MicroRNA-126 attenuates cell apoptosis by targeting TRAF7 in acute myeloid leukemia cells.

Acute myeloid leukemia (AML) has a 5-year survival rate of only about 30%-40% due to the self-renewal and differentiation ability of leukemia stem-like cells (LSCs). To address the potential for novel therapeutic targets in LSCs, we investigated the roles of miRNA-126 and tumor necrosis factor receptor-associated factor 7 (TRAF7) in AML. We used qRT-PCR and Western blot to investigate the expression levels of miRNA-126 and TRAF7 in AML cell lines. Then, we uncovered the effect of miRNA-126 on AML cell proliferation and apoptosis by MTT assay and flow cytometric analysis, respectively. Furthermore, dual-luciferase assay and Western blot were used to determine the target of miRNA-126 in AML and the potential mechanism by which cell apoptosis is suppressed by miRNA-126. We found that miRNA-126 was highly expressed in all of the AML cell lines, and that inhibition of miRNA-126 significantly induced cell death through apoptosis. The suppression of apoptosis in AML with high expression of miRNA-126 was caused by down-regulating TRAF7, which blocked the c-FLIP pathway. The role of miRNA-126 in AML makes it a potential therapeutic target to improve clinical outcomes for patients with AML.

[Clinical Effect of Tyrosine Kinase Inhibitors in the Treatment of P230 Chronic Myeloid Leukemia].

OBJECTIVE: To observe the curative efficacy of tyrosine kinase inhibitors (TKIs) in the treatment of e19a2 transcript (P230) CML chronic phase (CML-CP) patients. METHODS: The clinical data of 11 P230 CML-CP patients were collected from July 2008 to December 2019. Blood routine examination, bone marrow cytology, chromosome, and BCR-ABL qualitative and quantitative tests were performed at initial diagnosis. After TKIs treatment, BCR-ABL (P230)/ABL in peripheral blood was regularly detected to evaluate molecular response by real-time quantitative PCR. RESULTS: There were 11 patients (7 males and 4 females) in chronic phase from 6 domestic hospitals enrolled, their median age was 46 years old (range from 19 to 56 years old). Among 4 patients treated with imatinib (400 mg, qd) firstly, 3 cases switched to nilotinib (400 mg, bid) and 1 case switched to dasatinib (100 mg, qd) due to failure to achieve best molecular response at the landmark time or mutation of ABL kinase. Then major molecular response (MMR) was obtained within 1 year. In addition, 5 patients were treated with nilotinib (300 mg, bid) and 2 patients with dasatinib (100 mg, qd) as first-line treatment, all of them got MMR within 6 months. CONCLUSION: For intolerance or resistance to imatinib, second-generation TKIs can enable P230 CML patients to achieve deeper molecular response, and MMR in a short time.

Minimal residual disease monitoring in chronic myeloid leukemia patients after allogeneic hematopoietic stem cell transplantation using interphase fluorescence in situ hybridization and real-time quantitative reverse transcription PCR.

BACKGROUND AND OBJECTIVE: Interphase fluorescence in situ hybridization (FISH) and real-time quantitative reverse transcription PCR (RQ-PCR) are the common methods for monitoring minimal residual disease (MRD) in chronic myeloid leukemia (CML) patients. This study was to assess the value of monitoring BCR-ABL fusion gene level in CML patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT) using FISH and RQ-PCR. METHODS: BCR-ABL fusion gene levels were detected in the bone marrow of 31 patients with CML before and 3-48 months after allo-HSCT using FISH and RQ-PCR. RESULTS: BCR-ABL positive cells detected by FISH were decreased 3-30 months after allo-HSCT and BCR-ABL/ABL mRNA was reduced by 2 logarithmic units in RQ-PCR (P < 0.05). While no BCR-ABL positive cell was detected by FISH 30 months after allo-HSCT, BCR-ABL/ABL mRNA was detected by RQ-PCR and declined by more than 3 logarithmic units, (P < 0.05). CONCLUSIONS: Dynamic monitoring of BCR-ABL gene on molecular level in CML patients after allo-HSCT is useful in the early prediction of susceptibility to recurrence in the patients and in designing intervention, and is thus helpful in improving the overall survival rate after transplantation.

[Effect of Regulating A20 Expression on NF-κB Expression and Biological Characteristics of Jurkat Cells].

OBJECTIVE: To explore the effect of regulating A20 expression on NF-κB and biological characteristics of Jurkat cells with glucocorticoid (GC) resistance. METHODS: CCRF CEM and Jurkat cells were treated with dexamethasone (DEX) at concentrations of 100、10、1、0.1、0.01 and 0.001 µmol/L, and cultured for 24、48 and 72 h. The proliferation inhibition rate of Jurkat cell was detected by CCK-8. A20 plasmid was constructed, A20-siRNA was designed and synthesized, and transfected into Jurkat cells by liposome. CCK-8 was used to detect the proliferation rates of Jurkat cells in different concentrations of DEX group, DEX combined with A20 plasmid group and A20-siRNA group. The mRNA expression level of NF-κB was detected by RT-qPCR, the protein expression level of NF-κB was detected by Western blot, and the apoptosis of Jurkat cells was examined by flow cytometry. RESULTS: The inhibitory effects of DEX at different concentrations on the growth of CCRF CEM cells were time-dependent (r=0.984, P＜0.05) and concentration-dependent (r=0.966, P＜0.05). At the point of 24 hour, the IC50 approached 1 µmol/L in CCRF CEM cells. Great large differences began to appear between 1 and 10 µmol/L, the proliferation rate of Jurkat cells treated with 1 µmol/L DEX did not show a significant change. Therefore, 1 µmol/L was selected as control group. The cell proliferation rate of A20 plasmid transfection combined with different concentrations of DEX group was lower than that of DEX group and A20-siRNA combined with DEX group. After transfection of A20 plasmid, the expression level of NF-κB was significantly lower than that of control group (P＜0.05), and the apoptotic rate was significantly higher than that of control group (P＜0.05). After transfection of Jurkat cells with A20-siRNA, the expression level of NF-κB was significantly higher than that of control group (P＜0.05). The apoptotic rate of cells in A20-siRNA group was not significantly changed (P＞0.05). CONCLUSION: Jurkat cells are resistant to DEX. A20 overexpression combined with DEX can increase sensitivity of Jurkat cells with GC resistance and decrease the proliferation rate of Jurkat cells, down-regulate the expression level of NF-κB and promote the apoptosis of Jurkat cells.

[Preliminary study of proteins related to blast crisis in chronic myeloid leukemia].

OBJECTIVE: To identify and compare the expression profiles of differential proteins between chronic phase and blast crisis in chronic myeloid leukemia (CML) by proteomic analysis, and screen the proteins related to blast crisis. METHODS: The total cellular proteins from the bone marrow cells at chronic phase (CP) and blast crisis (BC) in CML were separated by two-dimensional polyacrylamide gel electrophoresis (2-DE) and analyzed with ImageMaster 5.0 software to screen the differential protein spots. Differential protein spots were identified by mass spectrometry for peptide mass fingerprint in combination with database searching from SWISS-PROT. Then 3 protein spots were selected to verify at protein and mRNA levels by Western blot and semi-quantitative RT-PCR, separately. RESULTS: Comparing gel pages from CML-CP and CML-BC, the expression of 13 protein spots decreased and 25 protein spots increased significantly in CML-BC. Twenty differential protein spots were identified by mass spectrometry and 15 were successfully determined. The results of Western blotting were similar to those of 2-DE and showed a high expression of hnRNPK, annexin A1 and RhoA. Semi-quantitative RT-PCR analysis showed that there was no correlation between the protein expression changes and mRNA levels of hnRNPK, annexin A1 and RhoA. CONCLUSION: A group of proteins associated with blast crisis are obtained and the results may provide clues for further research to elucidate the role of these proteins in CML-BC carcinogenesis and to develop potential associated biomarkers.

[Effect of Decitabine on DKK1 Gene Demethylation in Leukemia Cells].

OBJECTIVE: To explore the effect of decitabine on Dickkopf-1 (DKK1) gene expression level and its downstream Wnt signaling pathway in acute myeloid leukemia (AML) cell line HL-60. METHODS: Flow cytometry and DNA ladder analysis were performed to detect apoptosis in HL-60 cell treated with different concentration of decitabine. Methylation-specific polymerase chain reaction (MS-PCR) was used to examine the methylation status of DKK1 gene. The expressions of mRNA and protein were determined by qRT-PCR and Western blot, respectively. RESULTS: Flow cytometric detection showed that after treating HL-60 cell line with decitabine of different concentrations for 48 h, the early apoptosis of HL-60 cells increased significantly as compared with control group (P < 0.05). DNA ladder analysis showed that the DNA ladder and demethylation of DKK1 gene appeared. RT-PCR and Western blot showed that the expressions of mRNA and protein increased. The protein expressions of ß-catenin and C-MYC decreased. CONCLUSION: The decitabine can promote the apoptosis of HL-60 cells throngh demethylation of DDK1 gene and inhibition of Wnt signalling pathway.

Correlation between deletion of the CDKN2 gene and tyrosine kinase inhibitor resistance in adult Philadelphia chromosome-positive acute lymphoblastic leukemia.

BACKGROUND: Frequency relapses are common in Philadelphia chromosome-positive (Ph-positive) acute lymphoblastic leukemia (ALL) following tyrosine kinase inhibitors (TKIs). CDKN2A/B is believed to contribute to this chemotherapy resistance. METHODS: To further investigate the association between CDKN2 status and TKI resistance, the prevalence of CDKN2 deletions and its correlation with a variety of clinical features was assessed in 135 Ph-positive ALL patients using interphase fluorescence in situ hybridization (I-FISH). RESULTS: Results showed that no difference occurred between patients with CDKN2 deletion (44/135) and wild-type patients in sex, age, and complete remission (CR) rate following induction chemotherapy combined with tyrosine kinase inhibitors (TKIs). However, CDKN2 deletion carriers demonstrated higher white blood cell (WBC) count, enhanced rates of hepatosplenomegaly (P = 0.006), and upregulation of CD20 expression (P = 0.001). Moreover, deletions of CDKN2 resulted in lower rates of complete molecular response (undetectable BCR/ABL), increased cumulative incidence of relapse, short overall survival (OS), and disease-free survival (DFS) time (P < 0.05) even though these patients received chemotherapy plus TKIs followed by allogenic hematopoietic stem cell transplantation (Allo-HSCT). In the case of 44 patients who presented with CDKN2 deletion, 18 patients were treated with dasatinib treatment, and another 26 patients were treated with imatinib therapy, and our study found that there were no differences associated with OS (P = 0.508) and DFS (P = 0.555) between the two groups. CONCLUSIONS: CDKN2 deletion is frequently acquired during Ph-positive ALL progression and serves as a poor prognostic marker of long-term outcome in Ph-positive ALL patients with CDKN2 deletion even after the second-generation tyrosine kinase inhibitor treatment.

[Research Progress on DKK1 Gene in Leukemia].

A number of studies have demonstrated that the methylation of Dickkopf-1 (DKK1) gene promoter is related with the occurrence and development of many neoplastic diseases. By means of binding with corresponding receptors, DKK1 blocks the transduction pathway of Wnt/ß-catenin/TCF and inhibits the proliferation and invasion of tumor cells, inducing apoptosis. Leukemia is a hyperplastic disease of hematopoietic stem cell malignant clone. Its pathogenesis has been confirmed to be closely related with the aberrant activation of Wnt signaling pathway. This pathway is associated with the self-renewal and proliferation of the hematopoietic stem cells, which can regulate growth, differentiation, migration of the cells, angiogenesis and embryonic development. Its expression is regulated by some suppressor genes like Dickkopf 1 (DKK1). Leukemia often accompanied by methylation modification of the DKK1 gene, so as to leads to silencing itself and activation of the Wnt signaling pathway, which cause the occurrence of leukemia. Some therapeutic methods on leukemia aiming at DKK1 gene have been reported, among which DKK1 gene was demethylated. The intensive study on the expression and function of DKK1 should be important for the early diagnosis, treatment and prognosis. This article reviews the current progress in this field.

High-dose homoharringtonine versus standard-dose daunorubicin is effective and safe as induction and post-induction chemotherapy for elderly patients with acute myeloid leukemia: a multicenter experience from China.

The purpose of the study was to compare the antitumor efficacy and safety profile of high-dose homoharringtonine as induction and post-induction therapy compared to either standard-dose homoharringtonine or daunorubicin in elderly patients with newly diagnosed acute myeloid leukemia. A total of 254 patients, age range 60-77 years received induction and post-induction therapy containing daunorubicin, standard-dose homoharringtonine, or high-dose homoharringtonine. After one course of induction therapy, the overall complete remission rate was similar between treatment arms (58.7%, P = .92). Among 161 patients with acute myeloid leukemia (non-M5 subtype), estimated median overall survival was 39, 29, and 37 months, respectively, in the daunorubicin, standard-dose homoharringtonine, and high-dose homoharringtonine treatment groups (P = .53). In the 93 patients with acute myeloid leukemia-M5 subtype, there was a significant difference in estimated median overall survival: 24, 24, and 52 months, respectively, in the daunorubicin, standard-dose homoharringtonine, and high-dose homoharringtonine treatment groups (P = .003). There was no significant difference in drug-related adverse events between treatment arms. High-dose homoharringtonine does not clearly increase the complete remission rate of elderly patients with acute myeloid leukemia. However, in the subset of elderly patients with acute monocytic leukemia, high-dose homoharringtonine as a first-line regimen prolonged overall survival with minimal toxicity.

[Research advance on molecular genetics of CML blast crisis].

Philadelphia (Ph) chromosome at (9; 22) reciprocal chromosomal translocation producing BCR-ABL fusion gene, emerges in almost all patients with chronic myeloid leukemia (CML). The protein product of BCR-ABL is a constitutively active tyrosine kinase that drives the abnormal proliferation of CML cells. Blast crisis (BC) is the terminal phase of CML, which is often associated with additional chromosomal and molecular secondary changes. Although the mechanisms responsible for transition of CML chronic phase (CP) into BC remain poorly understood, ample evidence suggests that it depends on synergy of BCR/ABL with other genes dysregulated during disease progression, and signaling pathways are abnormally activated by BCR/ABL. With the application of imatinib, a ABL-specific tyrosine kinase inhibitor, its remarkable therapeutic effects suggest that blast crisis transition will be postponed in most patients with CML. Rate of cumulative best response in CML-CP patients from the IRIS trial after 5 years are 98% for complete hematologic response, 92% for major cytogenetic response and 87% for complete cytogenetic response. However, a minority of CML-CP patients and most patients in progression either fail or respond suboptimally to imatinib. There are many distinct patterns of resistance, and ABL kinase mutations is a common finding associated with clinical resistance. Dasatinib and nilotinib can restore hematologic and cytogenetic remission in the majority of patients with primary failure or acquired resistance in chronic phase. This review illustrates the molecular mechanisms underlying transition to CML-BC, also addresses oneself to how and why imatinib resistance occurs.

[Detection of ABL kinase domain point mutations in chronic myeloid leukemia patients receiving imatinib treatment].

OBJECTIVE: To analyze the frequency and clinical significance of ABL tyrosine kinase point mutations in chronic myeloid leukemia (CML) patients receiving imatinib treatment. METHODS: Nested reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on 40 bone marrow samples from 23 patients to amplify the ABL kinase domain, followed by direct sequencing and sequence homologous analysis. RESULTS: In the 23 patients analyzed, the ABL domain point mutations was detected in 7 patients who presented with 5 types of nucleotide changes, namely T315I(n=3), Y253H, E255K, F317L and G321W. The incidence of mutations in chronic phase (CP), accelerated phase (AP) and blast phase (BP) was 25.00%, 40.00% and 30.00%, respectively. For 6 of the 7 patients with mutations who were resistant to imatinib before sequencing, the daily drug dose had been increased to 600-800 mg daily for poor response to 400 mg/day imatinib. During the follow-up for 3-6 months, only the patient with F317L achieved major cytogenetic response (MCR), and the patient with Y253H and 1 of the 3 with T315I progressed to BP. The newly diagnosed patient with G321W IN cp achieved a complete hematologic remission and had a significant decrease of the proportion of BCR-ABL-positive cells. CONCLUSIONS: ABL kinase point mutation is an important mechanism of imatinib resistance. The type of mutations is associated with the level of resistance to imatinib, and detection of ABL kinase point mutations by direct sequencing may help estimate the prognosis and plan for therapeutic strategy adjustment.