Dexamethasone and vorinostat cooperatively promote differentiation and apoptosis in Kasumi-1 leukemia cells through ubiquitination and degradation of AML1-ETO / 中华血液学杂志

<p><b>OBJECTIVE</b>To probe the effects of dexamethasone (DEX) combined with histone deacetylase (HDAC) inhibitor vorinostat on inhibiting proliferation and inducing differentiation and apoptosis in Kasumi-1 leukemia cells, and its possible mechanisms in order to provide a theoretical basis for the treatment of AML1-ETO positive AML.</p><p><b>METHODS</b>The cell survival, differentiation and apoptosis rates were tested by MTT or flow cytometry analysis after Kasumi-1 cells were treated by DMSO, DEX (20 nmol/L), vorinostat (1 μmol/L) or DEX (20 nmol/L) in combination with vorinostat (1 μmol/L). WB and IP-WB were performed to detect AML1-ETO and its ubiquitination.</p><p><b>RESULTS</b>Treatment with the combination of DEX and vorinostat for 48 h led to statistically significant differences of inhibited proliferation [(42.06±8.20)%], increased differentiation [(52.83±8.97)%] and apoptosis [(52.92±2.53)%] of Kasumi-1 cells when compared with vorinostat [(33.82±9.41)%, (43.93±9.04)% and (42.98±3.01)%, respectively], DEX [(17.30±3.49)%, (22.53±4.51)% and (19.57±2.17)%, respectively] or control [(6.96±0.39)%, (21.73±2.03)% and (6.96±0.39)%, respectively]. Also significant ubiquitination and decreased AML1-ETO protein in Kasumi-1 cells after the combination treatment over single agent or control were observed.</p><p><b>CONCLUSION</b>The results indicated that DEX and vorinostat could synergistically inhibit the Kasumi-1 cells proliferation, induce Kasumi-1 cells differentiation and apoptosis through ubiquitination and degradation of AML1-ETO.</p>

Role of AML1a in abnormal proliferation and differentiation of murine hematopoietic cells / 中国实验血液学杂志

This study was aimed to explore the role and mechanism of AML1a in abnormal hematopoiesis in mice. Plasmids pMSCV-FLAG-AML1a-IRES-YFP and pMSCV-IRES-YFP together with envelope-encoding plasmid pECO and packaging plasmid pGP were respectively transfected into 293T cells by using a method of calcium phosphate precipitation to produce retrovirus. Bone marrow mononuclear cells (BMMNC) from male C57BL/6J mice were transfected with the retroviral vector MSCV expressing FLAG-AML1a fusion protein and yellow fluorescent protein (YFP). The cells were cultured in M3434 semi-solid medium for colony formation assay and in M5300 fluid medium containing murine IL-3 (mIL-3), IL-6 (mIL-6) and SCF (mSCF) for long-term culture. The results showed that transfection of AML1a into BMMNC enhanced colony formation, colony size of the AML1a group was significantly larger than that of the control group, and the colonies were mainly composed of CFU-E and CFU-GEMM. In the long-term culture, AML1a-transfected BMMNC showed differentiation block, while the control cells were in a more mature stage. It is concluded that AML1a may block the normal hematopoiesis at the stage of primitive progenitors. At the same time, AML1a also enhances the proliferation activity of primitive progenitor cells.