Xiang-Qin Weng

Eriocalyxin B induces apoptosis of t(8;21) leukemia cells through NF-|[kappa]|B and MAPK signaling pathways and triggers degradation of AML1-ETO oncoprotein in a caspase-3-dependent manner

Diterpenoids isolated from Labiatae family herbs have strong antitumor activities with low toxicity. In this study, Eriocalyxin B (EriB), a diterpenoid extracted from Isodon eriocalyx, was tested on human leukemia/lymphoma cells and murine leukemia models. Acute myeloid leukemia cell line Kasumi-1 was most sensitive to EriB. Significant apoptosis was observed, concomitant with Bcl-2/Bcl-XL downregulation, mitochondrial instability and caspase-3 activation. AML1-ETO oncoprotein was degraded in parallel to caspase-3 activation. EriB-mediated apoptosis was associated with NF-κB inactivation by preventing NF-κB nuclear translocation and inducing IκBα cleavage, and disturbance of MAPK pathway by downregulating ERK1/2 phosphorylation and activating AP-1. Without affecting normal hematopoietic progenitor cells proliferation, EriB was effective on primary t(8;21) leukemia blasts and caused AML1-ETO degradation. In murine t(8;21) leukemia models, EriB remarkably prolonged the survival time or decreased the xenograft tumor size. Together, EriB might be a potential treatment for t(8;21) leukemia by targeting AML1-ETO oncoprotein and activating apoptosis pathways.

Genomic Profiling of Adult and Pediatric B-cell Acute Lymphoblastic Leukemia.

Genomic landscapes of 92 adult and 111 pediatric patients with B-cell acute lymphoblastic leukemia (B-ALL) were investigated using next-generation sequencing and copy number alteration analysis. Recurrent gene mutations and fusions were tested in an additional 87 adult and 93 pediatric patients. Among the 29 newly identified in-frame gene fusions, those involving MEF2D and ZNF384 were clinically relevant and were demonstrated to perturb B-cell differentiation, with EP300-ZNF384 inducing leukemia in mice. Eight gene expression subgroups associated with characteristic genetic abnormalities were identified, including leukemia with MEF2D and ZNF384 fusions in two distinct clusters. In subgroup G4 which was characterized by ERG deletion, DUX4-IGH fusion was detected in most cases. This comprehensive dataset allowed us to compare the features of molecular pathogenesis between adult and pediatric B-ALL and to identify signatures possibly related to the inferior outcome of adults to that of children. We found that, besides the known discrepancies in frequencies of prognostic markers, adult patients had more cooperative mutations and greater enrichment for alterations of epigenetic modifiers and genes linked to B-cell development, suggesting difference in the target cells of transformation between adult and pediatric patients and may explain in part the disparity in their responses to treatment.

Functional features of RUNX1 mutants in acute transformation of chronic myeloid leukemia and their contribution to inducing murine full-blown leukemia

The BCR-ABL fusion protein generated by t(9;22)(q34;q11) in chronic myeloid leukemia (CML) plays an essential role in the pathogenesis of the myeloproliferative disorder status at the chronic phase of the disease, but progression from the chronic phase to blast crisis (BC) is believed to require additional mutations. To explore the underlying mechanisms for BC, which is characterized by a blockage of blood cell differentiation, we screened several genes crucial to hematopoiesis and identified 10 types of mutations in RUNX1 among 11 of 85 (12.9%) patients with acute transformation of CML. Most of the mutations occurred in the runt homology domain, including H78Q, W79C, R139G, D171G, R174Q, L71fs-ter94, and V91fs-ter94. Further studies indicated that RUNX1 mutants not only exhibited decreased transactivation activity but also had an inhibitory effect on the WT RUNX1. To investigate the leukemogenic effect of mutated RUNX1, H78Q and V91fs-ter94 were transduced into 32D cells or BCR-ABL-harboring murine cells, respectively. Consistent with the myeloblastic features of advanced CML patients with RUNX1 mutations, H78Q and V91fs-ter94 disturbed myeloid differentiation and induced a BC or accelerated phase-like phenotype in mice. These results suggest that RUNX1 abnormalities may promote acute myeloid leukemic transformation in a subset of CML patients.

Identification of fusion genes and characterization of transcriptome features in T-cell acute lymphoblastic leukemia

Significance To get more insights into the disease mechanism of T-cell acute lymphoblastic leukemia (T-ALL), particularly in an adult group, we addressed the genomic landscape in 130 patients, including 61 cases of adult T-ALL. A number of new genetic aberrations were identified using integrated transcriptome and genomic analysis. Distinct T-ALL subgroups were defined according to the interplay among different genetic abnormalities and gene transcription patterns. Characterization of genomic features of T-ALL is valuable not only for a better understanding of leukemogenesis, but also for patient stratification and tailored therapy. T-cell acute lymphoblastic leukemia (T-ALL) is a clonal malignancy of immature T cells. Recently, the next-generation sequencing approach has allowed systematic identification of molecular features in pediatric T-ALL. Here, by performing RNA-sequencing and other genomewide analysis, we investigated the genomic landscape in 61 adult and 69 pediatric T-ALL cases. Thirty-six distinct gene fusion transcripts were identified, with SET-NUP214 being highly related to adult cases. Among 18 previously unknown fusions, ZBTB16-ABL1, TRA-SALL2, and involvement of NKX2-1 were recurrent events. ZBTB16-ABL1 functioned as a leukemogenic driver and responded to the effect of tyrosine kinase inhibitors. Among 48 genes with mutation rates >3%, 6 were newly found in T-ALL. An aberrantly overexpressed short mRNA transcript of the SLC17A9 gene was revealed in most cases with overexpressed TAL1, which predicted a poor prognosis in the adult group. Up-regulation of HOXA, MEF2C, and LYL1 was often present in adult cases, while TAL1 overexpression was detected mainly in the pediatric group. Although most gene fusions were mutually exclusive, they coexisted with gene mutations. These genetic abnormalities were correlated with deregulated gene expression markers in three subgroups. This study may further enrich the current knowledge of T-ALL molecular pathogenesis.

RAF-1/MEK/ERK pathway regulates ATRA-induced differentiation in acute promyelocytic leukemia cells through C/EBPβ, C/EBPε and PU.1

MEK/ERK signal pathway was required for the differentiation of granulocytes, megakaryocytes and erythrocytes. Recently, MEK/ERK cascade was reported to be involved in all-trans retinoic acid (ATRA) induced differentiation in acute promyelocytic leukemia (APL) cells. However, the upstream and downstream molecules of MEK/ERK signal pathway in this cell model remains to be elucidated. In this work, we showed that RAF-1 was activated and the blockade of RAF-1 activation attenuated MEK/ERK activation as well as ATRA-induced differentiation. ATRA-enhanced protein levels of C/EBPβ, C/EBPε and PU.1, which were required for differentiation in APL cells, were suppressed by the specific inhibitor of MEK. However, MEK inhibition had no effect on the degradation of PML-RARα fusion protein or the restoration of PML nuclear bodies by ATRA treatment. Taken together, our study suggested that RAF-1/MEK/ERK cascade was involved in ATRA-induced differentiation in APL cells through enhancing the protein level of C/EBPβ, C/EBPε and PU.1.

Novel STAT5B-RARA fusion transcript in acute promyelocytic leukemia: identification and treatment response.

1Department of Hematology, Bei Zhan Hospital, Shanghai, China, 2State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui Jin Hospital Affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai, China, 3Jingjiang People’s Hospital, The Seventh Affiliated Hospital of Yangzhou University, Jingjiang, Jiangsu Province, China and 4Department of Hematology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China

Dasatinib synergizes with ATRA to trigger granulocytic differentiation in ATRA resistant acute promyelocytic leukemia cell lines via Lyn inhibition-mediated activation of RAF-1/MEK/ERK

All-trans retinoic acid (ATRA) resistance has been a critical problem in acute promyelocytic leukemia (APL) relapsed patients. In this study, dasatinib synergized with ATRA to trigger differentiation in ATRA-resistant APL cell lines. The combined treatment activated RAF-1, MEK and ERK as well as enhanced ATRA-promoted up-regulation of the protein level of PU.1, C/EBPβ and C/EBPε. U0126 (MEK specific inhibitor) and sorafenib tosylate (RAF-1 specific inhibitor) suppressed the combined treatment-induced differentiation, ERK phosphorylation and the up-regulation of C/EBPs and PU.1. Sorafenib tosylate also attenuated the MEK activity. However, the combined treatment did not enhance Ras activity and Ras inhibitor neither blocked MEK activation nor inhibited differentiation. Therefore, the combined treatment induced differentiation via Ras independent RAF-1/MEK/ERK. Earlier than RAF-1 activation, dasatinib suppressed Lyn activity, the predominant activated Src family kinase (SFK) and dephosphorylated RAF-1 at S259. Furthermore, SFK inhibitor, PP2 did suppress Lyn activity and mimicked the effect of dasatinib on ATRA-induced differentiation as well as decreased phosphorylation of RAF-1 at S259. Thus, it was suggested that Lyn inhibition might activate RAF-1 by the dephosphorylation of RAF at S259 and lead to differentiation. In conclusion, the combination of dasatinib and ATRA could overcome ATRA resistance through Lyn inhibition-mediated activation of RAF-1/MEK/ERK.

Kinase-associated gene mutation pattern and clinical relevance in 205 patients with core binding factor leukemias

Kinase-associated gene mutation pattern and clinical relevance in 205 patients with core binding factor leukemias

Clinical significance of day 5 peripheral blast clearance rate in the evaluation of early treatment response and prognosis of patients with acute myeloid leukemia

BackgroundMinimal residual disease detection in the bone marrow is usually performed in patients with acute myeloid leukemia undergoing one course of induction chemotherapy. To optimize the chemotherapy strategies, more practical and sensitive markers are needed to monitor the early treatment response during induction. For instance, peripheral blood (PB) blast clearance rate may be considered as such a monitoring marker.MethodsPB blasts were monitored through multiparameter flow cytometry (MFC). Absolute counts were determined before treatment (D0) and at specified time points of induction chemotherapy (D3, D5, D7, and D9). The cut-off value of D5 peripheral blast clearance rate (D5-PBCR) was defined through receiver operating characteristic (ROC) analysis. Prognostic effects were compared among different patient groups according to D5-PBCR cut-off value.ResultsD5-PBCR cut-off value was determined as 99.55%. Prognostic analysis showed that patients with D5-PBCR ≥99.55% more likely achieved complete remission (94.6% vs. 56.1%, P < 0.001) and maintained a relapse-free status than other patients (80.56% vs. 57.14%, P = 0.027). Survival analysis revealed that relapse-free survival (RFS) and overall survival (OS) were longer in patients with D5-PBCR ≥99.55% than in other patients (two-year OS: 71.0% vs. 38.7%, P = 0.011; two-year RFS: 69.4% vs. 30.7%, P = 0.026). In cytogenetic-molecular intermediate-risk group, a subgroup with worse outcome could be distinguished on the basis of D5-PBCR (<99.55%; OS: P = 0.033, RFS: P = 0.086).ConclusionsAn effective evaluation method of early treatment response was established by monitoring PB blasts through MFC. D5-PBCR cut-off value (99.55%) can be a reliable reference to predict treatment response and outcome in early stages of chemotherapy. The proposed marker may be used in induction regimen modification and help optimize cytogenetic-molecular prognostic risk stratification.

MiR21 sensitized B-lymphoma cells to ABT-199 via ICOS/ICOSL-mediated interaction of Treg cells with endothelial cells

BackgroundMicroRNAs (miRs) are involved in tumor progression by regulating tumor cells and tumor microenvironment. MiR21 is overexpressed in diffuse large B-cell lymphoma (DLBCL) and its biological impact on tumor microenvironment remains unclear.MethodsMiR21 was assessed by quantitative RT-PCR in patients with newly diagnosed DLBCL. The mechanism of action of miR21 on lymphoma progression and tumor angiogenesis was examined in vitro in B-lymphoma cell lines and in vivo in a murine xenograft model.ResultsSerum miR21 was significantly elevated in patients and associated with advanced disease stage, International Prognostic Index indicating intermediate-high and high-risk, and increased tumor angiogenesis. When co-cultured with immune cells and endothelial cells, miR21-overexpressing B-lymphoma cells were resistant to chemotherapeutic agents, but sensitive to Bcl-2 inhibitor ABT-199, irrespective of Bcl-2 expression on lymphoma cells. In both co-culture systems of Bcl-2positive and Bcl-2negative B-lymphoma cells, miR21 induced inducible co-stimulator (ICOS) expression on regulatory T (Treg) cells. Through crosstalking with Treg cells by ICOS ligand (ICOSL), endothelial cells were activated, resulting in stimulation of Bcl-2 expression and vessel formation. ABT-199 directly targeted Bcl-2 on endothelial cells, induced endothelial cell apoptosis and inhibited tumor angiogenesis. In a murine xenograft model established with subcutaneous injection of B-lymphoma cells, ABT-199 particularly retarded the growth of miR21-overexpressing tumors, consistent with the induction of endothelial cell apoptosis and inhibition of tumor angiogenesis.ConclusionsAs a serum oncogenic biomarker of B-cell lymphoma, miR21 indicated B-lymphoma cell sensitivity to ABT-199 via ICOS/ICOSL-mediated interaction of Treg cells with endothelial cells.