Jingci Yang

Methylation and decreased expression of SHP-1 are related to disease progression in chronic myelogenous leukemia

Despite the unprecedented success of tyrosine kinase inhibitors (TKIs) in treating chronic myelogenous leukemia (CML), some patients nevertheless progress to advanced stages of the disease. Thus far, the biological basis leading to CML progression remains poorly understood. SH2-containing tyrosine phosphatase 1 (SHP-1) is reported to bind to p210BCR‑ABL1 and to function as a tumor suppressor. Furthermore, its substrates have been found to be essential for p210BCR-ABL1 leukemogenesis or CML progression. In the present study, we found that SHP-1 mRNA and protein levels were markedly decreased in patients in the accelerated and blastic phases of CML (AP-CML and BP-CML) compared to those in the chronic phase (CP-CML). In vitro, we demonstrated that overexpression of SHP-1 reduced p210BCR-ABL1 protein expression and activity in the K562 CML cell line and negatively regulated the AKT, MAPK, MYC and JAK2/STAT5 signaling pathways. Moreover, using a methylation-specific polymerase chain reaction (MSP) assay, abnormal methylation of the SHP-1 gene promoter region was found both in K562 cells and bone marrow (BM) or peripheral blood (PB) cells from AP-CML and BP-CML patients. In conclusion, our findings suggest that decreased expression levels of SHP-1 caused by aberrant promoter hypermethylation may play a key role in the progression of CML by dysregulating BCR-ABL1, AKT, MAPK, MYC and JAK2/STAT5 signaling.

Artesunate induces apoptosis through caspase-dependent and -independent mitochondrial pathways in human myelodysplastic syndrome SKM-1 cells

Artesunate (ART) is a semi-synthetic derivative of artemisinin extracted from Artemisia annua (sweet wormwood) that is conventionally used in anti-malarial drugs and more recently in medications that induce tumor cell apoptosis. Here, we investigated the effects and mechanistic pathways of ART in human myelodysplastic syndrome (MDS), a condition that commonly progresses to acute myeloid leukemia (AML). Human MDS SKM-1 cells, primary bone marrow (PBM) mononuclear cells from patients with refractory anemia with excess blasts (RAEB) or MDS-AML (MDS cell group), and PBM stromal cells from three patients without hematological diseases (non-MDS cell group) were cultured for 24, 48, or 72 h with or without various ART concentrations. CCK-8, western blot, JC-1 fluorescence, and Annexin-V/Propidium iodide (PI) labeling were used to assess cell proliferation, protein levels, mitochondrial membrane potentials (MMPs) and apoptosis, respectively. ART administration dose- and time-dependently inhibited SKM-1 proliferation. At 24, 48, and 72 h, ART IC₅₀ values were 89.92, 4.24, and 1.28 μmol/L, respectively. ART only significantly inhibited proliferation in the MDS cell group, but it has little impact on proliferation of non-MDS cells. ART decreased MMPs, and dose-dependently induced SKM-1 cell apoptosis, peaking at 82.9% when treated with 200 μmol/L ART for 24h. Caspase-3 and -9 activation, poly(ADP-ribose) polymerase cleavage, decreased Bcl-2/Bax ratio and apoptosis inducing factor nuclear localization were implicated in apoptosis. Our results indicate that ART effectively induces apoptosis in SKM-1 cells through both caspase-dependent and -independent mitochondrial pathways.

Effect of interaction of magnetic nanoparticles of Fe3O4 and artesunate on apoptosis of K562 cells

The present study evaluated whether the magnetic nanoparticles of Fe3O4 (MNPs-Fe3O4) could enhance the activity of artesunate (ART), and to explore its potential mechanisms. Cytotoxicity of the copolymer of ART with MNPs-Fe3O4 on K562 cells was detected by MTT assay and the apoptosis rate of K562 cells was measured by flow cytometry. Protein expression levels of bcl-2, bax, bcl-rambo, caspase-3, and survivin in K562 cells were measured by Western blot. After being incubated with the copolymer of ART with MNPs-Fe3O4 for 48 hours, the growth inhibition rate of K562 cells was significantly increased compared with that of K562 cells treated with ART alone (P < 0.05), and the apoptosis rate of K562 cells was increased significantly compared with that of K562 cells treated with ART alone, suggesting that MNPs-Fe3O4 can enhance the activity of ART. Interestingly, the copolymer-induced cell death was attenuated by caspase inhibitor Z-VAD-FMK. Our results also showed that treatment with the copolymer of MNPs-Fe3O4 and ART increased the expression of bcl-2, bax, bcl-rambo, and caspase-3 proteins, and decreased the expression of survivin protein in K562 cells compared with ART treatment alone. These results suggest that MNPs-Fe3O4 can enhance ART-induced apoptosis, which may be related to the upregulation of bcl-rambo and downregulation of survivin.

Effect of bone marrow mesenchymal stem cells from blastic phase chronic myelogenous leukemia on the growth and apoptosis of leukemia cells.

Chronic myelogenous leukemia (CML) has a typical progressive course with transition from a chronic phase to a terminal blast crisis phase. However, the mechanisms that lead to disease progression remain unclear. Bone marrow mesenchymal stem cells (BMMSCs) play important roles in maintaining the bone marrow microenvironment. In the present study, the biological characteristics of BMMSCs were determined including proliferation, apoptosis and secretion of cytokines during blastic phase CML (CML-Bp). The effect of BMMSCs in CML-Bp on K562 human CML cells and the CML-Bp original generation leukemia cells were also explored. Our results showed that CML-Bp BMMSCs protect tumor cells and increase their anti-apoptotic ability through regulating the expression of apoptosis-related proteins and activating the Wnt pathway.