Lin Fu

High expression of RUNX1 is associated with poorer outcomes in cytogenetically normal acute myeloid leukemia

Depending on its expression level, RUNX1 can act as a tumor promoter or suppressor in hematological malignancies. The clinical impact of RUNX1 expression in cytogenetically normal acute myeloid leukemia (CN-AML) remained unknown, however. We evaluated the prognostic significance of RUNX1 expression using several public microarray datasets. In the testing group (n = 157), high RUNX1 expression (RUNX1high) was associated with poorer overall survival (OS; P = 0.0025) and event-free survival (EFS; P = 0.0025) than low RUNX1 expression (RUNX1low). In addition, the prognostic significance of RUNX1 was confirmed using European Leukemia Net (ELN) genetic categories and multivariable analysis, which was further validated using a second independent CN-AML cohort (n = 162, OS; P = 0.03953). To better understand the mechanisms of RUNX1, we investigated genome-wide gene/microRNAs expression signatures and cell signaling pathways associated with RUNX1 expression status. Several known oncogenes/oncogenic microRNAs and cell signaling pathways were all up-regulated, while some anti-oncogenes and molecules of immune activation were down-regulated in RUNX1high CN-AML patients. These findings suggest RUNX1high is a prognostic biomarker of unfavorable outcome in CN-AML, which is supported by the distinctive gene/microRNA signatures and cell signaling pathways.

Overexpression of ATP1B1 predicts an adverse prognosis in cytogenetically normal acute myeloid leukemia

ATP1B1 encodes the Na,K-ATPase β subunit, a key regulator of the Na+ and K+ electrochemical gradients across the plasma membrane and an essential regulator of cellular activity. We used several microarray datasets to test the prognostic efficacy of ATP1B1 expression in cytogenetically normal acute myeloid leukemia (CN-AML). Within the primary cohort (n = 157), high ATP1B1 expression (ATP1B1high) was associated with shorter overall survival (OS) and event-free survival (EFS) (P = 0.0068, P = 0.0039, respectively). Similar results were also obtained in the European Leukemia Net (ELN) Intermediate-I genetic category (OS: P = 0.0035, EFS: P = 0.0007). Multivariable analyses confirmed ATP1B1high is an independent predictor of shorter OS (P = 0.042) and EFS (P = 0.035). Analysis of another CN-AML cohort confirmed that ATP1B1high is associated with shorter OS (P = 0.0046, n = 162). In addition, up-regulation of oncogenes/onco-microRNAs such as MYCN, CCND2, CDK6, KIT and miR-155, among others, was associated with ATP1B1high, which may be indicative of ATP1B1s leukemogenicity. Our results may improve risk stratification and indicate new therapeutic targets for CN-AML.

A minicircuitry of microRNA-9-1 and RUNX1-RUNX1T1 contributes to leukemogenesis in t(8;21) acute myeloid leukemia

MicroRNA‐9‐1(miR‐9‐1) plays an important role in the mechanism that regulates the lineage fate of differentiating hematopoietic cells. Recent studies have shown that miR‐9‐1 is downregulated in t (8; 21) AML. However, the pathogenic mechanisms underlying miR‐9‐1 downregulation and the RUNX1‐RUNX1T1 fusion protein, generated from the translocation of t (8; 21) in AML, remain unclear. RUNX1‐RUNX1T1 can induce leukemogenesis through resides in and functions as a stable RUNX1‐RUNX1T1‐containing transcription factor complex. In this study, we demonstrate that miR‐9‐1 expression increases significantly after the treatment of RUNX1‐RUNX1T1 (+) AML cell lines with decitabine (a DNMT inhibitor) and trichostatin A (an HDAC inhibitor). In addition, we show that RUNX1‐RUNX1T1 triggers the heterochromatic silencing of miR‐9‐1 by binding to RUNX1‐binding sites in the promoter region of miR‐9‐1 and recruiting chromatin‐remodeling enzymes, DNMTs, and HDACs, contributing to hypermethylation of miR‐9‐1 in t (8; 21) AML. Furthermore, because RUNX1, RUNX1T1, and RUNX1‐RUNX1T1 are all regulated by miR‐9‐1, the silencing of miR‐9‐1 enhances the oncogenic activity of these genes. Besides, overexpression of miR‐9‐1 induces differentiation and inhibits proliferation in t (8; 21) AML cell lines. In conclusion, our results indicate a feedback circuitry involving miR‐9‐1 and RUNX1‐RUNX1T1, contributing to leukemogenesis in RUNX1‐RUNX1T1 (+) AML cell lines.

NLRP3 regulates platelet integrin αIIbβ3 outside-in signaling, hemostasis and arterial thrombosis

In addition to their hemostatic function, platelets play an important role in regulating the inflammatory response. The platelet NLRP3 inflammasome not only promotes interleukin-1β secretion, but was also found to be upregulated during platelet activation and thrombus formation in vitro. However, the role of NLRP3 in platelet function and thrombus formation in vivo remains unclear. In this study, we aimed to investigate the role of NLRP3 in platelet integrin αIIbβ3 signaling transduction. Using NLRP3−/− mice, we showed that NLRP3-deficient platelets do not have significant differences in expression of the platelet-specific adhesive receptors αIIbβ3 integrin, GPIba or GPVI; however, NLRP3−/− platelets transfused into wild-type mice resulted in prolonged tail-bleeding time and delayed arterial thrombus formation, as well as exhibiting impaired spreading on immobilized fibrinogen and defective clot retraction, concomitant with decreased phosphorylation of c-Src, Syk and PLCγ2 in response to thrombin stimulation. Interestingly, addition of exogenous recombinant interleukin-1β reversed the defect in NLRP3−/− platelet spreading and clot retraction, and restored thrombin-induced phosphorylation of c-Src/Syk/PLCγ2, whereas an anti-interleukin-1β antibody blocked spreading and clot retraction mediated by wild-type platelets. Using the direct NLRP3 inhibitor, CY-09, we demonstrated significantly reduced human platelet aggregation in response to threshold concentrations of collagen and ADP, as well as impaired clot retraction in CY-09-treated human platelets, supporting a role for NLRP3 also in regulating human platelet αIIbβ3 outside-in signaling. This study identifies a novel role for NLRP3 and interleukin-1β in platelet function, and provides a new potential link between thrombosis and inflammation, suggesting that therapies targeting NLRP3 or interleukin-1β might be beneficial for treating inflammation-associated thrombosis.

High expression of MAP7 predicts adverse prognosis in young patients with cytogenetically normal acute myeloid leukemia.

Microtubule-associated protein 7 (MAP7) plays an important role in cancer cells. In this study, we identified the prognostic significance of MAP7 expression in cytogenetically normal acute myeloid leukemia (CN-AML) patients (aged <60 years) based on several microarray datasets. In the first group (n = 129), high MAP7 expression (MAP7high) was associated with adverse overall survival (OS; P = 0.0441) and event-free survival (EFS; P = 0.0114) compared with low MAP7 expression (MAP7low). In addition, the prognostic significance of MAP7 was confirmed by European Leukemia Net (ELN) intermediate-I genetic categories and multivariable analysis. In the second independent group of CN-AML patients (aged <60 years), MAP7high was also associated with adverse OS (n = 88, OS; P = 0.00811). To understand the inherent mechanisms of MAP7’s prognosis, we investigated genome-wide gene/microRNA expression signatures associated with MAP7 expression. Several known oncogenic genes/microRNAs and anti-oncogenic genes/microRNAs were disordered in MAP7high CN-AML patients. In conclusion, MAP7high is an adverse prognostic biomarker for CN-AML, which may be attributed to the distinctive genome-wide gene/microRNA expression and related cell signaling pathways.

Roles of germline JAK2 activation mutation JAK2 V625F in the pathology of myeloproliferative neoplasms

Janus tyrosine kinase 2 (JAK2) mediates downstream signaling of cytokine receptors in all hematological lineages, constitutively active somatic JAK2 mutations play key roles in the pathology of myeloproliferative neoplasms (MPNs). Recently, germline JAK2 mutations are also associated with triple-negative MPNs. A novel germline mutation JAK2 V625F is reported to be involved in a subset of MPNs patients. However, the pathogenesis of this mutation caused MPN is still unclear. In this study, the homology models of JAK2 V625F showed that the newly formed interaction between F625 and Y613 disrupted the JAK2 JH1-JH2 domain interactions was responsible for its activation, when F625 and Y613 interaction was disrupted, its activity significantly decreased. While, when this interaction was repaired whether by forming hydrogen bond or salt bond, it would cause JAK2 activation. Biochemical studies also demonstrated that JAK2 V625F mutation led to JAK2-STAT5 pathway activation and promoted the proliferation of BaF3 cells. Thus, our results herein provide clues to understand the mechanism JAK2 V625F mutation caused MPNs and give information for the development of JAK2 mutation specific inhibitors.

Prognostic significance of microRNA-99a in acute myeloid leukemia patients undergoing allogeneic hematopoietic stem cell transplantation

Overexpression of microRNA-99a (miR-99a) have been associated with adverse prognosis in acute myeloid leukemia (AML). Nevertheless, whether it also predicts poor outcome in post-allogeneic hematopoietic stem cell transplantation (allo-HSCT) AML patients remains unclear. To further elucidate the prognostic value of miR-99a, 74 AML patients with miR-99a expression report who underwent allo-HSCT from The Cancer Genome Atlas database were identified and grouped into either miR-99ahigh or miR-99alow based on their miR-99a expression levels relative to the median. Two groups had similar clinical and molecular characteristics except that miR-99ahigh group had fewer patients of the French-American-British M4 subtype (P = 0.018) and more frequent CEBPA mutations (P = 0.005). Univariate analysis indicated that high miR-99a expression was unfavorable for both event-free survival (EFS) and overall survival (OS; P = 0.029; P = 0.012, respectively). Multivariate analysis suggested that high miR-99a expression was an independent risk factor for both EFS and OS in AML patients who underwent allo-HSCT [hazard ratio (HR) 1.909, 95% confidence interval (CI) 1.043–3.494, P = 0.036 and HR 2.179, 95% CI 1.192–3.982, P = 0.011, respectively]. Our results further proved that high miR-99a expression could predict worse outcome in AML patients, even in those who underwent intensive post-remission therapy such as allo-HCST.

BAALC and ERG expression levels at diagnosis have no prognosis impact on acute myeloid leukemia patients undergoing allogeneic hematopoietic stem cell transplantation

Brain and acute leukemia, cytoplasmic (BAALC) and ETS-related gene (ERG) expression levels are independent prognostic factors for acute myeloid leukemia (AML); however, their prognostic impacts on AML patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT) require further investigation. We studied 71 de novo AML patients treated with allo-HSCT and defined low and high expressers according to the median expression levels of BAALC and ERG at diagnosis respectively. High BAALC expression was associated with wild-type NPM1 (P = 0.000) and RUNX1 mutations (P = 0.027). High ERG expression was associated with FLT3-ITD absence (P = 0.003) and wild-type NPM1 (P = 0.001). BAALC and ERG expression levels were significantly correlated with each other (P = 0.001). Survival analyses including Kaplan-Meier curves and univariate and multivariate analysis consistently reported that there were no significant differences for both event-free survival (EFS) and overall survival (OS) (all P > 0.1), between high versus low BAALC and ERG expressers. Our study suggested that despite of their well-known adverse role in prognosis of AML, neither BAALC nor ERG expression levels at diagnosis had effect on survival of AML patients who underwent allo-HSCT.

AML1–ETO promotes SIRT1 expression to enhance leukemogenesis of t(8;21) acute myeloid leukemia

Recently, SIRT1 was found to play an important role in a variety of solid and hematologic malignancies. The expression and function of SIRT1 may differ completely depending on cell type and gene subtype, and it can act as a tumor suppressor or oncogene. We describe how SIRT1 mRNA and protein levels are overexpressed in t(8;21) AML cells. AML1-ETO triggers the activation of SIRT1 by binding at AML1 binding sites on the SIRT1 promoter. Pharmacologic targeting or RNAi-mediated inhibition of SIRT1 induces G1 arrest, apoptosis, and proliferation inhibition that is more sensitive in AML1-ETO-positive than AML1-ETO-negative cell lines. Our data suggest that targeting SIRT1 may be an attractive therapeutic strategy in t(8;21) AML.

Combining retinoic acid and oral arsenic may be potentially the first-line therapy for non-high-risk acute promyelocytic leukemia

Once regarded as a rapidly fatal disease, acute promyelocytic leukemia (APL) is now curable in most cases with the use of targeted treatment alone and without chemotherapy (CHT) (1). Platzbecker et al . (2) reported a prospective, randomized, multicenter, open-label, phase III noninferiority trial, which demonstrated the advantages of all-trans-retinoic acid (ATRA) and intravenous ATO over ATRA and CHT with significantly greater and more sustainable antileukemic efficacy over time for non-high-risk APL. The recent paper by Iland et al . (3) also revealed that ATRA and arsenic in initial therapy induction and consolidation for APL reduced the risk of relapse compared with historical controls. These studies demonstrated the advantages of combining ATRA and intravenous ATO over ATRA and CHT for non-high-risk APL.