defined using repeated measures of serum ferritin ≥1000â ng/mL. Variations in the HFE gene were investigated using PCR/restriction fragment length polymorphism (RFLP). The biomarkers of oxidative stress (plasmatic malonaldehyde (MDA), glutathione peroxidase (GPx) and superoxide dismutase (SOD)) were determined by spectrophotometry. RESULTS: The HFE gene variations were identified in 24 patients (30.77%) and 5 volunteers (5.74%). The H63D variant was observed in 35% and the C282Y variant as heterozygous in 5% of patients with MDS with IOL. One patient showed double heterozygous variant (C282Y/H63D) and serum ferritin of 11,649â ng/mL. In patients without IOL, the H63D variant was detected in 29.34%. Serum MDA levels were highest in patients with MDS with IOL, with a significant difference when compared with patients without IOL and healthy volunteers, pointing to the relationship between IOL and oxidative stress. The GPx and SOD were also significantly higher in these patients, indicating that lipid peroxidation increase was followed by an increase in antioxidant capacity. Higher ferritin levels were observed in patients with HFE gene variation. 95.7% of patients with MDS with the presence of HFE gene variations had received more of 20 transfusions. CONCLUSIONS: We observed a significant increase in MDA levels in patients with MDS and IOL, suggesting an increased lipid peroxidation in these patients. The accumulation of MDA alters the organisation of membrane phospholipids, contributing to the process of cellular degeneration. Results show that excess iron intensifies the process of cell damage through oxidative stress. TRIAL REGISTRATION NUMBER: Local Ethics Committee (licence 150/2009).