Enhanced Response of Acute Monocytic Leukemia Cells to Low-dose Cytarabine by 1,25-dihydroxyvitamin D3

Low-dose cytarabine combined with differentiating or DNA hypomethylating agents,such as vitamin D compounds,is a potential regimen to treat acute myeloid leukemia（AML） patients who are unfit for high-intensity chemotherapy.The present study aimed to determine which subset of AML would be most responsive to low-dose cytarabine with the differentiating agent 1,25-dihydroxyvitamin D3（1,25-D3）.Here,firstly,c Bio Portal database was used and we found out that vitamin D receptor（VDR） was highly expressed in acute monocytic leukemia（M5） and high VDR expression was associated with a poor survival of AML patients.Then,we confirmed that 1,25-D3 at clinical available concentration could induce more significant differentiation in acute monocytic leukemia cell lines（U937,MOLM-13,THP-1） and blasts from M5 patients than in non-monocytic cell lines（KG1 a and K562） and blasts from M2 patient.Finally,it was shown that the combination of 1,25-D3 and low-dose cytarabine further increased the differentiating rate,growth inhibition and G0/G1 arrest,while mild changes were found in the apoptosis in acute monocytic leukemia cell lines.Our study demonstrates that the enhanced response of acute monocytic leukemia cells to low-dose cytarabine by 1,25-D3 might indicate a novel therapeutic direction for patients with acute monocytic leukemia,especially for elderly and frail ones.

Interferon-γ Alters the Immune-related miRNA Expression of Microvesicles Derived from Mesenchymal Stem Cells

Increasing studies have demonstrated that interferon gamma（IFN-γ）,which serves as a critical inflammatory cytokine,is essential to induce the immunosuppressive effects of mesenchymal stem cells（MSCs）.However,the mechanisms underlying the enhanced immunosuppressive effects of IFN-γ-stimulated MSCs（γMSCs） are not fully understood.MSC-derived microvesicles（MSC-MVs） have been viewed as potential pivotal mediators of the immunosuppressive effects of MSCs.Moreover,micro RNAs（miR NAs） are important regulators of immunological processes and can be shuttled from cell to cell by MVs.The aim of our study was to analyze the the mi RNA expression signature of MVs derived from γMSCs（γMSC-MVs）,which may provide better understanding of the immunosuppressive property of their parent cells.Through mi RNA microarray and bioinformatics analysis,we found 62 significantly differentially expressed miR NAs（DEMs） in γMSC-MVs compared with MSC-MVs.And the potential target genes and signaling pathways regulated by DEMs were predicted and analyzed.Interestingly,many DEMs and predicted signaling pathways had been demonstrated to be involved in immunoregulation.Furthermore,the network between immunoregulation-related pathways and relevant DEMs was constructed.Collectively,our research on the mi RNA repertoires of γMSC-MVs not only provides new perspectives into the mechanisms underlying the enhanced immunosuppressive property of γMSCs,but also paves the way to clinical application of these potent organelles in the future.