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

The oncoprotein DEK controls growth-regulated gene expression by enhancing the DNA-binding activity of basic leucine zipper transcription factors

Overexpression of the oncogenic protein DEK is associated with a poor prognosis in various cancers. However, the molecular mechanisms by which DEK promotes cancer development and malignant transformation remain unclear. Previous studies have shown that DEK interacts with transcription factors, such as AP-2a and C/EBPα, and enhances their transcriptional activity. We hypothesized that DEK promotes cancer cell phenotypes by regulating transcription factors. We analyzed the interaction between DEK and the transcription factors to evaluate this hypothesis. We found that DEK binds to the basic regions within the basic leucine zipper (bZIP)- and basic helix-loop-helix leucine zipper (bHLH-ZIP)- transcription factors. Interestingly, DEK enhanced the DNA-binding capacity of two bZIP transcription factors, C/EBPα and ATF3, in vitro without being a component of the transcription factor-DNA complex. We performed DEK knockdown in lung adenocarcinoma A549 cells and examined the global transcriptome changes to determine the biological significance of the interaction between DEK and transcription factors. We found that diverse genes regulating cell growth and amino acid metabolism, which may potentially be regulated by c-Jun, a subunit of the bZIP transcription factor AP1, and c-Myc, a bHLH-ZIP transcription factor, were decreased by DEK knockdown. Consistent with these transcriptome changes, the cell growth, colony formation, and cell migration abilities of A549 cells were decreased by DEK knockdown. These results suggest that DEK promotes cancer cell malignancy by regulating the functions of the bZIP and bHLH-ZIP transcription factors.

Proto-oncogene DEK binds to pre-mRNAs and regulates the alternative splicing of Hippo signaling genes in HeLa cells

Our study aimed to explore how DEK, a carcinogenic protein with chromatin architectural function, genome-widely binds to RNA and affects the alternative splicing in cancer cells to decipher its molecular functions. To achieve this goal, cell phenotype experiments, RNA sequencing (RNA-seq), and improved RNA immunoprecipitation sequencing (iRIP-seq) were conducted to identify the function and regulated targets of DEK in HeLa cells. The results showed DEK overexpression promoted cell proliferation and invasion of HeLa cells. Meanwhile, DEK hardly affected transcript level expression of those high expressed genes, but splicing pattern of 411 genes was regulated by DEK in HeLa cells, which were enriched in Hippo signaling pathway. Moreover, DEK broadly bind the RNA of a total of 11, 112 genes, with a biased binding the 5' splice site (5'SS) consensus GGUAA motifs at the CDS and intronic regions. In addition, 297 DEK-binding genes showed different splicing pattern after DEK overexpression in HeLa cells. These genes were enriched in Hippo signaling pathway including CSNK1D. The RT-qPCR and RIP-PCR confirmed that DEK can bind to CSNK1D to regulate its alternative splicing in HeLa cells. In summary, our results indicated DEK could broadly bind and regulate the pre-mRNA splicing process, which provide new insights of mechanisms that DEK functions in various biological processes including cancer.

DEK regulates B-cell proliferative capacity and is associated with aggressive disease in low-grade B-cell lymphomas

This study sheds light on the pivotal role of the oncoprotein DEK in B-cell lymphoma. We reveal DEK expression correlates with increased tumor proliferation and inferior overall survival in cases diagnosed with low-grade B-cell lymphoma (LGBCL). We also found significant correlation between DEK expression and copy number alterations in LGBCL tumors, highlighting a novel mechanism of LGBCL pathogenesis that warrants additional exploration. To interrogate the mechanistic role of DEK in B-cell lymphoma, we generated a DEK knockout cell line model, which demonstrated DEK depletion caused reduced proliferation and altered expression of key cell cycle and apoptosis-related proteins, including Bcl-2, Bcl-xL, and p53. Notably, DEK depleted cells showed increased sensitivity to apoptosis-inducing agents, including venetoclax and staurosporine, which underscores the therapeutic potential of targeting DEK in B-cell lymphomas. Overall, our study contributes to a better understanding of DEK's role as an oncoprotein in B-cell lymphomas, highlighting its potential as both a promising therapeutic target and a novel biomarker for aggressive LGBCL. Further research elucidating the molecular mechanisms underlying DEK-mediated tumorigenesis could pave the way for improved treatment strategies and better clinical outcomes for patients with B-cell lymphoma.

DEK deficiency suppresses mitophagy to protect against house dust mite-induced asthma

DEK protein is highly expressed in asthma. However, the mechanism of DEK on mitophagy in asthma has not been fully understood. This study aims to investigate the role and mechanism of DEK in asthmatic airway inflammation and in regulating PINK1-Parkin-mediated mitophagy, NLRP3 inflammasome activation, and apoptosis. PINK1-Parkin mitophagy, NLRP3 inflammasome, and apoptosis were examined after gene silencing or treatment with specific inhibitors (MitoTEMPO, MCC950, and Ac-DEVD-CHO) in house dust mite (HDM) or recombinant DEK (rmDEK)-induced WT and DEK-/- asthmatic mice and BEAS-2B cells. The regulatory role of DEK on ATAD3A was detected using ChIP-sequence and co-immunoprecipitation. rmDEK promoted eosinophil recruitment, and co-localization of TOM20 and LC3B, MFN1 and mitochondria, LC3B and VDAC, and ROS generation, reduced protein level of MnSOD in HDM induced-asthmatic mice. Moreover, rmDEK also increased DRP1 expression, PINK1-Parkin-mediated mitophagy, NLRP3 inflammasome activation, and apoptosis. These effects were partially reversed in DEK-/- mice. In BEAS-2B cells, siDEK diminished the Parkin, LC3B, and DRP1 translocation to mitochondria, mtROS, TOM20, and mtDNA. ChIP-sequence analysis showed that DEK was enriched on the ATAD3A promoter and could positively regulate ATAD3A expression. Additionally, ATAD3A was highly expressed in HDM-induced asthma models and interacted with DRP1, and siATAD3A could down-regulate DRP1 and mtDNA-mediated mitochondrial oxidative damage. Conclusively, DEK deficiency alleviates airway inflammation in asthma by down-regulating PINK1-Parkin mitophagy, NLRP3 inflammasome activation, and apoptosis. The mechanism may be through the DEK/ATAD3A/DRP1 signaling axis. Our findings may provide new potential therapeutic targets for asthma treatment.

Hsa_circ_0001479 accelerates tumorigenesis of gastric cancer and mediates immune escape

Gastric cancer (GC) is a common fatal malignant tumor of the digestive tract, particularly in Asia. Circular RNA (circRNA) has been proved to regulate malignancy progression and immunotherapeutic efficacy in multiple tumors, including GC. Notably, the function of circRNAs in GC has not been completely revealed. Therefore, exploration of more GC related circRNAs may provide potential strategies for GC treatment. In the study, it was observed that hsa_circ_0001479 exhibited a high level of expression in GC and was subsequently found to be associated with the depth of invasion, lymph node metastasis, and TNM stage. Functionally, the overexpression of hsa_circ_0001479 was found to enhance the proliferation and migration of GC cells, as evidenced by various experiments such as CCK-8, EdU, colony forming and transwell. Dual-luciferase reporter assay verified that hsa_circ_0001479 upregulated DEK expression by sponge targeting miR-133a-5p. Further investigations indicated DEK affected the entry of β-catenin into the nucleus by activating Wnt/β-catenin signaling pathway to promote accumulation of downstream c-Myc. As a transcription factor, c-Myc combined with the promoter of hsa_circ_0001479 parent gene to stimulate hsa_circ_0001479 generation. Besides, hsa_circ_0001479 inhibited theinfiltration with CD8+T cells in GC and associated with immune checkpoints. In summary, hsa_circ_0001479 accelerated the development and metastasis of GC and mediates immune escape of CD8+T cells. Targeting it may provide a novel immunotherapy to better locally treat GC and reduce the incidence of metastases.

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.

Doxorubicin induces prolonged DNA damage signal in cells overexpressing DEK isoform-2

DEK has a short isoform (DEK isoform-2; DEK2) that lacks amino acid residues between 49–82. The full-length DEK (DEK isoform-1; DEK1) is ubiquitously expressed and plays a role in different cellular processes but whether DEK2 is involved in these processes remains elusive. We stably overexpressed DEK2 in human bone marrow stromal cell line HS-27A, in which endogenous DEKs were intact or suppressed via short hairpin RNA (sh-RNA). We have found that contrary to ectopic DEK1, DEK2 locates in the nucleus and nucleolus, causes persistent γH2AX signal upon doxorubicin treatment, and couldn’t functionally compensate for the loss of DEK1. In addition, DEK2 overexpressing cells were more sensitive to doxorubicin than DEK1-cells. Expressions of DEK1 and DEK2 in cell lines and primary tumors exhibit tissue specificity. DEK1 is upregulated in cancers of the colon, liver, and lung compared to normal tissues while both DEK1 and DEK2 are downregulated in subsets of kidney, prostate, and thyroid carcinomas. Interestingly, only DEK2 was downregulated in a subset of breast tumors suggesting that DEK2 can be modulated differently than DEK1 in specific cancers. In summary, our findings show distinct expression patterns and subcellular location and suggest non-overlapping functions between the two DEK isoforms.

Potential of DEK proto-oncogene as a prognostic biomarker for colorectal cancer: An evidence-based review

Given its role in tumorigenesis and its correlation with various pathologic features of colorectal cancer (CRC), DEK is considered to have the potential to predict CRC prognosis. This review attempts to summarize current knowledge and evidence supporting the potential of DEK as a prognostic biomarker of CRC. We searched meta-analyses, systematic reviews, cohort studies, and cell line studies published in the last 10 years. A literature search was conducted in PubMed, Pubmed Central (PMC), Proquest, EBSCOHost, Scopus, and Cochrane Library using the keywords 'colorectal/colon/rectal cancer', 'DEK', 'biomarker', and 'prognosis'. Studies that were not published in English, without accessible full text, unrelated to clinical questions, or conducted with a design unsuitable for the eligibility criteria were excluded. Seven included studies reported the potential of DEK as a prognostic biomarker of CRC and its role in cancer cell proliferation, invasion, and metastasis. This role is achieved through the Wnt/β-catenin pathway, prevention of apoptosis through destabilization of p53, and bridging inflammation and tumorigenesis through the nuclear factor (NF)-κB pathway, causing chronic inflammation and activation of tumorigenic genes. DEK overexpression is also associated with CRC clinical and pathological features, such as tumor size, lymph node metastasis, serosal invasion, differentiation, tumor staging, and epithelial-mesenchymal transition. DEK overexpression was found to be associated with lower survival and recovery rates. Its prognostic value was comparable with other prognostic biomarkers of CRC, such as BRAF, topoisomerase-1, and CEA. A cohort study reported that DEK overexpression was associated with a better response to fluoropyrimidine-based chemotherapy, while a cell-line study indicated a correlation between DEK overexpression with a worse response to irinotecan-based chemotherapy. In conclusion, considering its correlation with CRC pathology, its association with worse CRC patient survival, and its possibility to forecast the therapeutic response of various chemotherapeutic regimens, DEK has the potential to be used as a CRC prognostic biomarker.

IMMUNOEXPRESSION OF DEK AND PHOSPHO-P38 PROTEINS IN RECTAL CANCER BEFORE CHEMORADIATION THERAPY

BACKGROUND

Colorectal cancer is the third cause of cancer worldwide and a quarter of them are in the rectum. DEK oncogene is involved in several nuclear processes and can accelerate tumorigenesis.

OBJECTIVE

This study aims to evaluate the immunoexpression of DEK and Phospho-P38 proteins before neoadjuvant therapy in patients with rectum adenocarcinoma and correlate it with a clinical response and survival.

METHODS

Patients with adenocarcinoma of the middle and low rectum who underwent chemotherapy and radiotherapy followed by surgical tumor resection were included. The expression and quantification were studied by immunohistochemistry in the tumor biopsy tissues using a HScore system. Score ≥4 were considered positive and those with <4 negative.

RESULTS

22 patients were included with a mean age of 63.55 years (SD: ±13.49). The clinical-stage before treatment was T3 on 72.7%, T4 on 18.2%, 31.8% were N1, 50% N0 and all M0. After chemo and radiotherapy, 54.6% were T3; 22.7% were classified as T2; 9.1% as T1, and 13.6% were T0. Among the tumors, 22.7% were positive for DEK and 63.6% positive for Phospho-P38. There was a positive correlation between DEK protein before treatment and pTNM stage (P=0.011). Phospho-P38 protein showed no correlation with these parameters. Patients with a negative HScore had a mean survival of 141.33 months (95%CI: 112.41-170.25) and those with a positive HSscore had a mean survival of 25.10 months (95%CI: 17.36-32.84; P<0.001).

CONCLUSION

A higher expression of DEK was observed in advanced stages. Patients who presented DEK expression <4 had a higher survival, being a factor of worst prognosis.

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.

Gigantol inhibits cell proliferation and induces apoptosis by regulating DEK in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a common type of cancer, with a mortality of >80% worldwide. Gigantol is a bibenzyl compound that displays anticancer activity. The aim of the present study was to determine the biological activity of gigantol in NSCLC and to elucidate the underlying molecular mechanism of its action. The expression of DEK proto-oncogene (DEK) was measured in NSCLC tissues and cell lines by reverse transcription-quantitative PCR (RT-qPCR). The results suggested that DEK levels were significantly increased in NSCLC tissues and cell lines compared with adjacent non-tumor tissues and BEAS-2B normal bronchial epithelial cells, respectively. A549 cells were exposed to a series of gigantol concentrations (0, 25, 50 and 100 µM) and transfected with DEK small interfering RNA. The results of cell viability measured by MTT assay indicated that gigantol significantly decreased cell viability. Additionally, cell proliferation was assessed by CCK-8 and apoptosis was measured by flow cytometry. In comparison with the control group, gigantol treatment inhibited cell proliferation and promoted apoptosis, whereas DEK knockdown increased gigantol-induced suppression of proliferation and acceleration of apoptosis. Additionally, DEK overexpression reversed gigantol-induced effects on proliferation and apoptosis. Moreover, compared with the control group, gigantol treatment decreased Ki-67 and Bcl-2 expression levels, increased Bax expression levels and inactivated the Wnt/β-catenin signaling pathway, as assessed by RT-qPCR and/or western blot. DEK knockdown further increased gigantol-induced effects, but DEK overexpression reversed gigantol-induced effects. To conclude, the results of the present study suggested that gigantol inhibited cell proliferation and induced apoptosis by decreasing Ki-67 and Bcl-2 expression, increasing Bax expression and activating the Wnt/β-catenin signaling pathway by regulating DEK. The present study indicated the therapeutic potential of gigantol in patients with NSCLC. In addition, DEK may serve as a novel therapeutic target to enhance the effects of gigantol treatment.

DEK overexpression is predictive of poor prognosis in esophageal squamous cell carcinoma

INTRODUCTION

The DEK gene encodes a nuclear phosphoprotein which is involved in multiple cell metabolic processes, such as DNA damage repair, mRNA splicing, modifying chromatin structure and transcription regulation. DEK has been shown to be overexpressed in various solid human tumors and associated with patient prognosis. In this study, our aim was to investigate DEK protein expression and its relationship with clinicopathological parameters and prognosis in esophageal squamous cell carcinoma (ESCC).

MATERIAL AND METHODS

Tissue samples were collected from 120 routinely diagnosed ESCC patients who underwent surgical resection at the Zhongshan Hospital, Xiamen University in the period from June 2011 to May 2013. The expression of DEK was determined by immunohistochemistry.

RESULTS

DEK protein was ubiquitously distributed in the nucleus of ESCC cells, and its positive rate (71.7%) was significantly higher in cancer samples than those of para-carcinoma (21.4%) or normal esophageal (13.9%) tissues (p < 0.001). Similarly, significantly more cells overexpressing DEK were found in ESCC tissues (57.5%) in comparison with para-carcinoma samples (11.4%) and normal esophageal mucosa (0%, p < 0.001). The DEK overexpression rate was significantly different between patients with different tumor-node-metastasis (TNM) stages and differentiation degrees (p < 0.001). ESCC cases with elevated DEK amounts showed reduced disease-free and 5-year survival rates compared with those expressing low DEK amounts (p < 0.001). DEK overexpression was also confirmed to independently predict prognosis in ESCC (HR = 4.121, 95% CI: 1.803-9.42, p = 0.001).

CONCLUSIONS

DEK expression is positively correlated with reduced survival in ESCC patients. DEK has potential to be an independent biomarker in predicting prognosis of ESCC patients.

Role of the DEK oncogene in the development of squamous cell carcinoma

DEK is a highly conserved nuclear factor that plays an important role in the regulation of multiple cellular processes. DEK was discovered to be an oncogene as a fusion with NUP214 gene, which results in producing DEK-NUP214 proteins, in a subset of patients with acute myeloid leukemia. Subsequently, DEK overexpression was reported in many cancers, thus DEK itself is considered to be an oncoprotein. DEK has been reported to play important roles in the progression of early and late stage squamous cell carcinoma (SCC) and is useful for early diagnosis of the disease. These findings have made DEK an attractive therapeutic target, especially for human papillomavirus (HPV)-associated SCC. However, the mechanism of DEK in SCC remains unclear. In this review, we discuss human DEK oncogene-related SCC.

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.

The oncoprotein DEK affects the outcome of PARP1/2 inhibition during mild replication stress

DNA replication stress is a major source of genomic instability and is closely linked to tumor formation and progression. Poly(ADP-ribose)polymerases1/2 (PARP1/2) enzymes are activated in response to replication stress resulting in poly(ADP-ribose) (PAR) synthesis. PARylation plays an important role in the remodelling and repair of impaired replication forks, providing a rationale for targeting highly replicative cancer cells with PARP1/2 inhibitors. The human oncoprotein DEK is a unique, non-histone chromatin architectural protein whose deregulated expression is associated with the development of a wide variety of human cancers. Recently, we showed that DEK is a high-affinity target of PARylation and that it promotes the progression of impaired replication forks. Here, we investigated a potential functional link between PAR and DEK in the context of replication stress. Under conditions of mild replication stress induced either by topoisomerase1 inhibition with camptothecin or nucleotide depletion by hydroxyurea, we found that the effect of acute PARP1/2 inhibition on replication fork progression is dependent on DEK expression. Reducing DEK protein levels also overcomes the restart impairment of stalled forks provoked by blocking PARylation. Non-covalent DEK-PAR interaction via the central PAR-binding domain of DEK is crucial for counteracting PARP1/2 inhibition as shown for the formation of RPA positive foci in hydroxyurea treated cells. Finally, we show by iPOND and super resolved microscopy that DEK is not directly associated with the replisome since it binds to DNA at the stage of chromatin formation. Our report sheds new light on the still enigmatic molecular functions of DEK and suggests that DEK expression levels may influence the sensitivity of cancer cells to PARP1/2 inhibitors.

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.

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.

Oncogene DEK is highly expressed in lung cancerous tissues and positively regulates cell proliferation as well as invasion

DEK is a protein ubiquitously expressed in multicellular organisms as well as certain unicellular organisms. It is associated with the regulation of cell proliferation, differentiation, migration, apoptosis, senescence, self-renewal and DNA repairing. In tumor cells it is associated with the carcinogenesis process, however there have been few previous studies into the expression of DEK in lung cancer. In the present study the expression level of DEK mRNA and protein was detected in lung cancer tissues and non-cancerous counterparts by performing reverse transcription-quantitative polymerase chain reaction and immunohistochemical staining. It was revealed that the expression of DEK was increased in lung cancer tissues compared with normal tissue. Knock-down and over-expression of DEK in A549 cells were performed to determine the role of DEK in tumor formation. An MTT assay, colony formation assay and Matrigel invasion assay demonstrated that DEK positively regulated cell proliferation and invasion. These results suggest that DEK is highly expressed in lung cancer tissues and positively regulates cell proliferation and invasion.

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.

Epithelial‑mesenchymal transition in colorectal carcinoma cells is mediated by DEK/IMP3

To investigate the inhibitory effects of DEK/insulin‑like growth factor II mRNA binding protein 3 (IMP3) on epithelial‑mesenchymal transition (EMT) in colorectal carcinoma cells. SW620 and SW480 cell lines were selected. DEK‑interfering lentivirus was transfected to knockdown DEK expression. Subsequently, MTT assays and flow cytometry were utilized to measure cell viability, and apoptosis, respectively. Cell invasion was detected using a Transwell assay. Quantitative polymerase chain reaction and western blot analysis were used to detect the expression of E‑cadherin, vimentin, and matrix metalloproteinase (MMP)‑9. Compared with the blank control, cells transfected with DEK‑interfering lentivirus demonstrated a remarkable reduction in cell viability (P<0.05). The apoptotic rate in the DEK‑interfering lentivirus group was significantly enhanced compared with the blank control group (P<0.05). In the DEK‑interfering lentivirus group, the expression of E‑cadherin was significantly elevated (P<0.05), while the expression of vimentin and MMP‑9 were significantly reduced in both cell lines (P<0.05). The results of the present study demonstrated that EMT of colorectal carcinoma cells was partially mediated by DEK, which likely affected the invasive ability of colorectal carcinoma cells. In addition, cell proliferation and apoptosis were susceptible to DEK silencing. The current study has provided experimental evidence for the treatment of colorectal carcinoma using DEK silencing.

DEK promoted EMT and angiogenesis through regulating PI3K/AKT/mTOR pathway in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer associated with poor prognosis. As an oncogene, DEK involves in regulation of various cellular metabolisms and plays an important role in tumor growth and progression. Increasing evidences suggested that abnormal expression of DEK is closely related to multiple malignant tumors. However, the possible involvement of DEK in epithelial to mesenchymal transition (EMT) and angiogenesis in TNBC remains unclear. In the present study, we revealed that the over-expression of DEK was significantly correlated with clinical stage, differentiation, and lymph node (LN) metastasis of TNBC and indicated poor overall survival of TNBC patients. Moreover, we demonstrated that DEK depletion could significantly reduce cell proliferation, migration, invasion and angiogenesis in vitro. We also found that DEK promoted cancer cell angiogenesis and metastasis by activating the PI3K/AKT/mTOR pathway. Furthermore, we revealed the inhibitory effect of DEK depletion on tumor growth and progression in a xenograft tumor model in mice. These data indicated that DEK promotes TNBC cell proliferation, angiogenesis, and metastasis via PI3K/AKT/mTOR signaling pathway, and therefore, it might be a potential target in TNBC therapy.

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.

Prognostic role of DEK in human solid tumors: a meta-analysis

Recently, the oncogenic role of DEK has been recognized in several cancer types. However, its prognostic role in human solid tumor remains unclear. Thus, the present meta-analysis, based on 14 published studies (2208 patients) searched from PubMed, Web of Science, and EMBASE databases, assessed the prognostic value of DEK in human solid tumors. Furthermore, the pooled hazard ratio (HR) for overall survival (OS) was evaluated with fixed-effects models. A subgroup analysis was also performed according to the patients' ethnicities and tumor types. Data from these published studies were extracted, and the results showed that the overexpression of DEK was significantly associated with poor OS in human solid tumors. The combined hazards ratio was (HR = 1.83; 95% CI, 1.64-2.05, P < 0.00001) for OS (univariable analysis) with a fixed-effects model without any significant heterogeneity (P = 0.71, I² = 0%). The combined HR was (HR = 1.70; 95% CI, 1.48-1.96, P < 0.00001) for OS (multivariable analysis) with a fixed-effects model, and no significant heterogeneity was observed (P = 0.36, I² = 9%). Therefore, the overexpression of DEK was correlated with poor survival in human solid tumors, which suggests that the expression status of DEK is a valuable biomarker for the prediction of prognosis and serves as a novel therapeutic target in human solid tumors.

Expression of family with sequence similarity 172 member A and nucleotide-binding protein 1 is associated with the poor prognosis of colorectal carcinoma

In our previous studies, a functionally unknown gene, family with sequence similarity 172, member A (FAM172A), was identified. High levels of FAM172A suppressed the cell cycle process, arresting HepG2 cells in G1/S and inhibiting cell proliferation. The present study aimed to confirm the expression levels of FAM172A and nucleotide-binding protein 1 (NUBP1) in colorectal cancer (CRC) tissues and normal colorectal tissues. The impact of FAM172A and NUBP1 on the prognosis of patients with CRC was also analyzed. Immunohistochemical staining for FAM172A and NUBP1 was performed on 180 cancerous tissues and 60 normal paraffin-embedded tissues from patients with CRC. In total, 85 and 83% of 180 patients revealed positive expression of FAM172A and NUBP1, respectively. FAM172A expression level was associated with Tumor-Node-Metastasis (TNM) staging (P<0.001), the levels of serum carcinoembryonic antigen (CEA; P=0.023) and carbohydrate antigen 19–9 (CA19-9; P=0.016), lymph node involvement (P=0.004), tissue type (P=0.016), Dukes' staging (P<0.001) and NUBP1 (P=0.026). Furthermore, the expression level of NUBP1 was also markedly associated with the levels of serum CEA (P=0.006) and CA19-9 (P=0.001), TNM staging (P<0.001), lymph node involvement (P=0.005), histological typing (P=0.024) and Dukes' stage (P<0.001). Results of the univariate analysis demonstrated that there was a negative correlation between the expression level of FAM172A and overall survival (OS) and relapse-free survival (RFS) (P=0.013 and P=0.012, respectively), and there was also a negative correlation between NUBP1 expression level and OS and RFS (P<0.001 and P<0.001, respectively). With regards to OS and RFS, multivariate analysis revealed that expression levels of FAM172A and NUBP1 and tumor stage may be independent prognostic factors Thus, the present study suggested that FAM172A and NUBP1 may be prognostic makers for CRC.

DEK proto-oncogene is highly expressed in astrocytic tumors and regulates glioblastoma cell proliferation and apoptosis

Astrocytic tumors are the most common neuroepithelial neoplasms with high relapse rate after surgery. Understanding the molecular mechanisms for astrocytic tumorigenesis and progression will lead to early diagnosis and effective treatment of astrocytic tumors. The DEK mRNA and protein expression in normal brain tissues and astrocytic tumors was quantified. To investigate DEK functions in tumor cells, DEK gene was silenced with siRNA in U251 glioblastoma cells. Cell proliferation, cell cycle and apoptosis were then measured. The expression and activity of key genes that regulate cell proliferation and apoptosis were also measured. We identified DEK as a high expressed gene in astrocytic tumor tissues. DEK expression level was positively correlated with the pathological grade of astrocytic tumors. Gene silencing of DEK in U251 glioblastomas inhibited cell proliferation and blocked cells at G0/G1 phase of cell cycle. DEK depletion also induced cell apoptosis, with up-regulated expression of P53 and P21 and down-regulated expression of Bcl-2 and C-myc. The Caspase-3 activity in U251 cells was also significantly increased after knockdown. Our results provided evidences that DEK regulates proliferation and apoptosis of glioblastomas. DEK gene silencing may induce apoptosis through P53-dependent pathway. Our data indicated DEK plays multiple roles to facilitate tumor growth and maintenance. It can be used as a potential target for astrocytic tumor diagnosis and gene therapy.

TFEB-VEGFA (6p21.1) co-amplified renal cell carcinoma: a distinct entity with potential implications for clinical management

A subset of renal cell carcinomas shows TFEB overexpression secondary to MALAT1-TFEB gene fusion. As alternate mechanisms of TFEB overexpression are likely to have the same effect, we sought to determine the frequency of amplification of TFEB and the adjacent VEGFA gene at 6p21.1. As patients with metastatic renal cell carcinomas are managed with anti-VEGF therapies, we retrospectively assessed therapeutic response in patients with amplified tumors. Amplification status was analyzed for 875 renal cell carcinomas from our institution, a consultative case and 794 cases from The Cancer Genome Atlas. Cases were classified as having low level (5-10 copies), and high-level amplification (>10 copies), and were further analyzed for adjacent oncogene copy number status (n=6; 3 single-nucleotide polymorphism genomic microarray, 3 The Cancer Genome Atlas) and structural rearrangements (n=1; mate-pair sequencing). These were then reviewed for histopathology, immunophenotype, and response to VEGF-targeted therapy on follow-up. In all, 10/875 (1.1%) institutional cases, 1 consultative case, and 3/794 (0.4%) of The Cancer Genome Atlas cases showed TFEB high-level amplification, while 14/875 (1.6%) cases showed TFEB low-level amplification. All cases had associated VEGFA amplification. This was confirmed with evaluation for copy number changes (n=6). The 6p21.1 high and low-level amplified tumors occurred in adults (mean age: 66), with over half being ≥pT3 (13/25, 52%), and most showed oncocytic, tubulopapillary features and high grade (≥grade 3: 20/22, 91%). These were aggressive tumors with metastasis and death from renal cell carcinoma in 11 (of 24, 46%) cases. Four patients received targeted therapy and had a mean survival of 31 months (range: 17-50) post nephrectomy. In summary, a group of aggressive renal cell carcinomas show genomic amplification of the 6p21.1 region including TFEB and VEGFA genes and share morphologic features. Additional studies are warranted to determine whether these patients respond to anti-VEGF therapy.

DEK protein level is a biomarker of CD138positive normal and malignant plasma cells

Overexpression of DEK oncogene is associated with increased proliferation of carcinoma cells and it is observed in several solid tumors due to the amplification of the 6p22.3 chromosomal region where DEK locates. Although the same chromosomal amplification occurs in multiple myeloma (MM), a plasma cell neoplasm, whether the expression and the copy number of the DEK gene are affected in MM remains elusive. We show that despite the increased copy number in CD138positive MM cells (4 out of 41 MM samples), DEK mRNA expression was down-regulated compared with that in CD138negative bone marrow (BM) cells of the same patients (P<0.0001). DEK protein was not detectable by immunohistochemistry (IHC) in CD138positive normal plasma cells or in malignant plasma cells of MM patients (n = 56) whereas it was widely expressed in normal and neoplastic B-cells. Stable knockdown or overexpression of DEK in CD138positive MM cell lines did not affect the proliferation and viability of the cells profoundly in the presence or absence of chemotherapeutic agent melphalan whereas knockdown of DEK moderately but significantly increased the expression level of CD138 (p<0.01). Decreased DEK expression in plasma cells suggests a potential role of this gene in plasma cell development and lack of detectable DEK protein by IHC could be used as a biomarker for normal and malignant plasma cells.

DEK associates with tumor stage and outcome in HPV16 positive oropharyngeal squamous cell carcinoma

Oropharyngeal squamous cell carcinomas (OPSCC) are common, have poor outcomes, and comprise two biologically and clinically distinct diseases. While OPSCC that arise from human papillomavirus infections (HPV+) have better overall survival than their HPV- counterparts, the incidence of HPV+ OPSCC is increasing dramatically, affecting younger individuals which are often left with life-long co-morbidities from aggressive treatment. To identify patients which do poorly versus those who might benefit from milder regimens, risk-stratifying biomarkers are now needed within this population. One potential marker is the DEK oncoprotein, whose transcriptional upregulation in most malignancies is associated with chemotherapy resistance, advanced tumor stage, and worse outcomes. Herein, a retrospective case study was performed on DEK protein expression in therapy-naïve surgical resections from 194 OPSCC patients. We found that DEK was associated with advanced tumor stage, increased hazard of death, and interleukin IL6 expression in HPV16+ disease. Surprisingly, DEK levels in HPV16- OPSCC were not associated with advanced tumor stage or increased hazard of death. Overall, these findings mark HPV16- OPSCC as an exceptional malignancy were DEK expression does not correlate with outcome, and support the potential prognostic utility of DEK to identify aggressive HPV16+ disease.

DEK is required for homologous recombination repair of DNA breaks

DEK is a highly conserved chromatin-bound protein whose upregulation across cancer types correlates with genotoxic therapy resistance. Loss of DEK induces genome instability and sensitizes cells to DNA double strand breaks (DSBs), suggesting defects in DNA repair. While these DEK-deficiency phenotypes were thought to arise from a moderate attenuation of non-homologous end joining (NHEJ) repair, the role of DEK in DNA repair remains incompletely understood. We present new evidence demonstrating the observed decrease in NHEJ is insufficient to impact immunoglobulin class switching in DEK knockout mice. Furthermore, DEK knockout cells were sensitive to apoptosis with NHEJ inhibition. Thus, we hypothesized DEK plays additional roles in homologous recombination (HR). Using episomal and integrated reporters, we demonstrate that HR repair of conventional DSBs is severely compromised in DEK-deficient cells. To define responsible mechanisms, we tested the role of DEK in the HR repair cascade. DEK-deficient cells were impaired for γH2AX phosphorylation and attenuated for RAD51 filament formation. Additionally, DEK formed a complex with RAD51, but not BRCA1, suggesting a potential role regarding RAD51 filament formation, stability, or function. These findings define DEK as an important and multifunctional mediator of HR, and establish a synthetic lethal relationship between DEK loss and NHEJ inhibition.

DEK oncogene is overexpressed during melanoma progression

DEK is an oncoprotein involved in a variety of cellular functions, such as DNA repair, replication, and transcriptional control. DEK is preferentially expressed in actively proliferating and malignant cells, including melanoma cell lines in which DEK was previously demonstrated to play a critical role in proliferation and chemoresistance. Still, the impact of this protein in melanoma progression remains unclear. Thus, we performed a comprehensive analysis of DEK expression in different melanocytic tumors. The immunostaining results of 303 tumors demonstrated negligible DEK expression in benign lesions. Conversely, malignant lesions, particularly in metastatic cases, were largely positive for DEK expression, which was partially associated with genomic amplification. Importantly, DEK overexpression was correlated with histological features of aggressiveness in primary tumors and poor prognosis in melanoma patients. In conclusion, our study provides new insight into the involvement of DEK in melanoma progression, as well as proof of concept for its potential application as a marker and therapeutic target of melanoma.

DEK protein overexpression predicts poor prognosis in pancreatic ductal adenocarcinoma

DEK, a transcription factor, is involved in mRNA splicing, transcriptional control, cell division and differentiation. Recent studies suggest that DEK overexpression can promote tumorigenesis in a wide range of cancer cell types. However, little is known concerning the status of DEK in pancreatic ductal adenocarcinoma (PDAC). Based on the microarray data from Gene Expression Omnibus (GEO), the expression levels of DEK mRNA in PDAC tissues were significantly higher than levels in the adjacent non-tumor tissues. To explore the clinical features of DEK overexpression in PDAC, 87 PDAC and 52 normal pancreas tissues were selected for immunoenzyme staining of the DEK protein. Localization of the DEK protein was detected in PANC-1 pancreatic cancer cells using immunofluorescence (IF) staining. The correlations between DEK overexpression and the clinical features of PDAC were evaluated using the Chi-squared (χ2) 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. The expression levels of DEK mRNA in PDAC tissues were significantly higher than that in the adjacent non‑tumor tissues. The DEK protein showed a primarily nuclear staining pattern in PDAC. The positive rate of the DEK protein was 52.9% (46/87) in PDAC, which was significantly higher than that in the adjacent normal pancreatic tissues (7.7%, 4/52). DEK overexpression in PDAC was correlated with tumor size, histological grade, tumor‑node‑metastasis (TNM) stage and overall survival (OS) rates. In addition, multivariate analysis demonstrated that DEK overexpression was an independent prognostic factor along with histological grade and TNM stage in patients with PDAC. In conclusion, DEK overexpression is associated with PDAC progression and may be a potential biomarker for poor prognostic evaluation in PDAC.

Regulation of DEK expression by AP-2α and methylation level of DEK promoter in hepatocellular carcinoma

DEK is overexpressed in multiple invasive tumors. However, the transcriptional regulatory mechanism of DEK remains unclear. In the present study, progressive-type truncation assay indicated that CpG2-2 (-167 bp/+35 bp) was the DEK core promoter, whose methylation inhibited DEK expression. Bisulfite genomic sequencing analysis indicated that the methylation levels of the DEK promoter in normal hepatic cells and tissues were higher than those in hepatocellular carcinoma (HCC) cells. TFSEARCH result revealed transcription factor binding sites in CpG2-2. Among the sites, the AP-2α binding site showed the most significant methylation difference; hence, AP-2α is a key transcription factor that regulates DEK expression. Point or deletion mutation of the AP-2α binding site significantly reduced the promoter activity. Chromatin immunoprecipitation assay demonstrated the binding of AP-2α to the core promoter. Furthermore, knock down of endogenous AP-2α downregulated DEK expression, whereas overexpression of AP-2α upregulated DEK expression. Thus, AP-2α is an important transcription factor of DEK expression, which is correlated with the methylation level of the DEK core promoter in HCC.

The DEK oncogene activates VEGF expression and promotes tumor angiogenesis and growth in HIF-1α-dependent and -independent manners

The DEK oncogene is overexpressed in various cancers and overexpression of DEK correlates with poor clinical outcome. Vascular endothelial growth factor (VEGF) is the most important regulator of tumor angiogenesis, a process essential for tumor growth and metastasis. However, whether DEK enhances tumor angiogenesis remains unclear. Here, we show that DEK is a key regulator of VEGF expression and tumor angiogenesis. Using chromatin immunoprecipitation assay, we found that DEK promoted VEGF transcription in breast cancer cells (MCF7, ZR75-1 and MDA-MB-231) by directly binding to putative DEK-responsive element (DRE) of the VEGF promoter and indirectly binding to hypoxia response element (HRE) upstream of the DRE through its interaction with the transcription factor hypoxia-inducible factor 1α (HIF-1α), a master regulator of tumor angiogenesis and growth. DEK is responsible for recruitment of HIF-1α and the histone acetyltransferase p300 to the VEGF promoter. DEK-enhanced VEGF increases vascular endothelial cell proliferation, migration and tube formation as well as angiogenesis in the chick chorioallantoic membrane. DEK promotes tumor angiogenesis and growth in nude mice in HIF-1α-dependent and -independent manners. Immunohistochemical staining showed that DEK expression positively correlates with the expression of VEGF and microvessel number in 58 breast cancer patients. Our data establish DEK as a sequence-specific binding transcription factor, a novel coactivator for HIF-1α in regulation of VEGF transcription and a novel promoter of angiogenesis.

MiR-200a Suppresses the Proliferation and Metastasis in Pancreatic Ductal Adenocarcinoma through Downregulation of DEK Gene

MiR-200a has been reported to be able to suppress the epithelial-mesenchymal transition process in pancreatic cancer stem cells, suggesting that miR-200a could suppress the metastasis of pancreatic ductal adenocarcinoma (PDAC). However, its role in proliferation and metastasis of PDAC and the underlying mechanism by which miR-200a works in PDAC have not been elucidated. In our study, we for the first time identified that DEK gene is a direct downstream target of miR-200a. It was found that overexpression of miR-200a decreased DEK expression, suppressing the proliferation, migration, and invasion of PDAC cells. Meanwhile, knockdown of miR-200a can increase DEK level, promoting the proliferation, migration, and invasion of PDAC cells. Our study demonstrated that miR-200a suppresses the metastasis in pancreatic PDAC through downregulation of DEK, suggesting that miR-200a may be used as a novel potential marker in prediction of metastasis of PDAC.

Overexpression of DEK is an indicator of poor prognosis in patients with gastric adenocarcinoma

Increased expression of the human DEK proto-oncogene (DEK) gene has been associated with numerous human malignancies. The DEK protein is associated with chromatin reconstruction and gene transcription, and is important in cell apoptosis. The present study aimed to elucidate the role of DEK with regard to gastric adenocarcinoma tumor progression and patient prognosis. DEK protein expression was analyzed using immunohistochemistry in 192 tumors paired with adjacent non-cancerous gastric mucosa that had been surgically resected from patients with primary gastric adenocarcinoma. The association between DEK expression and the clinicopathological characteristics of the patients was evaluated using the χ² test and Fisher's exact test. The survival rates of the patients were calculated using the Kaplan-Meier method. Cox analysis evaluated the association between the expression of DEK and the survival rate of the patients. The DEK protein was expressed in 84 patients with gastric adenocarcinoma (43.8%) and in 20 of the paired normal gastric mucosa tissues (11.5%). The DEK expression rate was found to be associated with tumor size (P=0.006), tumor grade (P=0.023), lymph node metastasis (P=0.018), serous invasion (P=0.026), tumor stage (P=0.001) and Ki-67 expression (P=0.003). Furthermore, patients with gastric adenocarcinoma that expressed DEK had decreased disease-free (log-rank, 16.785; P<0.0001) and overall (log-rank, 15.759; P<0.0001) survival rates compared with patients without DEK expression. Patients with late-stage gastric adenocarcinoma that expressed DEK exhibited a lower overall survival rate compared with patients without DEK expression (P=0.002). Additional analysis revealed that DEK expression was an independent prognostic factor for the prognosis of gastric adenocarcinoma (hazard ratio, 0.556; 95% confidence interval, 0.337-0.918; P=0.022). From the results of the present study, it can be concluded that the detection of DEK protein expression in gastric adenocarcinoma tissues may be important for the diagnosis and prognosis of patients, and may be a targeted therapy for the treatment of gastric adenocarcinoma.

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.

Identification of the TP53-induced glycolysis and apoptosis regulator in various stages of colorectal cancer patients

The TP53-induced glycolysis and apoptosis regulator (TIGAR) is a p53 target gene known to regulate glycolysis by acting as fructose bis-phosphatase (FBPase) and modulate reactive oxygen species. TIGAR expression has been implicated in oncogenesis and progression of several human cancers. However, TIGAR expression is not known in various stages of colorectal cancer (CRC). There is an increase in the colorectal cancer incidence in Saudi Arabia. We sought to analyze TIGAR expression in this ethnic group. The aim of this study was to investigate the TIGAR expression in colorectal cancer (CRC) patients from Saudi Arabia. Tissue microarray (TMA) was constructed from 22 matched colorectal tumor tissues and adjacent normal tissues. TIGAR expression was examined in TMA slide using immunohistochemistry. TIGAR mRNA was determined in 14 matched tumor tissue and adjacent normal tissue. TIGAR protein expression was also examined in CRC tumor tissues and cell lines. Statistical analyses (t-test) were applied to evaluate the significance of TIGAR expression. TIGAR mRNA level was upregulated significantly in stage II (p<0.01) and stage III (p<0.05) when compared to adjacent normal tissue. Immunohistochemical studies revealed that TIGAR expression was increased in colorectal cancer. Strong TIGAR positive staining was found in 68% (15/22) of the tumor samples with nuclear localization. TIGAR staining was found to be significantly increased in early stage (stage I and II) CRC (p<0.05) and late stage (stage III and IV) CRC (p<0.01). TIGAR protein was also found to be highly expressed in stage II and III colorectal cancer tissues and CRC cell lines. These findings indicate that TIGAR is highly expressed at the mRNA and protein levels in colorectal cancer with prominent nuclear localization. TIGAR expression may be used as a bio-marker for detection of colorectal cancer and can be used as a target for developing therapeutics for the treatment of colorectal cancer.

DEK: A novel early screening and prognostic marker for breast cancer

The present study aimed to investigate the expression status and clinical implications of DEK in breast cancer, in order to contribute to developments in breast cancer management. DEK expression status was detected in 628 breast cancer specimens by western blot analysis and immunohistochemistry staining, and the correlation between DEK protein and clinico‑pathological parameters and prognosis of breast cancer was subsequently determined. In comparison to para-carcinoma tissues, DEK protein was highly expressed in breast cancer specimens and was correlated with chemotherapy resistance. In total, 61.94% (389/628) of breast cancer cases exhibited high expression of DEK. According to universal analysis, it was observed that age, tumor size, histological grade, metastatic nodes and distant metastasis (P=0.024, 0.001, 0.001, 0.001 and 0.001 respectively) are key factors associated with DEK. Furthermore, compared with samples with no or low DEK protein expression, high DEK expression resulted in a significantly increased distant metastasis rate and poor disease‑specific survival (P=0.001). In addition, DEK protein was detected as an independent prognostic factor (P=0.001) in the Cox regression analysis. DEK was correlated with chemotherapy resistance and may be an independent prognostic factor for breast cancer, as well as a potential therapeutic target.

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.

Genetics and epigenetics of human retinoblastoma

Retinoblastoma is a pediatric tumor of the developing retina from which the genetic basis for cancer development was first described. Inactivation of both copies of the RB1 gene is the predominant initiating genetic lesion in retinoblastoma and is rate limiting for tumorigenesis. Recent whole-genome sequencing of retinoblastoma uncovered a tumor that had no coding-region mutations or focal chromosomal lesions other than in the RB1 gene, shifting the paradigm in the field. The retinoblastoma genome can be very stable; therefore, epigenetic deregulation of tumor-promoting pathways is required for tumorigenesis. This review highlights the genetic and epigenetic changes in retinoblastoma that have been reported, with special emphasis on recent whole-genome sequencing and epigenetic analyses that have identified novel candidate genes as potential therapeutic targets.

High expression of NQO1 is associated with poor prognosis in serous ovarian carcinoma

Background

NAD(P)H:quinone oxidoreductase (NQO1) is a flavoprotein that catalyzes two-electron reduction and detoxification of quinones and its derivatives. NQO1 catalyzes reactions that have a protective effect against redox cycling, oxidative stress and neoplasia. High expression of NQO1 is associated with many solid tumors including those affecting the colon, breast and pancreas; however, its role in the progression of ovarian carcinoma is largely undefined. This study aimed to investigate the clinicopathological significance of high NQO1 expression in serous ovarian carcinoma.

Methods

NQO1 protein expression was assessed using immunohistochemical (IHC) staining in 160 patients with serous ovarian carcinoma, 62 patients with ovarian borderline tumors and 53 patients with benign ovarian tumors. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect NQO1 mRNA expression levels. The correlation between high NQO1 expression and clinicopathological features of ovarian carcinoma was evaluated by Chi-square and Fisher’s exact test. Overall survival (OS) rates of all of ovarian carcinoma patients were calculated using the Kaplan-Meier method, and univariate and multivariate analyses were performed using the Cox proportional hazards regression model.

Results

NQO1 protein expression in ovarian carcinoma cells was predominantly cytoplasmic. Strong, positive expression of NQO1 protein was observed in 63.8% (102/160) of ovarian carcinomas, which was significantly higher than in borderline serous tumors (32.3%, 20/62) or benign serous tumors (11.3%, 6/53). Importantly, the rate of strong, positive NQO1 expression in borderline serous tumors was also higher than in benign serous tumors. High expression of NQO1 protein was closely associated with higher histological grade, advanced clinical stage and lower OS rates in ovarian carcinomas. Moreover, multivariate analysis indicated that NQO1 was a significant independent prognostic factor, in addition to clinical stage, in patients with ovarian carcinoma.

Conclusions

NQO1 is frequently upregulated in ovarian carcinoma. High expressin of NQO1 protein may be an effective biomarker for poor prognostic evaluation of patients with serous ovarian carcinomas.

SiRNA knockdown of the DEK nuclear protein mRNA enhances apoptosis and chemosensitivity of canine transitional cell carcinoma cells

Transitional cell carcinoma (TCC) in dogs is an aggressive malignant neoplasm, originating in the epithelium of the urinary bladder. The DEK nuclear protein is overexpressed in several types of human bladder cancer, where it is involved in chromatin reconstruction, gene transcription and apoptosis. Since DEK represents a potential therapeutic target for canine TCC, this study was designed to investigate DEK expression in canine TCC and to determine the effects of DEK mRNA silencing on TCC cells in vitro. The gene expression profiles of seven selected cancer-associated genes was assessed in four canine TCC cell lines and expression of DEK protein was evaluated in bladder tissue biopsies from healthy dogs and those affected with cystitis or TCC. After transfection of four canine TCC cell lines with DEK-specific or scrambled siRNA, annexin V staining was performed to evaluate apoptosis, and methylthiazole tetrazolium assays were performed to assess both cell viability and sensitivity to carboplatin. DEK mRNA expression was relatively high in canine TCC cells and expression of the DEK protein was significantly greater in TCC tumours compared with the other tissue samples. After transfection with DEK-specific siRNA, apoptosis, cell growth inhibition, and enhanced sensitivity to carboplatin were observed in all TCC cells assessed. These research findings suggest that DEK could be a potential therapeutic target for canine TCC.

Expression and significance of DOK2 in colorectal cancer

A reduction in the levels of docking protein 2 (DOK2) expression has previously been reported in lung adenocarcinoma and gastric cancer, indicating that this protein acts as a tumor suppressor in solid tumors. The aim of the current study was to determine the significance of DOK2 in colorectal cancer. The study consisted of 102 patients who underwent curative surgery for colorectal cancer. Histopathological and immunohistochemical analysis of DOK2 protein expression levels was performed in issue samples, and univariate and multivariate analyses were used to investigate the correlation between prognosis and the clinicopathological parameters. DOK2 expression was confirmed in the normal colorectal mucosa tissues, which is consistent with the literature, whereas 34 out of 102 (33.3%) tumor specimens were negative. The results revealed that recurrence was more likely to develop in DOK2(-) patients compared with DOK2(+) patients. The DOK2(-) patients also exhibited a poorer five-year overall survival rate (59.1%) compared with the DOK2(+) group (76.4%; P=0.0328). These results indicate that DOK2 may potentially be used as a marker of poor prognosis in patients with colorectal cancer following curative resection.

DEK is a potential marker for aggressive phenotype and irinotecan-based therapy response in metastatic colorectal cancer

BACKGROUND

DEK is a transcription factor involved in stabilization of heterochromatin and cruciform structures. It plays an important role in development and progression of different types of cancer. This study aims to analyze the role of DEK in metastatic colorectal cancer.

METHODS

Baseline DEK expression was firstly quantified in 9 colorectal cell lines and normal mucosa by WB. SiRNA-mediated DEK inhibition was carried out for transient DEK silencing in DLD1 and SW620 to dissect its role in colorectal cancer aggressiveness. Irinotecan response assays were performed with SN38 over 24 hours and apoptosis was quantified by flow cytometry. Ex-vivo assay was carried out with 3 fresh tumour tissues taken from surgical resection and treated with SN38 for 24 hours. DEK expression was determined by immunohistochemistry in 67 formalin-fixed paraffin-embedded tumour samples from metastatic colorectal cancer patients treated with irinotecan-based therapy as first-line treatment.

RESULTS

The DEK oncogene is overexpressed in all colorectal cancer cell lines. Knock-down of DEK on DLD1 and SW620 cell lines decreased cell migration and increased irinotecan-induced apoptosis. In addition, low DEK expression level predicted irinotecan-based chemotherapy response in metastatic colorectal cancer patients with KRAS wild-type.

CONCLUSIONS

These data suggest DEK overexpression as a crucial event for the emergence of an aggressive phenotype in colorectal cancer and its potential role as biomarker for irinotecan response in those patients with KRAS wild-type status.

Mechanisms underlying cancer growth and apoptosis by DEK overexpression in colorectal cancer

Our previous study indicated that DEK protein was overexpressed in colorectal carcinoma (CRC) compared with the normal colorectal mucosa. DEK was also significantly correlated with the prognostic characteristics of patients with CRC, demonstrating that DEK played an important role in CRC progression. In this work, we evaluate the effects of DEK on biological behaviors in CRC and explore the related molecular mechanisms. The results showed that DEK was overexpressed in human CRC tissues, and was correlated with the Ki-67 index and the apoptotic index. DEK depletion by RNAi in SW-620 and HCT116 cells significantly decreased cell proliferation, but increased cell apoptosis. Upregulation of DEK was involved in the p53/MDM, Bcl-2 family, and caspase pathways. Our study demonstrates that DEK promotes the growth of CRC, and could be a therapeutic target in CRC.

De Novo proteome analysis of genetically modified tumor cells by a metabolic labeling/azide-alkyne cycloaddition approach

Activin receptor type II (ACVR2) is a member of the transforming growth factor type II receptor family and controls cell growth and differentiation, thereby acting as a tumor suppressor. ACVR2 inactivation is known to drive colorectal tumorigenesis. We used an ACVR2-deficient microsatellite unstable colon cancer cell line (HCT116) to set up a novel experimental design for comprehensive analysis of proteomic changes associated with such functional loss of a tumor suppressor. To this end we combined two existing technologies. First, the ACVR2 gene was reconstituted in an ACVR2-deficient colorectal cancer (CRC) cell line by means of recombinase-mediated cassette exchange, resulting in the generation of an inducible expression system that allowed the regulation of ACVR2 gene expression in a doxycycline-dependent manner. Functional expression in the induced cells was explicitly proven. Second, we used the methionine analog azidohomoalanine for metabolic labeling of newly synthesized proteins in our cell line model. Labeled proteins were tagged with biotin via a Click-iT chemistry approach enabling specific extraction of labeled proteins by streptavidin-coated beads. Tryptic on-bead digestion of captured proteins and subsequent ultra-high-performance LC coupled to LTQ Orbitrap XL mass spectrometry identified 513 proteins, with 25 of them differentially expressed between ACVR2-deficient and -proficient cells. Among these, several candidates that had already been linked to colorectal cancer or were known to play a key role in cell growth or apoptosis control were identified, proving the utility of the presented experimental approach. In principle, this strategy can be adapted to analyze any gene of interest and its effect on the cellular de novo proteome.

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.

Hsp70--a biomarker for tumor detection and monitoring of outcome of radiation therapy in patients with squamous cell carcinoma of the head and neck

BACKGROUND

Tumor but not normal cells frequently overexpress heat shock protein 70 (Hsp70) and present it on their cell surface (mHsp70) from where it can be actively released. Therefore, membrane (mHsp70) and soluble Hsp70 (sHsp70) were investigated as potential tumor biomarkers and for monitoring the outcome of radiation therapy.

METHODS

Biopsies and blood were collected from patients with squamous cell carcinoma of the head and neck (SCCHN) at different time points (before, during therapy and in the follow-up period). Hsp70 membrane expression was determined on single cell suspensions of tumor biopsies and reference tissues by flow cytometry, sHsp70 protein and antibody levels were determined in the serum of patients and healthy donors by ELISA and NK cell markers that are related to the presence of sHsp70 were analyzed in the patient's peripheral blood lymphocytes (PBL).

RESULTS

Tumor biopsies exhibited significantly increased mHsp70 expression levels compared to the reference tissue. Soluble Hsp70 levels were significantly higher in SCCHN patients compared to healthy human volunteers and high mHsp70 expression levels on tumor cells were associated with high sHsp70 levels in the serum of patients. Following surgery and radiotherapy sHsp70 levels in patients dropped in patients without tumor relapse in the follow-up period. In contrast to sHsp70 protein, anti-Hsp70 antibody levels remained nearly unaltered in the serum of SCCHN patients before and after therapy. Furthermore, sHsp70 protein but not anti-Hsp70 antibody levels were found to be associated with the tumor volume in SCCHN patients before start of therapy. The expression densities of the activatory NK cell markers CD56, CD94, NKG2D, NKp30, Nkp44, and NKp46 differed in patients following therapeutic intervention. A significant increase in the density of NKG2D was observed in SCCHN patients in the follow-up period after surgery and radiotherapy.

CONCLUSION

We suggest sHsp70 as a potential biomarker for detecting tumors and for monitoring the clinical outcome of radiotherapy in SCCHN patients.