Genes predictive of outcome and novel molecular classification schemes in adult acute myeloid leukemia

A syngeneic spontaneous zebrafish model of tp53-deficient, EGFRvIII, and PI3KCAH1047R-driven glioblastoma reveals inhibitory roles for inflammation during tumor initiation and relapse in vivo

High-throughput vertebrate animal model systems for the study of patient-specific biology and new therapeutic approaches for aggressive brain tumors are currently lacking, and new approaches are urgently needed. Therefore, to build a patient-relevant in vivo model of human glioblastoma, we expressed common oncogenic variants including activated human EGFRvIII and PI3KCAH1047R under the control of the radial glial-specific promoter her4.1 in syngeneic tp53 loss-of-function mutant zebrafish. Robust tumor formation was observed prior to 45 days of life, and tumors had a gene expression signature similar to human glioblastoma of the mesenchymal subtype, with a strong inflammatory component. Within early stage tumor lesions, and in an in vivo and endogenous tumor microenvironment, we visualized infiltration of phagocytic cells, as well as internalization of tumor cells by mpeg1.1:EGFP+ microglia/macrophages, suggesting negative regulatory pressure by pro-inflammatory cell types on tumor growth at early stages of glioblastoma initiation. Furthermore, CRISPR/Cas9-mediated gene targeting of master inflammatory transcription factors irf7 or irf8 led to increased tumor formation in the primary context, while suppression of phagocyte activity led to enhanced tumor cell engraftment following transplantation into otherwise immune-competent zebrafish hosts. Altogether, we developed a genetically relevant model of aggressive human glioblastoma and harnessed the unique advantages of zebrafish including live imaging, high-throughput genetic and chemical manipulations to highlight important tumor-suppressive roles for the innate immune system on glioblastoma initiation, with important future opportunities for therapeutic discovery and optimizations.

New directions for emerging therapies in acute myeloid leukemia: the next chapter

Conventional therapy for acute myeloid leukemia is composed of remission induction with cytarabine- and anthracycline-containing regimens, followed by consolidation therapy, including allogeneic stem cell transplantation, to prolong remission. In recent years, there has been a significant shift toward the use of novel and effective, target-directed therapies, including inhibitors of mutant FMS-like tyrosine kinase 3 (FLT3) and isocitrate dehydrogenase (IDH), the B-cell lymphoma 2 inhibitor venetoclax, and the hedgehog pathway inhibitor glasdegib. In older patients the combination of a hypomethylating agent or low-dose cytarabine, venetoclax achieved composite response rates that approximate those seen with standard induction regimens in similar populations, but with potentially less toxicity and early mortality. Preclinical data suggest synergy between venetoclax and FLT3- and IDH-targeted therapies, and doublets of venetoclax with inhibitors targeting these mutations have shown promising clinical activity in early stage trials. Triplet regimens involving the hypomethylating agent and venetoclax with FLT3 or IDH1/2 inhibitor, the TP53-modulating agent APR-246 and magrolimab, myeloid cell leukemia-1 inhibitors, or immune therapies such as CD123 antibody-drug conjugates and programmed cell death protein 1 inhibitors are currently being evaluated. It is hoped that such triplets, when applied in appropriate patient subsets, will further enhance remission rates, and more importantly remission durations and survival.

HSPG2 overexpression independently predicts poor survival in patients with acute myeloid leukemia

Heparan sulfate proteoglycan 2 (HSPG2), also known as perlecan, is a large multi-domain extracellular matrix proteoglycan, which contributes to the invasion, metastasis and angiogenesis of solid tumor. However, very little is known about the effect of HSPG2 on acute myeloid leukemia (AML). This study aims to investigate the prognostic value of the HSPG2 gene in terms of overall survival and leukemia-free survival in patients with AML. Bone marrow mononuclear cells (BMMCs) from 4 AML patients and 3 healthy controls were processed for RNA-Sequencing (RNA-seq). The mRNA expression level of HSPG2 in BMMCs and CD34⁺ hematopoietic stem/progenitor cells (HSPC) obtained from enrolled participants and human leukemic cell lines was detected by RT-qPCR. Then the correlations between the expression of HSPG2 and a variety of important clinical parameters, such as median white blood cell (WBC) count and bone marrow (BM) blasts, were further analyzed. The expression level of HSPG2 was significantly upregulated in AML patients at the time of diagnosis, downregulated after complete remission and then elevated again at relapse. Moreover, HSPG2 expression was associated with median WBC count (P < 0.001), median hemoglobin (P = 0.02), median platelet count (P = 0.001), and BM blasts (P < 0.001) in AML patients. Patients with high HSPG2 expression had both worse overall survival (OS) (P = 0.001) and poorer leukemia-free survival (LFS) (P = 0.047). In the multivariate analysis model, HSPG2 was identified as an independent prognostic biomarker of AML. Taken together, these results indicate that HSPG2 overexpression was associated with poor prognosis in AML patients, and may be a prognostic biomarker and therapeutic target of AML.

Molecular Targets for Combined Therapeutic Strategies to Limit Glioblastoma Cell Migration and Invasion

The highly invasive nature of glioblastoma imposes poor prospects for patient survival. Molecular evidence indicates glioblastoma cells undergo an intriguing expansion of phenotypic properties to include neuron-like signaling using excitable membrane ion channels and synaptic proteins, augmenting survival and motility. Neurotransmitter receptors, membrane signaling, excitatory receptors, and Ca2+ responses are important candidates for the design of customized treatments for cancers within the heterogeneous central nervous system. Relatively few published studies of glioblastoma multiforme (GBM) have evaluated pharmacological agents targeted to signaling pathways in limiting cancer cell motility. Transcriptomic analyses here identified classes of ion channels, ionotropic receptors, and synaptic proteins that are enriched in human glioblastoma biopsy samples. The pattern of GBM-enriched gene expression points to a major role for glutamate signaling. However, the predominant role of AMPA receptors in fast excitatory signaling throughout the central nervous system raises a challenge on how to target inhibitors selectively to cancer cells while maintaining tolerability. This review critically evaluates a panel of ligand- and voltage-gated ion channels and synaptic proteins upregulated in GBM, and the evidence for their potential roles in the pathological disease progress. Evidence suggests combinations of therapies could be more effective than single agents alone. Natural plant products used in traditional medicines for the treatment of glioblastoma contain flavonoids, terpenoids, polyphenols, epigallocatechin gallate, quinones, and saponins, which might serendipitously include agents that modulate some classes of signaling compounds highlighted in this review. New therapeutic strategies are likely to exploit evidence-based combinations of selected agents, each at a low dose, to create new cancer cell-specific therapeutics.

Microglia Induce PDGFRB Expression in Glioma Cells to Enhance Their Migratory Capacity

High-grade gliomas (HGGs) are the most aggressive and invasive primary brain tumors. The platelet-derived growth factor (PDGF) signaling pathway drives HGG progression, and enhanced expression of PDGF receptors (PDGFRs) is a well-established aberration in a subset of glioblastomas (GBMs). PDGFRA is expressed in glioma cells, whereas PDGFRB is mostly restricted to the glioma-associated stroma. Here we show that the spatial location of TAMMs correlates with the expansion of a subset of tumor cells that have acquired expression of PDGFRB in both mouse and human low-grade glioma and HCGs. Furthermore, M2-polarized microglia but not bone marrow (BM)-derived macrophages (BMDMs) induced PDGFRB expression in glioma cells and stimulated their migratory capacity. These findings illustrate a heterotypic cross-talk between microglia and glioma cells that may enhance the migratory and invasive capacity of the latter by inducing PDGFRB.

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PDGFRB⁺ glioma cells are in physical contact with IBA1⁺ TAMMs in mouse and human glioma

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Aggregation of PDGFRB⁺ glioma cells correlated with the accumulation of IBA1⁺ TAMMs

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Microglia but not bone marrow-derived macrophages induced PDGFRB expression in vitro

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M2-polarized microglia stimulated glioma cell migration dependent on PDGFRB

The Cytoskeletal Adapter Protein Spinophilin Regulates Invadopodia Dynamics and Tumor Cell Invasion in Glioblastoma

Glioblastoma is a primary brain cancer that is resistant to all treatment modalities. This resistance is due, in large part, to invasive cancer cells that disperse from the main tumor site, escape surgical resection, and contribute to recurrent secondary lesions. The adhesion and signaling mechanisms that drive glioblastoma cell invasion remain enigmatic, and as a result there are no effective anti-invasive clinical therapies. Here we have characterized a novel adhesion and signaling pathway comprised of the integrin αvβ8 and its intracellular binding partner, Spinophilin (Spn), which regulates glioblastoma cell invasion in the brain microenvironment. We show for the first time that Spn binds directly to the cytoplasmic domain of β8 integrin in glioblastoma cells. Genetically targeting Spn leads to enhanced invasive cell growth in preclinical models of glioblastoma. Spn regulates glioblastoma cell invasion by modulating the formation and dissolution of invadopodia. Spn-regulated invadopodia dynamics are dependent, in part, on proper spatiotemporal activation of the Rac1 GTPase. Glioblastoma cells that lack Spn showed diminished Rac1 activities, increased numbers of invadopodia, and enhanced extracellular matrix degradation. Collectively, these data identify Spn as a critical adhesion and signaling protein that is essential for modulating glioblastoma cell invasion in the brain microenvironment.

IMPLICATIONS

Tumor cell invasion is a major clinical obstacle in glioblastoma and this study identifies a new signaling pathway regulated by Spinophilin in invasive glioblastoma. Mol Cancer Res; 14(12); 1277-87. ©2016 AACR.

Overexpression of miR-210 is Associated with Poor Prognosis of Acute Myeloid Leukemia

Background

MicroRNAs play important roles in regulation of the initiation and progression of AML. MiR-210 is closely related with cancer development; however, whether miR-210 expression level correlates with clinical correlation in AML is unknown. Thus, the aim of this study was to investigate the potential relationship between miR-210 expression and AML prognosis.

Material/Methods

Real-time quantitative PCR was carried out to examine the expression level of miR-210 in bone marrow and serum obtained from AML patients and healthy controls. Then the correlation between miR-210 expression and a variety of important clinical parameters (such as overall survival, relapse-free survival, and prognostic value) were further studied.

Results

The expression level of miR-210 was significantly higher in the bone marrow and serum of AML patients than that of healthy controls (p<0.001). Moreover, miR-210 expression was associated with various AML clinicopathological parameters, including FAB classification and cytogenetics. The serum miR-210 expression level was reduced significantly when the patients achieved complete remission (p=0.02). The high miR-210 expression group had both poorer relapse-free survival (p=0.015) and worse overall survival (p=0.008). In the multivariate analysis model, miR-210 was identified as an independent prognostic marker.

Conclusions

MiR-210 up-regulation was associated with poor prognosis in AML and it might be useful as a marker for predicting the clinical outcome of AML patients.

Prognostic value of miR-29a expression in pediatric acute myeloid leukemia

OBJECTIVES

As a member of miR-29 family, miR-29a can act as either oncogene or tumor suppressor. However, its expression patterns in acute myeloid leukemia (AML) are controversial according to previous studies. Thus, the aim of this study was to determine the expression and clinical significance of miR-29a in pediatric AML.

METHODS

Expression levels of miR-29a in bone marrow mononuclear cells were detected by real-time quantitative PCR in a cohort of 106 patients with newly diagnosed pediatric AML. The prognostic values of miR-29a in pediatric AML were also analyzed.

RESULTS

Compared with normal controls, we demonstrated a significantly decreased expression of miR-29a in the bone marrow of pediatric AML patients (P<0.001). The expression levels of miR-29a were significantly lower in French-American-British classification subtype M7 than in other subtypes (P<0.001) and differed significantly across cytogenetic risk groups (P=0.002) with high miR-29a expression among those with favorable karyotypes. Moreover, low miR-29a expression was significantly associated with shorter relapse-free (P<0.001) and overall (P=0.008) survival in pediatric AML patients. Cox proportional hazards multivariate analysis of the univariate predictors identified cytogenetic risk and miR-29a expression as independent prognostic factors for relapse-free survival and overall survival. More interestingly, the prognostic value of miR-29a expression was more obvious in the subgroup of patients with intermediate-risk cytogenetics.

CONCLUSION

Our data indicate for the first time that the down-regulation of miR-29a was associated with advanced clinical features and poor prognosis of pediatric AML patients, suggesting that miR-29a down-regulation may be used as an unfavorable prognostic marker in pediatric AML.

Molecular diagnosis and prognosis with DNA microarrays

Microarray analysis makes it possible to determine thousands of gene expression values simultaneously. Changes in gene expression, as a response to diseases, can be detected allowing a better understanding and differentiation of diseases at a molecular level. By comparing different kinds of tissue, for example healthy tissue and cancer tissue, the microarray analysis indicates induced gene activity, repressed gene activity or when there is no change in the gene activity level. Fundamental patterns in gene expression are extracted by several clustering and machine learning algorithms. Certain kinds of cancer can be divided into subtypes, with different clinical outcomes, by their specific gene expression patterns. This enables a better diagnosis and tailoring of individual patient treatments.

The antioxidant protein peroxiredoxin 4 is epigenetically down regulated in acute promyelocytic leukemia

The antioxidant peroxiredoxin (PRDX) protein family comprises 6 members, which are implicated in a variety of cellular responses, including growth factor signal transduction. PRDX4 resides in the endoplasmic reticulum (ER), where it locally controls oxidative stress by reducing H₂O₂ levels. We recently provided evidence for a regulatory function of PRDX4 in signal transduction from a myeloid growth factor receptor, the granulocyte colony-stimulating factor receptor (G-CSFR). Upon activation, the ligand-induced G-CSFR undergoes endocytosis and routes via the early endosomes where it physically interacts with ER-resident PRDX4. PRDX4 negatively regulates G-CSFR mediated signaling. Here, we investigated whether PRDX4 is affected in acute myeloid leukemia (AML); genomic alterations and expression levels of PRDX4 were investigated. We show that genomic abnormalities involving PRDX4 are rare in AML. However, we find a strong reduction in PRDX4 expression levels in acute promyelocytic leukemia (APL) compared to normal promyelocytes and different molecular subtypes of AML. Subsequently, the possible role of DNA methylation and histone modifications in silencing of PRDX4 in APLs was investigated. We show that the reduced expression is not due to methylation of the CpG island in the promoter region of PRDX4 but correlates with increased trimethylation of histone 3 lysine residue 27 (H3K27me3) and lysine residue 4 (H3K4me3) at the transcriptional start site (TSS) of PRDX4, indicative of a bivalent histone code involved in transcriptional silencing. These findings suggest that the control of G-CSF responses by the antioxidant protein PRDX4 may be perturbed in APL.

CD147 and VEGF co-expression predicts prognosis in patients with acute myeloid leukemia

OBJECTIVE

To investigate the possible role of CD147 and vascular endothelial growth factor in progression and prognosis of acute myeloid leukemia.

METHODS

Immunohistochemical staining was performed to detect the expression of CD147 and vascular endothelial growth factor in paraffin-embedded sections from 62 bone marrow biopsies obtained from an equal number of patients with newly diagnosed acute myeloid leukemia.

RESULTS

CD147 and vascular endothelial growth factor expression in the bone marrow of acute myeloid leukemia patients were significantly higher than those in normal controls (both P < 0.001). Expression of them was significantly increased in patients with a high degree of microvessel density compared with those with a low degree (CD147: P = 0.009; vascular endothelial growth factor: P = 0.01) and correlated well with bone marrow microvessel density (CD147: P = 0.01; vascular endothelial growth factor: P = 0.02). In addition, higher levels of CD147 and vascular endothelial growth factor were also found in acute myeloid leukemia patients with an unfavorable karyotype compared with those with intermediate and favorable karyotypes (both P = 0.01). Moreover, the expression of CD147 was significantly correlated with that of vascular endothelial growth factor (P < 0.001). Furthermore, the co-expression of CD147 and vascular endothelial growth factor in the bone marrow indicated a poor prognosis in acute myeloid leukemia and was an independent prognostic factor for overall survival by multivariate analysis.

CONCLUSIONS

Our data show for the first time that the co-expression of CD147 and vascular endothelial growth factor may indicate a poor prognosis in acute myeloid leukemia and may be a highly sensitive marker for predicting the clinical outcome of patients.