The Transcription Factor Evi-1 Is Overexpressed, Promotes Proliferation, and Is Prognostically Unfavorable in Infratentorial Ependymomas

Expanded phenotypic and hematologic abnormalities beyond bone marrow failure in MECOM-associated syndromes

The MECOM gene encodes multiple protein isoforms that are essential for hematopoietic stem cell self-renewal and maintenance. Germline MECOM variants have been associated with congenital thrombocytopenia, radioulnar synostosis and bone marrow failure; however, the phenotypic spectrum of MECOM-associated syndromes continues to expand and novel pathogenic variants continue to be identified. We describe eight unrelated patients who add to the previously known phenotypes and genetic defects of MECOM-associated syndromes. As each subject presented with unique MECOM variants, the series failed to demonstrate clear genotype-to-phenotype correlation but may suggest a role for additional modifiers that affect gene expression and subsequent phenotype. Recognition of the expanded hematologic and non-hematologic clinical features allows for rapid molecular diagnosis, early identification of life-threatening complications, and improved genetic counseling for families. A centralized international publicly accessible database to share annotated MECOM variants would advance their clinical interpretation and provide a foundation to perform functional MECOM studies.

JAM-A signals through the Hippo pathway to regulate intestinal epithelial proliferation

JAM-A is a tight-junction-associated protein that contributes to regulation of intestinal homeostasis. We report that JAM-A interacts with NF2 and LATS1, functioning as an initiator of the Hippo signaling pathway, well-known for regulation of proliferation. Consistent with these findings, we observed increased YAP activity in JAM-A-deficient intestinal epithelial cells (IEC). Furthermore, overexpression of a dimerization-deficient mutant, JAM-A-DL1, failed to initiate Hippo signaling, phenocopying JAM-A-deficient IEC, whereas overexpression of JAM-A-WT activated Hippo signaling and suppressed proliferation. Lastly, we identify EVI1, a transcription factor reported to promote cellular proliferation, as a contributor to the pro-proliferative phenotype in JAM-A-DL1 overexpressing IEC downstream of YAP. Collectively, our findings establish a new role for JAM-A as a cell-cell contact sensor, raising implications for understanding the contribution(s) of JAM-A to IEC proliferation in the mammalian epithelium.

Targeted Therapy with Sirolimus and Nivolumab in a Child with Refractory Multifocal Anaplastic Ependymoma

Pediatric ependymoma (EPN) is the third most common central nervous system (CNS) tumor, with 90% arising intracranially. Management typically involves maximal surgical resection and radiotherapy, but patients’ outcome is poor. Moreover, there are only a few therapeutical options available for recurrent or refractory disease. In this report, we present the case of a 7-year-old girl with relapsed refractory multifocal grade III EPN who failed conventional treatments and experienced a stable and durable response to the immune checkpoint inhibitor (ICPI) nivolumab in association with the mammalian target of rapamycin (m-TOR) inhibitor sirolimus. This experimental therapy was targeted on immune phenotypical analyses of the patient’s last relapse tumor sample, and this procedure should be routinely done to find new possible therapeutical approaches in recurrent solid tumors.

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.

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.

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.

Ecotropic virus integration-1 and calreticulin as novel prognostic markers in triple-negative breast cancer: A retrospective cohort study

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, for which no specific targete d therapy is currently available. The present study aimed to examine the associations of ecotropic virus integration site 1 (EVI-1) and calreticulin (CRT) with other clinicopathological variables and the prognosis of patients with TNBC. The present retrospective cohort study reviewed the medical records of patients with TNBC treated in the Affiliated Hospitals of Jinzhou Medical University between January 2010 and June 2015. The protein expression levels of EVI-1 and CRT in tumor samples obtained from the patients were examined by immunohistochemical analysis. Univariate and multivariate regression analyses were used to identify associations between clinical characteristics and disease-free survival (DFS) or overall survival (OS). Kaplan-Meier analysis was performed to observe the survival condition (DFS/OS) according to EVI-1 and CRT expression. A total of 88 TNBC patients were included in the present study. Tumor tissues in 52 (59.1%) patients were EVI-1 positive, and tumor tissues in 64 (72.7%) patients were CRT-positive, and these rates were significantly higher compared with those in the corresponding paracancerous tissues (P<0.05). Multivariate analysis revealed that EVI-1 and CRT expression levels were independent variables associated with OS and DFS, and high expression of both CRT and EVI-1 was significantly associated with decreased OS and DFS compared with the other subgroups (low EVI-1/low CRT expression, low EVI-1/high CRT expression and high EVI-1/low CRT expression) of patients with TNBC. EVI-1 and CRT expression in TNBC was significantly correlated with poor outcome. Evaluation of the EVI-1 and CRT status may provide insight into prognosis prediction for patients with TNBC.

EVI‑1 acts as an oncogene and positively regulates calreticulin in breast cancer

Ecotropic viral integration site‑1 (EVI‑1) is an important transcription factor involved in oncogenesis. Aberrant EVI‑1 expression has been reported to be a characteristic of multiple types of malignancies; however, very little is known about how EVI‑1 regulates breast cancer. Current knowledge of how target genes mediate the biological function of EVI‑1 remains limited. In the present study, overexpression of EVI‑1 promoted cell proliferation, migration, and invasion, and inhibited apoptosis in breast cancer. By contrast, silencing of EVI‑1 inhibited cell proliferation, migration and invasion, and enhanced apoptosis in breast cancer. In addition, the results also revealed that the aberrant expression of EVI‑1 regulates genes associated with the apoptotic pathway in breast cancer. Furthermore, EVI‑1 was also likely to target the promoter region of calreticulin (CRT) in vitro. It was concluded that EVI‑1 can affect epithelial mesenchymal transition‑associated genes by regulating the expression of CRT in breast cancer. The results revealed that EVI‑1 may be a potential effective therapeutic target in breast cancer.

miR-1 inhibits the proliferation of breast cancer stem cells by targeting EVI-1

Purpose

Breast cancer stem cells (BCSCs) have been regarded as the key factor for treatment failure in breast cancer. The abnormal expression of miRNAs plays a significant role in different tumor types. However, the role of miR-1 in breast cancer remains poorly understood. The purpose of this study was to evaluate the effects of miR-1 on the proliferation and apoptosis of BCSCs.

Materials and methods

CD44⁺/CD24^−/low/epithelial-specific antigen⁺ BCSCs were isolated by flow cytometry. Real-time PCR and Western blotting were used to determine the expression of miRNAs, mRNAs, and epithelial–mesenchymal transition (EMT)-related genes. Cell proliferation and apoptosis were measured using the Cell Counting Kit-8 assay and Annexin V-fluorescein isothiocyanate flow cytometry, respectively. Luciferase reporter assay was used to verify whether miR-1 targeted ecotropic virus integration-1 (EVI-1). The role of miR-1 in breast cancer in vivo was evaluated using BCSCs xenograft mouse models.

Results

In this study, we demonstrated that miR-1 was significantly downregulated in breast cancer tissues compared to the adjacent non-tumor tissues. The luciferase reporter assay verified that EVI-1 was a direct target of miR-1, and upregulation of miR-1 negatively correlated with the expression of EVI-1 in BCSCs at both the transcriptional and posttranslational levels. Furthermore, overexpression of miR-1 inhibited BCSCs proliferation and promoted apoptosis, which was reversed by the overexpression of EVI-1. In addition, we demonstrated that aberrant expression of miR-1 could regulate EMT-related genes in BCSCs. Finally, immunohistochemical staining demonstrated that EVI-1 expression was decreased in BCSCs tumors following intra-tumoral miR-1 agomir treatment compared to the control group.

Conclusion

miR-1 can negatively regulate the expression of EVI-1 and, thus, affect BCSCs proliferation, apoptosis, and EMT-related markers. Taken together, these findings demonstrate that miR-1 could be employed as a therapeutic strategy in the treatment of breast cancer.

EVI1 carboxy-terminal phosphorylation is ATM-mediated and sustains transcriptional modulation and self-renewal via enhanced CtBP1 association

The transcriptional regulator EVI1 has an essential role in early hematopoiesis and development. However, aberrantly high expression of EVI1 has potent oncogenic properties and confers poor prognosis and chemo-resistance in leukemia and solid tumors. To investigate to what extent EVI1 function might be regulated by post-translational modifications we carried out mass spectrometry- and antibody-based analyses and uncovered an ATM-mediated double phosphorylation of EVI1 at the carboxy-terminal S858/S860 SQS motif. In the presence of genotoxic stress EVI1-WT (SQS), but not site mutated EVI1-AQA was able to maintain transcriptional patterns and transformation potency, while under standard conditions carboxy-terminal mutation had no effect. Maintenance of hematopoietic progenitor cell clonogenic potential was profoundly impaired with EVI1-AQA compared with EVI1-WT, in particular in the presence of genotoxic stress. Exploring mechanistic events underlying these observations, we showed that after genotoxic stress EVI1-WT, but not EVI1-AQA increased its level of association with its functionally essential interaction partner CtBP1, implying a role for ATM in regulating EVI1 protein interactions via phosphorylation. This aspect of EVI1 regulation is therapeutically relevant, as chemotherapy-induced genotoxicity might detrimentally sustain EVI1 function via stress response mediated phosphorylation, and ATM-inhibition might be of specific targeted benefit in EVI1-overexpressing malignancies.

Rethinking childhood ependymoma: a retrospective, multi-center analysis reveals poor long-term overall survival

Ependymoma is the third most common brain tumor in children, but there is a paucity of large studies with more than 10 years of follow-up examining the long-term survival and recurrence patterns of this disease. We conducted a retrospective chart review of 103 pediatric patients with WHO Grades II/III intracranial ependymoma, who were treated at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and Chicago’s Ann & Robert H. Lurie Children’s Hospital between 1985 and 2008, and an additional 360 ependymoma patients identified from the Surveillance Epidemiology and End Results (SEER) database. For the institutional cohort, we evaluated clinical and histopathological prognostic factors of overall survival (OS) and progression-free survival (PFS) using the log-rank test, and univariate and multivariate Cox proportional-hazards models. Overall survival rates were compared to those of the SEER cohort. Median follow-up time was 11 years. Ten-year OS and PFS were 50 ± 5% and 29 ± 5%, respectively. Findings were validated in the independent SEER cohort, with 10-year OS rates of 52 ± 3%. GTR and grade II pathology were associated with significantly improved OS. However, GTR was not curative for all children. Ten-year OS for patients treated with a GTR was 61 ± 7% and PFS was 36 ± 6%. Pathological examination confirmed most recurrent tumors to be ependymoma, and 74% occurred at the primary tumor site. Current treatment paradigms are not sufficient to provide long-term cure for children with ependymoma. Our findings highlight the urgent need to develop novel treatment approaches for this devastating disease.

The role of EVI-1 in normal hematopoiesis and myeloid malignancies (Review)

Ecotropic virus integration site-1 (EVI-1) gene, locus on chromosome 3 (3q26.2) in the human genome, was first found in the AKXD strain of mice, in a model of retrovirus-induced acute myeloid leukemia (AML) established twenty years ago. Since then, EVI-1 was regarded as one of the most invasive proto-oncogenes in human leukemia. EVI-1 can encode a unique zinc-finger protein of 145 kDa that can bind with DNA, and its overexpression was closely related to human hemopoietic diseases. Furthermore, accumulating research indicates that EVI-1 is involved in the differentiation, apoptosis and proliferation of leukemia cells. The present review focuses on the biochemical properties of EVI-1 which plays a role in myeloid malignancies.

Hematogenous dissemination of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most frequent and aggressive brain tumor in adults. The dogma that GBM spread is restricted to the brain was challenged by reports on extracranial metastases after organ transplantation from GBM donors. We identified circulating tumor cells (CTCs) in peripheral blood (PB) from 29 of 141 (20.6%) GBM patients by immunostaining of enriched mononuclear cells with antibodies directed against glial fibrillary acidic protein (GFAP). Tumor cell spread was not significantly enhanced by surgical intervention. The tumor nature of GFAP-positive cells was supported by the absence of those cells in healthy volunteers and the presence of tumor-specific aberrations such as EGFR gene amplification and gains and losses in genomic regions of chromosomes 7 and 10. Release of CTCs was associated with EGFR gene amplification, suggesting a growth potential of these cells. We demonstrate that hematogenous GBM spread is an intrinsic feature of GBM biology.

Mice carrying a hypomorphic Evi1 allele are embryonic viable but exhibit severe congenital heart defects

The ecotropic viral integration site 1 (Evi1) oncogenic transcription factor is one of a number of alternative transcripts encoded by the Mds1 and Evi1 complex locus (Mecom). Overexpression of Evi1 has been observed in a number of myeloid disorders and is associated with poor patient survival. It is also amplified and/or overexpressed in many epithelial cancers including nasopharyngeal carcinoma, ovarian carcinoma, ependymomas, and lung and colorectal cancers. Two murine knockout models have also demonstrated Evi1's critical role in the maintenance of hematopoietic stem cell renewal with its absence resulting in the death of mutant embryos due to hematopoietic failure. Here we characterize a novel mouse model (designated Evi1^fl3) in which Evi1 exon 3, which carries the ATG start, is flanked by loxP sites. Unexpectedly, we found that germline deletion of exon3 produces a hypomorphic allele due to the use of an alternative ATG start site located in exon 4, resulting in a minor Evi1 N-terminal truncation and a block in expression of the Mds1-Evi1 fusion transcript. Evi1^δex3/δex3 mutant embryos showed only a mild non-lethal hematopoietic phenotype and bone marrow failure was only observed in adult Vav-iCre/+, Evi1^fl3/fl3 mice in which exon 3 was specifically deleted in the hematopoietic system. Evi1^δex3/δex3 knockout pups are born in normal numbers but die during the perinatal period from congenital heart defects. Database searches identified 143 genes with similar mutant heart phenotypes as those observed in Evi1^δex3/δex3 mutant pups. Interestingly, 42 of these congenital heart defect genes contain known Evi1-binding sites, and expression of 18 of these genes are also effected by Evi1 siRNA knockdown. These results show a potential functional involvement of Evi1 target genes in heart development and indicate that Evi1 is part of a transcriptional program that regulates cardiac development in addition to the development of blood.

Ependymoma stem cells are highly sensitive to temozolomide in vitro and in orthotopic models

BACKGROUND

Ependymoma management remains challenging because of the inherent chemoresistance of this tumor. To determine whether ependymoma stem cells (SCs) might contribute to therapy resistance, we investigated the sensitivity of ependymoma SCs to temozolomide and etoposide.

METHODS

The efficacies of the two DNA damaging agents were explored in two ependymoma SC lines in vitro and in vivo models.

RESULTS

Ependymoma SC lines were highly sensitive to temozolomide and etoposide in vitro, but only temozolomide impaired tumor-initiation properties. Consistently, temozolomide but not etoposide showed significant antitumoral activity on ependymoma SC-driven subcutaneous and orthotopic xenografts by reducing the mitotic fraction. In vitro temozolomide at the EC50 (10 µM) induced accumulation of cells in the G2/M phase that was unexpectedly accompanied by downregulation of p27 and p21 without modulation of full-length p53 (FLp53). Differentiation-committed ependymoma SCs acquired resistance to temozolomide. Inhibition of proliferation was partly due to apoptosis, that occurred earlier in differentiated cells as compared to neurospheres. The activation of apoptosis correlated with an increase in p53β/γ isoforms without modulation of FLp53 under both serum-free and differentiation-promoting media. Incubation of cells in both conditions with temozolomide resulted in increased glioneuronal differentiation exhibiting elevated glial fibrillary acidic protein, galactosylceramidase, and βIII-tubulin expression compared to untreated controls. O(6)-methylguanine DNA methyltransferase (MGMT) transcript levels were very low in SCs, and were increased by treatment and, epigenetically, by differentiation through MGMT promoter unmethylation.

CONCLUSION

Ependymoma growth might be impaired by temozolomide through preferential depletion of a less differentiated, more tumorigenic, MGMT-negative cell population with stem-like properties.

The role of EVI1 in myeloid malignancies

The EVI1 oncogene at human chr 3q26 is rearranged and/or overexpressed in a subset of acute myeloid leukemias and myelodysplasias. The EVI1 protein is a 135 kDa transcriptional regulator with DNA-binding zinc finger domains. Here we provide a critical review of the current state of research into the molecular mechanisms by which this gene plays a role in myeloid malignancies. The major pertinent cellular effects are blocking myeloid differentiation and preventing cellular apoptosis, and several potential mechanisms for these phenomena have been identified. Evidence supports a role for EVI1 in inducing cellular quiescence, and this may contribute to the resistance to chemotherapy seen in patients with neoplasms that overexpress EVI1. Another isoform, MDS1-EVI1 (or PRDM3), encoded by the same locus as EVI1, harbors an N-terminal histone methyltransferase(HMT) domain; experimental findings indicate that this protein and its HMT activity are critical for the progression of a subset of AMLs, and this provides a potential target for therapeutic intervention.

Current and evolving knowledge of prognostic factors for pediatric ependymomas

Ependymomas are one of the most common pediatric malignant brain tumors. Prognosis, especially in young children, remains poor due to their inherent chemo- and radio-resistance and effective treatment remains one of the more difficult tasks in pediatric oncology: up to half of the patients may die from the disease. The only reproducible prognostic factor is the extent of surgery; neither histological grading nor other biomarkers can be used to reliably make treatment decisions in clinical practice. None of the studies identifying new biomarkers have been conducted prospectively, only few have been undertaken within the context of a clinical trial and most have been conducted with limited samples (often including adults and childhood samples). International collaboration is needed to improve ependymoma prognostication.

Global Identification of EVI1 Target Genes in Acute Myeloid Leukemia

The ecotropic virus integration site 1 (EVI1) transcription factor is associated with human myeloid malignancy of poor prognosis and is overexpressed in 8-10% of adult AML and strikingly up to 27% of pediatric MLL-rearranged leukemias. For the first time, we report comprehensive genomewide EVI1 binding and whole transcriptome gene deregulation in leukemic cells using a combination of ChIP-Seq and RNA-Seq expression profiling. We found disruption of terminal myeloid differentiation and cell cycle regulation to be prominent in EVI-induced leukemogenesis. Specifically, we identified EVI1 directly binds to and downregulates the master myeloid differentiation gene Cebpe and several of its downstream gene targets critical for terminal myeloid differentiation. We also found EVI1 binds to and downregulates Serpinb2 as well as numerous genes involved in the Jak-Stat signaling pathway. Finally, we identified decreased expression of several ATP-dependent P2X purinoreceptors genes involved in apoptosis mechanisms. These findings provide a foundation for future study of potential therapeutic gene targets for EVI1-induced leukemia.

Emerging insights into the ependymoma epigenome

Ependymoma is the third most common pediatric brain tumor, yet because of the paucity of effective therapeutic interventions, 45% of patients remain incurable. Recent transcriptional and copy number profiling of the disease has identified few driver genes and in fact points to a balanced genomic profile. Candidate gene approaches looking at hypermethylated promoters and genome-wide epigenetic arrays suggest that DNA methylation may be critical to ependymoma pathogenesis. This review attempts to highlight existing and emerging evidence implicating the ependymoma epigenome as a key player and that epigenetic modifiers may offer new targeted therapeutic avenues for patients.

Spinal cord ependymomas in children and adolescents

BACKGROUND

Spinal cord ependymomas are very rare among children and adolescents. Due to their rarity, our current knowledge of these tumors is based on case reports and few retrospective case series.

METHODS

The present review summarizes the currently available literature on childhood spinal cord ependymomas.

RESULTS

Although overall survival rates are favorable, relapse incidence is high, particularly in myxopapillary ependymomas. Since long-term follow-up data are provided in a limited number of studies only, the true relapse incidence is unknown. Maximal safe radical surgery is the backbone of treatment for children with spinal cord ependymomas, but the impact of adjuvant treatment on progression and survival is still unclear. Presently, the decision to initiate non-surgical treatment depends primarily on the WHO grade of the tumor and the extent of resection. In terms of the known side effects, early radiotherapy should be avoided in children with WHO grade II spinal cord ependymomas irrespective of the extent of resection but is indicated in anaplastic spinal cord ependymomas both after complete and incomplete resection. The high relapse incidence in myxopapillary ependymomas argue for the use of early radiotherapy, but its definitive impact on progression has to be proven in larger series. Close surveillance is important due to the high recurrence rate in all patients with spinal cord ependymomas.

CONCLUSION

Prospective collection of both clinical and molecular data from a greater number of patients with spinal cord ependymomas within an international collaboration is the prerequisite to establish standardized management guidelines for these rare CNS tumors.

The Prdm family: expanding roles in stem cells and development

Members of the Prdm family are characterized by an N-terminal PR domain that is related to the SET methyltransferase domain, and multiple zinc fingers that mediate sequence-specific DNA binding and protein-protein interactions. Prdm factors either act as direct histone methyltransferases or recruit a suite of histone-modifying enzymes to target promoters. In this way, they function in many developmental contexts to drive and maintain cell state transitions and to modify the activity of developmental signalling pathways. Here, we provide an overview of the structure and function of Prdm family members and discuss the roles played by these proteins in stem cells and throughout development.

Ecotopic viral integration site 1 (EVI1) regulates multiple cellular processes important for cancer and is a synergistic partner for FOS protein in invasive tumors

Ecotropic viral integration site 1 (EVI1) is an oncogenic dual domain zinc finger transcription factor that plays an essential role in the regulation of hematopoietic stem cell renewal, and its overexpression in myeloid leukemia and epithelial cancers is associated with poor patient survival. Despite the discovery of EVI1 in 1988 and its emerging role as a dominant oncogene in various types of cancer, few EVI1 target genes are known. This lack of knowledge has precluded a clear understanding of exactly how EVI1 contributes to cancer. Using a combination of ChIP-Seq and microarray studies in human ovarian carcinoma cells, we show that the two zinc finger domains of EVI1 bind to DNA independently and regulate different sets of target genes. Strikingly, an enriched fraction of EVI1 target genes are cancer genes or genes associated with cancer. We also show that more than 25% of EVI1-occupied genes contain linked EVI1 and activator protein (AP)1 DNA binding sites, and this finding provides evidence for a synergistic cooperative interaction between EVI1 and the AP1 family member FOS in the regulation of cell adhesion, proliferation, and colony formation. An increased number of dual EVI1/AP1 target genes are also differentially regulated in late-stage ovarian carcinomas, further confirming the importance of the functional cooperation between EVI1 and FOS. Collectively, our data indicate that EVI1 is a multipurpose transcription factor that synergizes with FOS in invasive tumors.

Overexpression of Evi-1 oncoprotein represses TGF-β signaling in colorectal cancer

Human colorectal cancer (CRC) cells are resistant to the anti-proliferative effect of transforming growth factor-β (TGF-β), suggesting that disruption of TGF-β signaling plays an important role in colorectal carcinogenesis. Ecotropic virus integration site-1 (Evi-1) oncoprotein represses TGF-β signaling by interacting with Smads, but its role in CRC has not been established. The purpose of this study is to determine whether Evi-1 plays role(s) in CRCs and to characterize Evi-1 transcript(s) in CRCs. Evi-1 was overexpressed in 53% of human CRC samples, 100% of colon adenoma samples, and 100% of human colon cancer cell lines tested. Using 5' RACE, we cloned a novel Evi-1 transcript (Evi-1e) from a human CRC tissue and found that this novel transcript was expressed at a higher level in CRC tissues than in normal tissues and was the major Evi-1 transcript in CRCs. Transient Evi-1 transfection inhibited TGF-β-induced transcriptional activity and reversed the growth inhibitory effect of TGF-β in MC-26 mouse colon cancer cells. In conclusion, we have identified overexpression of Evi-1 oncoprotein as a novel mechanism by which a subset of human CRCs may escape TGF-β regulation. We have also identified a novel Evi-1 transcript, Evi-1e, as the major Evi-1 transcript expressed in human CRCs.