BACKGROUND: Myelodysplastic neoplasms (MDS) are heterogeneous hematopoietic disorders characterized by ineffective hematopoiesis and genome instability. Mobilization of transposable elements (TEs) is an important source of genome instability leading to oncogenesis, whereas small PIWI-interacting RNAs (piRNAs) act as cellular suppressors of TEs. However, the roles of TEs and piRNAs in MDS remain unclear. METHODS: In this study, we examined TE and piRNA expression through parallel RNA and small RNA sequencing of CD34+ hematopoietic stem cells from MDS patients. RESULTS: Comparative analysis of TE and piRNA expression between MDS and control samples revealed several significantly dysregulated molecules. However, significant differences were observed between lower-risk MDS (LR-MDS) and higher-risk MDS (HR-MDS) samples. In HR-MDS, we found an inverse correlation between decreased TE levels and increased piRNA expression and these TE and piRNA levels were significantly associated with patient outcomes. Importantly, the upregulation of PIWIL2, which encodes a key factor in the piRNA pathway, independently predicted poor prognosis in MDS patients, underscoring its potential as a valuable disease marker. Furthermore, pathway analysis of RNA sequencing data revealed that dysregulation of the TE‒piRNA axis is linked to the suppression of processes related to energy metabolism, the cell cycle, and the immune response, suggesting that these disruptions significantly affect cellular activity. CONCLUSIONS: Our findings demonstrate the parallel dysregulation of TEs and piRNAs in HR-MDS patients, highlighting their potential role in MDS progression and indicating that the PIWIL2 level is a promising molecular marker for prognosis.

• Klíčová slova
• Bioinformatics, Biomarkers, Myelodysplastic neoplasms, Next-generation sequencing, Transposable elements, piRNA,
• Publikační typ
• časopisecké články MeSH

Mutations in the splicing factor 3b subunit 1 (SF3B1) gene are frequent in myelodysplastic neoplasms (MDS). Because the splicing process is involved in the production of circular RNAs (circRNAs), we investigated the impact of SF3B1 mutations on circRNA processing. Using RNA sequencing, we measured circRNA expression in CD34+ bone marrow MDS cells. We defined circRNAs deregulated in a heterogeneous group of MDS patients and described increased circRNA formation in higher-risk MDS. We showed that the presence of SF3B1 mutations did not affect the global production of circRNAs; however, deregulation of specific circRNAs was observed. Particularly, we demonstrated that strong upregulation of circRNAs processed from the zinc finger E-box binding homeobox 1 (ZEB1) transcription factor; this upregulation was exclusive to SF3B1-mutated patients and was not observed in those with mutations in other splicing factors or other recurrently mutated genes, or with other clinical variables. Furthermore, we focused on the most upregulated ZEB1-circRNA, hsa_circ_0000228, and, by its knockdown, we demonstrated that its expression is related to mitochondrial activity. Using microRNA analyses, we proposed miR-1248 as a direct target of hsa_circ_0000228. To conclude, we demonstrated that mutated SF3B1 leads to deregulation of ZEB1-circRNAs, potentially contributing to the defects in mitochondrial metabolism observed in SF3B1-mutated MDS.

• Klíčová slova
• SF3B1, ZEB1, circular RNA, myelodysplastic neoplasms, splicing,
• MeSH
• akutní myeloidní leukemie * MeSH
• fosfoproteiny genetika   MeSH
• kruhová RNA genetika   MeSH
• lidé MeSH
• mutace genetika   MeSH
• myelodysplastické syndromy * genetika   MeSH
• sestřihové faktory genetika   MeSH
• transkripční faktory genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosfoproteiny MeSH
• kruhová RNA MeSH
• sestřihové faktory MeSH
• SF3B1 protein, human MeSH Prohlížeč
• transkripční faktory MeSH

BACKGROUND/AIM: Prediction of response to azacitidine (AZA) treatment is an important challenge in hematooncology. In addition to protein coding genes (PCGs), AZA efficiency is influenced by various noncoding RNAs (ncRNAs), including long ncRNAs (lncRNAs), circular RNAs (circRNAs), and transposable elements (TEs). MATERIALS AND METHODS: RNA sequencing was performed in patients with myelodysplastic syndromes or acute myeloid leukemia before AZA treatment to assess contribution of ncRNAs to AZA mechanisms and propose novel disease prediction biomarkers. RESULTS: Our analyses showed that lncRNAs had the strongest predictive potential. The combined set of the best predictors included 14 lncRNAs, and only four PCGs, one circRNA, and no TEs. Epigenetic regulation and recombinational repair were suggested as crucial for AZA response, and network modeling defined three deregulated lncRNAs (CTC-482H14.5, RP11-419K12.2, and RP11-736I24.4) associated with these processes. CONCLUSION: The expression of various ncRNAs can influence the effect of AZA and new ncRNA-based predictive biomarkers can be defined.

• Klíčová slova
• Noncoding RNAs, acute myeloid leukemia, azacytidine, circular RNAs, myelodysplastic syndrome, transposable elements,
• MeSH
• akutní myeloidní leukemie * farmakoterapie   genetika   MeSH
• azacytidin farmakologie   terapeutické užití   MeSH
• epigeneze genetická MeSH
• lidé MeSH
• myelodysplastické syndromy * farmakoterapie   genetika   MeSH
• RNA dlouhá nekódující * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• azacytidin MeSH
• RNA dlouhá nekódující * MeSH

Hypoplastic myelodysplastic syndrome (hMDS) and aplastic anemia (AA) are rare hematopoietic disorders characterized by pancytopenia with hypoplastic bone marrow (BM). hMDS and idiopathic AA share overlapping clinicopathological features, making a diagnosis very difficult. The differential diagnosis is mainly based on the presence of dysgranulopoiesis, dysmegakaryocytopoiesis, an increased percentage of blasts, and abnormal karyotype, all favouring the diagnosis of hMDS. An accurate diagnosis has important clinical implications, as the prognosis and treatment can be quite different for these diseases. Patients with hMDS have a greater risk of neoplastic progression, a shorter survival time and a lower response to immunosuppressive therapy compared with patients with AA. There is compelling evidence that these distinct clinical entities share a common pathophysiology based on the damage of hematopoietic stem and progenitor cells (HSPCs) by cytotoxic T cells. Expanded T cells overproduce proinflammatory cytokines (interferon‑γ and tumor necrosis factor‑α), resulting in decreased proliferation and increased apoptosis of HSPCs. The antigens that trigger this abnormal immune response are not known, but potential candidates have been suggested, including Wilms tumor protein 1 and human leukocyte antigen class I molecules. Our understanding of the molecular pathogenesis of these BM failure syndromes has been improved by next‑generation sequencing, which has enabled the identification of a large spectrum of mutations. It has also brought new challenges, such as the interpretation of variants of uncertain significance and clonal hematopoiesis of indeterminate potential. The present review discusses the main clinicopathological differences between hMDS and acquired AA, focuses on the molecular background and highlights the importance of molecular testing.

• Klíčová slova
• acquired aplastic anemia, dysregulated non‑coding RNAs, hypoplastic myelodysplastic syndrome, immunopathogenesis, mutational landscape,
• MeSH
• autoimunitní hemolytická anemie etiologie   genetika   MeSH
• imunita genetika   imunologie   MeSH
• lidé MeSH
• myelodysplasticko-myeloproliferativní nemoci etiologie   genetika   MeSH
• prognóza MeSH
• syndromy selhání kostní dřeně etiologie   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH