Retroviral activation of a novel gene encoding a zinc finger protein in IL-3-dependent myeloid leukemia cell lines

The ETV6-MECOM fusion protein promotes EMT-related properties by repressing the transactivation activity of E-cadherin promoter in K562 leukemia cells

The ETV6-MECOM fusion gene, produced by the rare and recurrent chromosomal translocation t(3; 12) (q26; p13), is associated with high mortality and short survival in myeloid leukemia. However, its function and underlying mechanisms in leukemia progression remain unknown. In this study, leukemia-stable K562 cells expressing the ETV6-MECOM fusion protein were used to investigate the effects of the ETV6-MECOM oncoprotein. K562-ETV6-MECOM cells were undifferentiated and had reduced colony formation, increased cell migration and invasion, and increased sphere number and diameter in a spheroid formation assay, presenting epithelial-to-mesenchymal transition (EMT) traits. The expression of E-cadherin, a hallmark of EMT, was significantly downregulated at the transcriptional and translational level in K562-ETV6-MECOM cells to explore the mechanistic basis of EMT. Stepwise truncation, DNA sequence deletion, mutation analysis for E-cadherin promoter transactivation, and a dual luciferase assay indicated that the regulatory region of ETV6-MECOM is located in the DNA motif -1116 TTAAAA-1111 of E-cadherin promoter. Moreover, a chromatin immunoprecipitation assay showed that this oncoprotein binds to the DNA motif -1116 TTAAAA-1111 with the anti-EVI1 antibody. Although ETV6-MECOM upregulated the expressions of EMT master regulators, including SNAIL, SLUG, ZEB2, and TWIST2, their knockdown had no effect on EMT-related properties. However, overexpression of E-cadherin eliminated EMT traits in the presence of the ETV6-MECOM oncoprotein. These data confirmed that the ETV6-MECOM oncoprotein, not SNAIL, SLUG, ZEB2, or TWIST2, plays a critical role in inducing EMT traits in leukemia K562 cells. ETV6-MECOM induces EMT-related properties by downregulating the transcriptional expression of E-cadherin and repressing its transactivation activity by binding to its core motif -1116TTAAAA-1111 in leukemia K562 cells. These findings could contribute to the development of a therapeutic target for patients with myeloid leukemia characterized by ETV6-MECOM.

Preclinical efficacy of targeting epigenetic mechanisms in AML with 3q26 lesions and EVI1 overexpression

AML with chromosomal alterations involving 3q26 overexpresses the transcription factor (TF) EVI1, associated with therapy refractoriness and inferior overall survival in AML. Consistent with a CRISPR screen highlighting BRD4 dependency, treatment with BET inhibitor (BETi) repressed EVI1, LEF1, c-Myc, c-Myb, CDK4/6, and MCL1, and induced apoptosis of AML cells with 3q26 lesions. Tegavivint (TV, BC-2059), known to disrupt the binding of nuclear β-catenin and TCF7L2/LEF1 with TBL1, also inhibited co-localization of EVI1 with TBL1 and dose-dependently induced apoptosis in AML cell lines and patient-derived (PD) AML cells with 3q26.2 lesions. TV treatment repressed EVI1, attenuated enhancer activity at ERG, TCF7L2, GATA2 and MECOM loci, abolished interactions between MYC enhancers, repressing AML stemness while upregulating mRNA gene-sets of interferon/inflammatory response, TGF-β signaling and apoptosis-regulation. Co-treatment with TV and BETi or venetoclax induced synergistic in vitro lethality and reduced AML burden, improving survival of NSG mice harboring xenografts of AML with 3q26.2 lesions.

EVI1-mediated Programming of Normal and Malignant Hematopoiesis

Ecotropic viral integration site 1 (EVI1), encoded at the MECOM locus, is an oncogenic zinc finger transcription factor with diverse roles in normal and malignant cells, most extensively studied in the context of hematopoiesis. EVI1 interacts with other transcription factors in a context-dependent manner and regulates transcription and chromatin remodeling, thereby influencing the proliferation, differentiation, and survival of cells. Interestingly, it can act both as a transcriptional activator as well as a transcriptional repressor. EVI1 is expressed, and fulfills important functions, during the development of different tissues, including the nervous system and hematopoiesis, demonstrating a rigid spatial and temporal expression pattern. However, EVI1 is regularly overexpressed in a variety of cancer entities, including epithelial cancers such as ovarian and pancreatic cancer, as well as in hematologic malignancies like myeloid leukemias. Importantly, EVI1 overexpression is generally associated with a very poor clinical outcome and therapy-resistance. Thus, EVI1 is an interesting candidate to study to improve the prognosis and treatment of high-risk patients with "EVI1high" hematopoietic malignancies.

High EVI1 and PARP1 expression as favourable prognostic markers in high-grade serous ovarian carcinoma

BACKGROUND

Mechanisms of development and progression of high-grade serous ovarian cancer (HGSOC) are poorly understood. EVI1 and PARP1, part of TGF-ß pathway, are upregulated in cancers with DNA repair deficiencies with DNA repair deficiencies and may influce disease progression and survival. Therefore we questioned the prognostic significance of protein expression of EVI1 alone and in combination with PARP1 and analyzed them in a cohort of patients with HGSOC.

METHODS

For 562 HGSOC patients, we evaluated EVI1 and PARP1 expression by immunohistochemical staining on tissue microarrays with QuPath digital semi-automatic positive cell detection.

RESULTS

High EVI1 expressing (> 30% positive tumor cells) HGSOC were associated with improved progression-free survival (PFS) (HR = 0.66, 95% CI: 0.504-0.852, p = 0.002) and overall survival (OS) (HR = 0.45, 95% CI: 0.352-0.563, p < 0.001), including multivariate analysis. Most interestingly, mutual high expression of both proteins identifies a group with particularly good prognosis. Our findings were proven technically and clinically using bioinformatical data sets for single-cell sequencing, copy number variation and gene as well as protein expression.

CONCLUSIONS

EVI1 and PARP1 are robust prognostic biomarkers for favorable prognosis in HGSOC and imply further research with respect to their reciprocity.

High-Throughput Identification, Modeling, and Analysis of Cancer Driver Genes In Vivo

The vast number of genomic and molecular alterations in cancer pose a substantial challenge to uncovering the mechanisms of tumorigenesis and identifying therapeutic targets. High-throughput functional genomic methods in genetically engineered mouse models allow for rapid and systematic investigation of cancer driver genes. In this review, we discuss the basic concepts and tools for multiplexed investigation of functionally important cancer genes in vivo using autochthonous cancer models. Furthermore, we highlight emerging technical advances in the field, potential opportunities for future investigation, and outline a vision for integrating multiplexed genetic perturbations with detailed molecular analyses to advance our understanding of the genetic and molecular basis of cancer.

The adverse impact of ecotropic viral integration site-1 (EVI1) overexpression on the prognosis of acute myeloid leukemia with KMT2A gene rearrangement in different risk stratification subtypes

INTRODUCTION

AML patients with KMT2A-MLLT3 and other 11q23 abnormalities belong to the intermediate and high-risk level groups, respectively. Whether the poor prognostic value of Ecotropic Viral Integration site-1 (EVI1) overexpression suits either the subtypes of KMT2A-MLLT3 or Non-KMT2A-MLLT3 AML patients (intermediate and high risk group) needs to be further investigated.

METHODS

We retrospectively analyzed the clinical characteristics of 166 KMT2A-r and KMT2A-PTD AML patients.

RESULTS

For the Non-KMT2A-MLLT3 group, patients in the EVI1-high subgroup had shorter OS and DFS and higher CIR than those in the EVI1-low subgroup (p = .027, p = .018, and p = .020, respectively). Additionally, both KMT2A-MLLT3 and Non-KMT2A-MLLT3 patients who received chemotherapy alone had poorer prognosis than patients who also received allogeneic hematopoietic stem cell transplant (allo-HSCT) regardless of their EVI1 expression level (all p < .001). For transplanted patients with KMT2A-MLLT3 or Non-KMT2A-MLLT3 rearrangement, the EVI1-high subgroup had worse prognosis than the EVI1-low subgroup (all p < .05). The 2-year CIR of the KMT2A-MLLT3 and Non-KMT2A-MLLT3 groups with high EVI1 expression was high (52% and 49.6%, respectively). However, for patients with low EVI1 expression, the 2-year CIR of transplanted patients with KMT2A-MLLT3 and Non-KMT2A-MLLT3 was relatively low.

CONCLUSIONS

Our study showed that for the Non-KMT2A-MLLT3 group, the EVI1-high group had shorter OS and DFS than the EVI1-low group. High EVI1 expression showed an adverse effect in AML with KMT2A rearrangement in different risk stratification subtypes. For the EVI1-high patients with non-KMT2A-MLLT3 rearrangement, other novel regimens towards relapse should be taken into consideration.

AKT inhibition sensitizes EVI1 expressing colon cancer cells to irinotecan therapy by regulating the Akt/mTOR axis

PURPOSE

Ecotropic viral integration site 1 (EVI1) is an oncogenic transcription factor that has been attributed to chemotherapy resistance in different cancers. As yet, however, its role in colon cancer drug resistance is not completely understood. Here, we set out to investigate the functional and therapeutic relevance of EVI1 in colon cancer drug resistance.

METHODS

The EVI1 gene was knocked down in colon cancer cells that were subsequently tested for susceptibility to irinotecan using in vitro assays and in vivo subcutaneous mouse colon cancer models. The effect of EVI1 knockdown on the AKT-mTOR signaling pathway was assessed using cell line models, immunohistochemistry and bioinformatics tools. The anti-proliferative activity of AKT inhibitor GSK690693 and its combination with irinotecan was tested in colon cancer cell line models (2D and 3D). Finally, the therapeutic efficacy of GSK690693 and its combination with irinotecan was evaluated in xenografted EVI1 expressing colon cancer mouse models.

RESULTS

We found that EVI1 knockdown decreased cancer stem cell-like properties and improved irinotecan responses in both cell line and subcutaneous mouse models. In addition, we found that EVI1 downregulation resulted in inhibition of AKT/mTOR signaling and RICTOR expression. Knocking down RICTOR expression increased the cytotoxic effects of irinotecan in EVI1 downregulated colon cancer cells. Co-treatment with irinotecan and ATP-competitive AKT inhibitor GSK690693 significantly reduced colon cancer cell survival and tumor progression rates.

CONCLUSION

Inhibition of the AKT signaling cascade by GSK690693 may serve as an alternative to improve the irinotecan response in EVI1-expressing colon cancer cells.

MECOM gene overexpression in pediatric patients with acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is characterized by blocked or aberrant differentiation of hematopoietic stem cells. The MECOM gene overexpression in hematopoietic progenitors induces myeloid differentiation block, resulting in increased self-renewal and survival of these transformed progenitors. However, its exact role in AML remains unclear. We aimed to estimate the prevalence of MECOM overexpression among pediatric AML patients, and assess its impact on clinical outcome.

PATIENTS AND METHODS

Real-time quantitative polymerase chain reaction and Livak method (2^ΔΔCt) were used to determine relative MECOM expression level among 243 pediatric patients with AML. MECOM overexpression was considered if the cumulative relative expression was above 1 (2^-ΔΔCt) and was designated as MECOM^pos.

RESULTS

Of 243 AML patients tested 57(23.5%) demonstrated MECOM^pos. Patients with MECOM^pos had significantly lower median age. The frequency of MECOM^pos was significantly higher among AML patients with 11q23 abnormalities, complex karyotypes and among high- and intermediate-risk groups compared to low-risk group (p = .014). MECOM^pos patients had significantly lower overall survival (OS) (38.7 vs. 78.9%, p < .001), event-free survival (EFS) (37.3% vs. 68.4%, p < .001), and had higher cumulative incidence of relapse (49.5% vs. 23.5%, p = .002) at 36 months compared to MECOM^neg patients. Multivariate analysis revealed that MECOM^pos was an adverse prognostic factor for OS (hazards ratio (HR) = 2.11, 95% confidence interval (CI) 1.24-3.60, p = .006) and EFS (HR= 1.71, 95% CI 1.07-2.75, p = .025). The logistic regression model showed that MECOM^pos was an independent prognostic factor regardless of minimal residual disease status post first induction therapy in the intermediate-risk group (odds ratio 2.89; 95% CI 1.19-6.57, p = .018).

CONCLUSION

The aberrant MECOM gene expression is an adverse prognostic factor, especially in patients without previously known cytogenetic risk factors. Our results suggest the potential benefit from pretreatment screening for MECOM gene overexpression in newly diagnosed AML patients for better risk stratification and treatment adjustment.

Low EVI1 expression at diagnosis predicted poor outcomes in pediatric Ph-negative B cell precursor acute lymphoblastic leukemia patients

Abnormally high ecotropic viral integration site 1 (EVI1) expression has been recognized as a poor prognostic factor in acute myeloid leukemia patients. However, its prognostic impact in B cell precursor acute lymphoblastic leukemia (BCP-ALL) remains unknown. A total of 176 pediatric Ph-negative BCP-ALL patients who received at least 1 course of chemotherapy and received chemotherapy only during follow-up were retrospectively tested for EVI1 transcript levels by real-time quantitative PCR at diagnosis, and survival analysis was performed. Clinical and EVI1 expression data of 129 pediatric BCP-ALL patients were downloaded from therapeutically applicable research to generate effective treatments (TARGET) database for validation. In our cohort, the median EVI1 transcript level was 0.33% (range, 0.0068-136.2%), and 0.10% was determined to be the optimal cutoff value for patient grouping by receiver operating characteristic curve analysis. Low EVI1 expression (<0.10%) was significantly related to lower 5-year relapse-free survival (RFS) and overall survival (OS) rates (P = 0.017 and 0.018, respectively). Multivariate analysis showed that EVI1 expression <0.10% was an independent adverse prognostic factor for RFS and OS. TARGET data showed that low EVI1 expression tended to be related to a lower 5-year OS rate (P = 0.066). In conclusion, low EVI1 expression at diagnosis could predict poor outcomes in pediatric Ph-negative BCP-ALL patients receiving chemotherapy.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.1939818 .

Effects of Pubertal Exposure to Butyl Benzyl Phthalate, Perfluorooctanoic Acid, and Zeranol on Mammary Gland Development and Tumorigenesis in Rats

Endocrine-disrupting chemicals (EDCs)—including butyl benzyl phthalate (BBP), perfluorooctanoic acid (PFOA), and zeranol (α-ZAL, referred to as ZAL hereafter)—can interfere with the endocrine system and produce adverse effects. It remains unclear whether pubertal exposure to low doses of BBP, PFOA, and ZAL has an impact on breast development and tumorigenesis. We exposed female Sprague Dawley rats to BBP, PFOA, or ZAL through gavage for 21 days, starting on day 21, and analyzed their endocrine organs, serum hormones, mammary glands, and transcriptomic profiles of the mammary glands at days 50 and 100. We also conducted a tumorigenesis study for rats treated with PFOA and ZAL using a 7,12-dimethylbenz[a]anthracene (DMBA) model. Our results demonstrated that pubertal exposure to BBP, PFOA, and ZAL affected endocrine organs and serum hormones, and induced phenotypic and transcriptomic changes. The exposure to PFOA + ZAL induced the most phenotypic and transcriptomic changes in the mammary gland. PFOA + ZAL downregulated the expression of genes related to development at day 50, whereas it upregulated genes associated with tumorigenesis at day 100. PFOA + ZAL exposure also decreased rat mammary tumor latency, reduced the overall survival of rats after DMBA challenge, and affected the histopathology of mammary tumors. Therefore, our study suggests that exposure to low doses of EDCs during the pubertal period could induce changes in the endocrine system and mammary gland development in rats. The inhibition of mammary gland development by PFOA + ZAL might increase the risk of developing mammary tumors through activation of signaling pathways associated with tumorigenesis.

EVI1 Promotes the Proliferation and Invasive Properties of Human Head and Neck Squamous Cell Carcinoma Cells

Head and neck squamous cell carcinoma (HNSCC) is a frequent malignancy with a poor prognosis. So far, the EGFR inhibitor cetuximab is the only approved targeted therapy. A deeper understanding of the molecular and genetic basis of HNSCC is needed to identify additional targets for rationally designed, personalized therapeutics. The transcription factor EVI1, the major product of the MECOM locus, is an oncoprotein with roles in both hematological and solid tumors. In HNSCC, high EVI1 expression was associated with an increased propensity to form lymph node metastases, but its effects in this tumor entity have not yet been determined experimentally. We therefore overexpressed or knocked down EVI1 in several HNSCC cell lines and determined the impact of these manipulations on parameters relevant to tumor growth and invasiveness, and on gene expression patterns. Our results revealed that EVI1 promoted the proliferation and migration of HNSCC cells. Furthermore, it augmented tumor spheroid formation and the ability of tumor spheroids to displace an endothelial cell layer. Finally, EVI1 altered the expression of numerous genes in HNSCC cells, which were enriched for Gene Ontology terms related to its cellular functions. In summary, EVI1 represents a novel oncogene in HNSCC that contributes to cellular proliferation and invasiveness.

Mds1CreERT2, an inducible Cre allele specific to adult-repopulating hematopoietic stem cells

Hematopoietic ontogeny consists of two broad programs: an initial hematopoietic stem cell (HSC)-independent program followed by HSC-dependent hematopoiesis that sequentially seed the fetal liver and generate blood cells. However, the transition from HSC-independent to HSC-derived hematopoiesis remains poorly characterized. To help resolve this question, we developed Mds1CreERT2 mice, which inducibly express Cre-recombinase in emerging HSCs in the aorta and label long-term adult HSCs, but not HSC-independent yolk-sac-derived primitive or definitive erythromyeloid (EMP) hematopoiesis. Our lineage-tracing studies indicate that HSC-derived erythroid, myeloid, and lymphoid progeny significantly expand in the liver and blood stream between E14.5 and E16.5. Additionally, we find that HSCs contribute the majority of F4/80+ macrophages in adult spleen and marrow, in contrast to their limited contribution to macrophage populations in brain, liver, and lungs. The Mds1CreERT2 mouse model will be useful to deconvolute the complexity of hematopoiesis as it unfolds in the embryo and functions postnatally.

Identification of therapeutic targets of the hijacked super-enhancer complex in EVI1-rearranged leukemia

Deregulation of the EVI1 proto-oncogene by the GATA2 distal hematopoietic enhancer (G2DHE) is a key event in high-risk acute myeloid leukemia carrying 3q21q26 aberrations (3q-AML). Upon chromosomal rearrangement, G2DHE acquires characteristics of a super-enhancer and causes overexpression of EVI1 at 3q26.2. However, the transcription factor (TF) complex of G2DHE remains poorly characterized. The aim of this study was to unravel key components of G2DHE-bound TFs involved in the deregulation of EVI1. We have identified several CEBPA and RUNX1 binding sites to be enriched and critical for G2DHE function in 3q-AML cells. Using ChIP-SICAP (ChIP followed by selective isolation of chromatin-associated proteins), a panel of chromatin interactors of RUNX1 and CEBPA were detected in 3q-AML, including PARP1 and IKZF1. PARP1 inhibition (PARPi) caused a reduction of EVI1 expression and a decrease in EVI1-G2DHE interaction frequency, highlighting the involvement of PARP1 in oncogenic super-enhancer formation. Furthermore, 3q-AML cells were highly sensitive to PARPi and displayed morphological changes with higher rates of differentiation and apoptosis as well as depletion of CD34 + cells. In summary, integrative analysis of the 3q-AML super-enhancer complex identified CEBPA and RUNX1 associated proteins and nominated PARP1 as a potential new therapeutic target in EVI1 + 3q-AML.

Alopecia in Harlequin mutant mice is associated with reduced AIF protein levels and expression of retroviral elements

We investigated the contribution of apoptosis-inducing factor (AIF), a key regulator of mitochondrial biogenesis, in supporting hair growth. We report that pelage abnormalities developed during hair follicle (HF) morphogenesis in Harlequin (Hq) mutant mice. Fragility of the hair cortex was associated with decreased expression of genes encoding structural hair proteins, though key transcriptional regulators of HF development were expressed at normal levels. Notably, Aifm1 (R200 del) knockin males and Aifm1(R200 del)/Hq females showed minor hair defects, despite substantially reduced AIF levels. Furthermore, we cloned the integrated ecotropic provirus of the Aifm1Hq allele. We found that its overexpression in wild-type keratinocyte cell lines led to down-regulation of HF-specific Krt84 and Krtap3-3 genes without altering Aifm1 or epidermal Krt5 expression. Together, our findings imply that pelage paucity in Hq mutant mice is mechanistically linked to severe AIF deficiency and is associated with the expression of retroviral elements that might potentially influence the transcriptional regulation of structural hair proteins.

Myeloid neoplasms associated with t(3;12)(q26.2;p13) are clinically aggressive, show myelodysplasia, and frequently harbor chromosome 7 abnormalities

Sporadic reports of t(3;12)(q26.2;p13) indicate that this abnormality is associated with myeloid neoplasms, myelodysplasia, and a poor prognosis. To better characterize neoplasms with this abnormality, we assessed 20 patients utilizing clinicopathological data, cytogenetic, and targeted next-generation sequencing analysis. We also performed literature review of 58 prior reported cases. Patients included ten men and ten women with median age 55.8 years (range, 27.8-78.8). Diagnoses included 11 acute myeloid leukemia (AML, 5 de novo and 6 secondary), 5 myelodysplastic syndromes (MDS, 3 de novo excess blasts-2 and 2 therapy-related), 2 chronic myeloid leukemia BCR-ABL1-positive blast phase (1 de novo and 1 secondary), 1 primary myelofibrosis (secondary), and 1 mixed-phenotype acute leukemia T/myeloid (MPAL, secondary). Morphologic dysplasia was identified in all AML cases (5/5), MDS cases (4/4), therapy-related cases (3/3), half of myeloproliferative neoplasm cases (1/2), and one MPAL case assessed. The t(3;12) was detected de novo and in subsequent workups in 9 and 11 patients, respectively. Seven patients had t(3;12) only and eight patients had additional chromosome 7 abnormalities. Fluorescence in-situ hybridization detected MECOM (n = 11) and ETV6 (n = 7) rearrangements in all cases assessed. FLT3 internal tandem duplication was identified in five (25%) patients. We identified 13 genetic abnormalities in the de novo group (n = 9), and 25 in the secondary disease group (n = 11). All patients received chemotherapy, with seven allogeneic and two autologous stem cell transplantations. At last follow-up, 14 (70%) patients died with median survival of 6.3 months (range, 0.1-17.3) after detection of t(3;12). In summary, t(3;12)(q26.2;p13) is a rare cytogenetic abnormality in myeloid neoplasms. Myelodysplasia, chromosome 7 abnormalities, and high blast counts are common, and the prognosis is poor. Given the close relationship between the presence of this cytogenetic abnormality and the MDS-related changes, we recommend adding t(3;12)(q26.2;p13) to the list of AML with myelodysplasia-related changes defining abnormalities of the World Health Organization 2017 classification of myeloid neoplasms.

Emerging Roles of PRDM Factors in Stem Cells and Neuronal System: Cofactor Dependent Regulation of PRDM3/16 and FOG1/2 (Novel PRDM Factors)

PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1) (PR) homologous domain containing (PRDM) transcription factors are expressed in neuronal and stem cell systems, and they exert multiple functions in a spatiotemporal manner. Therefore, it is believed that PRDM factors cooperate with a number of protein partners to regulate a critical set of genes required for maintenance of stem cell self-renewal and differentiation through genetic and epigenetic mechanisms. In this review, we summarize recent findings about the expression of PRDM factors and function in stem cell and neuronal systems with a focus on cofactor-dependent regulation of PRDM3/16 and FOG1/2. We put special attention on summarizing the effects of the PRDM proteins interaction with chromatin modulators (NuRD complex and CtBPs) on the stem cell characteristic and neuronal differentiation. Although PRDM factors are known to possess intrinsic enzyme activity, our literature analysis suggests that cofactor-dependent regulation of PRDM3/16 and FOG1/2 is also one of the important mechanisms to orchestrate bidirectional target gene regulation. Therefore, determining stem cell and neuronal-specific cofactors will help better understanding of PRDM3/16 and FOG1/2-controlled stem cell maintenance and neuronal differentiation. Finally, we discuss the clinical aspect of these PRDM factors in different diseases including cancer. Overall, this review will help further sharpen our knowledge of the function of the PRDM3/16 and FOG1/2 with hopes to open new research fields related to these factors in stem cell biology and neuroscience.

In vivo functional screening for systems-level integrative cancer genomics

With the genetic portraits of all major human malignancies now available, we next face the challenge of characterizing the function of mutated genes, their downstream targets, interactions and molecular networks. Moreover, poorly understood at the functional level are also non-mutated but dysregulated genomes, epigenomes or transcriptomes. Breakthroughs in manipulative mouse genetics offer new opportunities to probe the interplay of molecules, cells and systemic signals underlying disease pathogenesis in higher organisms. Herein, we review functional screening strategies in mice using genetic perturbation and chemical mutagenesis. We outline the spectrum of genetic tools that exist, such as transposons, CRISPR and RNAi and describe discoveries emerging from their use. Genome-wide or targeted screens are being used to uncover genomic and regulatory landscapes in oncogenesis, metastasis or drug resistance. Versatile screening systems support experimentation in diverse genetic and spatio-temporal settings to integrate molecular, cellular or environmental context-dependencies. We also review the combination of in vivo screening and barcoding strategies to study genetic interactions and quantitative cancer dynamics during tumour evolution. These scalable functional genomics approaches are transforming our ability to interrogate complex biological systems.

Arsenite suppresses the transcriptional activity of EVI1 through the binding to CCHC-type Zn finger domain

Transcription factor EVI1 is essential for normal hematopoiesis in embryos but is aberrantly elevated in bone marrow cells of myelodysplastic syndrome (MDS) patients. EVI1 and its downstream GATA-2 appear to be a possible therapeutic target of MDS. Here we found that treatment of EVI1-expressing K562 cells with arsenite (As(III)) reduced the mRNA and protein levels of EVI1 and GATA-2. A gel shift assay using the nuclear extract of K562 cells showed that As(III) suppressed the DNA-binding activity of EVI1. The DNA-binding activity of the recombinant EVI1 protein was also suppressed by As(III) but was recovered by excess amounts of dithiothreitol, suggesting the involvement of cysteine residues of EVI1. Since the 7th Zn finger domain of EVI1, having a motif of CCHC, is known to be involved in DNA-binding, the synthetic peptide of 7th Zn finger domain was reacted with As(III) and subjected to MALDI-TOF-MS analysis. The results showed that As(III) binds to this peptide via three cysteine residues. As(III)-induced reduction of the DNA-binding activity of the recombinant EVI1 was abolished by the mutations of each of three cysteine residues to alanine in the 7th Zn finger domain. These results demonstrate that As(III) causes the down-regulation of EVI1 and GATA-2 by inhibiting the transcriptional activity of EVI1 through the binding to the cysteine residues of CCHC-type Zn finger domain.

Multifaceted Role of PRDM Proteins in Human Cancer

The PR/SET domain family (PRDM) comprise a family of genes whose protein products share a conserved N-terminal PR [PRDI-BF1 (positive regulatory domain I-binding factor 1) and RIZ1 (retinoblastoma protein-interacting zinc finger gene 1)] homologous domain structurally and functionally similar to the catalytic SET [Su(var)3-9, enhancer-of-zeste and trithorax] domain of histone methyltransferases (HMTs). These genes are involved in epigenetic regulation of gene expression through their intrinsic HMTase activity or via interactions with other chromatin modifying enzymes. In this way they control a broad spectrum of biological processes, including proliferation and differentiation control, cell cycle progression, and maintenance of immune cell homeostasis. In cancer, tumor-specific dysfunctions of PRDM genes alter their expression by genetic and/or epigenetic modifications. A common characteristic of most PRDM genes is to encode for two main molecular variants with or without the PR domain. They are generated by either alternative splicing or alternative use of different promoters and play opposite roles, particularly in cancer where their imbalance can be often observed. In this scenario, PRDM proteins are involved in cancer onset, invasion, and metastasis and their altered expression is related to poor prognosis and clinical outcome. These functions strongly suggest their potential use in cancer management as diagnostic or prognostic tools and as new targets of therapeutic intervention.

Two effects of GATA2 enhancer repositioning by 3q chromosomal rearrangements

Chromosomal inversion and translocation between 3q21 and 3q26 [inv (3)(q21.3q26.2) and t(3;3)(q21.3;q26.2), respectively] give rise to acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), which have poor prognoses. The chromosomal rearrangements reposition a GATA2 distal hematopoietic enhancer from the original 3q21 locus to the EVI1 (also known as MECOM) locus on 3q26. Therefore, the GATA2 enhancer from one of two GATA2 alleles drives EVI1 gene expression in hematopoietic stem and progenitor cells, which promotes the accumulation of abnormal progenitors and induces leukemogenesis. On the other hand, one allele of the GATA2 gene loses its enhancer, which results in reduced GATA2 expression. The GATA2 gene encodes a transcription factor critical for the generation and maintenance of hematopoietic stem and progenitor cells. GATA2 haploinsufficiency has been known to cause immunodeficiency and myeloid leukemia. Notably, reduced GATA2 expression suppresses the differentiation but promotes the proliferation of EVI1-expressing leukemic cells, which accelerates EVI1-driven leukemogenesis. A series of studies have shown that the GATA2 enhancer repositioning caused by the chromosomal rearrangements between 3q21 and 3q26 provokes misexpression of both the EVI1 and GATA2 genes and that these two effects coordinately elicit high-risk leukemia.

EVI1 triggers metabolic reprogramming associated with leukemogenesis and increases sensitivity to L-asparaginase

Metabolic reprogramming of leukemia cells is important for survival, proliferation, and drug resistance under conditions of metabolic stress in the bone marrow. Deregulation of cellular metabolism, leading to development of leukemia, occurs through abnormally high expression of transcription factors such as MYC and Ecotropic Virus Integration site 1 protein homolog (EVI1). Overexpression of EVI1 in adults and children with mixed lineage leukemia-rearrangement acute myeloid leukemia (MLL-r AML) has a very poor prognosis. To identify a metabolic inhibitor for EVI1-induced metabolic reprogramming in MLL-r AML, we used an XFp extracellular flux analyzer to examine metabolic changes during leukemia development in mouse models of AML expressing MLL-AF9 and Evi1 (Evi1/MF9). Oxidative phosphorylation (OXPHOS) in Evi1/MF9 AML cells accelerated prior to activation of glycolysis, with a higher dependency on glutamine as an energy source. Furthermore, EVI1 played a role in glycolysis as well as driving production of metabolites in the tricarboxylic acid cycle. L-asparaginase (L-asp) exacerbated growth inhibition induced by glutamine starvation and suppressed OXPHOS and proliferation of Evi1/MF9 both in vitro and in vivo; high sensitivity to L-asp was caused by low expression of asparagine synthetase (ASNS) and L-asp-induced suppression of glutamine metabolism. In addition, samples from patients with EVI1⁺MF9 showed low ASNS expression, suggesting that it is a sensitive marker of L-asp treatment. Clarification of metabolic reprogramming in EVI1⁺ leukemia cells may aid development of treatments for EVI1⁺MF9 refractory leukemia.

Ecotropic viral integration site 1 regulates EGFR transcription in glioblastoma cells

Purpose

Ecotropic viral integration site-1 (EVI1) is a transcription factor that contributes to the unfavorable prognosis of leukemia, some epithelial cancers, and glial tumors. However, the biological function of EVI1 in glioblastoma multiforme (GBM) remains unclear. Based on microarray experiments, EVI1 has been reported to regulate epidermal growth factor receptor (EGFR) transcription. Signal transduction via EGFR plays an essential role in glioblastoma. Therefore, we performed this study to clarify the importance of EVI1 in GBM by focusing on the regulatory mechanism between EVI1 and EGFR transcription.

Methods

We performed immunohistochemical staining and analyzed the EVI1-expression in glioma tissue. To determine the relationship between EVI1 and EGFR, we induced siRNA-mediated knockdown of EVI1 in GBM cell lines. To investigate the region that was essential for the EVI1 regulation of EGFR expression, we conducted promoter reporter assays. We performed WST-8 assay to investigate whether EVI1 affected on the proliferation of GBM cells or not.

Results

It was observed that 22% of GBM tissues had over 33% of tumor cells expressing EVI1, whereas no lower-grade glioma tissue had over 33% by immunohistochemistry. In A172 and YKG1 cells, the expression levels of EGFR and EVI1 correlated. Analysis of the EGFR promoter region revealed that the EGFR promoter (from − 377 to − 266 bp) was essential for the EVI regulation of EGFR expression. We showed that EVI1 influenced the proliferation of A172 and YKG1 cells.

Conclusion

This is the first study reporting the regulation of EGFR transcription by EVI1 in GBM cells.

Electronic supplementary material

The online version of this article (10.1007/s11060-019-03310-z) contains supplementary material, which is available to authorized users.

Direct interaction between the PRDM3 and PRDM16 tumor suppressors and the NuRD chromatin remodeling complex

Aberrant isoform expression of chromatin-associated proteins can induce epigenetic programs related to disease. The MDS1 and EVI1 complex locus (MECOM) encodes PRDM3, a protein with an N-terminal PR-SET domain, as well as a shorter isoform, EVI1, lacking the N-terminus containing the PR-SET domain (ΔPR). Imbalanced expression of MECOM isoforms is observed in multiple malignancies, implicating EVI1 as an oncogene, while PRDM3 has been suggested to function as a tumor suppressor through an unknown mechanism. To elucidate functional characteristics of these N-terminal residues, we compared the protein interactomes of the full-length and ΔPR isoforms of PRDM3 and its closely related paralog, PRDM16. Unlike the ΔPR isoforms, both full-length isoforms exhibited a significantly enriched association with components of the NuRD chromatin remodeling complex, especially RBBP4. Typically, RBBP4 facilitates chromatin association of the NuRD complex by binding to histone H3 tails. We show that RBBP4 binds to the N-terminal amino acid residues of PRDM3 and PRDM16, with a dissociation constant of 3.0 μM, as measured by isothermal titration calorimetry. Furthermore, high-resolution X-ray crystal structures of PRDM3 and PRDM16 N-terminal peptides in complex with RBBP4 revealed binding to RBBP4 within the conserved histone H3-binding groove. These data support a mechanism of isoform-specific interaction of PRDM3 and PRDM16 with the NuRD chromatin remodeling complex.

CGRP-CRLR/RAMP1 signal is important for stress-induced hematopoiesis

Ecotropic viral integration site-1 (EVI1) has a critical role in normal and malignant hematopoiesis. Since we previously identified high expression of calcitonin receptor like receptor (CRLR) in acute myeloid leukemia (AML) with high EVI1 expression, we here characterized the function of CRLR in hematopoiesis. Since higher expression of CRLR and receptor activity modifying protein 1 (RAMP1) was identified in immature hematopoietic bone marrow (BM) cells, we focused on calcitonin gene-related peptide (CGRP), a specific ligand for the CRLR/RAMP1 complex. To elucidate the role of CGRP in hematopoiesis, Ramp1-deficient (Ramp1^-/-) mice were used. The steady-state hematopoiesis was almost maintained in Ramp1^-/- mice; however, the BM repopulation capacity of Ramp1^-/- mice was significantly decreased, and the transplanted Ramp1^-/- BM mononuclear cells had low proliferation capacity with enhanced reactive oxygen species (ROS) production and cell apoptosis. Thus, CGRP is important for maintaining hematopoiesis during temporal exposures with proliferative stress. Moreover, continuous CGRP exposure to mice for two weeks induced a reduction in the number of BM immature hematopoietic cells along with differentiated myeloid cells. Since CGRP is known to be increased under inflammatory conditions to regulate immune responses, hematopoietic exhaustion by continuous CGRP secretion under chronic inflammatory conditions is probably one of the important mechanisms of anti-inflammatory responses.

Nasopharyngeal carcinoma: understanding its molecular biology at a fine scale

Among all cancers, the incidence of nasopharyngeal carcinoma (NPC) is quite high in the endemic regions. NPC is a head and neck cancer with poor survival rate, and is rare throughout most of the world but common in certain geographic areas, like southern Asia and some regions of North East India (Nagaland, Manipur, and Mizoram). A clear understanding of its etiology is still lacking, but NPC is widely suspected to be the result of both genetic susceptibility and exposure to environmental factors or Epstein-Barr virus infection. Diagnosis in the early stages needs a high index of clinical acumen, and, although most cross-sectional imaging investigations show the tumor with precision, confirmation is dependent on histology. This article reviews all related research reports on NPC histopathological classifications worldwide that have been published within the past 20 years. Genome-wide association studies suggested that there might be common disease mechanisms between that disease and NPC. Personalized management rules, quality assessment of life in patients, and an understanding of the essential mechanisms of recurrence could be directed toward research into recurrent NPC. Hence, this literature would offer otolaryngologists a deeper insight into the etiological and management aspects of NPC.

EVI1 overexpression reprograms hematopoiesis via upregulation of Spi1 transcription

Inv(3q26) and t(3:3)(q21;q26) are specific to poor-prognosis myeloid malignancies, and result in marked overexpression of EVI1, a zinc-finger transcription factor and myeloid-specific oncoprotein. Despite extensive study, the mechanism by which EVI1 contributes to myeloid malignancy remains unclear. Here we describe a new mouse model that mimics the transcriptional effects of 3q26 rearrangement. We show that EVI1 overexpression causes global distortion of hematopoiesis, with suppression of erythropoiesis and lymphopoiesis, and marked premalignant expansion of myelopoiesis that eventually results in leukemic transformation. We show that myeloid skewing is dependent on DNA binding by EVI1, which upregulates Spi1, encoding master myeloid regulator PU.1. We show that EVI1 binds to the -14 kb upstream regulatory element (-14kbURE) at Spi1; knockdown of Spi1 dampens the myeloid skewing. Furthermore, deletion of the -14kbURE at Spi1 abrogates the effects of EVI1 on hematopoietic stem cells. These findings support a novel mechanism of leukemogenesis through EVI1 overexpression.

Suppression of GPR56 expression by pyrrole-imidazole polyamide represents a novel therapeutic drug for AML with high EVI1 expression

G protein-coupled receptor 56 (GPR56) is highly expressed in acute myeloid leukemia (AML) cells with high EVI1 expression (EVI1^high AML). Because GPR56 is a transcriptional target of EVI1 and silencing of GPR56 expression induces apoptosis, we developed a novel drug to suppress GPR56 expression in EVI1^high AML cells. For this purpose, we generated pyrrole-imidazole (PI) polyamides specific to GPR56 (PIP/56-1 or PIP/56-2) as nuclease-resistant novel compounds that interfere with the binding of EVI1 to the GPR56 promoter in a sequence-specific manner. Treatment of EVI1^high AML cell lines (UCSD/AML1 and Kasumi-3) with PIP/56-1 or PIP/56-2 effectively suppressed GPR56 expression by inhibiting binding of EVI1 to its promoter, leading to suppression of cell growth with increased rates of apoptosis. Moreover, intravenous administration of PIP/56-1 into immunodeficient Balb/c-RJ mice subcutaneously transplanted with UCSD/AML1 cells significantly inhibited tumor growth and extended survival. Furthermore, organ infiltration by leukemia cells in immunodeficient Balb/c-RJ mice, which were intravenously transplanted using UCSD/AML1 cells, was successfully inhibited by PIP/56-1 treatment with no apparent effects on murine hematopoietic cells. In addition, PIP treatment did not inhibit colony formation of human CD34⁺ progenitor cells. Thus, PI polyamide targeting of GPR56 using our compound is promising, useful, and safe for the treatment of EVI1^high AML.

JDP2: An oncogenic bZIP transcription factor in T cell acute lymphoblastic leukemia

A substantial subset of patients with T cell acute lymphoblastic leukemia (T-ALL) develops resistance to steroids and succumbs to their disease. JDP2 encodes a bZIP protein that has been implicated as a T-ALL oncogene from insertional mutagenesis studies in mice, but its role in human T-ALL pathogenesis has remained obscure. Here we show that JDP2 is aberrantly expressed in a subset of T-ALL patients and is associated with poor survival. JDP2 is required for T-ALL cell survival, as its depletion by short hairpin RNA knockdown leads to apoptosis. Mechanistically, JDP2 regulates prosurvival signaling through direct transcriptional regulation of MCL1. Furthermore, JDP2 is one of few oncogenes capable of initiating T-ALL in transgenic zebrafish. Notably, thymocytes from rag2:jdp2 transgenic zebrafish express high levels of mcl1 and demonstrate resistance to steroids in vivo. These studies establish JDP2 as a novel oncogene in high-risk T-ALL and implicate overexpression of MCL1 as a mechanism of steroid resistance in JDP2-overexpressing cells.

Human PRDM2: Structure, function and pathophysiology

PRDM2/RIZ is a member of a superfamily of histone/protein methyltransferases (PRDMs), which are characterized by the conserved N-terminal PR domain, with methyltransferase activity and zinc finger arrays at the C-terminus. Similar to other family members, two main protein types, known as RIZ1 and RIZ2, are produced from the PRDM2 locus differing by the presence or absence of the PR domain. The imbalance in their respective amounts may be an important cause of malignancy, with the PR-positive isoform commonly lost or downregulated and the PR-negative isoform always being present at higher levels in cancer cells. Interestingly, the RIZ1 isoform also represents an important target of estradiol action downstream of the interaction with hormone receptor. Furthermore, the imbalance between the two products could also be a molecular basis for other human diseases. Thus, understanding the molecular mechanisms underlying PRDM2 function could be useful in the pathophysiological context, with a potential to exploit this information in clinical practice.

Ecotropic viral integration site 1 promotes metastasis independent of epithelial mesenchymal transition in colon cancer cells

The most indecipherable component of solid cancer is the development of metastasis which accounts for more than 90% of cancer-related mortalities. A developmental program termed epithelial-mesenchymal transition (EMT) has also been shown to play a critical role in promoting metastasis in epithelium-derived solid tumors. By analyzing publicly available microarray datasets, we observed that ecotropic viral integration site 1 (EVI1) correlates negatively with SLUG, a master regulator of EMT. This correlation was found to be relevant as we demonstrated that EVI1 binds to SLUG promoter element directly through the distal set of zinc fingers and downregulates its expression. Many studies have shown that the primary role of SLUG during EMT and EMT-like processes is the regulation of cell motility in most of the cancer cells. Knockdown of EVI1 in metastatic colon cancer cell and subsequent passage through matrigel not only increased the invading capacity but also induced an EMT-like morphological feature of the cells, such as spindle-shaped appearance and led to a significant reduction in the expression of the epithelial marker, E-CADHERIN and increase in the expression of the mesenchymal marker, N-CADHERIN. The cells, when injected into immunocompromised mice, failed to show any metastatic foci in distant organs however the ones with EVI1, metastasized in the intraperitoneal layer and also showed multiple micro metastatic foci in the lungs and spleen. These findings suggest that in colon cancer EVI1 is dispensable for epithelial-mesenchymal transition, however, is required for metastasis.

Acute myeloid leukemia with t(3;21)(q26.2;q22) developing following low-dose methotrexate therapy for rheumatoid arthritis and expressing two AML1/MDS1/EVI1 fusion proteins: A case report

The t(3;21)(q26.2;q22) translocation is a rare chromosomal abnormality exhibited almost exclusively in therapy-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/AML) or in the blastic crisis phase of chronic myelogenous leukemia, which results in the fusion of the runt related transcription factor 1 (RUNX1, also called AML1) gene at 21q22 to the myelodysplasia syndrome 1 (MDS1)-ecotropic virus integration site 1 (EVI1) complex locus (MECOM) at 3q26.2, generating various fusion transcripts, including AML1/MDS1/EVI1 (AME). The present study examined the case of an 84-year-old Japanese woman who developed t-MDS/AML with t(3;21)(q26.2;q22) subsequent to receiving low-dose methotrexate (MTX) treatment for rheumatoid arthritis. Following treatment with MTX for 6 years, the patient developed anemia and neutropenia, and MTX was discontinued. A total of 3 years later, the patient was diagnosed with MDS with t(3;21)(q26.2;q22) and del (5q), which progressed rapidly to AML within 3 months. The patients was subsequently treated with azacitidine and cytarabine chemotherapy, but succumbed to the disease 6 months after diagnosis. Sequencing analysis of the nested reverse transcription-PCR products from the leukemic cells revealed the expression of two types of alternatively-spliced AME transcripts with or without RUNX1 exon 6 sequences. Western blot analysis of the leukemic cells of the patient additionally revealed that the corresponding AME fusion protein products were expressed at high levels, and that these cells also prominently expressed CCAAT/enhancer-binding protein α, the repression of which has been reported to be involved in leukemogenesis mediated by AME. To the best of our knowledge, the case discussed in the present study represents the first report of MDS/AML with t(3;21)(q26.2;q22) developing following low-dose MTX therapy for rheumatoid arthritis. Nonetheless, the clinical and molecular features of the patient in the present study were representative of those patients who typically develop this disease following exposure to chemotherapy or radiotherapy for primary malignancy, which implicates MTX in the pathogenesis of t-MDS/AML. Moreover, we confirmed the expression of two AME fusion proteins for the first time in primary leukemic cells and analyzed several cellular factors implicated in AME-mediated leukemogenesis to gain some insight into its molecular mechanisms.

The MDS and EVI1 complex locus (MECOM) isoforms regulate their own transcription and have different roles in the transformation of hematopoietic stem and progenitor cells

Transcriptional activation of the EVI1 oncogene (3q26) leads to aggressive forms of human acute myeloid leukemia (AML). However, the mechanism of EVI1-mediated leukemogenesis has not been fully elucidated. Previously, by characterizing the EVI1 promoter, we have shown that RUNX1 and ELK1 directly regulate EVI1 transcription. Intriguingly, bioinformatic analysis of the EVI1 promoter region identified the presence of several EVI1 potential binding sites. Thus, we hypothesized that EVI1 could bind to these sites regulating its own transcription. In this study, we show that there is a functional interaction between EVI1 and its promoter, and that the different EVI1 isoforms (EVI1-145kDa, EVI1-Δ324 and MDS1-EVI1) regulate the transcription of EVI1 transcripts through distinct promoter regions. Moreover, we determine that the EVI1-145kDa isoform activates EVI1 transcription, whereas EVI1-Δ324 and MDS1-EVI1 act as repressors. Finally, we demonstrate that these EVI1 isoforms are involved in cell transformation; functional experiments show that EVI1-145kDa prolongs the maintenance of hematopoietic stem and progenitor cells; conversely, MDS1-EVI1 repressed hematopoietic stem and progenitor colony replating capacity. We demonstrate for the first time that EVI1 acts as a regulator of its own expression, highlighting the complex regulation of EVI1, and open new directions to better understand the mechanisms of EVI1 overexpressing leukemias.

Activation of EVI1 transcription by the LEF1/β-catenin complex with p53-alteration in myeloid blast crisis of chronic myeloid leukemia

The presence of a BCR-ABL1 fusion gene is necessary for the pathogenesis of chronic myeloid leukemia (CML) through t(9;22)(q34;q11) translocation. Imatinib, an ABL tyrosine kinase inhibitor, is dramatically effective in CML patients; however, 30% of CML patients will need further treatment due to progression of CML to blast crisis (BC). Aberrant high expression of ecotropic viral integration site 1 (EVI1) is frequently observed in CML during myeloid-BC as a potent driver with a CML stem cell signature; however, the precise molecular mechanism of EVI1 transcriptional regulation during CML progression is poorly defined. Here, we demonstrate the transcriptional activity of EVI1 is dependent on activation of lymphoid enhancer-binding factor 1 (LEF1)/β-catenin complex by BCR-ABL with loss of p53 function during CML-BC. The activation of β-catenin is partly dependent on BCR-ABL expression through enhanced GSK3β phosphorylation, and EVI1 expression is directly enhanced by the LEF1/β-catenin complex bound to the EVI1 promoter region. Moreover, the loss of p53 expression is inversely correlated with high expression of EVI1 in CML leukemia cells with an aggressive phase of CML, and a portion of the activation mechanism of EVI1 expression is dependent on β-catenin activation through GSK3β phosphorylation by loss of p53. Therefore, we found that the EVI1 activation in CML-BC is dependent on LEF1/β-catenin activation by BCR-ABL expression with loss of p53 function, representing a novel selective therapeutic approach targeting myeloid blast crisis progression.

[EVI1 expression, clinical and cytogenetical characteristics in 447 patients with acute myeloid leukemia]

Objective: To investigate EVI1 expression and its associated clinical and cytogenetic characteristics in 447 acute myeloid leukemia (AML) patients. Methods: EVI1 expressions were measured in 447 AML cases from Jan. 2007 to Apr. 2015 to couple with clinical, cytogenetic and mutations' characteristics to summarize the features of AMLs with high EVI1 expression. Results: 17.9% of AML were high EVI1 expression (EVI1 +), and the remainder low EVI1 expression (EVI1-). No significant differences between the two groups in terms of age, sex, hemoglobin level, white blood cell count and platelet count were observed. More M0, M5 and M6 subtypes were observed in EVI1+ group (P= 0.027, 0.004 and 0.011, respectively). Cytogenetic abnormalities of 11q15, 11q23/MLL, 3q26, -7/7q- and t (9;11) were observed more frequently in EVI1 + group (P<0.001, <0.001, <0.001, <0.001, =0.014, respectively). Normal karyotype, inv (16), t (8;21) were observed more frequent in EVI1- group (P=0.001, 0.009, 0.002, respectively). EVI1 + was more observed in high risk cytogenetics. Mutation of NPM1 was more observed in EVI1- group (P <0.001). Remission rate in EVI1 + group was significantly lower than EVI1- group (P<0.001). Leukemia-free survival was improved in EVI1 + AML patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Conclusions: High EVI1 expression was more observed in FAB subgroup M5, harbored more cytogenetic abnormalities of 11p15, 11q23/MLL, 3q26 rearrangement, -7/7q- and t (9;11). Remission rate of high EVI1 expression AML was lower, which could be improved by allo-HSCT.

Insights into the role of reactive sulfhydryl groups of Carbonic Anhydrase III and VII during oxidative damage

Carbonic anhydrases (CAs) III and VII are two cytosolic isoforms of the α-CA family which catalyze the physiological reaction of carbon dioxide hydration to bicarbonate and proton. Despite these two enzymes share a 49% sequence identity and present a very similar three-dimensional structure, they show profound differences when comparing the specific activity for CO₂ hydration reaction, with CA VII being much more active than CA III. Recently, CA III and CA VII have been proposed to play a new role as scavenger enzymes in cells where oxidative damage occurs. Here, we will examine functional and structural features of these two isoforms giving insights into their newly proposed protective role against oxidative stress.

The New Clinicopathologic and Molecular Findings in Myeloid Neoplasms With inv(3)(q21q26)/t(3;3)(q21;q26.2)

Context.—

Inv(3)(q21q26)/t(3;3)(q21;q26.2) is the most common form of genetic abnormality of the so-called 3q21q26 syndrome. Myeloid neoplasms with 3q21q26 aberrancies include acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and blast crisis of myeloproliferative neoplasms. Recent advances on myeloid neoplasms with inv(3)/t(3;3) with regard to clinicopathologic features and novel molecular or genomic findings warrant a comprehensive review on this topic.

Objective.—

To review the clinicopathologic features and molecular as well as genomic alterations in myeloid neoplasms with inv(3)/t(3;3).

Data Sources.—

The data came from published articles in English-language literature.

Conclusions.—

At the clinicopathologic front, recent studies on MDS with inv(3)/t(3;3) have highlighted their overlapping clinicopathologic features with and similar overall survival to that of inv(3)/t(3;3)-harboring AML regardless of the percentage of myeloid blasts. On the molecular front, AML and MDS with inv(3)/t(3;3) exhibit gene mutations, which affect the RAS/receptor tyrosine kinase pathway. Furthermore, functional genomic studies using genomic editing and genome engineering have shown that the reallocation of the GATA2 distal hematopoietic enhancer to the proximity of the promoter of ectopic virus integration site 1 (EVI1) without the formation of a new oncogenic fusion transcript is the molecular mechanism underlying these inv(3)/t(3;3) myeloid neoplasms. Although the AML and MDS with inv(3)/t(3;3) are listed as a separate category of myeloid malignancies in the 2008 World Health Organization classification, the overlapping clinicopathologic features, similar overall survival, and identical patterns at the molecular and genomic levels between AML and MDS patients with inv(3)/t(3;3) may collectively favor a unification of AML and MDS with inv(3)/t(3;3) as AML or myeloid neoplasms with inv(3)/t(3;3) regardless of the blast count.

EVI1 Interferes with Myeloid Maturation via Transcriptional Repression of Cebpa, via Binding to Two Far Downstream Regulatory Elements

One mechanism by which oncoproteins work is through perturbation of cellular maturation; understanding the mechanisms by which this occurs can lead to the development of targeted therapies. EVI1 is a zinc finger oncoprotein involved in the development of acute myeloid leukemia; previous work has shown it to interfere with the maturation of granulocytes from immature precursors. Here we investigate the mechanism by which that occurs, using an immortalized hematopoietic progenitor cell line, EML-C1, as a model system. We document that overexpression of EVI1 abrogates retinoic acid-induced maturation of EML cells into committed myeloid cells, a process that can be documented by the down-regulation of stem cell antigen-1 and acquisition of responsiveness to granulocyte-macrophage colony-stimulating factor. We show that this requires DNA binding capacity of EVI1, suggesting that downstream target genes are involved. We identify the myeloid regulator Cebpa as a target gene and identify two EVI1 binding regions within evolutionarily conserved enhancer elements at +35 and +37 kb relative to the gene. EVI1 can strongly suppress Cebpa transcription, and add-back of Cebpa into EVI1-expressing EML cells partially corrects the block in maturation. We identify the DNA sequences to which EVI1 binds at +35 and +37 kb and show that mutation of one of these releases Cebpa from EVI1-induced suppression. We observe a more complex picture in primary bone marrow cells, where EVI1 suppresses Cebpa in stem cells but not in more committed progenitors. Our data thus identify a regulatory node by which EVI1 contributes to leukemia, and this represents a possible therapeutic target for treatment of EVI1-expressing leukemia.

Predictive value of high EVI1 expression in AML patients undergoing myeloablative allogeneic hematopoietic stem cell transplantation in first CR

The EVI1 gene is a transcriptional regulator of hematopoietic stem cell self renewal and its overexpression is associated with adverse prognosis in de novo AML. Whether the overexpression of EVI1 also predicts poor outcome of AML patients undergoing myeloablative allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first CR (CR1) is still unclear. Thirty-two (21.2%) out of 151 patients were categorized as high EVI1 expression (EVI1+), and 119 (78.8%) patients were categorized as low EVI1 expression (EVI1-). The frequency of EVI1+ was much higher in the adverse-risk group than the intermediate-risk group (53% vs 19%, P=0.005). EVI1+ patients were significantly likely to harbor with translocations involving the MLL gene on 11q23 (8/9). Significantly poor results were observed in the EVI1+ cohort in terms of leukemia-free survival (LFS) (in 24 months 52.6 vs 71.0%, P=0.027), overall survival (OS) (in 24 months 52.8 vs 72.4%, P=0.012), and cumulative incidence of relapse (in 24 months 39.5 vs 22.5%, P=0.013). Multivariable analysis revealed that low EVI1 expression as an independent prognostic factor favoring LFS (hazards ratio=0.47, 95% confidence interval 0.26-0.86, P=0.01) but not OS. Our results indicate high EVI1 expression might predict high risk of relapse in AML patients undergoing myeloablative allo-HSCT in CR1.

Expression of MECOM is associated with unfavorable prognosis in glioblastoma multiforme

Background

MDS1 and EVI1 complex locus protein EVI1 (MECOM) is an oncogenic transcription factor in several kinds of cancers. However, the clinical significance of MECOM in glioblastoma multiforme (GBM) has not been well elucidated.

Patients and methods

Our study enrolled 86 resected samples of GBM in three medical centers. We detected the expression of MECOM in all the 86 samples by immunohistochemistry and compared the difference of MECOM mRNA between tumor tissues and adjacent tissues with real-time polymerase chain reaction. With immunoblotting, we detected the MECOM expression in different GBM cell lines. Moreover, we analyzed the correlation between MECOM expression and clinicopathologic factors with chi-square test, and evaluated the prognostic value of MECOM with univariate and multivariate analysis.

Results

In GBM tissue, the percentage of MECOM high expression is 41.9% (36/86). The mRNA of MECOM in tumor tissues is remarkably higher than that in adjacent tissues, indicating the oncogenic role of MECOM in GBM. MECOM exists in all the detected cell lines with different abundance. Moreover, MECOM is correlated with poorer overall survival rate (P=0.033) and can be identified as an independent prognostic factor in GBM (P=0.042).

Conclusion

MECOM could be considered as an independent prognostic factor in GBM, predicting it as a potential and promising molecular drug target.

Review: Aberrant EVI1 expression in acute myeloid leukaemia

Deregulated expression of the ecotropic virus integration site 1 (EVI1) gene is the molecular hallmark of therapy-resistant myeloid malignancies bearing chromosomal inv(3)(q21q26·2) or t(3;3)(q21;q26·2) [hereafter referred to as inv(3)/t(3;3)] abnormalities. EVI1 is a haematopoietic stemness and transcription factor with chromatin remodelling activity. Interestingly, the EVI1 gene also shows overexpression in 6-11% of adult acute myeloid leukaemia (AML) cases that do not carry any 3q aberrations. Deregulated expression of EVI1 is strongly associated with monosomy 7 and 11q23 abnormalities, which are known to be associated with poor response to treatment. However, EVI1 overexpression has been revealed as an important independent adverse prognostic marker in adult AML and defines distinct risk categories in 11q23-rearranged AML. Recently, important progress has been made in the delineation of the mechanism by which EVI1 becomes deregulated in inv(3)/t(3;3) as well as the cooperating mutations in this specific subset of AML with dismal prognosis.

Mutations in MECOM, Encoding Oncoprotein EVI1, Cause Radioulnar Synostosis with Amegakaryocytic Thrombocytopenia

Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) is an inherited bone marrow failure syndrome, characterized by thrombocytopenia and congenital fusion of the radius and ulna. A heterozygous HOXA11 mutation has been identified in two unrelated families as a cause of RUSAT. However, HOXA11 mutations are absent in a number of individuals with RUSAT, which suggests that other genetic loci contribute to RUSAT. In the current study, we performed whole exome sequencing in an individual with RUSAT and her healthy parents and identified a de novo missense mutation in MECOM, encoding EVI1, in the individual with RUSAT. Subsequent analysis of MECOM in two other individuals with RUSAT revealed two additional missense mutations. These three mutations were clustered within the 8(th) zinc finger motif of the C-terminal zinc finger domain of EVI1. Chromatin immunoprecipitation and qPCR assays of the regions harboring the ETS-like motif that is known as an EVI1 binding site showed a reduction in immunoprecipitated DNA for two EVI1 mutants compared with wild-type EVI1. Furthermore, reporter assays showed that MECOM mutations led to alterations in both AP-1- and TGF-β-mediated transcriptional responses. These functional assays suggest that transcriptional dysregulation by mutant EVI1 could be associated with the development of RUSAT. We report missense mutations in MECOM resulting in a Mendelian disorder that provide compelling evidence for the critical role of EVI1 in normal hematopoiesis and in the development of forelimbs and fingers in humans.

Azacitidine treatment for patients with myelodysplastic syndrome and acute myeloid leukemia with chromosome 3q abnormalities

Acute Myeloid Leukemia (AML) and myelodysplasia (MDS) with chromosome 3q abnormalities have a dismal outcome either untreated or with conventional treatments. Azacitidine (AZA) is now considered as the standard of care in high-risk MDS and oligoblastic AML patients. The objective of this study was to evaluate the impact of azacitine treatment in this cytogenetic subgroup. We report here a multicentre retrospective study of 157 patients treated with AZA for AML/MDS with chromosome 3q abnormalities and 27 patients with isolated EVI-1 overexpression. Median age was 65 years, 40 patients (25%) had inv(3)(q21q26.2) or t(3;3)(q21;q26.2), 36 patients (23%) had other balanced 3q26 rearrangements, 8 patients (5%) had balanced 3q21 rearrangements and 73 patients (46%) had other 3q abnormalities. The overall response rate was 50% (29% CR). Median overall survival was 10.6 months. By multivariate analysis, patients with lower bone marrow blast counts, higher platelet counts, non-complex cytogenetics, and absence of prior treatment with intensive chemotherapy had a better outcome. 27 patients were allo-transplanted and achieved a 21-month median OS. Balanced 3q21 translocations were associated with a better response rate and overall survival. Outcome of patients with isolated EVI-1 overexpression was comparable to that of patients with chromosome 3q lesions. Thus, AML/MDS patients with 3q abnormalities appear to be a heterogeneous group in their response to AZA, and AZA may represent a suitable option in particular as a bridge to allogeneic transplantation.

The oncogene EVI1 enhances transcriptional and biological responses of human myeloid cells to all-trans retinoic acid

The product of the ecotropic virus integration site 1 (EVI1) gene, whose overexpression is associated with a poor prognosis in myeloid leukemias and some epithelial tumors, regulates gene transcription both through direct DNA binding and through modulation of the activity of other sequence specific transcription factors. Previous results from our laboratory have shown that EVI1 influenced transcription regulation in response to the myeloid differentiation inducing agent, all-trans retinoic acid (ATRA), in a dual manner: it enhanced ATRA induced transcription of the RARβ gene, but repressed the ATRA induction of the EVI1 gene itself. In the present study, we asked whether EVI1 would modulate the ATRA regulation of a larger number of genes, as well as biological responses to this agent, in human myeloid cells. U937 and HL-60 cells ectopically expressing EVI1 through retroviral transduction were subjected to microarray based gene expression analysis, and to assays measuring cellular proliferation, differentiation, and apoptosis. These experiments showed that EVI1 modulated the ATRA response of several dozens of genes, and in fact reinforced it in the vast majority of cases. A particularly strong synergy between EVI1 and ATRA was observed for GDF15, which codes for a member of the TGF-β superfamily of cytokines. In line with the gene expression results, EVI1 enhanced cell cycle arrest, differentiation, and apoptosis in response to ATRA, and knockdown of GDF15 counteracted some of these effects. The potential clinical implications of these findings are discussed.

Chronic neutrophilic leukemia with overexpression of EVI-1, and concurrent CSF3R and SETBP1 mutations: A case report

Chronic neutrophilic leukemia (CNL) is a rare type of myeloproliferative neoplasm, characterized by sustained neutrophilia, splenomegaly, bone marrow granulocytic hyperplasia (without evidence of dysplasia) and an absence of the Philadelphia chromosome. Thus far, ~150 cases of CNL have been described in the literature; however, none have demonstrated overexpression of the ecotropic viral integration site-1 (EVI-1, also known as MECOM) gene. The present study describes a case that fulfilled the World Health Organization diagnostic criteria for CNL, and was associated with overexpression of EVI-1, as well as novel concurrent mutations of colony stimulating factor 3 receptor (CSF3R) and SET binding protein-1 (SETBP1). In addition, the current study briefly reviewed the relevant literature regarding novel genetic findings associated with the diagnosis and treatment of CNL. To the best of our knowledge, this is the first case report of CNL with associated EVI-1 overexpression, and concurrent CSF3R and SETBP1 mutations.

Epstein-Barr virus BALF3 mediates genomic instability and progressive malignancy in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer prevalent throughout Southern China and Southeast Asia. Patient death following relapse after primary treatment remains all too common but the cause of NPC relapse is unclear. Clinical and epidemiological studies have revealed the high correlation among NPC development, Epstein-Barr virus (EBV) reactivation and host genomic instability. Previously, recurrent EBV reactivation was shown to cause massive genetic alterations and enhancement of tumor progression in NPC cells and these may be required for NPC relapse. Here, EBV BALF3 has the ability to induce micronuclei and DNA strand breaks. After recurrent expression of BALF3 in NPC cells, genomic copy number aberrations, determined by array-based comparative genomic hybridization, had accumulated to a significant extent and tumorigenic features, such as cell migration, cell invasion and spheroid formation, increased with the rounds of induction. In parallel experiments, cells after highly recurrent induction developed into larger tumor nodules than control cells when inoculated into NOD/SCID mice. Furthermore, RNA microarrays showed that differential expression of multiple cancer capability-related genes and oncogenes increased with recurrent BALF3 expression and these changes correlated with genetic aberrations. Therefore, EBV BALF3 is a potential factor that mediates the impact of EBV on NPC relapse.

EVI1, a target gene for amplification at 3q26, antagonizes transforming growth factor-β-mediated growth inhibition in hepatocellular carcinoma

EVI1 (ecotropic viral integration site 1) is one of the most aggressive oncogenes associated with myeloid leukemia. We investigated DNA copy number aberrations in human hepatocellular carcinoma (HCC) cell lines using a high-density oligonucleotide microarray. We found that a novel amplification at the chromosomal region 3q26 occurs in the HCC cell line JHH-1, and that MECOM (MDS1 and EVI1 complex locus), which lies within the 3q26 region, was amplified. Quantitative PCR analysis of the three transcripts transcribed from MECOM indicated that only EVI1, but not the fusion transcript MDS1-EVI1 or MDS1, was overexpressed in JHH-1 cells and was significantly upregulated in 22 (61%) of 36 primary HCC tumors when compared with their non-tumorous counterparts. A copy number gain of EVI1 was observed in 24 (36%) of 66 primary HCC tumors. High EVI1 expression was significantly associated with larger tumor size and higher level of des-γ-carboxy prothrombin, a tumor marker for HCC. Knockdown of EVI1 resulted in increased induction of the cyclin-dependent kinase inhibitor p15(INK) (4B) by transforming growth factor (TGF)-β and decreased expression of c-Myc, cyclin D1, and phosphorylated Rb in TGF-β-treated cells. Consequently, knockdown of EVI1 led to reduced DNA synthesis and cell viability. Collectively, our results suggest that EVI1 is a probable target gene that acts as a driving force for the amplification at 3q26 in HCC and that the oncoprotein EVI1 antagonizes TGF-β-mediated growth inhibition of HCC cells.

A murine model of acute myeloid leukemia with Evi1 overexpression and autocrine stimulation by an intracellular form of GM-CSF in DA-3 cells

The poor treatment response of acute myeloid leukemia (AML) overexpressing high-risk oncogenes such as EVI1, demands specific animal models for new treatment evaluations. Evi1 is a common site of activating integrations in murine leukemia virus (MLV)-induced AML and in retroviral and lentiviral gene-modified HCS. Still, a model of overt AML induced by Evi1 has not been generated. Cell lines from MLV-induced AML are growth factor-dependent and non-transplantable. Hence, for the leukemia maintenance in the infected animals, a growth factor source such as chronic immune response has been suggested. We have investigated whether these leukemias are transplantable if provided with growth factors. We show that the Evi1(+)DA-3 cells modified to express an intracellular form of GM-CSF, acquired growth factor independence and transplantability and caused an overt leukemia in syngeneic hosts, without increasing serum GM-CSF levels. We propose this as a general approach for modeling different forms of high-risk human AML using similar cell lines.