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Background: The ubiquitin-proteasome system (UPS) plays a crucial role in regulating the levels and functions of a large number of proteins in the cell, which are important for cancer cell growth and survival. The proteasome is highly activated in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), which is the most common malignancy in children. The attempt to inhibit proteasome as a therapeutic strategy has been successful for some malignancies. Materials and Methods: In this experimental study, human BCP-ALL cell lines NALM-6 and SUP-B15 were treated with carfilzomib with and without the chemotherapeutic agents. The XTT assay evaluated the viability of the cells. Cell cycle analysis and apoptosis assay were assessed by flow cytometry. RQ-PCR and western blotting evaluated the expression of pro-/anti-apoptotic signals. A drug combination study for synergistic or additive effects of carfilzomib with doxorubicin or dexamethasone was performed. Results: We observed that carfilzomib alone induced G2/M cell cycle arrest and caspase-dependent apoptosis in the human BCP-ALL cells (NALM-6 and SUP-B15). Gene and protein expression analysis indicated the upregulation of pro-apoptotic as well as downregulation of the cell survival and proliferative signals (Pvalue< 0.05). The synergy of carfilzomib with doxorubicin or dexamethasone was revealed in BCP-ALL cells. Conclusion: Our results indicated that proteasome inhibition induces p53-mediated apoptosis in BCP-ALL cells. Since carfilzomib has a synergistic effect with anti-leukemic agents doxorubicin and dexamethasone in BCP-ALL cells, this combined-modality approach might be befitting for patients who do not respond well to conventional chemotherapy. [ABSTRACT FROM AUTHOR]

Context: Philadelphia (Ph)-negative myeloproliferative neoplasms (MPNs), including essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) from a group of disorders characterized by dysregulated JAK-STAT functionality, abnormal hematopoiesis, as well as increased production of proliferative cytokines. In addition to JAK2V617Fmutation, additional gene alterations that are involved in epigenetic mechanisms, particularly de novo DNA methyltransferase 3A (DNMT3A), have been described in Ph-negative MPN biology. Aims: The aim of this study is to evaluate the H/C/S/P mutations in codon R882 of DNMT3A gene among patients with Ph-negative MPNs. Subjects and Methods: This study was conducted on 64 newly diagnosed patients with PV, ET, and PMF who referred to Shafa Hospital, Ahvaz, Iran. In the beginning, 5 mL whole blood was drawn from each patient, and the DNMT3A R882 codon mutations were investigated following the isolation of peripheral blood mononuclear cells by DNA amplification protocol using polymerase chain reaction and DNA sequencing techniques. Results: The R882H G > A mutation, which results in an amino acid substitution at position 882 of DNMT3A gene from arginine (R) to histidine (H), was observed in two patients (3.1%) with JAK2V617F positive PV and JAK2V617Fnegative PMFs. Conclusions: Based on the results, DNMT3A-R882 mutations occur at a low frequency in patients with Ph-negative MPNs. To the best of our knowledge, this is the first study to specifically estimate the prevalence of DNMT3A mutations among Ph-negative MPN patients living in the Middle East. It is recommended to investigate these mutants as a secondary defect along with common major complications in such patients. [ABSTRACT FROM AUTHOR]

Dysregulated expression of miRNAs can play a vital role in pathogenesis of leukemia. The shortened telomere length, and elevated telomerase activity in acute promyelocytic leukemia cells are mainly indicative of extensive proliferative activity. This study aimed to investigate the effect of overexpression of miR-138 on telomerase activity, and cell proliferation of acute promyelocytic leukemia NB4 cells. MiR-138 was overexpressed in NB4 cells using GFP hsa-miR-138-expressing lentiviruses. hTERT mRNA and protein expression levels were assessed by qRT-PCR and western blot analysis. For evaluation of apoptosis, annexin-V staining and activation of caspases were assessed using flow cytometry and western blot analysis, respectively. Our data demonstrate that overexpression of miR-138 attenuated the hTERT mRNA and protein expression levels. In addition, cell growth was inhibited, and malignant cells underwent caspase mediated-apoptosis in response to miR-138 overexpression. These findings suggest that loss of miR-138 expression may be associated with increased telomerase activity in NB4 cells. Therefore, strategies for up-regulation of miR-138 may result in inhibition of malignant cell growth, and provide a promising therapeutic approach for acute promyelocytic leukemia., Competing Interests: The authors declare no conflict of interest.