Limb development genes underlie variation in human fingerprint patterns.

Fingerprints are of long-standing practical and cultural interest, but little is known about the mechanisms that underlie their variation. Using genome-wide scans in Han Chinese cohorts, we identified 18 loci associated with fingerprint type across the digits, including a genetic basis for the long-recognized "pattern-block" correlations among the middle three digits. In particular, we identified a variant near EVI1 that alters regulatory activity and established a role for EVI1 in dermatoglyph patterning in mice. Dynamic EVI1 expression during human development supports its role in shaping the limbs and digits, rather than influencing skin patterning directly. Trans-ethnic meta-analysis identified 43 fingerprint-associated loci, with nearby genes being strongly enriched for general limb development pathways. We also found that fingerprint patterns were genetically correlated with hand proportions. Taken together, these findings support the key role of limb development genes in influencing the outcome of fingerprint patterning.

PRDM paralogs antagonistically balance Wnt/ß-catenin activity during craniofacial chondrocyte differentiation.

Cranial neural crest cell (NCC)-derived chondrocyte precursors undergo a dynamic differentiation and maturation process to establish a scaffold for subsequent bone formation, alterations in which contribute to congenital birth defects. Here, we demonstrate that transcription factor and histone methyltransferase proteins Prdm3 and Prdm16 control the differentiation switch of cranial NCCs to craniofacial cartilage. Loss of either paralog results in hypoplastic and disorganized chondrocytes due to impaired cellular orientation and polarity. We show that these proteins regulate cartilage differentiation by controlling the timing of Wnt/ß-catenin activity in strikingly different ways: Prdm3 represses whereas Prdm16 activates global gene expression, although both act by regulating Wnt enhanceosome activity and chromatin accessibility. Finally, we show that manipulating Wnt/ß-catenin signaling pharmacologically or generating prdm3-/-;prdm16-/- double mutants rescues craniofacial cartilage defects. Our findings reveal upstream regulatory roles for Prdm3 and Prdm16 in cranial NCCs to control Wnt/ß-catenin transcriptional activity during chondrocyte differentiation to ensure proper development of the craniofacial skeleton.

Promoter-centred chromatin interactions associated with EVI1 expression in EVI1+3q- myeloid leukaemia cells.

EVI1 expression is associated with poor prognosis in myeloid leukaemia, which can result from Chr.3q alterations that juxtapose enhancers to induce EVI1 expression via long-range chromatin interactions. More often, however, EVI1 expression occurs unrelated to 3q alterations, and it remained unclear if, in these cases, EVI1 expression is similarly caused by aberrant enhancer activation. Here, we report that, in EVI1+3q- myeloid leukaemia cells, the EVI1 promoter interacts via long-range chromatin interactions with promoters of distally located, active genes, rather than with enhancer elements. Unlike in 3q+ cells, EVI1 expression and long-range interactions appear to not depend on CTCF/cohesin, though EVI1+3q- cells utilise an EVI1 promoter-proximal site to enhance its expression that is also involved in CTCF-mediated looping in 3q+ cells. Long-range interactions in 3q- cells connect EVI1 to promoters of multiple genes, whose transcription correlates with EVI1 in EVI1+3q- cell lines, suggesting a shared mechanism of transcriptional regulation. In line with this, CRISPR interference-induced silencing of two of these sites minimally, but consistently reduced EVI1 expression. Together, we provide novel evidence of features associated with EVI1 expression in 3q- leukaemia and consolidate the view that EVI1 in 3q- leukaemia is largely promoter-driven, potentially involving long-distance promoter clustering.

Aberrant ecotropic viral integration site-1 (EVI-1) and myocyte enhancer factor 2 C gene (MEF2C) in adult acute myeloid leukemia are associated with adverse t (9:22) & 11q23 rearrangements.

Acute myeloid leukemia (AML) shows multiple chromosomal translocations & point mutations which can be used to refine risk-adapted therapy in AML patients. Ecotropic viral integration site-1 (EVI-1) & myocyte enhancer factor 2 C gene (MEF2C) are key regulatory transcription factors in hematopoiesis and leukemogenesis & both drive immune escape. This prospective study involved 80 adult de novo AML patients recruited from Oncology Center, Mansoura University, between March 2019 and July 2021. The MEF2C and EVI1 expression were measured using a Taqman probe-based qPCR assay. The results revealed that EVI1 and MEF2C expression were significantly elevated in AML patients as compared to control subjects (p = 0.001. 0.007 respectively). Aberrant expressions of EVI1 and MEF2C showed a significant negative correlation with hemoglobin levels (p = 0.034, 0.025 respectively), & bone marrow blasts (p = 0.007, 0.002 respectively). 11q23 translocation was significantly associated with EVI1 and MEF2C (p = 0.004 and 0.02 respectively). Also, t (9;22) was significantly associated with EVI1 and MEF2C (p = 0.01 and 0.03 respectively), higher expression of EVI1 and MEF2C were significantly associated with inferior outcome after induction therapy (p = 0.001 and 0.018 respectively) and shorter overall survival (p = 0.001, 0.014 respectively). In conclusion, EVI1 & MEF2C were significantly expressed in AML cases. EVI1 & MEF2C overexpression were significantly associated with 11q23 rearrangements and t (9;22) and were indicators for poor outcome in adult AML patients; These results could be a step towards personalized therapy in those patients.

A novel missense mutation in the MECOM gene in a Chinese boy with radioulnar synostosis with amegakaryocytic thrombocytopenia.

Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) type 2, caused by MDS1 and EVI1 complex locus (MECOM) gene mutations, is a rare inherited bone marrow failure syndrome (IBMFS) with skeletal anomalies, characterized by varying presentation of congenital thrombocytopenia (progressing to pancytopenia), bilateral proximal radioulnar synostosis, and other skeletal abnormalities. Due to limited knowledge and heterogenous manifestations, clinical diagnosis of the disease is challenging. Here we reported a novel MECOM mutation in a Chinese boy with typical clinical features for RUSAT-2. Trio-based whole exome sequencing of buccal swab revealed a novel heterozygous missense mutation in exon 11 of the MECOM gene (chr3:168818673; NM_001105078.3:c.2285G > A). The results strongly suggest that the variant was a germline mutation and disease-causing mutation. The patient received matched unrelated donor hematopoetic stem cell transplantation (HSCT). This finding was not only expanded the pathogenic mutation spectrum of MECOM gene, but also provided key information for clinical diagnosis and treatment of RUSAT-2.

A novel mutation in MECOM affects MPL regulation in vitro and results in thrombocytopenia and bone marrow failure.

MECOM-associated syndrome (MECOM-AS) is a rare disease characterized by amegakaryocytic thrombocytopenia, progressive bone marrow failure, pancytopenia and radioulnar synostosis with high penetrance. The clinical phenotype may also include finger malformations, cardiac and renal alterations, hearing loss, B-cell deficiency and predisposition to infections. The syndrome, usually diagnosed in the neonatal period because of severe thrombocytopenia, is caused by mutations in the MECOM gene, encoding for the transcription factor EVI1. The mechanism linking the alteration of EVI1 function and thrombocytopenia is poorly understood. In a paediatric patient affected by severe thrombocytopenia, we identified a novel variant of the MECOM gene (p.P634L), whose effect was tested on pAP-1 enhancer element and promoters of targeted genes showing that the mutation impairs the repressive activity of the transcription factor. Moreover, we demonstrated that EVI1 controls the transcriptional regulation of MPL, a gene whose mutations are responsible for congenital amegakaryocytic thrombocytopenia (CAMT), potentially explaining the partial overlap between MECOM-AS and CAMT.

Clinical features and prognostic implications of ecotropic viral integration site 1 (EVI1) in childhood acute lymphoblastic leukemia.

In contrast to the extensive knowledge on EVI1 in myeloid malignancies, few data are available on the EVI1 transcript in pediatric ALL. The purpose of this study was to examine the clinical and biological significance of EVI1 and validate its prognostic significance in pediatric patients with ALL. Here, we examined the clinical and biological significance of EVI1 expression, as measured by real-time polymerase chain reaction (PCR) in 837 children with newly diagnosed ALL treated on the National Protocol of Childhood Leukemia in China (NPCLC)-ALL-2008 protocol, and aimed to explore their prognostic significance in pediatric ALL patients. The EVI1 expression was detected in 27 of 837 (3.2%) patients. No statistically significant differences in prednisone response, complete remission (CR) rates and relapse rates were found between EVI1 overexpression (EVI1+) group and EVI1- group. Moreover, we found no significant difference in event-free survival (EFS) and overall survival (OS) between these two groups, also multivariate analysis did not identify EVI1+ as an independent prognostic factor. In the subgroup analysis, there was no difference in clinical outcome between EVI1+ and EVI1- patients in standard­risk (SR), intermediate-risk (IR) and high-risk (HR) groups. In the minimal residual disease (MRD)<10-4 group, EVI1+ patients have significantly lower EFS and OS rates compared to EVI1- patients. Further large­scale and well­designed prospective studies are required to confirm the results in the future.

[The role of SF3B1 mutations in EVI1-rearranged myeloid neoplasms].

In acute myeloid leukemia (AML), EVI1 rearrangement represented by inv(3)(q21q26) or t(3;3)(q21;q26) causes EVI1 overexpression via structural rearrangement of an enhancer, and confers poor prognosis. My colleagues and I performed a mutational analysis of EVI1-rearranged myeloid neoplasms and identified SF3B1, a core RNA splicing factor, as the most commonly co-mutated gene. Indeed, latent leukemia development in transgenic mice bearing the humanized inv(3)(q21q26) allele was significantly accelerated by co-occurrence of Sf3b1 mutation. Intriguingly, we found that this SF3B1 mutant induced mis-splicing of EVI1 itself, which generated an aberrant EVI1 isoform with in-frame insertion of 6 amino acids near the DNA-binding domain of EVI1. This aberrant EVI1 isoform exhibited DNA-binding activity different from wild-type EVI1 and significantly enhanced the self-renewal capacity of murine hematopoietic stem cells. We also identified the cryptic branch point and exonic splicing enhancer required for this EVI1 mis-splicing induced by the SF3B1 mutant. These data provide a basis for further elucidation of the molecular mechanism and potential therapeutic candidates for EVI1-rearranged AML.

EVI1 expression in early-stage breast cancer patients treated with neoadjuvant chemotherapy.

BACKGROUND: Overexpression of the EVI1 (ecotropic viral integration site 1) oncogene has recently been implicated as a prognostic factor in breast cancer (BC), particularly in triple-negative BC (TNBC). In this study we aimed to investigate frequency and clinical relevance of EVI1 expression in newly diagnosed BC treated with neoadjuvant chemotherapy. METHODS: EVI1 expression was determined by immunohistochemistry using H-score as a cumulative measurement of protein expression in pretherapeutic biopsies of BC patients treated with anthracycline/taxane based neoadjuvant chemotherapy within the GeparTrio trial. EVI1 was analyzed as a continuous variable and dichotomized into low or high based on median expression. Endpoints were pathological complete response (pCR), disease-free survival (DFS) and overall survival (OS). RESULTS: Of the 993 tumors analyzed, 882 had available subtype information: 50.8% were HR + /HER2-, 15% HR + /HER2 + , 9.8% HR-/HER2 + , and 24.5% TNBC. Median EVI1 H-score was 112.16 (range 0.5-291.4). High EVI1 expression was significantly associated with smaller tumor size (p = 0.002) but not with BC subtype. Elevated EVI1 levels were not significantly associated with therapy response and survival in the entire cohort or within BC subtypes. However, TNBC patients with high EVI1 showed a trend towards increased pCR rates compared to low group (37.7% vs 27.5%, p = 0.114; odds ratio 1.60 (95%CI 0.90-2.85, p = 0.110) and numerically better DFS (HR = 0.77 [95%CI 0.48-1.23], log-rank p = 0.271) and OS (HR = 0.76 [95% 0.44-1.31], log-rank p = 0.314) without reaching statistical significance. CONCLUSION: EVI1 was not associated with response to neoadjuvant therapy or patient survival in the overall cohort. Further analyses are needed to verify our findings especially in the pathological work-up of early-stage HER2-negative BC patients. TRIAL REGISTRATION: NCT00544765.

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 .

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.

Study of mRNA of WT1, BAALC, EVI1, PRAME and HMGA2 genes in whole blood samples.

Simultaneous quantitative measurement of mRNA of the WT1, BAALC, EVI1, PRAME and HMGA2 genes in whole blood samples reflects the specific pathological proliferative activity in acute leukemia and their ratio is promising as a diagnostic marker. The transcriptome profile of acute leukemia cells is usually assessed using NGS or microarray techniques after a preliminary procedure for isolation of mononuclear cells. However, the results of using the multiplex PCR reaction for the simultaneous determination of all above mRNAs in whole blood samples have not been published so far. Determination of mRNA of WT1, BAALC, EVI1, PRAME and HMGA2 genes in venous blood level samples by multiplex RT-PCR. The study included 127 blood samples from patients who diagnosis of acute leukemia was subsequently confirmed. In the comparison group, 87 samples of patients without oncohematological diagnosis were selected, including 31 samples (K1) with a normal blood formula and 56 samples (K2) with a violation of the cellular composition - anemia, leukocytosis and thrombocytopenia. RNA isolation and reverse transcription were performed using the Ribozol-D and Reverta-L kits (TsNIIE, Russia). Determination of the mRNA expression level of the WT1, BAALC, EVI1, PRAME and HMGA2 genes by multiplex real-time PCR using a homemade multiplex PCR kit. The mRNA level was characterized by high interindividual variation and did not correlate with the rate of circulating leukocytes or blood blasts. Expression of WT1 mRNA was observed in whole blood only in one patient from the control group and in 112 (88%) patients with leukemia and was combined with a decrease in the level of HMGA2 mRNA expression and BAALC mRNA values. In contrast to the control groups, patients with leukemia had higher levels of BAALC mRNA in AML and ALL, increased PRAME mRNA in AML and APL, but lower levels of HMGA2 in APL.

The conserved and divergent roles of Prdm3 and Prdm16 in zebrafish and mouse craniofacial development.

The formation of the craniofacial skeleton is a highly dynamic process that requires proper orchestration of various cellular processes in cranial neural crest cell (cNCC) development, including cell migration, proliferation, differentiation, polarity and cell death. Alterations that occur during cNCC development result in congenital birth defects and craniofacial abnormalities such as cleft lip with or without cleft palate. While the gene regulatory networks facilitating neural crest development have been extensively studied, the epigenetic mechanisms by which these pathways are activated or repressed in a temporal and spatially regulated manner remain largely unknown. Chromatin modifiers can precisely modify gene expression through a variety of mechanisms including histone modifications such as methylation. Here, we investigated the role of two members of the PRDM (Positive regulatory domain) histone methyltransferase family, Prdm3 and Prdm16 in craniofacial development using genetic models in zebrafish and mice. Loss of prdm3 or prdm16 in zebrafish causes craniofacial defects including hypoplasia of the craniofacial cartilage elements, undefined posterior ceratobranchials, and decreased mineralization of the parasphenoid. In mice, while conditional loss of Prdm3 in the early embryo proper causes mid-gestation lethality, loss of Prdm16 caused craniofacial defects including anterior mandibular hypoplasia, clefting in the secondary palate and severe middle ear defects. In zebrafish, prdm3 and prdm16 compensate for each other as well as a third Prdm family member, prdm1a. Combinatorial loss of prdm1a, prdm3, and prdm16 alleles results in severe hypoplasia of the anterior cartilage elements, abnormal formation of the jaw joint, complete loss of the posterior ceratobranchials, and clefting of the ethmoid plate. We further determined that loss of prdm3 and prdm16 reduces methylation of histone 3 lysine 9 (repression) and histone 3 lysine 4 (activation) in zebrafish. In mice, loss of Prdm16 significantly decreased histone 3 lysine 9 methylation in the palatal shelves but surprisingly did not change histone 3 lysine 4 methylation. Taken together, Prdm3 and Prdm16 play an important role in craniofacial development by maintaining temporal and spatial regulation of gene regulatory networks necessary for proper cNCC development and these functions are both conserved and divergent across vertebrates.

Evi1 regulates Notch activation to induce zebrafish hematopoietic stem cell emergence.

During development, hematopoietic stem cells (HSCs) emerge from aortic endothelial cells (ECs) through an intermediate stage called hemogenic endothelium by a process known as endothelial-to-hematopoietic transition (EHT). While Notch signaling, including its upstream regulator Vegf, is known to regulate this process, the precise molecular control and temporal specificity of Notch activity remain unclear. Here, we identify the zebrafish transcriptional regulator evi1 as critically required for Notch-mediated EHT In vivo live imaging studies indicate that evi1 suppression impairs EC progression to hematopoietic fate and therefore HSC emergence. evi1 is expressed in ECs and induces these effects cell autonomously by activating Notch via pAKT Global or endothelial-specific induction of notch, vegf, or pAKT can restore endothelial Notch and HSC formations in evi1 morphants. Significantly, evi1 overexpression induces Notch independently of Vegf and rescues HSC numbers in embryos treated with a Vegf inhibitor. In sum, our results unravel evi1-pAKT as a novel molecular pathway that, in conjunction with the shh-vegf axis, is essential for activation of Notch signaling in VDA endothelial cells and their subsequent conversion to HSCs.

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.

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.

Inhibitory effect of CP-25 on intimal formation and vascular hyperplasia via suppression of GRK2/ERK1/2/EVI1 signaling.

Excessive proliferation, migration and dedifferentiation of vascular smooth muscle cells (VSMCs) are the center of intimal formation during in-stent restenosis and vein graft disease. Paeoniflorin-6'-O-benzene sulfonate (CP-25) is known to suppress inflammation and atherogenesis. However, the potential effect of CP-25 on intimal formation remains elusive. In the present study, we found that CP-25 significantly attenuated wire injury-induced intimal formation in C57BL/6 mice (intimal area: 2.64 ± 0.25 × 104 µm2 vs. 1.53 ± 0.21 × 104 µm2, P < 0.05) and vascular hyperplasia indicated by PCNA staining. In vitro experiments showed that CP-25 significantly alleviated human aortic smooth muscle cell (HASMC) proliferation, migration and dedifferentiation induced by PDGF-BB. Mechanistically, CP-25 inhibited GRK2 phosphorylation through PDGF receptor in the presence of PDGF-BB. In accordance with these results, CP-25 disrupted the interaction of GRK2 with ERK1/2 and suppressed the activation of ERK1/2 signaling in HASMCs. EVI1, which is considered as a downstream of ERK1/2 signaling and a novel transcription factor for VSMC differentiation, was also downregulated by CP-25 treatment. Moreover, overexpression of EVI1 partly restored the decreased proliferation and dedifferentiation of HASMCs treated by CP-25. Collectively, these findings suggested that CP-25 could alleviate intimal formation in response to wire injury via suppression of the interaction of GRK2 and ERK1/2 and EVI1 activation, indicating CP-25 might serve as a potent pharmaceutical for intimal formation.

EVI1 oncoprotein expression and CtBP1-association oscillate through the cell cycle.

Aberrantly high expression of EVI1 in acute myeloid leukaemia (AML) is associated with poor prognosis. For targeted treatment of EVI1 overexpressing AML a more detailed understanding of aspects of spatiotemporal interaction dynamics of the EVI1 protein is important. EVI1 overexpressing SB1690CB AML cells were used for quantification and protein interaction studies of EVI1 and ΔEVI1. Cells were cell cycle-synchronised by mimosine and nocodazole treatment and expression of EVI1 and related proteins assessed by western blot, immunoprecipitation and immunofluorescence. EVI1 protein levels oscillate through the cell cycle, and EVI1 is degraded partly by the proteasome complex. Both EVI1 and ΔEVI1 interact with the co-repressor CtBP1 but dissociate from CtBP1 complexes during mitosis. Furthermore, a large fraction of EVI1, but not ΔEVI1 or CtBP1, resides in the nuclear matrix. In conclusion, EVI1- protein levels and EVI1-CtBP1 interaction dynamics vary though the cell cycle and differ between EVI1 and ΔEVI1. These data ad to the functional characterisation of the EVI1 protein in AML and will be important for the development of targeted therapeutic approaches for EVI1-driven AML.

EVI-1 modulates arsenic trioxide induced apoptosis through JNK signalling pathway in leukemia cells.

High expression of the oncogene ecotropic viral integration site-1 (EVI-1) is an independent negative prognostic indicator of survival in leukemia patients. This study aimed to examine the effects of arsenic trioxide (ATO) on EVI-1 in acute myeloid leukemia (AML). Mononuclear cells were isolated from the bone marrow and peripheral blood of AML patients and healthy donors. EVI-1 expression in hematopoietic cells was evaluated by RT-qPCR and Western blot analysis. EVI-1 was highly expressed in both primary AML and leukemia cell lines (THP-1 and K562). ATO down-regulated EVI-1 mRNA in zebrafish in vivo as well as in primary leukemia cells and THP-1 and K562 cells in vitro. Additionally, ATO treatment induced apoptosis, down-regulated both EVI-1 mRNA and oncoprotein expression, increased the expression of pro-apoptosis proteins, and decreased the expression of anti-apoptotic proteins in leukemia cells in vitro. EVI-1 expression in leukemia cells (THP-1 and K562) transduced with EVI-1 siRNA was significantly reduced. Silencing EVI-1 had a significant effect on the activation of the JNK pathway and the induction of leukemia cell apoptosis. ATO may downregulate EVI-1 mRNA and oncoprotein levels and block the inhibitory effects of EVI-1 on the JNK pathway, which activates the JNK apoptotic pathway, thereby leading to the apoptosis of EVI-1 in AML patients.

Role of miR-96/EVI1/miR-449a Axis in the Nasopharyngeal Carcinoma Cell Migration and Tumor Sphere Formation.

The Wnt signaling pathway is one of the major signaling pathways used by cancer stem cells (CSC). Ecotropic Viral Integration Site 1 (EVI1) has recently been shown to regulate oncogenic development of tumor cells by interacting with multiple signaling pathways, including the Wnt signaling. In the present study, we found that the Wnt modulator ICG-001 could inhibit the expression of EVI1 in nasopharyngeal carcinoma (NPC) cells. Results from loss-of-function and gain-of-function studies revealed that EVI1 expression positively regulated both NPC cell migration and growth of CSC-enriched tumor spheres. Subsequent studies indicated ICG-001 inhibited EVI1 expression via upregulated expression of miR-96. Results from EVI1 3'UTR luciferase reporter assay confirmed that EVI1 is a direct target of miR-96. Further mechanistic studies revealed that ICG-001, overexpression of miR-96, or knockdown of EVI1 expression could restore the expression of miR-449a. The suppressive effect of miR-449a on the cell migration and tumor sphere formation was confirmed in NPC cells. Taken together, the miR-96/EVI1/miR-449a axis is a novel pathway involved in ICG-001-mediated inhibition of NPC cell migration and growth of the tumor spheres.