The DEK oncogene is a target of steroid hormone receptor signaling in breast cancer

The impact of the chromatin binding DEK protein in hematopoiesis and acute myeloid leukemia

Hematopoiesis is an exquisitely regulated process of cellular differentiation to create diverse cell types of the blood. Genetic mutations, or aberrant regulation of gene transcription, can interrupt normal hematopoiesis. This can have dire pathological consequences, including acute myeloid leukemia (AML), in which generation of the myeloid lineage of differentiated cells is interrupted. In this literature review, we discuss how the chromatin remodeling DEK protein can control hematopoietic stem cell quiescence, hematopoietic progenitor cell proliferation, and myelopoiesis. We further discuss the oncogenic consequences of the t(6;9) chromosomal translocation, which creates the DEK-NUP214 (aka: DEK-CAN) fusion gene, during the pathogenesis of AML. Combined, the literature indicates that DEK is crucial for maintaining homeostasis of hematopoietic stem and progenitor cells, including myeloid progenitors.

Role of DEK in carcinogenesis, diagnosis, prognosis, and therapeutic outcome of breast cancer: An evidence-based clinical review

Breast cancer is a significantly burdening women's cancer with limited diagnostic modalities. DEK is a novel biomarker overexpressed in breast cancers, currently exhaustively researched for its diagnosis and prognosis. Search for relevant meta-analyses, cohorts, and experimental studies in the last fifteen years was done in five large scientific databases. Non-English, non-full text articles or unrelated studies were excluded. Thirteen articles discussed the potential of DEK to estimate breast cancer characteristics, treatment outcomes, and prognosis. This proto-oncogene plays a role in breast carcinogenesis, increasing tumour proliferation and invasion, preventing apoptosis, and creating an immunodeficient tumour milieu with M2 tumour-associated macrophages. DEK is also associated with worse clinicopathological features and survival in breast cancer patients. Using a Kaplan-Meier plotter data analysis, DEK expression predicts worse overall survival (HR 1.24, 95%CI: 1.01-1.52, p = 0.039), comparable to other biomarkers. DEK is a promising novel biomarker requiring further research to determine its bedside applications.

Novel molecular mechanisms in Alzheimer's disease: The potential role of DEK in disease pathogenesis

Alzheimer's disease and age-related dementias (AD/ADRD) are debilitating diseases that exact a significant physical, emotional, cognitive, and financial toll on the individual and their social network. While genetic risk factors for early-onset AD have been identified, the molecular and genetic drivers of late-onset AD, the most common subtype, remain a mystery. Current treatment options are limited for the 35 million people in the United States with AD/ADRD. Thus, it is critically important to identify novel molecular mechanisms of dementia-related pathology that may be targets for the development of new interventions. Here, we summarize the overarching concepts regarding AD/ADRD pathogenesis. Then, we highlight one potential molecular driver of AD/ADRD, the chromatin remodeling protein DEK. We discuss in vitro, in vivo, and ex vivo findings, from our group and others, that link DEK loss with the cellular, molecular, and behavioral signatures of AD/ADRD. These include associations between DEK loss and cellular and molecular hallmarks of AD/ADRD, including apoptosis, Tau expression, and Tau hyperphosphorylation. We also briefly discuss work that suggests sex-specific differences in the role of DEK in AD/ADRD pathogenesis. Finally, we discuss future directions for exploiting the DEK protein as a novel player and potential therapeutic target for the treatment of AD/ADRD.

In silico gene expression and pathway analysis of DEK in the human brain across the lifespan

DEK, a chromatin-remodelling phosphoprotein, is associated with various functions and biological pathways in the periphery, including inflammation, oncogenesis, DNA repair, and transcriptional regulation. We recently identified an association between DEK loss and central nervous system diseases, such as Alzheimer's. To understand DEK's potential role in disease, it is critical to characterize DEK in healthy human brain to distinguish between neural DEK expression and function in healthy versus diseased states like dementia. We utilized two public databases, BrainCloud and Human Brain Transcriptome, and analysed DEK mRNA expression across the lifespan in learning and memory relevant brain regions. Since DEK loss induces phenotypes associated with brain ageing (e.g., DNA damage and apoptosis), we hypothesized that neural DEK expression may be highest during foetal development and lower in elderly individuals. In agreement with this hypothesis, DEK was most prominently expressed during foetal development in all queried forebrain areas, relative to other ages. Consistent with its roles in the periphery, pathways related to DEK in the brain were associated with cellular proliferation, DNA replication and repair, apoptosis, and inflammation. We also found novel neural development-relevant pathways (e.g., synaptic transmission, neurite outgrowth, and myelination) to be enriched from genes correlated with DEK expression. These findings suggest that DEK is important for human brain development. Overall, we highlight age-related changes in neural DEK expression across the human lifespan and illuminate novel biological pathways associated with DEK that are distinct from normal brain ageing. These findings may further our understanding of how DEK impacts brain function and disease susceptibility.

Long Non-Coding LEF1-AS1 Sponge miR-5100 Regulates Apoptosis and Autophagy in Gastric Cancer Cells via the miR-5100/DEK/AMPK-mTOR Axis

DEK and miR-5100 play critical roles in many steps of cancer initiation and progression and are directly or indirectly regulated by most promoters and repressors. LEF1-AS1 as a long non-coding RNA can regulate tumor development through sponge miRNA. The effect and regulatory mechanism of DEK on autophagy and apoptosis in gastric cancer (GC), and the role between miR-5100 and DEK or miR-5100 and LEF1-AS1 are still unclear. Our study found that DEK was highly expressed in gastric cancer tissues and cell lines, and knockdown of DEK inhibited the autophagy of cells, promoted apoptosis, and suppressed the malignant phenotype of gastric cancer. DEK regulates autophagy and apoptosis through the AMPK/mTOR signaling pathway. In addition, miR-5100 inhibits autophagy and promotes apoptosis in GC cells while LEF1-AS1 had the opposite effect. Studies have shown that miR-5100 acts by targeting the 3'UTR of DEK, and LEF1-AS1 regulates the expression of miR-5100 by sponging with mIR-5100. In conclusion, our results found that LEF1-AS1 and miR-5100 sponge function, and the miR-5100/DEK/AMPK/mTOR axis regulates autophagy and apoptosis in gastric cancer cells.

A Novel Three-Gene Score as a Predictive Biomarker for Pathologically Complete Response after Neoadjuvant Chemotherapy in Triple-Negative Breast Cancer

Although triple-negative breast cancer (TNBC) typically responds better to neoadjuvant chemotherapy (NAC) compared to the other subtypes, a pathological complete response (pCR) is achieved in less than half of the cases. We established a novel three-gene score using genes based on the E2F target gene set that identified pCR after NAC, which showed robust performance in both training and validation cohorts (total of n = 3862 breast cancer patients). We found that the three-gene score was elevated in TNBC compared to the other subtypes. A high score was associated with Nottingham histological grade 3 in TNBC. Across multiple cohorts, high-score TNBC enriched not only E2F targets but also G2M checkpoint and mitotic spindle, which are all cell proliferation-related gene sets. High-score TNBC was associated with homologous recombination deficiency, high mutation load, and high infiltration of Th1, Th2, and gamma-delta T cells. However, the score did not correlate with drug sensitivity for paclitaxel, 5-fluorouracil, cyclophosphamide, and doxorubicin in TNBC human cell lines. High-score TNBC was significantly associated with a high rate of pCR not only in the training cohort but also in the validation cohorts. High-score TNBC was significantly associated with better survival in patients who received chemotherapy but not in patients who did not receive chemotherapy. The three-gene score is associated with a high mutation rate, immune cell infiltration, and predicts response to NAC in TNBC.

MiR-138-5p Inhibits the Proliferation of Gastric Cancer Cells by Targeting DEK

Background

Increasing evidence suggests that microRNAs (miRNAs) play critical roles in cancer progression. Therefore, investigating the function of miRNAs that are aberrantly expressed in gastric cancer (GC) and characterizing the involved underlying mechanism are essential for the treatment of gastric cancer. MiR-138-5p was found to be down-regulated in multiple cancers, which acted as a tumor suppressor in cancer progression; however, whether and how miR-138-5p regulates the malignant behaviors of GC has not been fully understood.

Methods

The level of miR-138-5p in GC tissues and cell lines was detected by RT-qPCR. The effects of miR-138-5p on the growth of GC cells were evaluated by the in vitro Cell Counting Kit-8 (CCK-8) assay, cell apoptosis, cell cycle analysis, wound-healing assay, and in vivo xenograft mice model. The targets of miR-138-5p were predicted using the miRDB online tool, confirmed by luciferase report assay and Western blot.

Results

MiR-138-5p was frequently decreased in GC tissues and cell lines. Decreased expression of miR-138-5p was significantly associated with the lymph node metastasis of GC patients. Overexpression of miR-138-5p suppressed GC cell proliferation, migration, increased cell apoptosis as well as inhibited the tumor growth in vivo. DEK oncogene was predicted as a potential target of miR-138-5p. MiR-138-5p bound the 3'-UTR of DEK and inhibited the level of DEK in GC cells. Restoration of DEK abrogated miR-138-5p overexpression-mediated suppression of GC cell proliferation and cell cycle arrest.

Conclusion

Our results demonstrated the anti-cancer role of miR-138-5p in GC by targeting DEK, which suggested miR-138-5p as a potential therapeutic target for the treatment of patient with GC.

DEK Expression in Breast Cancer Cells Leads to the Alternative Activation of Tumor Associated Macrophages

Breast cancer (BC) is the second leading cause of cancer deaths among women. DEK is a known oncoprotein that is highly expressed in over 60% of breast cancers and is an independent marker of poor prognosis. However, the molecular mechanisms by which DEK promotes tumor progression are poorly understood. To identify novel oncogenic functions of DEK, we performed RNA-Seq analysis on isogenic Dek-knockout and complemented murine BC cells. Gene ontology analyses identified gene sets associated with immune system regulation and cytokine-mediated signaling and differential cytokine and chemokine expression was confirmed across Dek-proficient versus Dek-deficient cells. By exposing murine bone marrow-derived macrophages (BMDM) to tumor cell conditioned media (TCM) to mimic a tumor microenvironment, we showed that Dek-expressing breast cancer cells produce a cytokine milieu, including up-regulated Tslp and Ccl5 and down-regulated Cxcl1, Il-6, and GM-CSF, that drives the M2 polarization of macrophages. We validated this finding in primary murine mammary tumors and show that Dek expression in vivo is also associated with increased expression of M2 macrophage markers in murine tumors. Using TCGA data, we verified that DEK expression in primary human breast cancers correlates with the expression of several genes identified by RNA-Seq in our murine model and with M2 macrophage phenotypes. Together, our data demonstrate that by regulating the production of multiple secreted factors, DEK expression in BC cells creates a potentially immune suppressed tumor microenvironment, particularly by inducing M2 tumor associated macrophage (TAM) polarization.

Cordycepin Inhibits Cancer Cell Proliferation and Angiogenesis through a DEK Interaction via ERK Signaling in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a malignant tumor that arises from the epithelial cells of the bile duct and is notorious for its poor prognosis. The clinical outcome remains disappointing, and thus more effective therapeutic options are urgently required. Cordycepin, a traditional Chinese medicine, provides multiple pharmacological strategies in antitumors, but its mechanisms have not been fully elucidated. In this study, we reported that cordycepin inhibited the viability and proliferation capacity of CCA cells in a time- and dose-dependent manner determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and colony formation assay. Flow cytometry and Hoechst dye showed that cordycepin induced cancer cell apoptosis via extracellular signal-regulated kinase (ERK) 1/2 deactivation. Moreover, cordycepin significantly reduced the angiogenetic capabilities of CCA in vitro as examined by tube formation assay. We also discovered that cordycepin inhibited DEK expression by using Western blot assay. DEK serves as an oncogenic protein that is overexpressed in various gastrointestinal tumors. DEK silencing inhibited CCA cell viability and angiogenesis but not apoptosis induction determined by Western blot and flow cytometry. Furthermore, cordycepin significantly inhibited tumor growth and angiogenic capacities in a xenograft model by downregulating the expression of DEK, phosphorylated ERK1/2 CD31 and von Willebrand factor (vWF). Taken together, we demonstrated that cordycepin inhibited CCA cell proliferation and angiogenesis with a DEK interaction via downregulation in ERK signaling. These data indicate that cordycepin may serve as a novel agent for CCA clinical treatment and prognosis improvement. SIGNIFICANCE STATEMENT: Cordycepin provides multiple strategies in antitumors, but its mechanisms are not fully elucidated, especially on cholangiocarcinoma (CCA). We reported that cordycepin inhibited the viability of CCA cells, induced apoptosis via extracellular signal-regulated kinase 1/2 deactivation and DEK inhibition, and reduced the angiogenetic capabilities of CCA both in vivo and in vitro.

A palladium(II) complex with the Schiff base 4-chloro-2-(N-ethyliminomethyl)-phenol: Synthesis, structural characterization, and in vitro and in silico biological activity studies

The synthesis and characterization of the Pd(II) complex of the formula [Pd(L)₂] 1 with the Schiff base 4-chloro-2-(N-ethyliminomethyl)-phenol (HL) as derived in situ via the condensation reaction of 5-chloro-salicylaldehyde and ethylamine was undertaken. The structure of 1 was verified by single-crystal X-ray crystallography. The ability of 1 to interact with calf-thymus (CT) DNA was studied by UV-vis and viscosity experiments, and its ability to displace ethidium bromide (EB) from the DNA-EB conjugate was revealed by fluorescence spectroscopy. It was found that intercalation is the most possible mode of interaction with CT DNA. Additionally, DNA electrophoretic mobility experiments showed that 1 interacts with the plasmid pBluescript SK(+) (pDNA) as proved by the formation of unusual mobility DNA bands and degradation of relaxed pDNA at concentration of 5 mM. The interaction of 1 with human (HSA) and bovine serum albumin (BSA) was monitored revealing its reversible binding to albumins. The complex showed noteworthy antimicrobial activity against one (Bacillus subtilis) of the five tested bacteria. In order to explain the described in vitro activity of the compound, we adopted molecular docking studies on the crystal structure of HSA, BSA, CT DNA and DNA-gyrase. Furthermore, in silico predictive tools have been employed to study the properties of the complex. The in silico studies are adopted on a multitude of proteins involved in cancer growth, as well as prediction of drug-induced changes of gene expression profile, protein- and mRNA-based prediction results, prediction of sites of metabolism, cytotoxicity for cancer cell lines, etc.

Aqueous Humor Markers in Retinoblastoma, a Review

Purpose

Retinoblastoma (Rb) is the most common primary intraocular cancer in children. Unlike with most solid tumors, direct biopsy is contraindicated due to risk of tumor dissemination. However, recent therapeutic techniques have allowed for the safe extraction of aqueous humor (AH) from eyes undergoing therapy, providing the unique opportunity to use AH as a liquid biopsy for Rb. Although the extraction of AH in Rb eyes undergoing therapy is new, the consideration of whether there are tumor biomarkers in the AH is not. The current manuscript is a systematic review of all studies that have examined biomarkers in the AH of Rb eyes. The authors hypothesized that AH sampling and analysis of tumor biomarkers may have new clinical relevance for the diagnosis, prognosis, and/or management of Rb.

Methods

A comprehensive database search (PubMed, Web of Science, Embase, and Cochrane Databases) was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement to identify articles on AH markers in Rb eyes. Inclusion criteria included English language articles with original reports on AH markers in the eyes of patients with confirmed Rb. Data on marker type, number of eyes, marker means and ranges, and when available, control values and clinicopathological correlations were collected. Articles were stratified based on marker type, and assessed quantitatively and qualitatively.

Results

An initial database search produced 325 articles, and an additional 11 articles were identified through searching citations. After removing duplicates and applying the eligibility criteria, we selected 27 articles to be included in the current review. A total of 463 eyes with histologically confirmed Rb were included in this review. The various markers and their values, with comparison to controls and clinicopathological correlations, are discussed.

Conclusions

AH sampling and tumor biomarker analysis in eyes without undergoing enucleation have the potential to revolutionize the management of Rb.

Translational Relevance

Although previous studies evaluated markers in the AH only after enucleation and not at diagnosis or during therapy, the clinical relevance of these markers was limited. However, recent changes in the management of Rb have allowed for safe sampling of the aqueous during therapy and, thus, correlation of tumor biomarkers with disease course. Thus, the authors felt it important to revisit previous research to evaluate whether these markers may now be applicable for the diagnosis, prognosis, or management of Rb

Expression of DEK in pancreatic cancer and its correlation with clinicopathological features and prognosis

Background: The oncogene DEK, which was originally identified as part of the protein product of the DEK-CAN fusion oncogene, has been shown to promote tumorigenesis in a variety of cancer cell types. However, little is known about the expression and role of DEK in pancreatic ductal adenocarcinoma (PDAC), which is one of the most refractory malignant tumors worldwide and has poor prognosis. Our study aimed to understand the role of DEK in the development and progression of pancreatic adenocarcinoma.

Materials and methods: We used western blotting and immunohistochemistry to examine the expression of DEK in pancreatic adenocarcinoma cells and tissues. We analyzed the correlation between DEK expression and clinicopathological characteristics and prognosis in 163 pancreatic adenocarcinoma patients.

Results: Protein levels of DEK in pancreatic adenocarcinoma tissues (76/136, 55.9%) were significantly higher than those in adjacent non-tumor tissues (16.2%, 22/136). A high expression level of DEK was associated with poor prognosis (P<0.001).In addition, the combination of CA19-9 and DEK expression (P<0.001) was a better prognostic indicator than CA19-9 expression alone (P=0.012).

Conclusions: DEK may play a significant role as a valuable biomarker in the development and progression of pancreatic adenocarcinoma. The combination of DEK and CA19-9 improves the prognostic prediction in patients with pancreatic adenocarcinoma.

Sex differences in DEK expression in the anterior cingulate cortex and its association with dementia severity in schizophrenia

DEK is a chromatin-remodeling phosphoprotein found in most human tissues, but its expression and function in the human brain is largely unknown. DEK depletion in vitro induces cellular and molecular anomalies associated with cognitive impairment, including down-regulation of the canonical Wnt/β-catenin signaling pathway. ToppGene analyses link DEK loss to genes associated with various dementias and age-related cognitive decline. To examine the role of DEK in cognitive impairment in severe mental illness, DEK protein expression was assayed by immunoblot in the anterior cingulate cortex (ACC) of subjects with schizophrenia. Cognitive impairment is a core feature of schizophrenia and cognitive function in subjects was assessed antemortem using the clinical dementia rating (CDR) scale. DEK protein expression was not significantly altered in schizophrenia (n = 20) compared to control subjects (n = 20). Further analysis revealed significant reduction in DEK protein expression in women with schizophrenia, and a significant increase in expression in men with schizophrenia, relative to their same-sex controls. DEK protein expression levels were inversely correlated with dementia severity in women. Conversely, in men, DEK protein expression and dementia severity were positively correlated. Notably, there was no sex difference in DEK protein expression in the control group, suggesting that this sex difference is specific to schizophrenia and not due to inherent differences in DEK expression between males and females. These results suggest a novel, sex-specific role for DEK in cognitive performance and highlight a putative sex-specific link between central nervous system DEK protein expression and a neuropsychiatric disease that is commonly associated with cognitive impairment.

The unique DEK oncoprotein in women's health: A potential novel biomarker

Breast and cervical cancer are the first and fourth cancer types with the highest prevalence in women, respectively. The developmental profiles of cancer in women can vary by genetic markers and cellular events. In turn, age and lifestyle influence in the cellular response and also on the cancer progression and relapse. The human DEK protein, a histone chaperone, belongs to a specific subclass of chromatin topology modulators, being involved in the regulation of DNA-dependent processes. These epigenetic mechanisms have dynamic and reversible nature, have been proposed as targets for different treatment approaches, especially in tumor therapy. The expression patterns of DEK vary between healthy and cancer cells. High expression of DEK is associated with poor prognosis in many cancer types, suggesting that DEK takes part in oncogenic activities via different molecular pathways, including inhibition of senescence and apoptosis. The focus of this review was to highlight the role of the DEK protein in these two female cancers.

Dek overexpression in murine epithelia increases overt esophageal squamous cell carcinoma incidence

Esophageal cancer occurs as either squamous cell carcinoma (ESCC) or adenocarcinoma. ESCCs comprise almost 90% of cases worldwide, and recur with a less than 15% five-year survival rate despite available treatments. The identification of new ESCC drivers and therapeutic targets is critical for improving outcomes. Here we report that expression of the human DEK oncogene is strongly upregulated in esophageal SCC based on data in the cancer genome atlas (TCGA). DEK is a chromatin-associated protein with important roles in several nuclear processes including gene transcription, epigenetics, and DNA repair. Our previous data have utilized a murine knockout model to demonstrate that Dek expression is required for oral and esophageal SCC growth. Also, DEK overexpression in human keratinocytes, the cell of origin for SCC, was sufficient to cause hyperplasia in 3D organotypic raft cultures that mimic human skin, thus linking high DEK expression in keratinocytes to oncogenic phenotypes. However, the role of DEK over-expression in ESCC development remains unknown in human cells or genetic mouse models. To define the consequences of Dek overexpression in vivo, we generated and validated a tetracycline responsive Dek transgenic mouse model referred to as Bi-L-Dek. Dek overexpression was induced in the basal keratinocytes of stratified squamous epithelium by crossing Bi-L-Dek mice to keratin 5 tetracycline transactivator (K5-tTA) mice. Conditional transgene expression was validated in the resulting Bi-L-Dek_K5-tTA mice and was suppressed with doxycycline treatment in the tetracycline-off system. The mice were subjected to an established HNSCC and esophageal carcinogenesis protocol using the chemical carcinogen 4-nitroquinoline 1-oxide (4NQO). Dek overexpression stimulated gross esophageal tumor development, when compared to doxycycline treated control mice. Furthermore, high Dek expression caused a trend toward esophageal hyperplasia in 4NQO treated mice. Taken together, these data demonstrate that Dek overexpression in the cell of origin for SCC is sufficient to promote esophageal SCC development in vivo.

Neuroanatomical Distribution of DEK Protein in Corticolimbic Circuits Associated with Learning and Memory in Adult Male and Female Mice

DEK, a chromatin-remodeling gene expressed in most human tissues, is known for its role in cancer biology and autoimmune diseases. DEK depletion in vitro reduces cellular proliferation, induces DNA damage subsequently leading to apoptosis, and down-regulates canonical Wnt/β-catenin signaling, a molecular pathway essential for learning and memory. Despite a recognized role in cancer (non-neuronal) cells, DEK expression and function is not well characterized in the central nervous system. We conducted a gene ontology analysis (ToppGene), using a cancer database to identify genes associated with DEK deficiency, which pinpointed several genes associated with cognitive-related diseases (i.e., Alzheimer's disease, presenile dementia). Based on this information, we examined DEK expression in corticolimbic structures associated with learning and memory in adult male and female mice using immunohistochemistry. DEK was expressed throughout the brain in both sexes, including the medial prefrontal cortex (prelimbic, infralimbic and dorsal peduncular). DEK was also abundant in all amygdalar subdivisions (basolateral, central and medial) and in the hippocampus including the CA1, CA2, CA3, dentate gyrus (DG), ventral subiculum and entorhinal cortex. Of note, compared to males, females had significantly higher DEK immunoreactivity in the CA1, indicating a sex difference in this region. DEK was co-expressed with neuronal and microglial markers in the CA1 and DG, whereas only a small percentage of DEK cells were in apposition to astrocytes in these areas. Given the reported inverse cellular and molecular profiles (e.g., cell survival, Wnt pathway) between cancer and Alzheimer's disease, these findings suggest a potentially important role of DEK in cognition.

Promotion of cell proliferation by the proto-oncogene DEK enhances oral squamous cell carcinogenesis through field cancerization

Oral squamous cell carcinoma (OSCC) develops through a multistep carcinogenic process involving field cancerization. The DEK gene is a proto-oncogene with functions in genetic and epigenetic modifications, and has oncogenic functions, including cellular proliferation, differentiation, and senescence. DEK overexpression is associated with malignancies; however, the functional roles of DEK overexpression are unclear. We demonstrated that DEK-expressing cells were significantly increased in human dysplasia/carcinoma in situ and OSCC. Furthermore, we generated ubiquitous and squamous cell-specific doxycycline (DOX)-inducible Dek mice (iDek and iDek-e mice respectively). Both DOX+ iDek and iDek-e mice did not show differences in the oral mucosa compared with DOX- mice. In the environment exposed to carcinogen, DOX-treated (DOX+) iDek mice showed field cancerization and OSCC development. Microarray analysis revealed that DEK overexpression was mediated by the upregulation of DNA replication- and cell cycle-related genes, particularly those related to the G1 /S transition. Tongue tumors overexpressing DEK showed increased proliferating cell nuclear antigen and elongator complex protein 3 expression. Our data suggest that DEK overexpression enhanced carcinogenesis, including field cancerization, in OSCC by stimulating the G1 /S phase transition and promoting DNA replication, providing important insights into the potential applications of DEK as a target in the treatment and prevention of OSCC.

Silencing DEK downregulates cervical cancer tumorigenesis and metastasis via the DEK/p-Ser9-GSK-3β/p-Tyr216-GSK-3β/β-catenin axis

Cervical cancer is the second most common gynecological malignancy. The mechanisms of the genesis and progression of cervical cancer are complicated and not thoroughly understood. DEK is reported as an oncogene in various cancers, such as acute myeloid leukemia, bladder cancer, breast cancer and hepatocellular cancer. However, its role in cervical cancer has not been well studied. In our study, we confirmed the DEK protein as an oncoprotein in cervical cancer tissues which is correlated to cervical cancer FIGO staging and tumor type. Moreover, in vitro loss of DEK inhibited cervical cancer cell proliferation, migration and invasion. We proved that silencing DEK downregulated Wnt/β-catenin and MMP-9, and silencing DEK increased GSK-3β activity via regulating its phosphorylation instead of translation. Silencing DEK reduced p-Ser9-GSK-3β and increased p-Tyr216-GSK-3β, which resulted in β-catenin degradation. Finally, the xenograft model in nude mice proved that silencing DEK impaired cervical cancer cell tumorigenicity. This research unveiled the function of DEK in tumorigenesis and metastasis via the DEK/p-Ser9-GSK-3β/p-Tyr216-GSK-3β/β-catenin axis in cervical cancer and gave insights into DEK-targeting therapy for patients suffering from cervical cancer.

Transformation of human CD34+ hematopoietic progenitor cells with DEK-NUP214 induces AML in an immunocompromised mouse model

Acute myeloid leukemia (AML) is a heterogeneous disease comprising a large number of subtypes defined by specific chromosome abnormalities. One such subtype carries the t(6;9)(p22;q34) chromosome rearrangement, which leads to expression of the DEK-NUP214 chimeric gene, and has a particularly poor outcome. To provide a better understanding of the molecular etiology of these relatively rare individual AML variants, it is necessary to generate in vivo models, which can also serve as a means to evaluate targeted therapies based on their specific genetic abnormalities. Here, we describe the development of a human cell AML, generated in CD34+ human hematopoietic progenitor cells xenografted into immunocompromised mice that express human myeloid cell growth factors. Within 6 months, these mice develop a human cell AML with phenotypic characteristics of the primary t(6;9) disease and a CD45+CD13+CD34+CD38+ immunophenotype. Gene expression studies show that members of the HOX family of genes (HOXA9, 10, B3, B4 and PBX3) are highly upregulated in the AML from this mouse model as well as from primary human t(6;9) AML. Gene expression analysis also identified several other significantly disregulated pathways involving KRAS, BRCA1 and ALK, for example. This is the first report of a humanized model of the DEK-NUP214 disease and provides a means to study the development and treatment of this particular subtype of AML.

Critical role of DEK and its regulation in tumorigenesis and metastasis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality globally. Therefore, it is quite essential to identify novel HCC-related molecules for the discovery of new prognostic markers and therapeutic targets. As an oncogene, DEK plays an important role in cell processes and participates in a variety of cellular metabolic functions, and its altered expression is associated with several human malignancies. However, the functional significance of DEK and the involved complex biological events in HCC development and progression are poorly understood. Here, combing the results from clinical specimens and cultured cell lines, we uncover a critical oncogenic role of DEK, which is highly expressed in HCC cells. DEK protein encompasses two isoforms (isoforms 1 and 2) and isoform 1 is the most frequently expressed DEK isoform in HCC cells. DEK depletion by using shRNA inhibited the cell proliferation and migration in vitro and suppressed tumorigenesis and metastasis in mouse models. Consistently, DEK overexpression regardless of which isoform produced the opposite effects. Further studies showed that DEK induced cell proliferation through upregulating cell cycle related CDK signaling, and promoted cell migration and EMT, at least in part, through the repression of β-catenin/E-cadherin axis. Interestingly, isoform 1 induced cell proliferation more efficiently than isoform 2, however, no functional differences existed between these two isoforms in cell migration. Together, our study indicates that DEK expression is required for tumorigenesis and metastasis of HCC, providing molecular insights for DEK-related pathogenesis and a basis for developing new strategies against HCC.

Significance of DEK overexpression for the prognostic evaluation of non-small cell lung carcinoma

In the present study, we explored the role of DEK expression for the prognostic evaluation of non-small cell lung carcinoma (NSCLC). DEK protein and mRNA expression levels were detected in NSCLC cells and fresh tissue samples of NSCLC paired with adjacent non-tumor tissues, respectively. NSCLC cases (n=196) meeting strict follow-up criteria were selected for immunohistochemical staining of DEK protein. Correlations between DEK expression and clinicopathological features of the NSCLC cases were evaluated using Chi-square tests. Survival rates were calculated using the Kaplan-Meier method, and the relationship between prognostic factors and patient overall survival was analyzed using Cox proportional hazard analysis. Based on the results, the levels of DEK protein and mRNA were significantly upregulated in 6 fresh tissue samples of NSCLC. Immunohistochemical analysis showed that the DEK expression rate was significantly higher in the NSCLC samples compared with either the adjacent non-tumor tissues or normal lung tissues. DEK expression was correlated with poor differentiation and late pathological stage of NSCLC. DEK expression was also correlated with low disease-free survival and overall survival rates. In the early-stage group, disease-free and overall survival rates of patients with DEK expression were significantly lower than those of patients without DEK expression. Further analysis using a Cox proportional hazard regression model revealed that DEK expression emerged as a significant independent hazard factor for the overall survival rate of patients with NSCLC. Consequently, DEK plays an important role in the progression of NSCLC. DEK may potentially be used as an independent biomarker for the prognostic evaluation of NSCLC.

IRAK1 is a novel DEK transcriptional target and is essential for head and neck cancer cell survival

The chromatin-binding DEK protein was recently reported to promote the growth of HPV+ and HPV- head and neck squamous cell carcinomas (HNSCCs). Relevant cellular and molecular mechanism(s) controlled by DEK in HNSCC remain poorly understood. While DEK is known to regulate specific transcriptional targets, global DEK-dependent gene networks in HNSCC are unknown. To identify DEK transcriptional signatures we performed RNA-Sequencing (RNA-Seq) in HNSCC cell lines that were either proficient or deficient for DEK. Bioinformatic analyses and subsequent validation revealed that IRAK1, a regulator of inflammatory signaling, and IRAK1-dependent regulatory networks were significantly repressed upon DEK knockdown in HNSCC. According to TCGA data, 14% of HNSCC specimens overexpressed IRAK1, thus supporting possible oncogenic functions. Furthermore, genetic or pharmacologic inhibition of IRAK1 in HNSCC cell lines was sufficient to attenuate downstream signaling such as ERK1/2 and to induce HNSCC cell death by apoptosis. Finally, targeting DEK and IRAK1 simultaneously enhanced cell death as compared to targeting either alone. Our findings reveal that IRAK1 promotes cell survival and is an attractive therapeutic target in HNSCC cells. Thus, we propose a model wherein IRAK1 stimulates tumor signaling and phenotypes both independently and in conjunction with DEK.

MicroRNA-592 targets DEK oncogene and suppresses cell growth in the hepatocellular carcinoma cell line HepG2

MicroRNAs (miRNAs) are classes of small, non-coding RNAs that regulate the translation of target mRNA transcripts. In this study, we demonstrated that miR-592 was downregulated in human hepatocellular carcinoma (HCC) and could suppress growth of the human HCC cell line HepG2. A tumor oncogene, DEK, was identified as a direct target of miR-592. Luciferase report assay indicated miR-592 regulates DEK expression though bind to its 3'UTR. Furthermore, knockdown of DEK also suppressed cell proliferation of HepG2 cells, which was consist with miR-592. At last, we suggested that DEK was upregulated in HCC tissues inversely with miR-592. These results demonstrated that miR-592 targets DEK transcript and suppresses HCC cell growth, and may provide potential therapeutic target in human HCC.

Dissecting the Potential Interplay of DEK Functions in Inflammation and Cancer

There is a long-standing correlation between inflammation, inflammatory cell signaling pathways, and tumor formation. Understanding the mechanisms behind inflammation-driven tumorigenesis is of great research and clinical importance. Although not entirely understood, these mechanisms include a complex interaction between the immune system and the damaged epithelium that is mediated by an array of molecular signals of inflammation—including reactive oxygen species (ROS), cytokines, and NFκB signaling—that are also oncogenic. Here, we discuss the association of the unique DEK protein with these processes. Specifically, we address the role of DEK in chronic inflammation via viral infections and autoimmune diseases, the overexpression and oncogenic activity of DEK in cancers, and DEK-mediated regulation of NFκB signaling. Combined, evidence suggests that DEK may play a complex, multidimensional role in chronic inflammation and subsequent tumorigenesis.

The DEK oncoprotein and its emerging roles in gene regulation

The DEK oncogene is highly expressed in cells from most human tissues and overexpressed in a large and growing number of cancers. It also fuses with the NUP214 gene to form the DEK-NUP214 fusion gene in a subset of acute myeloid leukemia. Originally characterized as a member of this translocation, DEK has since been implicated in epigenetic and transcriptional regulation, but its role in these processes is still elusive and intriguingly complex. Similarly multifaceted is its contribution to cellular transformation, affecting multiple cellular processes such as self-renewal, proliferation, differentiation, senescence and apoptosis. Recently, the roles of the DEK and DEK-NUP214 proteins have been elucidated by global analysis of DNA binding and gene expression, as well as multiple functional studies. This review outlines recent advances in the understanding of the basic functions of the DEK protein and its role in leukemogenesis.

DEK over-expression promotes mitotic defects and micronucleus formation

The DEK gene encodes a nuclear protein that binds chromatin and is involved in various fundamental nuclear processes including transcription, RNA splicing, DNA replication and DNA repair. Several cancer types characteristically over-express DEK at the earliest stages of transformation. In order to explore relevant mechanisms whereby DEK supports oncogenicity, we utilized cancer databases to identify gene transcripts whose expression patterns are tightly correlated with that of DEK. We identified an enrichment of genes involved in mitosis and thus investigated the regulation and possible function of DEK in cell division. Immunofluorescence analyses revealed that DEK dissociates from DNA in early prophase and re-associates with DNA during telophase in human keratinocytes. Mitotic cell populations displayed a sharp reduction in DEK protein levels compared to the corresponding interphase population, suggesting DEK may be degraded or otherwise removed from the cell prior to mitosis. Interestingly, DEK overexpression stimulated its own aberrant association with chromatin throughout mitosis. Furthermore, DEK co-localized with anaphase bridges, chromosome fragments, and micronuclei, suggesting a specific association with mitotically defective chromosomes. We found that DEK over-expression in both non-transformed and transformed cells is sufficient to stimulate micronucleus formation. These data support a model wherein normal chromosomal clearance of DEK is required for maintenance of high fidelity cell division and chromosomal integrity. Therefore, the overexpression of DEK and its incomplete removal from mitotic chromosomes promotes genomic instability through the generation of genetically abnormal daughter cells. Consequently, DEK over-expression may be involved in the initial steps of developing oncogenic mutations in cells leading to cancer initiation.

The DEK oncogene promotes cellular proliferation through paracrine Wnt signaling in Ron receptor-positive breast cancers

Disease progression and recurrence are major barriers to survival for breast cancer patients. Understanding the etiology of recurrent or metastatic breast cancer and underlying mechanisms is critical for the development of new treatments and improved survival. Here, we report that two commonly overexpressed breast cancer oncogenes, Ron (Recepteur d'Origine Nantaise) and DEK, cooperate to promote advanced disease through multipronged effects on β-catenin signaling. The Ron receptor is commonly activated in breast cancers, and Ron overexpression in human disease stimulates β-catenin nuclear translocation and is an independent predictor of metastatic dissemination. Dek is a chromatin-associated oncogene whose expression has been linked to cancer through multiple mechanisms, including β-catenin activity. We demonstrate here that Dek is a downstream target of Ron receptor activation in murine and human models. The absence of Dek in the MMTV-Ron mouse model led to a significant delay in tumor development, characterized by decreased cell proliferation, diminished metastasis and fewer cells expressing mammary cancer stem cell markers. Dek complementation of cell lines established from this model was sufficient to promote cellular growth and invasion. Mechanistically, Dek expression stimulated the production and secretion of Wnt ligands to sustain an autocrine/paracrine canonical β-catenin signaling loop. Finally, we show that Dek overexpression promotes tumorigenic phenotypes in immortalized human mammary epithelial MCF10A cells and, in the context of Ron receptor activation, correlates with disease recurrence and metastasis in patients. Overall, our studies demonstrate that DEK overexpression, due in part to Ron receptor activation, drives breast cancer progression through the induction of Wnt/β-catenin signaling.

DEK promotes HPV-positive and -negative head and neck cancer cell proliferation

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide, and patient outcomes using current treatments remain poor. Tumor development is etiologically associated with tobacco or alcohol use and/or human papillomavirus (HPV) infection. HPV-positive HNSCCs, which frequently harbor wild-type p53, carry a more favorable prognosis and are a biologically distinct subgroup when compared with their HPV-negative counterparts. HPV E7 induces expression of the human DEK gene, both in vitro and in vivo. In keratinocytes, DEK overexpression is sufficient for causing oncogenic phenotypes in the absence of E7. Conversely, DEK loss results in cell death in HPV-positive cervical cancer cells at least in part through p53 activation, and Dek knockout mice are relatively resistant to the development of chemically induced skin papillomas. Despite the established oncogenic role of DEK in HPV-associated cervical cancer cell lines and keratinocytes, a functional role of DEK has not yet been explored in HNSCC. Using an established transgenic mouse model of HPV16 E7-induced HNSCC, we demonstrate that Dek is required for optimal proliferation of E7-transgenic epidermal cells and for the growth of HNSCC tumors. Importantly, these studies also demonstrate that DEK protein is universally upregulated in both HPV-positive and -negative human HNSCC tumors relative to adjacent normal tissue. Furthermore, DEK knockdown inhibited the proliferation of HPV-positive and -negative HNSCC cells, establishing a functional role for DEK in human disease. Mechanistic studies reveal that attenuated HNSCC cell growth in response to DEK loss was associated with reduced expression of the oncogenic p53 family member, ΔNp63. Exogenous ΔNp63 expression rescued the proliferative defect in the absence of DEK, thereby establishing a functional DEK-ΔNp63 oncogenic pathway that promotes HNSCC. Taken together, our data demonstrate that DEK stimulates HNSCC cellular growth and identify ΔNp63 as a novel DEK effector.

The DEK oncoprotein binds to highly and ubiquitously expressed genes with a dual role in their transcriptional regulation

BACKGROUND

The DEK gene is highly expressed in a wide range of cancer cells, and a recurrent translocation partner in acute myeloid leukemia. While DEK has been identified as one of the most abundant proteins in human chromatin, its function and binding properties are not fully understood.

METHODS

We performed ChIP-seq analysis in the myeloid cell line U937 and coupled it with epigenetic and gene expression analysis to explore the genome-wide binding pattern of DEK and its role in gene regulation.

RESULTS

We show that DEK preferentially binds to open chromatin, with a low degree of DNA methylation and scarce in the heterochromatin marker H3K9me(3) but rich in the euchromatin marks H3K4me(2/3), H3K27ac and H3K9ac. More specifically, DEK binding is predominantly located at the transcription start sites of highly transcribed genes and a comparative analysis with previously established transcription factor binding patterns shows a similarity with that of RNA polymerase II. Further bioinformatic analysis demonstrates that DEK mainly binds to genes that are ubiquitously expressed across tissues. The functional significance of DEK binding was demonstrated by knockdown of DEK by shRNA, resulting in both significant upregulation and downregulation of DEK-bound genes.

CONCLUSIONS

We find that DEK binds to transcription start sites with a dual role in activation and repression of highly and ubiquitously expressed genes.

High expression of oncoprotein DEK predicts poor prognosis of small cell lung cancer

Oncoprotein DEK plays an important role in cancer tumorigenesis. To explore the clinical implication of DEK expression on prognostic evaluation in small cell lung cancer (SCLC), 130 cases of SCLC with strict follow-up were selected for immunohistochemical (IHC) staining of DEK protein. The correlation between DEK expression and clinicopathological features of SCLC was evaluated using the Chi-square and Fisher's exact tests, survival rates were calculated using the Kaplan-Meier method and univariate and multivariate analyses were performed using the Cox proportional hazards regression model. IHC analysis demonstrated that DEK protein staining was strongly positive and significantly higher (44.62%) in SCLC compared with either adjacent non-tumor or normal lung tissues (P < 0.001 for both). DEK expression correlated with large tumor size (P = 0.025) and late pathologic stage (P = 0.005). Moreover, it correlated with low disease-free (P = 0.004) and 5-year (P = 0.005) survival rates. In the late-stage group, disease-free and 5-year survival rates of patients with high level DEK expression were significantly lower than those with low level DEK expression (P = 0.006 and P = 0.001, respectively). Furthermore, Cox analysis revealed that DEK expression emerged as a significant independent hazard factor for the overall survival rate of patients with SCLC (HR: 1.594, 95% CI: 1.087-2.336, P = 0.017). In conclusion, DEK plays an important role in the progression of SCLC. DEK may potentially be used as an independent biomarker for the prognostic evaluation of SCLC.

Concise review: role of DEK in stem/progenitor cell biology

Understanding the factors that regulate hematopoiesis opens up the possibility of modifying these factors and their actions for clinical benefit. DEK, a non-histone nuclear phosphoprotein initially identified as a putative proto-oncogene, has recently been linked to regulate hematopoiesis. DEK has myelosuppressive activity in vitro on proliferation of human and mouse hematopoietic progenitor cells and enhancing activity on engraftment of long-term marrow repopulating mouse stem cells, has been linked in coordinate regulation with the transcription factor C/EBPα, for differentiation of myeloid cells, and apparently targets a long-term repopulating hematopoietic stem cell for leukemic transformation. This review covers the uniqueness of DEK, what is known about how it now functions as a nuclear protein and also as a secreted molecule that can act in paracrine fashion, and how it may be regulated in part by dipeptidylpeptidase 4, an enzyme known to truncate and modify a number of proteins involved in activities on hematopoietic cells. Examples are provided of possible future areas of investigation needed to better understand how DEK may be regulated and function as a regulator of hematopoiesis, information possibly translatable to other normal and diseased immature cell systems.

DEK over expression as an independent biomarker for poor prognosis in colorectal cancer

BACKGROUND

The DEK protein is related to chromatin reconstruction and gene transcription, and plays an important role in cell apoptosis. High expression levels of the human DEK gene have been correlated with numerous human malignancies. This study explores the roles of DEK in tumor progression and as a prognostic determinant of colorectal cancer.

METHODS

Colorectal cancer specimens from 109 patients with strict follow-up, and colorectal adenomas from 52 patients were selected for analysis of DEK protein by immunohistochemistry. The correlations between DEK over expression and the clinicopathological features of colorectal cancers were evaluated by Chi-square test and Fisher's exact tests. The survival rates were calculated by the Kaplan-Meier method, and the relationship between prognostic factors and patient survival was also analyzed by the Cox proportional hazard models.

RESULTS

DEK protein showed a nuclear immunohistochemical staining pattern in colorectal cancers. The strongly positive rate of DEK protein was 48.62% (53/109) in colorectal cancers, which was significantly higher than that in either adjacent normal colon mucosa (9.17%, 10/109) or colorectal adenomas (13.46%, 7/52). DEK over expression in colorectal cancers was positively correlated with tumor size, grade, lymph node metastasis, serosal invasion, late stage, and disease-free survival- and 5-year survival rates. Further analysis showed that patients with late stage colorectal cancer and high DEK expression had worse survival rates than those with low DEK expression. Moreover, multivariate analysis showed high DEK expression, serosal invasion, and late stage are significant independent risk factors for mortality in colorectal cancer.

CONCLUSIONS

DEK plays an important role in the progression of colorectal cancers and it is an independent poor prognostic factor of colorectal cancers.

The genomic landscape of retinoblastoma: a review

Retinoblastoma is a paediatric ocular tumour that continues to reveal much about the genetic basis of cancer development. Study of genomic aberrations in retinoblastoma tumours has exposed important mechanisms of cancer development and identified oncogenes and tumour suppressors that offer potential points of therapeutic intervention. The recent development of next-generation genomic technologies has allowed further refinement of the genomic landscape of retinoblastoma at high resolution. In a relatively short period of time, a wealth of genetic and epigenetic data has emerged on a small number of tumour samples. These data highlight the inherent molecular complexity of this cancer despite the fact that most retinoblastomas are initiated by the inactivation of a single tumour suppressor gene. This review outlines the current understanding of the genomic, genetic and epigenetic changes in retinoblastoma, highlighting recent genome-wide analyses that have identified exciting candidate genes worthy of further validation as potential prognostic and therapeutic targets.