[The Effect of si-PKM2 on Proliferation and Apoptosis of Acute Leukemic Cells and Its Molecular Mechanism].

OBJECTIVE: To investigate the effect of glycolytic enzyme pyruvate kinase type 2 (PKM2) on the proliferation and apoptosis of human leukemia HL-60 cells. METHODS: si-PKM2 plasmid was transfected into HL-60 cells (set as si-PKM2 group), and blank vector transfected cells were set as control group (si-Ctl group). The expression levels of PKM2 mRNA and protein in si-Ctl group and si-PKM2 group were detected by RT-qPCR and Western blot. CCK-8 cell detection kit was used to detect the proliferation ability of the cells in the two groups. Flow cytometry was used to detect the changes of cell cycle and apoptosis. Western blot and RT-qPCR were used to detect the changes of p-Akt and p-mTOR protein levels in PI3K/Akt/mTOR signaling pathway and the changes of glycolysis-related mRNA levels of the cells in the two groups. The changes in glucose consumption and lactic acid production of the cells were assayed. Over expressed PKM2, HL-60 cells were treated with PI3K inhibitor LY294002 or galactose, the changes in cell proliferation ability, cell cycle and apoptosis, as well as changes in glucose consumption and lactic acid production were detected. RESULTS: Interfered by si-PKM2, mRNA and protein levels of PKM2 in si-PKM2 group significantly decreased, and proliferation ability of the cells was also reduced (P<0.05). After PKM2 knockdown, the cells were significantly blocked at G1 phase, and cell apoptosis was obviously induced (P<0.05). p-Akt and p-mTOR levels were lower in si-PKM2 group than those in si-Ctl group. The glucose consumption and lactic acid production significantly decreased in si-PKM2 cells. Overexpressed PKM2, HL-60 cells were treated with PI3K inhibitor LY294002. The glucose consumption and lactate acid production induced by overexpressed PKM2 were reduced. Overexpressed PKM2, HL-60 cells showed no significant changes in cell proliferation, cycle and apoptosis when cultured with galactose. CONCLUSION: PKM2 knockdown can inhibit the proliferation and induce apoptosis of HL-60 cells, and its molecular mechanism may be related to the PKM2-mediated PI3K/Akt/mTOR-glycolysis, which suggesting that PKM2 may serve as a molecular target for the prevention and treatment of leukemia.

The Long Noncoding RNA MEG3 and its Target miR-147 Regulate JAK/STAT Pathway in Advanced Chronic Myeloid Leukemia.

BACKGROUND: Long non-coding (lnc) RNAs plays an important role in chronic myeloid leukemia (CML). In this study, we aimed to uncover the mechanism of the lncRNA maternally expressed 3 (MEG3) and its target microRNA-147 (miR-147) in CML. METHODS: Sixty CML patients and 10 healthy donors were included in the study. The methylation of MEG3 and miR-147 promoter was determined by methylation-specific PCR. The relationship of MEG3 and miR-147 was explored by luciferase assay. The interactions of proteins were studied by RNA pull-down assay, RNA immunoprecipitation and co-immunoprecipitation. FINDINGS: Patients in accelerated phase CML (CML-AP) and blast phase CML (CML-BP) showed lower expressions of MEG3 and miR-147 and higher expressions of DNMT1, DNMT3B, MBD2, MECP2 and HDAC1 compared to the controls. These patients also showed a higher degree of methylation of MEG3 and miR-147 while there was a reduction after chidamide treatment. Furthermore, the overexpression of MEG3 and miR-147 inhibited cell proliferation both in vivo and in vitro, promoted apoptosis and decreased the expressions of DNMT1, DNMT3A, DNMT3B, MBD2, HDAC1 and MECP2. We also found MEG3 interacted with DNMT1, JAK2, STAT3, HDAC1, and TYK2, and JAK2 was bound to STAT3, STAT5 and MYC. More interestingly, JAK2 was bound to TYK2 by the bridge of MEG3. INTERPRETATION: LncRNA MEG3 and its target miR-147 may serve as a novel therapeutic target for CML blast crisis, and chidamide might have a potential clinical application in treating CML blast crisis.

Association between methylation of tumor suppressor gene SOCS1 and acute myeloid leukemia.

Suppressor of cytokine signaling­1 (SOCS1) is a widely recognized tumor suppressor gene. Silencing of SOCS1 expression as a result of promoter methylation is associated with occurrence and development of solid tumors such as liver, cervical and pancreatic cancer. However, the association between SOCS1 gene methylation and acute myeloid leukemia (AML) has not been well explored. In the present study, we examined whether gene expression and methylation status of SOCS1 was altered in AML, and whether this was related to disease occurrence and development. To assess this hypothesis, we analyzed SOCS1 in four groups of AML patients: i) Initial treatment group (IT); ii) relapsed/refractory group (RR); iii) remission group (RE); and iv) normal control group (NC). We also used leukemia cell lines U937 and THP­1 to study the underlying molecular mechanism of SOCS1 in AML, mainly the JAK2/STAT pathway. We used several techniques such as quantitative PCR (qPCR), methylation­specific PCR (MS­PCR), western blotting, flow cytometry and cell transfection techniques to analyze the expression and methylation status of SOCS1. We found that the SOCS1 gene methylation rate in the IT and RR groups was significantly higher than that in the RR and NC groups (48, 80 vs. 0 and 0%, respectively). Furthermore, mRNA and protein expression was significantly lower in the IT and RR groups when compared to the RE and NC groups. We also found that the JAK2/STAT signaling pathway was negatively affected by SOCS1. SOCS1 gene methylation caused gene silencing of SOCS1 which overcame the suppression of the downstream JAK2/STAT signaling pathway by SOCS1, and promoted the growth and proliferation of AML cells.

[Clinical Analysis of 12 cases of Systemic Lupus Erythematosus Associated with Thrombotic Thrombocytopenic Purpura].

OBJECTIVE: To investigate the clinical manifestations, treatment strategies and outcomes of 12 patients with systemic lupus erythematosus (SLE) associated with thrombotic thrombocytopenic purpura(TTP). METHODS: The clinical data from 12 cases of SLE associated with TTP admitted in the Second Hospital of Hebei Medical University from January 2002 to August 2015 were retrospectively analyzed. RESULTS: 12 cases of SLE associated with TTP included 11 females and 1 male, their median age was 34.5 years old, among them 5 cases of TTP were diagnosed during the treatment of SLE, 7 cases of TTP were comfirmed together with SLE on admission. The hemolytic anemia, thrombocytopenia and neurological deficits appeared in all the patients, the renal impairment was observed in 10 cases, the schistocytes of peripheral blood smears (>1%) were present in 9 cases, a severely reduction of ADAMTS 13 activity (<5%) with inhibitor-positive had been demonstrated in 5 cases, all of the 12 patients were treated with glucocorticoid, and 11 cases were treated in combination with other drug(10 cases combined with cytotoxics, 1 case with intravenous gamma globulin, 1 case with rituximab), plasma exchange were used in 10 cases, and 2 cases died, 2 cases without receiving plasma exchange all died, renal damage was observed in all the dead patients. CONCLUSION: Clinical manifestation and repeated examinations of peripheral blood smears are helpful for early diagnosis of SLE associated with TTP, the plasma exchange combined with glucocortcoids is an effective treatment method, the renal impairment may be a risk factor related with poor prognosis.

[BMMSC from blastic phase CML down-regulate leukemia cell apoptosis].

The purpose of this study was to investigate the effect of bone marrow mesenchymal stem cells (BMMSC) from patients with chronic myeloid leukemia (CML) in blastic phase (Bp) on K562 cells and the primary CML-Bp cells, and to explore its potential mechanisms. K562 cells and primary CML-Bp cells were co-cultured with BMMSC of different groups; the cell proliferation was detected by MTT method, the cell apoptosis rate and mitochondrial membrane potential were measured by flow cytometry, the expression levels of Caspase-8, Caspase-9, and activated Caspase-3 in cells were measured by Western blot. The results showed that the CML-Bp BMMSC could enhance the survival rate of K562 cells treated with adviamycin (ADM) and display protective effect on K562 cells and primary CML-Bp mononuctear cells, inhibited ADM-induced leukimia cell apoptosis (P < 0.05); as compared with CML-chronic phase (CML-Cp) BMMSC and normal BMMSC, the CML-Bp BMMSC showed the highest protective effect on leukemic cells, the mitochondrial membrane potential of co-cultured cells slightly droped (P < 0.05). In the CML-Bp BMMSC cultured with K562 cells, the expression level of caspase-3 was more down-regulated than that in K562 alone plus ADM group, while the expression of caspase-9 significantly increased (P < 0.05). It is concluded that the CML-Bp BMMSC down-regulates ADM-induced leukemia cell appoptosis, its mechanism may relate with the inhibition of mitochondrial membrane potential drop, the stabilization of unactive expression of caspase-9 and down-regulation of caspase-3 expression.