Aims DNA methylation has its distribution influenced by DNA demethylation processes with the catalytic conversion of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC). Myelodysplastic syndrome (MDS) has been associated with epigenetic dysregulation of genes related to DNA repair system, chronic immune response and cell cycle.
Methods We evaluated the tissue DNA methylation/hydroxymethylation in bone marrow trephine biopsies of 73 patients with MDS, trying to correlate with the mRNA expression of 21 genes (POLH, POLL, REV3L, POLN, POLQ, POLI, POLK, IRF-1, IRF-2, IRF-3, IRF-4, IRF-5, IRF6, IRF-7, IRF-8,IRF-9, MAD2, CDC20, AURKA, AURKB and TPX2).
Results The M-score (5mC) was significantly higher in patients with chromosomal abnormalities than patients with normal karyotype (95% CI –27.127779 to –2.368020; p=0.022). We observed a higher 5mC/5hmC ratio in patients classified as high-risk subtypes compared with low-risk subtypes (95% CI –72.922115 to –1.855662; p=0.040) as well as patients with hypercellular bone marrow compared with patients with normocellular/hypocellular bone marrow (95% CI –69.189259 to –0.511828; p=0.047) and with the presence of dyserythropoiesis (95% CI 17.077703 to 51.331388; p=0.001). DNA pols with translesion activity are significantly influenced by methylation. As 5mC immunoexpression increases, the expressions of POLH (r=−0.816; r2 =0.665; p=0.000), POLQ (r=−0.790; r2=0.624; p=0.001), PCNA (r=−0.635; r2=0.403; p=0.020), POLK (r=−0.633; r2=0.400; p=0.036 and REV1 (r=−0.578; r2=0.334; p=0.049) decrease.
Conclusions Our results confirm that there is an imbalance in the DNA methylation in MDS, influencing the development of chromosomal abnormalities which may be associated with the low expression of DNA polymerases with translesion synthesis polymerases activity.
- myelodysplastic syndromes
- medical oncology
Data availability statement
All data relevant to the study are included in the article or uploaded as supplemental information.
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GMC and DPB are joint first authors.
Handling editor Mary Frances McMullin.
GMC and DPB contributed equally.
Contributors GMC, APNNA and RFP designed the study. GMC, DSdP and AMS constructed the tissue microarray and IHC. TMA scoring was done by GMC, DPB, FDRF and RFP. GMC and DPB performed all the statistical analyses under supervision from HLR-J and RFP. SMMM, CLMF and RTGdO contributed to the acquisition and interpretation of the data. The manuscript was written by DPB, GMC and RFP. All authors read and approved the final manuscript.
Funding This study has been supported by CAPES, CNPq (PRONEX) and FUNCAP.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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