Increase of microRNA-210, Decrease of Raptor Gene Expression and Alteration of Mammalian Target of Rapamycin Regulated Proteins following Mithramycin Treatment of Human Erythroid Cells

Abstract

Expression and regulation of microRNAs is an emerging issue in erythroid differentiation and globin gene expression in hemoglobin disorders. In the first part of this study microarray analysis was performed both in mithramycin-induced K562 cells and erythroid precursors from healthy subjects or β-thalassemia patients producing low or high levels of fetal hemoglobin. We demonstrated that: (a) microRNA-210 expression is higher in erythroid precursors from β-thalassemia patients with high production of fetal hemoglobin; (b) microRNA-210 increases as a consequence of mithramycin treatment of K562 cells and human erythroid progenitors both from healthy and β-thalassemia subjects; (c) this increase is associated with erythroid induction and elevated expression of γ-globin genes; (d) an anti-microRNA against microRNA-210 interferes with the mithramycin-induced changes of gene expression. In the second part of the study we have obtained convergent evidences suggesting raptor mRNA as a putative target of microRNA-210. Indeed, microRNA-210 binding sites of its 3’-UTR region were involved in expression and are targets of microRNA-210-mediated modulation in a luciferase reporter assays. Furthermore, (i) raptor mRNA and protein are down-regulated upon mithramycin-induction both in K562 cells and erythroid progenitors from healthy and β-thalassemia subjects. In addition, (ii) administration of anti-microRNA-210 to K562 cells decreased endogenous microRNA-210 and increased raptor mRNA and protein expression. Finally, (iii) treatment of K562 cells with premicroRNA-210 led to a decrease of raptor mRNA and protein. In conclusion, microRNA-210 and raptor are involved in mithramycin-mediated erythroid differentiation of K562 cells and participate to the fine-tuning and control of γ-globin gene expression in erythroid precursor cells.

Extracellular vesicles impose quiescence on residual hematopoietic stem cells in the leukemic niche

“…The data align well with the loss of known Raptor functions in the mTOR pathway, namely HSC activation, proliferation, and ribosome biogenesis [36,39,61,62]. Thus, our results fit a model of translational suppression by AML-EV miRNA [64] and find support in existing reports of miRNA suppression of protein synthesis [65,66] and Raptor deregulation in hematopoietic cells [67][68][69]. Our data were further consistent with observations of reversible HSC quiescence by others [16,23] and support the direct action of AML-EV miRNA on mTOR and protein synthesis suppression that is readily reversed in a naïve niche, i.e., following transplantation to a healthy host.…”

Does HbF induction by hydroxycarbamide work through MIR210 in sickle cell anaemia patients?

“…SCA patients showed a baseline 4·06 ± 1·089‐fold increase in HBG2 expression when compared to normal healthy controls, which further increased to 7·26 ± 1·29‐fold after HC therapy. HBG2 expression showed a strong positive correlation with expression of MIR210 (Spearman's correlation coefficient: 0·9295; P < 0·0001) (Fig B), similar to the observations reported by Bianchi et al ().…”

“…There are some molecular targets for MIR210 ( HDAC1, SIN3A, PLK1, PTBP3 [ROD1], E2F3, RPTOR [KIAA1303], FANK1, CYB5R2 ), which might be involved in HBG2 regulation and HbF induction. Bianchi et al () reported RPTOR, FANK1 and CYB5R2 as putative targets of MIR210 in erythroid cells in association with increased HbF production.…”

MicroRNA miR-93-5p regulates expression of IL-8 and VEGF in neuroblastoma SK-N-AS cells

“…As expected, one of the control levels is transcription-related to the interaction between IL-8 and VEGF promoters and different transcription factors, such as NF-κB, AP-1 and C-EBP/NF-IL-6 (7)(8)(9)(10)(11)(12). In addition, the expression of IL-8 and VEGF genes may be under the control of epigenetic mechanisms, such as those regulated by microRNAs in cancer, differentiation and inflammatory processes (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”