The IRF9-SIRT1-P53 axis is involved in the growth of human acute myeloid leukemia.

Acute myeloid leukemia (AML) is a highly heterogeneous disease, with biologically and prognostically different subtypes. Although a growing number of distinct AML subsets have been increasingly characterized, patient management has remained disappointingly uniform. The molecular mechanism underlying AML needs to be further investigated. Here we identify IRF9 as a negative regulator of human AML. We show that IRF9 mRNA and protein levels are down-regulated in human AML samples compared with samples from healthy donors. IRF9 knockdown promotes proliferation, colony formation and survival of OCI/AML-2 and OCI/AML-3 cells, whereas IRF9 overexpression obtains oppose results. Mechanism analysis shows that IRF9 binds SIRT1 promoter and represses SIRT1 expression in OCI/AML-2 and OCI/AML-3 cells. In AML samples, the expression of SIRT1 is up-regulated and negatively correlated with IRF9 level. IRF9 also increases the acetylation of p53, a deacetylation substrate of SIRT1, and promotes the expression of p53 target genes. Knockdown of p53 blocks the effects of IRF9 on cell survival and growth in vitro. These findings provide evidence that IRF9 serves as an important regulator in human AML by repressing SIRT1-p53 pathway and that IRF9 may be a potential target for AML treatment.

IRF3 is involved in human acute myeloid leukemia through regulating the expression of miR-155.

Acute myeloid leukemia (AML) is a serious disease of the hematopoietic system characterized by de-differentiation and uncontrolled proliferation of immature hematopoietic precursor cells in the bone marrow. However, the underlying mechanism of AML development remains largely unknown. Here in this study, we report the function of IRF3, a member of the interferon-regulatory factor (IRF) family, in human AML. We first show that IRF3 mRNA and protein levels are significantly up-regulated in human AML compared with healthy donors. IRF3 knockdown inhibits cellular proliferation and colony formation in OCI/AML-2 and OCI/AML-3 cells. In addition, IRF3 knockdown induces apoptosis of OCI/AML-2 and OCI/AML-3 cells, whereas IRF3 overexpression promotes cell survival. Further mechanism study shows that IRF3 is positively correlated with miR-155, which is considered as an oncogenic microRNA in AML. We show that IRF3 binds to the promoter of miR-155 and promotes the expression of miR-155 in OCI/AML-2 and OCI/AML-3 cells. In conclusion, our evidence show that IRF3 overexpression in AML promotes cell growth and survival, and miR-155 is involved, indicating that IRF3 may be a potential new biomarker and therapeutic target for AML.

[Proliferation and Apoptosis of Leukemia Cell Line K562 Treated with HSP90 Inhibitor 17-DMAG].

OBJECTIVE: To investigate the role of HSP90 in proliferation and apoptosis of leukemia cells K562 through detecting the effect of HSP90 inhibitors 17-[2-(Dimethylamino) ethyl] amino-17-desmethoxygeldanamycin(17-DMAG) on leukemia K562 cell lines. METHODS: The K562 cells were treated with HSP90 inhibitors 17-DMAG, the semi-quantitative PCR was used to detect HSP90 gene expression, the WST was used to detect the effect 17-DMAG on cell proliferation as well as Annexin V flow cytometry was used to detect the cell apoptosis. RESULTS: After 17-DMAG treated the K562 cells in different stage, the K562 cell growth was obviously inhibited with time dependent (48 h)(r=0.9918) and dose dependent(3.2 µmol/L) manners (r=0.9999) (P<0.01); after the K562 cells in different stage were treated with different concentrations of 17-DMAG, the K562 cells showed significant apoptosis and with dosage-dependent mauner (r=0.9903)(P<0.01); HSP90 mRNA expression decreased significantly after K562 cells were treated with different concentrations of 17-DMAG for 48 hours. 17-DAMG down-regulated the HSP90 mRNA expression in dosage-dependent mauner as well(r=0.9227) (P<0.01). CONCLUSION: HSP90 inhibitor 17-DMAG can inhibit the proliferation of K562 cells and induce their apoptosis. This study result provides laboratory basis for the treatment of leukemia patients with 17-DMAG.

[Effect of Heat Shock Protein 90 Inhibitor 17-DMAG on Proliferation and Apoptosis of Acute Lymphocytic Leukemia Cell Line Jurkat].

OBJECTIVE: To explore the effect of heat shock protein 90(HSP90) inhibitor 17-DMAG, an inhibitor specific for heat shock protein 90, on the proliferation and apoptosis of acute lymphocytic leukemia cell lines Jurkat. METHODS: Jurkat cells were collected, then were treated with 17-DMAG. The expression of HSP90 was examined by semi-quantitative RT-PCR analysis, the effect of 17-DMAG on cell proliferation were detected by using WST, and cell apoptosis were detected by using flow cytometry with Annexin V/PI double stenining. RESULTS: After Jurkat cells were treated with different concentrations of 17-DMAG for 48 hours, the HSP90 mRNA expression decreased significantly in dose dependent manner (r=0.9530, P<0.01). The IC50 was 3.17 mmol/L when the Jurkat cells were treated with 17-DMAG for 48 h; after treating Jurkat cell with 17-DMAG, the cell proliferation was inhibited(r=0.9903, P< 0.01), the cell apoptosis was increased in dose dependent manner (r=0.9876, P<0.01). CONCLUSION: 17-DMAG can inhibit the Jurkat cell proliferation and induce the Jurkat cell apoptosis.

Retraction: IRF9 inhibits human acute myeloid leukemia through the SIRT1-p53 signaling pathway.

doi: 10.1002/1873-3468.12600 The above article from FEBS Letters, published online on the 18th of February 2017 in Wiley Online Library (http://wileyonlinelibrary.com), has been withdrawn by agreement between the Journal Managing Editor Felix Wieland and John Wiley & Sons Ltd., on behalf of the Federation of European Biochemical Sciences. The withdrawal has been agreed following repeated attempts by the journal and publisher to contact the authors regarding the publication of their article. Since no responses from the authors have been received the journal is unable to complete publication.

[Expression of Aurora Family Genes in Acute Leukemia and Its Clinical Significance].

OBJECTIVE: To explore the mRNA expression of Aurora-A,B,C(AUR-A,B,C) in acute leukemia(AL) and their correlations with the clinical indications. METHODS: The mRNA expression levels of AUR-A,B,C in 73 cases of newly diagnosed AL (untreated group), 20 cases of AL with remission (remission group) and 14 healthy volunteers as control (healthy group) were detected by QRT-PCR, and the difference of expression levels in difference groups, their correlations with clinical indicators and the correlation between the AUR-A,B,C mRNA expression levels themselves were analyzed. RESULTS: The mRNA expression levels of AUR-A,B,C in untreated group were all higher than those in healthy group and remission group(P<0.01), but there was not significant difference between healthy group and remission group(P>0.05); the mRNA expressions of AUR-A,B,C in acute lymphoblastic leukemia(ALL) group were all significantly higher than that in AML group(P<0.01). The mRNA expression of AUR-A,B,C in high risk group was higher than that in low risk group(P<0.05), but there was no difference in mRNA expression of AUR-A,B,C between high risk group and middle risk group as well as between middle risk group and low risk group(P>0.05). The mRNA expression of AUR-A, B, C in CD34, CD71 and CD56 negative group was not statistically different from that in CD34,CD71 and CD56 positive group(P>0.05). In 73 cases of newly diagnosed AL, the mRNA expression levels of AUR-A, B significantly were positively correlated with lactate dehydrogenase(LDH) level and risk stratification (r=0.279, P=0.017; r=0.314, P=0.007 and r=0.277, P=0.018; r=0.349, P=0.002), while the mRNA expression levels of AUR-A, B were not significantly correlated with age, WBC count, blast ratio in bone marrow at initial diagnosis and remission or no-remission after 1 cours of chemotherapy; the mRNA expression level of AUR-C was significantly positively correlated with WBC count (r=0.263, P=0.025), and LDH level (r=0.348, P=0.003) at initial diagnosis and risk stratificantion(r=0.376, P=0.001), and negatively correlated with age (r=-0.241, P=0.040), and was not significantly correlated with blast ratio in bone marrow at initial diagnosis and remission or noremission after 1 course of chemotherapy. There were significant positive correlations in the mRNA expression between AUR-A and B (r=0.444, P=0.000), AUR-B and C (r=0.763, P=0.000) as well as AUR-A and C (r=0.616, P=0.000). CONCLUSION: Aur-A, B, C mRNA were highly expressed in patients with newly diagnosed AL, moreover the mRNA expression levels of Aur-A,B,C were positively correlated with each other, the high expression of Aur-A, B, C are associated with leukemia types, risk stratification, WBC count and LDH level at initial diagnosis, so they all maybe used as the prognostic markers and potential therapeutic targets.

High expression of heat shock protein 90 alpha and its significance in human acute leukemia cells.

This study investigated the expression of heat shock protein 90 alpha (Hsp90α) in acute leukemia cells. The expression of Hsp90α was investigated in leukemia cell lines and human bone marrow mononuclear cells derived from acute leukemia patients and from healthy individuals using polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. Compared with cells from healthy individuals, the expression of Hsp90α in the untreated patients was higher. Similarly high levels were observed in remission patients. Significantly higher expression levels were observed in all the tested cell lines, and in cells from refractory and relapsed patients. No obvious relationship was observed between the occurrence of graft versus host disease and the expression of Hsp90α. The untreated patients showing higher expression levels of Hsp90α had lower complete remission rates. During remission of untreated patients, the expression of Hsp90α decreased and reached the lowest level after transplantation, but the expression increased again before relapse. Hsp90α was highly expressed in leukemia cells. The expression level of Hsp90α was associated with leukemia prognosis. However, no obvious relationship was observed between the occurrence of graft versus host disease and the expression of Hsp90α.

[Effects of histone deacetylase inhibitor on the expression of angiogenesis related factors in Kasumi-1 leukemic cell line].

OBJECTIVE: To investigate the effects of two histone deacetylase (HDAC) inhibitors, valproic acid (VPA) and TSA, on the expression of vascular endothelial growth factor (VEGF) and its receptor KDR of the leukemia cell line Kasumi-1 cells, and to explore their potential mechanism in leukemia angiogenesis. METHOD: Kasumi-1 cells were treated with VPA and TSA at different concentrations for 3 days. The mRNA and protein expression levels of VEGF and KDR were determined by semi-quantitative RT-PCR and Western blot, and the bFGF mRNA by semi-quantitative RT-PCR. RESULTS: As compared with that of control groups, VPA at 3 mmol/L downregulated the VEGF mRNA expression level for VEGF(121) from 0.632 ± 0.014 to 0.034 ± 0.004 and for VEGF(165) from 0.526 ± 0.021 to 0.015 ± 0.001, for KDR mRNA from 0.258 ± 0.034 to 0.038 ± 0.000, and for bFGF mRNA from 0.228 ± 0.017 to 0.086 ± 0.015. TSA downregulated the VEGF mRNA and KDR mRNA at concentration of 100 nmol/L, but its effect on bFGF mRNA only at higher concentration. CONCLUSION: HDAC inhibitors might inhibit the leukemia angiogenesis by regulating the expression of VEGF and its recptor.

[Reversed effect of valproic acid on transcription inhibition of AML1-ETO fusion protein of kasumi-1 leukemic cell line].

This study was aimed to investigate the mechanism of histone deacetylase (HDAC) inhibitor, valproic acid (VPA), reversing transcription inhibition of AML1-ETO fusion protein in Kasumi-1 cell line. The mRNA expressions of AML1-ETO, AML1 and cyclin D2 were detected by semi-quantitation RT-PCR after treating kasumi-1 cells with VPA at different doses/and different time points. The results indicated that the mRNA expression of AML1-ETO showed no obvious change, when kasumi-1 cells were treated with VPA. Compared with control group, the expression level of AML1 mRNA significantly increased in a dose-dependent manner. Compared with control group, the expression level of cyclin D2 mRNA significantly decreased when kasumi-1 cells had been treated with 3 mmol/L VPA as well as kasumi-1 cells were treated with different concentrations of VPA for 3 days. In conclusion, VPA could remove transcription inhibition of AML1-ETO fusion protein, increase transcription of AML1 and down-regulate mRNA expression of AML1 target gene cyclin D2 through HDAC inhibiting activity.