iASPP is a member of the apoptosisstimulating proteins of p53 (ASPP) family and negatively regulates the apoptotic function of p53. In a hematopoietic system, overexpression of iASPP results in blockage of apoptosis, which may play a role in regulating hematopoietic stem cell (HSC) numbers. To address this, we first analyzed the expression of iASPP in patients with acute leukemia (AL) and found it was highly expressed in patients with AL. We further established a transgenic mouse model in which human iASPP was specifically expressed in hematopoietic cells. Overexpression of iASPP led to an increase in the proportion of long-term HSCs, short-term HSCs, multipotent progenitors, and common myeloid progenitor. HSCs from iASPP transgenic mice had an advantage in long-term reconstitution potential. In addition, the hematopoietic cells from iASPP transgenic mice exhibited a significantly lower level of p53 dependent apoptosis. After irradiation damage, hematopoietic cells of iASPP transgenic mice had a higher level of gamma-H2AX expression, which lasted for a longer time. These results provide the first evidence that the iASPP can increase HSC populations and reconstitution capacity. Interestingly, in response to cell damage stimuli, hematopoietic cells can be protected against apoptosis by iASPP; meanwhile these apoptosis-resistant cells would have more mutation accumulation, which might be the potential risk for malignant transformation.

Icaritin, a hydrolytic product of icaritin, is isolated from the traditional Chinese medicinal herb epimedium. Icaritin inhibits the proliferation of several tumor cell lines, but its effect on acute myeloid leukemia (AML) and underlying mechanisms remain to be identified. In the present study, we demonstrated that icaritin inhibits the proliferation of human AML cell lines NB4, HL60, and U937, in a dose- and time-dependent manner. Importantly, icaritin showed anti-leukemia activity on bone marrow mononuclear cells from 15 newly diagnosed AML patients. Flow cytometry analyses indicated that icaritin induces AML cells apoptosis. Icaritin induced activation of caspase-9, -3, -7 and the cleavage of PARP as measured by Western blotting. Icaritin downregulates p-ERK and p-AKT and inhibits the expression of c-myc. These results suggest that icaritin is a promising candidate drug for the treatment of AML. The underlying mechanisms of icaritin anti-AML activity are associated with inhibition of the MAPK/ERK and PI3K/AKT signals and downregulation of c-myc.

OBJECTIVE:To investigate the expression of PTEN (phosphatase and tension homology deletion on chromosome 10, PTEN) and its pseudogene PTENP1 in acute leukemia (AL) and correlation between them, and to explore the role of PTENP1 on the PTEN expression in AL cells.METHODS:PTEN and PTENP1 mRNA expression were evaluated in bone marrow (BM) samples from 138 newly diagnosed AL patients and 15 healthy controls by quantitative real-time RT-PCR (qRT-PCR). pCDH1-PTENP1 3'UTR-GFP lentivirus vectors were constructed. 293T cells were transfected by calcium phosphate precipitation to produce retrovirus. HL-60 cell line was infected with the retroviral vectors expressing pCDH1-GFP and pCDH1-PTENP1 3'UTR-GFP respectively. The flow cell sorter was used to sort the HL-60 with GFP positively expressed. The mRNA expression of PTEN and PTENP1 was detected by qRT-PCR, the expression of PTEN protein by western blot, and the impact of PTENP13'UTR on the proliferation of HL-60 cells by MTT assay.RESULTS:AML patients showed significantly lower PTEN and PTENP1 mRNA expression in BM compared to healthy controls. Correlation analysis showed that the expression of PTEN and PTENP1 mRNA were positively correlated (P < 0.05). The 108 cases of PTENP1(+) AML were classified according to the prognostic classification of 2011 NCCN Clinical Practice Guidelines in AML, there was no difference among different subgroups. HL-60 cell line was infected with the retroviral vectors expressing pCDH1-GFP (control group) and pCDH1-PTENP1 3'UTR-GFP respectively. Compared with the control group, PTENP1 mRNA level of HL-60 infected with the retroviral vectors expressing pCDH1-PTENP1 3'UTR-GFP increased significantly, and PTEN mRNA level also increased. While the PTEN protein level and the cell growth rate of the PTENP1 3'UTR group didn't change significantly.CONCLUSION:PTEN and PTENP1 mRNA expression level of BM cells from AL patients is significantly lower. There is a positive correlation between expression of PTEN and PTENP1 mRNA. PTENP1 may regulate the expression of PTEN in mRNA level.

The purpose of this study was to investigate the effect and molecular mechanism of metformin (Met) on biological characteristics of acute promyelocytic leukemia (APL) cell line NB4. NB4 cells were treated with various concentrations of Met for different time, MTT method was used to detect cell proliferation, the alteration of cell apoptosis was analyzed by flow cytometry, and the change of cell adhesion ability was examined by cell adhesion assay. NB4 cells were pretreated with U0126, a specific inhibitor for extracellular signal-regulated kinase (ERK) phosphorylation, ERK phosphorylation was assessed by Western blot analysis, apoptosis and cell adhesion ability were evaluated by flow cytometry and cell adhesion test respectively. The results showed that Met could inhibit the cell proliferation, induce the cell apoptosis and increase the ability of cell adhesion. The pretreatment of NB4 cells with 5 µmol/L U0126 could effectively inhibit the phosphorylation of ERK, and reduce cell apoptosis and adhesion induced by 5 mmol/L Met. It is concluded that Met can inhibit the proliferation and promote the apoptosis and adhesion of NB4 cells. MEK/ERK signaling pathway may be one of the molecular mechanisms of metformin on NB4 cells.

Background: Mutations at arginine 132 of isocitrate dehydrogenase 1/2 (IDH1/2) have recently been demonstrated to be recurrent gene alterations in acute myeloid leukemia (AML). Subsequently, this mutation was also found in a variety of other hematologic malignancies, including myelodysplastic syndromes, myeloproliferative diseases, and non-Hodgkin lymphoma. Only a few cases were so far identified in acute lymphoblastic leukemia (ALL). To study the IDH status in ALL patients, we analyzed 54 adult and 34 pediatric ALL samples' IDH1/2 gene. Results: Three adult cases and no pediatric case with an isocitrate dehydrogenase 1 (IDH1) mutation were identified. No isocitrate dehydrogenase 2 (IDH2) mutation was identified in the total of 88 samples. The frequency of the IDH1 mutation in adult ALL was 5.5%. Among the three IDH1-mutated patients, two had normal karyotype and expressed the myeloid lineage markers. All three patients with an IDH1 mutation relapsed or died within 6 months. Conclusions: The results suggested that the IDH1 R132 mutation might be a recurrent gene alteration in ALL; patients carrying the mutation have a trend to aberrantly express myeloid antigen and the mutation may imply a dismal outcome.

Recent studies have shown that metformin, a widely used antidiabetic agent, may reduce the risk of cancer development. In this study, we investigated the antitumoral effect of metformin on both acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) cells. Metformin induced apoptosis with partial differentiation in an APL cell line, NB4, but only displayed a proapoptotic effect on several non-M3 AML cell lines. Further analysis revealed that a strong synergistic effect existed between metformin and all-trans retinoic acid (ATRA) during APL cell maturation and that metformin induced the hyperphosphorylation of extracellular signal-regulated kinase (ERK) in APL cells. U0126, a specific MEK/ERK activation inhibitor, abrogated metformin-induced differentiation. Finally, we found that metformin induced the degradation of the oncoproteins PML-RARα and c-Myc and activated caspase-3. In conclusion, these results suggest that metformin treatment may contribute to the enhancement of ATRA-induced differentiation in APL, which may deepen the understanding of APL maturation and thus provide insight for new therapy strategies.

Objective To evaluate the efficacy and safety of imatinib in chronic myeloid leukemia (CML) patients and analyse the factors affecting the survival. Methods 135 CML patients receiving imatinib were evaluated for hematologic, cytogenetic, and molecular responses and adverse events. Results The median follow-up was 20 (range 3-67) months. The rate of cumulative complete hematological response (CHR), major cytogenetic response (MCyR), complete cytogenetic response( CCyR ) and complete molecular response (CMoR) in chronic phase CML patients were 97.9 %, 78.3 %, 72.2 % and 35.1%, respectively.These rates were significantly higher in chronic phase than in accelerated phase and blastic phase (P ＜0.001).The rate of CCyR in low-risk patients was significantly higher than high-risk patients (P =0.048). The estimated overall survival (OS) rate at 1, 3 and 5 year for chronic phase patients were (97.8±1.5) %, (95.2±2.4) % and (91.9±3.2) %, respectively. The estimated progression-free (PFS) survival rate at 1, 3 and 5 year were (92.6±2.7) %, (85.5±3.7) % and (81.3±4.3) %, respectively. The OS rate for accelerated phase patients at 6, 12 and 24 month were (93.8±6.1) %, (72.5±11.8) % and (64.5±12.9) %, the PFS rate were (92.3±7.4) %,(64.5±14.7) %, (53.7±15.7) %, respectively. The OS rate for blastic phase patients at 6, 12 and 19 month were (86.4±7.3) %, (45.4±11.4) %, (19.4±9.8) %, the PFS rate were (70.1±12.6) %, (37.6±15.6) % and (18.8±15.4) %, respectively. The OS and PFS of patients in chronic phase who achieved CCyR or CMoR were better than patients only achieved CHR (P ≤0.001). Multivariate analysis for survival of chronic phase patients indicated that imatinib resistance was the unfavourable factor for PFS (P =0.000, RR =46.744) and OS(P =0.007, RR =20.270). The non-hematological toxicity of imatinib was slight and tolerable, severe hematological toxicity was the major reason for dose reduction or drug discontinuation. Conclusion The efficacy of imatinib in chronic phase CML patients is significantly superior to which in accelerated phase and blastic phase; Achieving CCyR even CMoR is the most important thing for longer survival, iinatinib resistance is the major problem in the treatment with imatinib.

急性髓系白血病(AML)是一组在临床及遗传学上均具有异质性的疾病.在以细胞遗传学为基础的预后分组中,大约45%AML患者的核型是正常的,被列入中危组.但是,这组患者基于不同的分子学特征,其临床结局不尽相同.近期分子学研究显示,因获得性基因突变和基因表达改变的存在导致了该组患者预后的显著异质性,而且,其与白血病的发生机制有关,许多被证实的基因改变已经成为或即将成为特异性治疗靶点.本文就近年来证实的基因改变与白血病形成的关系及其预后影响作一综述。