Expressional changes of genes and miRNA in common megakaryocyte-erythroid progenitors from lower-risk myelodysplastic syndrome

Noncoding RNAs and their therapeutics in paclitaxel chemotherapy: Mechanisms of initiation, progression, and drug sensitivity

The identification of agents that can reverse drug resistance in cancer chemotherapy, and enhance the overall efficacy is of great interest. Paclitaxel (PTX) belongs to taxane family that exerts an antitumor effect by stabilizing microtubules and inhibiting cell cycle progression. However, PTX resistance often develops in tumors due to the overexpression of drug transporters and tumor-promoting pathways. Noncoding RNAs (ncRNAs) are modulators of many processes in cancer cells, such as apoptosis, migration, differentiation, and angiogenesis. In the present study, we summarize the effects of ncRNAs on PTX chemotherapy. MicroRNAs (miRNAs) can have opposite effects on PTX resistance (stimulation or inhibition) via influencing YES1, SK2, MRP1, and STAT3. Moreover, miRNAs modulate the growth and migration rates of tumor cells in regulating PTX efficacy. PIWI-interacting RNAs, small interfering RNAs, and short-hairpin RNAs are other members of ncRNAs regulating PTX sensitivity of cancer cells. Long noncoding RNAs (LncRNAs) are similar to miRNAs and can modulate PTX resistance/sensitivity by their influence on miRNAs and drug efflux transport. The cytotoxicity of PTX against tumor cells can also be affected by circular RNAs (circRNAs) and limitation is that oncogenic circRNAs have been emphasized and experiments should also focus on onco-suppressor circRNAs.

Expression, Regulation and Function of microRNA as Important Players in the Transition of MDS to Secondary AML and Their Cross Talk to RNA-Binding Proteins

Myelodysplastic syndromes (MDS), heterogeneous diseases of hematopoietic stem cells, exhibit a significant risk of progression to secondary acute myeloid leukemia (sAML) that are typically accompanied by MDS-related changes and therefore significantly differ to de novo acute myeloid leukemia (AML). Within these disorders, the spectrum of cytogenetic alterations and oncogenic mutations, the extent of a predisposing defective osteohematopoietic niche, and the irregularity of the tumor microenvironment is highly diverse. However, the exact underlying pathophysiological mechanisms resulting in hematopoietic failure in patients with MDS and sAML remain elusive. There is recent evidence that the post-transcriptional control of gene expression mediated by microRNAs (miRNAs), long noncoding RNAs, and/or RNA-binding proteins (RBPs) are key components in the pathogenic events of both diseases. In addition, an interplay between RBPs and miRNAs has been postulated in MDS and sAML. Although a plethora of miRNAs is aberrantly expressed in MDS and sAML, their expression pattern significantly depends on the cell type and on the molecular make-up of the sample, including chromosomal alterations and single nucleotide polymorphisms, which also reflects their role in disease progression and prediction. Decreased expression levels of miRNAs or RBPs preventing the maturation or inhibiting translation of genes involved in pathogenesis of both diseases were found. Therefore, this review will summarize the current knowledge regarding the heterogeneity of expression, function, and clinical relevance of miRNAs, its link to molecular abnormalities in MDS and sAML with specific focus on the interplay with RBPs, and the current treatment options. This information might improve the use of miRNAs and/or RBPs as prognostic markers and therapeutic targets for both malignancies.

Severe ineffective erythropoiesis discriminates prognosis in myelodysplastic syndromes: analysis based on 776 patients from a single centre

The underlying mechanisms and clinical significance of ineffective erythropoiesis in myelodysplastic syndromes (MDS) remain to be fully defined. We conducted the ex vivo erythroid differentiation of megakaryocytic-erythroid progenitors (MEPs) from MDS patients and discovered that patient-derived erythroblasts exhibit precocity and premature aging phenotypes, partially by inducing the pro-aging genes, like ERCC1. Absolute reticulocyte count (ARC) was chosen as a biomarker to evaluate the severity of ineffective erythropoiesis in 776 MDS patients. We found that patients with severe ineffective erythropoiesis displaying lower ARC (<20 × 10⁹/L), were more likely to harbor complex karyotypes and high-risk somatic mutations (p < 0.05). Lower ARCs are associated with shorter overall survival (OS) in univariate analysis (p < 0.001) and remain significant in multivariable analysis. Regardless of patients of lower-risk who received immunosuppressive therapy or higher-risk who received decitabine treatment, patients with lower ARC had shorter OS (p < 0.001). Whereas no difference in OS was found between patients receiving allo-hematopoietic stem cell transplantations (Allo-HSCT) (p = 0.525). Our study revealed that ineffective erythropoiesis in MDS may be partially caused by premature aging and apoptosis during erythroid differentiation. MDS patients with severe ineffective erythropoiesis have significant shorter OS treated with immunosuppressive or hypo-methylating agents, but may benefit from Allo-HSCT.