BackgroundmiRNA is a microRNA that negatively regulates protein expression at post-transcriptional or translational level. It is widely involved in the pathogenesis of tumors. miR-98 belongs to the let-7 family, and its overexpression can increase the sensitivity to drugs in solid cancer cells. However, the function of miR-98 in leukemia is still unclear. In this study, the effect of miR-98 on drug resistance and proliferation of leukemia cells were investigated.MethodsReal-time quantitative polymerase chain reaction analyzed the expression difference between miR-98 and E2F1 in leukemia cell lines, K562 and K562/A02. The downstream target gene of miR-98 was predicted by TargetScan; K562/A02 was transiently transfected with miR-98 mimic to upregulate the expression of miR-98; real-time quantitative polymerase chain reaction and Western blot were used to analyze the expression alterations of E2F1; cell counting kit-8 was used to evaluate the influence on K562/A02 proliferation and sensitivity to chemotherapeutic drugs; meanwhile, Western blot was used to analyze the expression of p21, Bax, matrix metalloproteinase 9 and ABCG2 proteins.ResultsE2F1 is one of the target genes of miR-98 proved by bioinformatics. Compared with the K562, the level of miRNA-98 expression was decreased in K562/A02, but the level of E2F1 expression was upregulated. Leukemia cell line K562/A02 was transfected with miR-98 mimic to upregulate the expression of miR-98, the expression of E2F1 was significantly decreased. After upregulating the miR-98 expression in K562/A02, the proliferation was weakened, and the sensitivity to chemotherapy was increased. Western blot showed that upregulated miR-98 expression increased the levels of p21 and BAX proteins in K562/A02 cells, and decreased the levels of matrix metalloprotease 9 and ABCG2 proteins, which were significantly different compared with those before miR-98 mimic transfection.ConclusionIn the leukemia drug-resistant cell line K562/A02, the targeted upregulated expression of miR-98 could decrease the proliferation of leukemia cells and improve the sensitivity to chemotherapeutics by inhibiting E2F1 expression. miR-98 might be a potential target for overcoming leukemia multidrug resistance.

The present study aimed to evaluate the therapeutic efficacy of dasatinib in a patient with nucleoporin 214-tyrosine protein kinase ABL1 proto-oncogene 1 (NUP214-ABL1)-positive early T-cell precursor-acute lymphoblastic leukemia (ETP-ALL), as well as that of selinexor and dasatinib for NUP214-ABL1-positive ETP-ALL in vitro. ETP leukemia is a form of T-cell ALL (T-ALL) with poor prognosis. The NUP214-ABL1 gene is present in ~6% of T-ALL cases, however the prevalence of NUP214-ABL1 gene expression in ETP-ALL in particular has not yet been verified. The current study reports the rare case of a 29-year-old man with ETP-ALL harboring the NUP214-ABL1 fusion gene, presenting with low-grade fever, stomachache and splenomegaly. The patient was successfully treated with dasatinib and vincristine, idarubicin, cyclophosphamide and prednisone (VICP) chemotherapy. The therapeutic efficacy of selinexor and dasatinib was also evaluated in vitro. Apoptosis was analyzed using Annexin V/propidium iodide staining and flow cytometry, and poly ADP-ribose polymerase (PARP) cleavage was detected using western blot analysis. The results demonstrated that the apoptotic cell population significantly increased following selinexor or dasatinib treatment compared with the control (P<0.05). Furthermore, combined selinexor and dasatinib treatment led to a significant increase in cell apoptosis compared with either treatment alone (P<0.05). The apoptosis results were confirmed by PARP cleavage. Thus, NUP214-ABL1 fusion gene expression should be tested in T-ALL, including ETP-ALL. Dasatinib used in combination with traditional induction chemotherapy may reverse the high induction failure of ETP-ALL with NUP214-ABL1 fusion gene; however, further prospective studies are required to confirm this. Therefore, selinexor with or without dasatinib may serve as a potential salvage therapy in the case of relapse and may be developed as a novel treatment for ETP-ALL with the NUP214-ABL1 fusion gene.

Abstract. Acute myeloid leukaemia (AML) is a type of heterogeneous disease derived from haematopoietic stem cells. Cytogenetic characterisation is essential for diagnosis and prognosis stratification. Here, we present the case of a 43-year-old female diagnosed with leukaemia, who demonstrated a rare chromosomal change of t(11; 12) (p15; q13) along with a positive FLT3-ITD mutation. The patient had a white blood cell count of 76.41x10 9 /l. Bone marrow morphology revealed that monoblasts accounted for 25.5% of cells, and premonocytes accounted for 49.0%. This patient strongly responded to idarubicin and Ara-c (cytarabine) chemotherapy, which rapidly eliminated the leukaemia cell clones. However, the proliferation rate of the leukaemia cells was high during the intermission of chemotherapy. Subsequently, following two courses of chemotherapy, full haematological remission could not be attained. AML patients with t(11; 12) (p15; q13) combined with FLT3-ITD mutations are expected to have a short life expectancy; however, early haematopoietic stem cell transplantation therapy may improve the treatment outcome for these patients.

Arsenic Trioxide (ATO) has shown remarkable efficacy for the treatment of multiple myeloma (MM). However, the mechanism by which ATO exerts its inhibitory effect on the proliferation of myeloma cells remains to be clarified. We study the inhibitory effect of ATO at various concentrations on the proliferation of the myeloma cell line RPMI 8226 and discussed the molecular mechanism of ATO on myeloma cell line. Our results proved that ATO had a significant dose-dependent and time-dependent inhibitory effect on the expressions of the Notch receptor (Notch1) and Notch ligand (Jag2). Data from the real-time PCR assay showed that the mRNA expression levels of the Jag2 gene and its downstream gene Hes1 were both significantly down-regulated after the myeloma cells were treated with ATO while the expression of the tumor suppressor gene PTEN was up-regulated. These results elucidated the molecular mechanism underlying the ATO mediated inhibition of myeloma cell proliferation. This is the first report on the anti-myeloma activity in myeloma cells through inhibition of the Notch signaling pathway.

DNA methyltransferases (including DNMT1, DNMT3A and DNMT3B), catalyze the transfer of methyl groups from S-adenosyl-l-methionine to cytosine position 5; this methylation in promoter regions silences gene expression. In addition, DNMT1 plays a critical role in the maintenance of genomic DNA methylation during DNA replication. In the present study, silencing of DNMT1 with siRNA was performed in RPMI-8226 human multiple myeloma (MM) cells, and the impact on gene methylation status and proliferation of the cells was analyzed. Upon DNMT1 downregulation, proliferation decreased significantly compared with that in the control, non-transfected cells. The expression of B-cell lymphoma 2 and nuclear factor κB proteins was also significantly reduced. Furthermore, nested methylation-specific polymerase chain reaction revealed that methylation of the tumor suppressor genes, suppressor of cytokine signaling 1 and p16, was significantly reduced upon DNMT1 knockdown. Our results suggest that DNMT1 silencing may be a promising strategy to consider during development of novel MM treatment strategies.