Role of miRNA-4298/PADI4 axis in the apoptosis of leukemia cells induced by Nrf2 inhibitor 4f / 中华微生物学和免疫学杂志

Objective:To investigate the role of miRNA-4298/PADI4/p53 signal axis in mediating 4f-induced apoptosis of leukemia cells.Methods:The cell growth density was observed under inverted microscope and the proliferation of leukemia cells was detected by CCK-8 counting assay. The expression of PADI4 and P53 at mRNA level was detected by qRT-PCR. Cell cycle and apoptosis were measured with flow cytometry. The expression of PADI4, P53, Bcl-2, Bax, caspase-3 and caspase-9 at protein level was detected by Western blot. Differential miRNA and mRNA expression profiles was detected by next generation sequencing. Databases such as TargetScan were used to predict the potential upstream and downstream genes of PADI4. A luciferase reporter assay was used to detect the 3′UTR of PADI4 targeted by miRNA-4298. Cell transfection assay was used to detect the effect siRNA, PADI4 vector, miRNA mimics and miRNA inhibitor in interference and rescue.Results:Nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor 4f could inhibit the proliferation of THP-1, K562 and U937 cells, and induce the apoptosis of these leukemia cells. It downregulated the expression of PADI4 mainly through the binding activity of miRNA-4298 to miRNA sponges, which resulted in the proliferation inhibition and apoptosis of leukemia cells. The inhibited proliferation and apoptosis of leukemia cells by 4f were associated with the increase of P53 expression after the decrease of PADI4 expression. The PADI4-dependent upregulation of P53 led to the ratio inversion of downstream Bcl-2/Bax, which activated caspase-3 or caspase-9 to induce the apoptosis of leukemia cells.Conclusions:The apoptosis of leukemia cells induced by Nrf2 inhibitor 4f was mainly associated with the miRNA-4298/PADI4/p53 axis, suggesting that it might be a novel signaling pathway for targeted therapy.

Effects of arsenic trioxide on the methylation of TMS1 gene in K562 cells / 中华血液学杂志

<p><b>OBJECTIVE</b>To detect the methylation status of TMS1 gene and its demethylation by arsenic trioxide (As₂O₃) in K562 cells.</p><p><b>METHODS</b>K562 cells were treated with different concentrations of As₂O₃ for 48 hours. Methylation-specific PCR (MSP) was used to determine the methylation status of TMS1. RT-PCR and Western blot were used to detect the levels of TMS1 mRNA and protein. TMS1 associated apoptosis proteins Bcl-2/Bax were also analyzed by Western blot. Apoptosis were evaluated by flow cytometry using Annexin V/propium iodide (PI) double staining.</p><p><b>RESULTS</b>TMS1 gene was completely methylated in K562 cells and the levels of TMS1 mRNA and protein were low (0.01±0.01, 0.09±0.02), which could be reversed (mRNA: 0.72±0.04; protein: 1.30±0.06; P<0.01) by 2 μmol/L As2O3 via overt demethylation of TMS1 gene. Apoptosis in experiment group (12.24±1.06) was significantly higher than that in control group (2.05±0.16, P<0.05). In experiment group, the down-expression of antiapoptotic protein Bcl-2 and up-expression of pro-apoptotic protein Bax led to an obvious decline ratio of Bcl-2/Bax (0.56±0.12), as compared to the control group (1.94±0.14, P<0.01).</p><p><b>CONCLUSION</b>As₂O₃ could up-regulate TMS1 gene expression by reversing its hypermethylation and induced apoptosis by down-regulation of Bcl-2/Bax ratio in K562 cells.</p>

Induction of apoptosis by osthole in HL-60 cells and the molecular mechanism research / 国际肿瘤学杂志

Objective To detect the effect of osthole on proliferation and apoptosis of HL-60 cells and its molecular mechanism.Methods HL-60 cells proliferation was measured through the CCK8 assay method.The cell morphological changes were observed by Hoechst33342 staining after 8 h of drug effect.Induction of apoptosis was determined by flow cytometry and fluorescent microscopy.Expressions of Bcl-2 and Bax mRNA were evaluated by RT-PCR,and the expressions of cleaved caspase-3,caspase-8,caspase-9,Fas and FasL were evaluated by using western bolt assay.Results Osthole could inhibit the proliferation of HL-60 cells,the maximum inhibiting rate was (90.7 ±4.5)％,F =138.46,P =0.000; the apoptosis rate was 33.6％,F =27.75,P =0.006.The changes of apoptosis of cells and nucleus were shown in cell morphological observation.Osthole affected the decrease of the mRNA levels of Bcl-2 and the increase of the Bax mRNA levels via a dosedependent manner(F =210.12,P =0.000).Western blotting demonstrated that osthole could lead to the increase of the expression levels of cleaved caspase-3,caspase-8,caspase-9,Fas and FasL in the HL-60 cell line via a time-dependent manner.Conclusion Data suggests that osthole inhibits proliferation and induces apoptosis of HL-60 cells through mitochondria-dependent pathway and death-receptor pathway.

Prospective multicentre study of chemotherapeutic regimen containing pirarubicin on the treatment of relapsed or refractory acute myeloid leukemia in adults / 中华血液学杂志

<p><b>OBJECTIVE</b>To compare the efficacy and toxicity of the chemotherapeutic regimen containing pirarubicin and mitoxantrone on the treatment of relapsed or refractory acute myeloid leukemia (AML) in adults.</p><p><b>METHODS</b>In this open prospective multicentre study, we randomly assigned patients with relapsed or refractory AML to receive TAE regimen (pirarubicin+cytarabine+etoposide) versus MAE regimen (mitoxantrone + cytarabine + etoposide). The efficacy and toxicity were compared between the two groups.</p><p><b>RESULTS</b>56 patients entered this clinical trial. The complete remission (CR) rate on TAE arm was 79.0% versus 55.6% on MAE arm with the overall response (OR) rates of 86.8% versus 88.9%, respectively. The CR was higher on TAE arm (P=0.035) but with no significant difference between the two groups regarding the overall response (OR) rate. The regimens were well tolerated in both groups. Hematologic and non-hematologic toxicity were similar except relatively lower the mean dosage of G-CSF, red blood cells and platelets transfusion on TAE arm. No significant differences were seen between the two groups regarding the overall survival and relapse free survival rates.</p><p><b>CONCLUSION</b>TAE regimen might be an effective salvage therapy in patients with relapsed or refractory AML.</p>

Study on molecular regulation mechanism of VEGF in HL-60 cells after induced differentiation / 国际肿瘤学杂志

Objective To study the molecular regulation mechanism of VEGF in the model of ATRA induced differentiation in HL-60 cells,and to provide new targets for leukemia anti-angiogenic therapy.Methods The morphology was observed by Wright-Gimesa staining; HL-60 cells differentiation was detected by NBT reduction experiment.VEGF,STAT3,c-myc mRNAs were measured by reverse transcription-PCR;VEGF,STAT3 and c-myc proteins were determined by Western blot.Results The proliferation of HL-60 cells was inhibited obviously by ATRA(1 μmol/L) with the induction of differentiation,NBT positive rate was 82.59％ (t =-24.157,P ＜ 0.01) ; VEGF mRNA (t =7.339,P ＜ 0.05),STAT3 mRNA (t =3.667,P ＜0.05) and c-myc mRNA (t =6.858,P ＜ 0.05) were all down-regulated.VEGF protein (t =3.386,P ＜0.05),STAT3 protein(t =4.074,P ＜ 0.05) and c-myc protein (t =3.333,P ＜ 0.05) were all down-regulated.Conclusion VEGF expression level is reduced with the procession of differentiation of HL-60 cells,which may be largely correlated with the down regulation of STAT3 and c-myc.

Molecular mechanism of different sensitivities of PML-RARα to apoptosis induced by apoptosis inducing agents / 国际肿瘤学杂志

Objective To study the molecular mechanism of different sensitivities to apoptosis induced by low concentration of As2O3 in PML-RARα negative HL-60 cells and PML-RARα positive NB4 cells. Meth-ods NB4 and HL-60 cells were cultured with As2O3 for 1 to 4 days; cell proliferation were detected by MTT method; the apoptosis was detected by flow cytometry,Bcl-2,Bax and Fas mRNA were determined by RT-PCR. Results The proliferation of NB4 cells was inhibited obviously by As2O3(1.0 μmol/L)with the induction of apoptosis( P <0.05) ,which was accompanied by the down-regulation of Bcl-2 mRNA expression( P <0.05)and the ratio of Bcl-2/Bax(P <0.05), but there was no obvious variation of Bax and Fas expression( P >0.05). Inhibition of proliferation and apoptosis were not obvious in PML-RARα negative HL-60 cells induced by low concentration As2O3 ( P >0.05), and there was no obvious variation of Bcl-2, Bax, Fas mRNA expres-sion or Bcl/Bax ratio( P >0.05). Conclusion The ratio of Bcl-2/Bax is contributed to the different sensitiv-ities of PML-RARα negative HL-60 cells and positive NB4 cells induced by low concentration of As2O3.

Effect of arsenic trioxide on cytokine expression by acute promyelocytic leukemia cells / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To detect the expression of cytokines by acute promyelocytic leukemia (APL) cells before and after exposure to arsenic trioxide.</p><p><b>METHODS</b>Diagnoses were performed according to the FAB cytological classification criteria and cytogenetic criteria. Bone marrow or blood samples from APL patients were collected in heparinized tubes, then primary APL cells were separated by traditional Ficoll-Hypaque density centrifugation and purified after adherence to plastic surfaces. IL-1(beta), IL-6, IL-8, TNF alpha and G-CSF levels in the leukemia cell culture supernatants were detected by ELISA. At the same time, nitro blue tetrazolium (NBT) reduction test was used to detect the differentiation of APL cells.</p><p><b>RESULTS</b>After 96 hours exposure to arsenic trioxide, 10 - 6 mol/L in vitro or 10 mg/d in vivo, APL cells showed a significant increase of IL-1(beta) (P < 0.05) and G-CSF (P < 0.05) production, and a significant decrease of IL-6 (P < 0.05) and IL-8 (P < 0.05). However, there was no obvious variation of TNF alpha when compared with APL cells without exposure to arsenic trioxide. On the other hand, the proliferation ratio of APL cells in vitro was statistically correlated to the IL-1(beta) secretion ratio or G-CSF secretion ratio. The cell number ratio in patients with detectable IL-1(beta) or G-CSF was higher than that without detectable IL-1(beta) or G-CSF.</p><p><b>CONCLUSION</b>IL-1(beta) and G-CSF secretion may play an important role in the proliferation of APL cells after exposure to arsenic trioxide.</p>