Gene Summary

Gene:ELK3; ETS transcription factor ELK3
Aliases: ERP, NET, SAP2, SAP-2
Summary:This gene encodes a member of the ETS-domain transcription factor family and the ternary complex factor (TCF) subfamily. Proteins in this subfamily regulate transcription when recruited by serum response factor to bind to serum response elements. This protein is activated by signal-induced phosphorylation; studies in rodents suggest that it is a transcriptional inhibitor in the absence of Ras, but activates transcription when Ras is present. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jan 2015]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:ETS domain-containing protein Elk-3
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Latest Publications: ELK3 (cancer-related)

Yoo SM, Lee CJ, An HJ, et al.
RSK2-Mediated ELK3 Activation Enhances Cell Transformation and Breast Cancer Cell Growth by Regulation of c-fos Promoter Activity.
Int J Mol Sci. 2019; 20(8) [PubMed] Free Access to Full Article Related Publications
Ribosomal S6 kinase 2 (RSK2), regulated by Ras/Raf/MEKs/ERKs, transmits upstream activation signals to downstream substrates including kinases and transcription and epigenetic factors. We observed that ELK members, including ELK1, 3, and 4, highly interacted with RSK2. We further observed that the RSK2-ELK3 interaction was mediated by N-terminal kinase and linker domains of RSK2, and the D and C domains of ELK3, resulting in the phosphorylation of ELK3. Importantly, RSK2-mediated ELK3 enhanced

Ahmad A, Zhang W, Wu M, et al.
Tumor-suppressive miRNA-135a inhibits breast cancer cell proliferation by targeting ELK1 and ELK3 oncogenes.
Genes Genomics. 2018; 40(3):243-251 [PubMed] Related Publications
Breast cancer is the most common malignant disease amongst women. miRNAs are small, non-coding RNAs that regulate gene expression, thus have the potential to play an important role during cancer development. Emerging evidence shows that miR-135a is down-regulated in breast cancer cells, but the functional roles of miR-135a in breast cancer cells remains unexplored. For this purpose, we investigated the expression of miR-135a in breast cancer cells and explored its functional role during breast cancer progression. In vitro study showed that miR-135a may be a novel tumor suppressor. Further studies showed that transcription factors ELK1 and ELK3 are direct target genes of miR-135a that modulates the suppressive function of miR-135a in breast cancer cells. Induced expression of miR-135a significantly downregulated the expression of ELK1 and ELK3 both at mRNA and protein levels. Furthermore, the effect of miR-135a in MCF-7 and T47D cells was investigated by the overexpression of miR-135a mimics. In vitro, induced expression of miR-135a in breast cancer cells inhibited cell Proliferation and clongenicity. Moreover, a luciferase activity assay revealed that miR-135a could directly target the 3'-untranslated region (3' UTRS) of ELK1 and ELK3 oncogenes. In addition, rescue experiment demonstrated that the promoted cell growth by transcription factors ELK1 and ELK3 was attenuated by the over-expression of miR-135a. Our study demonstrates that miR-135a regulates cell proliferation in breast cancer by targeting ELK1 and ELK3 oncogenes, and suggests that miR-135a potentially can act as a tumor suppressor.

Kim KS, Kim J, Oh N, et al.
ELK3-GATA3 axis modulates MDA-MB-231 metastasis by regulating cell-cell adhesion-related genes.
Biochem Biophys Res Commun. 2018; 498(3):509-515 [PubMed] Related Publications
GATA3 is a master regulator that drives mammary epithelial cell differentiation, and the suppression of GATA3 expression is associated with the development of aggressive breast cancer. However, the mechanism through which GATA3 loss drives cancer development is poorly understood. Previously, we reported that ELK3 suppression in MDA-MB-231 (ELK3 KD) resulted in the reprogramming of these cells from a basal to luminal subtype, which was associated with the induction of GATA3 expression, and that the ELK3-GATA3 axis orchestrated the metastatic characteristics of MDA-MB-231. Here, we show that GATA3 suppression in ELK3 knockdown MDA-MB-231 cells (ELK3/GATA3 DKD) restores the metastatic ability comparably to that of control MDA-MB-231 cells, even though the epithelial cell morphology and TGF-β signaling of ELK3 KD are not recovered in ELK3/GATA3 DKD. The expression of E-cadherin and tight junctional proteins, including occludin, claudin and ZO-1, which is activated in ELK3 KD, is suppressed in ELK3/GATA3 DKD. These results reveal the possibility that the ELK3-GATA3 axis determines the metastatic characteristics of MDA-MB-231 by regulating the expression of cell-cell adhesion factors.

Urayama KY, Takagi M, Kawaguchi T, et al.
Regional evaluation of childhood acute lymphoblastic leukemia genetic susceptibility loci among Japanese.
Sci Rep. 2018; 8(1):789 [PubMed] Free Access to Full Article Related Publications
Genome-wide association studies (GWAS) performed mostly in populations of European and Hispanic ancestry have confirmed an inherited genetic basis for childhood acute lymphoblastic leukemia (ALL), but these associations are less clear in other races/ethnicities. DNA samples from ALL patients (aged 0-19 years) previously enrolled onto a Tokyo Children's Cancer Study Group trial were collected during 2013-2015, and underwent single nucleotide polymorphism (SNP) microarray genotyping resulting in 527 B-cell ALL for analysis. Cases and control data for 3,882 samples from the Nagahama Study Group and Aichi Cancer Center Study were combined, and association analyses across 10 previous GWAS-identified regions were performed after targeted SNP imputation. Linkage disequilibrium (LD) patterns in Japanese and other populations were evaluated using the varLD score based on 1000 Genomes data. Risk associations for ARID5B (rs10821936, OR = 1.84, P = 6 × 10

Gutierrez-Camino A, Martin-Guerrero I, García-Orad A
Genetic susceptibility in childhood acute lymphoblastic leukemia.
Med Oncol. 2017; 34(10):179 [PubMed] Related Publications
Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy and a leading cause of death due to disease in children. The genetic basis of ALL susceptibility has been supported by its association with certain congenital disorders and, more recently, by several genome-wide association studies (GWAS). These GWAS identified common variants in ARID5B, IKZF1, CEBPE, CDKN2A, PIP4K2A, LHPP and ELK3 influencing ALL risk. However, the risk variants of these SNPs were not validated in all populations, suggesting that some of the loci could be population specific. On the other hand, the currently identified risk SNPs in these genes only account for 19% of the additive heritable risk. This estimation indicates that additional susceptibility variants could be discovered. In this review, we will provide an overview of the most important findings carried out in genetic susceptibility of childhood ALL in all GWAS and subsequent studies and we will also point to future directions that could be explored in the near future.

Oh N, Park JI, Park JH, et al.
The role of ELK3 to regulate peritumoral lymphangiogenesis and VEGF-C production in triple negative breast cancer cells.
Biochem Biophys Res Commun. 2017; 484(4):896-902 [PubMed] Related Publications
Tumor-induced lymphangiogenesis, a major conduit for cancer cell dissemination from the primary tumor site to lymph nodes and beyond, eventually leads to metastasis in cancer patients. Given the recent evidence revealing that the suppression of ELK3 inhibits the metastasis of triple-negative breast cancer cells, we aimed to study the underlying mechanism of impaired metastasis in ELK3-suppressed MDA-MB-231 cells (ELK3 KD) with regard to lymphangiogenesis. We found that the secretome of ELK3 KD cells inhibited tube formation, whereas it promoted the migration and invasion of lymphatic endothelial cells (LECs) in vitro. In vivo analysis revealed that peritumoral lymphatic vessels were not developed around the xenografted tumors of ELK3 KD. We further revealed that the suppression of NF-κB signaling in ELK3 KD was the primary cause of the reduced VEGFC expression. Taken together, we suggest that ELK3 is an upstream regulator of the NF-κB signaling pathway, the inhibition of which leads to the suppression of peritumoral lymphatic vessel development, possibly due to a low VEGFC expression.

Lee JH, Hur W, Hong SW, et al.
ELK3 promotes the migration and invasion of liver cancer stem cells by targeting HIF-1α.
Oncol Rep. 2017; 37(2):813-822 [PubMed] Related Publications
Hepatocellular carcinoma (HCC) is the fifth most common solid cancer and the third most common cause of cancer-related mortality. HCC develops via a multistep process associated with genetic aberrations that facilitate HCC invasion and migration and promote metastasis. A growing body of evidence indicates that cancer stem cells (CSCs) are responsible for tumorigenesis, cancer cell invasion and metastasis. Despite the extremely small proportion of cancer cells represented by this subpopulation of HCC cells, CSCs play a key role in cancer metastasis and poor prognosis. ELK3 (Net/SAP-2/Erp) is a transcription factor that is activated by the Ras/extracellular signal-regulated kinase (ERK) signaling pathway. It plays several important roles in various physiological processes, including cell migration, invasion, wound healing, angiogenesis and tumorigenesis. In the present study, we investigated the role of ELK3 in cancer cell invasion and metastasis in CD133+/CD44+ liver cancer stem cells (LCSCs). We isolated LCSCs expressing CD133 and CD44 from Huh7 HCC cells and evaluated their metastatic potential using invasion and migration assays. We found that CD133+/CD44+ cells had increased metastatic potential compared with non-CD133+/CD44+ cells. We also demonstrated that ELK3 expression was upregulated in CD133+/CD44+ cells and that this aberration enhanced cell migration and invasion. In addition, we identified the molecular mechanism by which ELK3 promotes cancer cell migration and invasion. We found that silencing of ELK3 expression in CD133+/CD44+ LCSCs attenuated their metastatic potential by modulating the expression of heat shock-induced factor-1α (HIF-1α). Collectively, the results of the present study demonstrated that ELK3 overexpression promoted metastasis in CD133+/CD44+ cells by regulating HIF-1α expression and that silencing of ELK3 expression attenuated the metastatic potential of CD133+/CD44+ LCSCs. In conclusion, modulation of ELK3 expression may represent a novel therapeutic strategy for preventing HCC metastasis and invasion.

Vijayakrishnan J, Kumar R, Henrion MY, et al.
A genome-wide association study identifies risk loci for childhood acute lymphoblastic leukemia at 10q26.13 and 12q23.1.
Leukemia. 2017; 31(3):573-579 [PubMed] Free Access to Full Article Related Publications
Genome-wide association studies (GWASs) have shown that common genetic variation contributes to the heritable risk of childhood acute lymphoblastic leukemia (ALL). To identify new susceptibility loci for the largest subtype of ALL, B-cell precursor ALL (BCP-ALL), we conducted a meta-analysis of two GWASs with imputation using 1000 Genomes and UK10K Project data as reference (totaling 1658 cases and 7224 controls). After genotyping an additional 2525 cases and 3575 controls, we identify new susceptibility loci for BCP-ALL mapping to 10q26.13 (rs35837782, LHPP, P=1.38 × 10

Kong SY, Kim KS, Kim J, et al.
The ELK3-GATA3 axis orchestrates invasion and metastasis of breast cancer cells in vitro and in vivo.
Oncotarget. 2016; 7(40):65137-65146 [PubMed] Free Access to Full Article Related Publications
Triple-negative breast cancer is a highly aggressive tumor subtype that lacks effective therapeutic targets. Here, we show that ELK3 is overexpressed in a subset of breast cancers, in particular basal-like and normal-like/claudin-low cell lines. Suppression of ELK3 in MDA-MB-231 cells led to transdifferentiation from an invasive mesenchymal phenotype to a non-invasive epithelial phenotype both in vitro and in vivo. Suppression of ELK3 resulted in extensive changes in genome expression profiles. Among these, GATA3, a master suppressor of metastasis, was epigenetically activated. Also, suppression of GATA3 led to the restoration of migration and invasion. These results suggest that the ELK3-GATA3 axis is a major pathway that promotes metastasis of MDA-MB-231 cells.

Du Y, Ter-Minassian M, Brais L, et al.
Genetic associations with neuroendocrine tumor risk: results from a genome-wide association study.
Endocr Relat Cancer. 2016; 23(8):587-94 [PubMed] Free Access to Full Article Related Publications
The etiology of neuroendocrine tumors remains poorly defined. Although neuroendocrine tumors are in some cases associated with inherited genetic syndromes, such syndromes are rare. The majority of neuroendocrine tumors are thought to be sporadic. We performed a genome-wide association study (GWAS) to identify potential genetic risk factors for sporadic neuroendocrine tumors. Using germline DNA from blood specimens, we genotyped 909,622 SNPs using the Affymetrix 6.0 GeneChip, in a cohort comprising 832 neuroendocrine tumor cases from Dana-Farber Cancer Institute and Massachusetts General Hospital and 4542 controls from the Harvard School of Public Health. An additional 241 controls from Dana-Farber Cancer Institute were used for quality control. We assessed risk associations in the overall cohort, and in neuroendocrine tumor subgroups. We identified no potential risk associations in the cohort overall. In the small intestine neuroendocrine tumor subgroup, comprising 293 cases, we identified risk associations with three SNPs on chromosome 12, all in strong LD. The three SNPs are located upstream of ELK3, a transcription factor implicated in angiogenesis. We did not identify clear risk associations in the bronchial or pancreatic neuroendocrine subgroups. This large-scale study provides initial evidence that presumed sporadic small intestine neuroendocrine tumors may have a genetic etiology. Our results provide a basis for further exploring the role of genes implicated in this analysis, and for replication studies to confirm the observed associations. Additional studies to evaluate potential genetic risk factors for sporadic pancreatic and bronchial neuroendocrine tumors are warranted.

Semenchenko K, Wasylyk C, Cheung H, et al.
XRP44X, an Inhibitor of Ras/Erk Activation of the Transcription Factor Elk3, Inhibits Tumour Growth and Metastasis in Mice.
PLoS One. 2016; 11(7):e0159531 [PubMed] Free Access to Full Article Related Publications
Transcription factors have an important role in cancer but are difficult targets for the development of tumour therapies. These factors include the Ets family, and in this study Elk3 that is activated by Ras oncogene /Erk signalling, and is involved in angiogenesis, malignant progression and epithelial-mesenchymal type processes. We previously described the identification and in-vitro characterisation of an inhibitor of Ras / Erk activation of Elk3 that also affects microtubules, XRP44X. We now report an initial characterisation of the effects of XRP44X in-vivo on tumour growth and metastasis in three preclinical models mouse models, subcutaneous xenografts, intra-cardiac injection-bone metastasis and the TRAMP transgenic mouse model of prostate cancer progression. XRP44X inhibits tumour growth and metastasis, with limited toxicity. Tumours from XRP44X-treated animals have decreased expression of genes containing Elk3-like binding motifs in their promoters, Elk3 protein and phosphorylated Elk3, suggesting that perhaps XRP44X acts in part by inhibiting the activity of Elk3. Further studies are now warranted to develop XRP44X for tumour therapy.

Park JH, Kim KP, Ko JJ, Park KS
PI3K/Akt/mTOR activation by suppression of ELK3 mediates chemosensitivity of MDA-MB-231 cells to doxorubicin by inhibiting autophagy.
Biochem Biophys Res Commun. 2016; 477(2):277-82 [PubMed] Related Publications
Drug resistance in breast cancer remains a major obstacle of clinical therapy. We found that suppression of ELK3 in the triple negative breast cancer cell line MDA-MB-231 impaired autophagy and led to a hypersensitive response to doxorubicin treatment. In ELK3-knockdown MDA-MB-231 cells (ELK3 KD), autophagy was not activated under starvation conditions, which is a major stimulus of autophagy activation. We revealed that activation of the PI3K/Akt pathway was the main cause of impaired autophagy in ELK3 KD. Our results suggest that targeting ELK3 may be a potential approach to overcome doxorubicin resistance in breast cancer therapeutics.

Suárez E, González L, Pérez-Mitchell C, et al.
Pathway Analysis using Gene-expression Profiles of HPV-positive and HPV-negative Oropharyngeal Cancer Patients in a Hispanic Population: Methodological Procedures.
P R Health Sci J. 2016; 35(1):3-8 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: The incidence of oral cavity and pharyngeal cancer in Puerto Rican men is higher than it is in the men of any other ethnic/racial group in the United States of America (US). The information regarding the effect of the human papilloma virus (HPV) in the gene-expression profile among patients with this cancer is limited in Hispanic community. We aim to describe the methodology for future studies to identify the molecular networks for determining overrepresented signaling and metabolic canonical pathways, based on the differential gene-expression profiles of HPV+ and HPV- samples from patients with oropharyngeal squamous cell carcinoma in Puerto Rico.
METHODS: We analyzed the RNA expression of 5 tissue samples from subjects diagnosed with oropharyngeal squamous cell carcinoma, 2 HPV+ and 3 HPV-, using Affymetrix GeneChips. The relative difference between the average gene expressions of the HPV+ and HPV- samples was assessed, based on the fold change (log2-scale).
RESULTS: Our analysis revealed 10 up regulated molecules (Mup1, LRP1, P14KA, ALYREF, and BHMT) and 5 down regulated ones (PSME4, KEAP1, ELK3, FAM186B, and PRELID1), at a cutoff of 1.5-fold change. Ingenuity Pathway Analysis showed the following biological functions to be affected in the HPV+ samples: cancer, hematological disease, and RNA post-transcriptional modification. QRT-PCR analysis confirmed only the differential regulation of ALYREF, KEAP1, and FAM186B genes.
CONCLUSION: The relevant methodological procedures described are sufficient to detect the most significant biological functions and pathways according to the HPV status in patients with oropharyngeal cancer in Puerto Rico.

Heo SH, Lee JY, Yang KM, Park KS
ELK3 Expression Correlates With Cell Migration, Invasion, and Membrane Type 1-Matrix Metalloproteinase Expression in MDA-MB-231 Breast Cancer Cells.
Gene Expr. 2015; 16(4):197-203 [PubMed] Related Publications
ELK3 is a member of the Ets family of transcription factors. Its expression is associated with angiogenesis, vasculogenesis, and chondrogenesis. ELK3 inhibits endothelial migration and tube formation through the regulation of MT1-MMP transcription. This study assessed the function of ELK3 in breast cancer (BC) cells by comparing its expression between basal and luminal cells in silico and in vitro. In silico analysis showed that ELK3 expression was higher in the more aggressive basal BC cells than in luminal BC cells. Similarly, in vitro analysis showed that ELK3 mRNA and protein expression was higher in basal BC cells than in normal cells and luminal BC cells. To investigate whether ELK3 regulates basal cell migration or invasion, knockdown was achieved by siRNA in the basal BC cell line MDA-MB-231. Inhibition of ELK3 expression decreased cell migration and invasion and downregulated MT1-MMP, the expression of which is positively correlated with tumor cell invasion. In silico analysis revealed that ELK3 expression was associated with that of MT1-MMP in several BC cell lines (0.98 Pearson correlation coefficient). Though MT1-MMP expression was upregulated upon ELK3 nuclear translocation, ELK3 did not directly bind to the 1.3-kb promoter region of the MT1-MMP gene. These results suggest that ELK3 plays a positive role in the metastasis of BC cells by indirectly regulating MT1-MMP expression.

Yang H, Schramek D, Adam RC, et al.
ETS family transcriptional regulators drive chromatin dynamics and malignancy in squamous cell carcinomas.
Elife. 2015; 4:e10870 [PubMed] Free Access to Full Article Related Publications
Tumor-initiating stem cells (SCs) exhibit distinct patterns of transcription factors and gene expression compared to healthy counterparts. Here, we show that dramatic shifts in large open-chromatin domain (super-enhancer) landscapes underlie these differences and reflect tumor microenvironment. By in vivo super-enhancer and transcriptional profiling, we uncover a dynamic cancer-specific epigenetic network selectively enriched for binding motifs of a transcription factor cohort expressed in squamous cell carcinoma SCs (SCC-SCs). Many of their genes, including Ets2 and Elk3, are themselves regulated by SCC-SC super-enhancers suggesting a cooperative feed-forward loop. Malignant progression requires these genes, whose knockdown severely impairs tumor growth and prohibits progression from benign papillomas to SCCs. ETS2-deficiency disrupts the SCC-SC super-enhancer landscape and downstream cancer genes while ETS2-overactivation in epidermal-SCs induces hyperproliferation and SCC super-enhancer-associated genes Fos, Junb and Klf5. Together, our findings unearth an essential regulatory network required for the SCC-SC chromatin landscape and unveil its importance in malignant progression.

Huang C, Sheng Y, Jia J, Chen L
Identification of melanoma biomarkers based on network modules by integrating the human signaling network with microarrays.
J Cancer Res Ther. 2014; 10 Suppl:C114-24 [PubMed] Related Publications
BACKGROUND: Melanoma is a leading cause of cancer death. Thus, accurate prognostic biomarkers that will assist rational treatment planning need to be identified.
METHODS: Microarray analysis of melanoma and normal tissue samples was performed to identify differentially expressed modules (DEMs) from the signaling network and ultimately detect molecular markers to support histological examination. Network motifs were extracted from the human signaling network. Then, significant expression-correlation differential modules were identified by comparing the network module expression-correlation differential scores under normal and disease conditions using the gene expression datasets. Finally, we obtained DEMs by the Wilcoxon rank test and considered the average gene expression level in these modules as the classification features for diagnosing melanoma.
RESULTS: In total, 99 functional DEMs were identified from the signaling network and gene expression profiles. The area under the curve scores for cancer module genes, melanoma module genes, and whole network modules are 92.4%, 90.44%, and 88.45%, respectively. The classification efficiency rates for nonmodule features are 71.04% and 79.38%, which correspond to the features of cancer genes and melanoma cancer genes, respectively. Finally, we acquired six significant molecular biomarkers, namely, module 10 (CALM3, Ca 2+ , PKC, PDGFRA, phospholipase-g, PIB5PA, and phosphatidylinositol-3-kinase), module 14 (SRC, Src homology 2 domain-containing [SHC], SAM68, GIT1, transcription factor-4, CBLB, GRB2, VAV2, LCK, YES, PTCH2, downstream of tyrosine kinase [DOK], and KIT), module 16 (ELK3, p85beta, SHC, ZFYVE9, TGFBR1, TGFBR2, CITED1, SH3KBP1, HCK, DOK, and KIT), module 45 (RB, CCND3, CCNA2, CDK4, and CDK6), module 75 (PCNA, CDK4, and CCND1), and module 114 (PSD93, NMDAR, and FYN).
CONCLUSION: We explored the gene expression profile and signaling network in a global view and identified DEMs that can be used as diagnostic or prognostic markers for melanoma.

Chan JK, Kiet TK, Blansit K, et al.
MiR-378 as a biomarker for response to anti-angiogenic treatment in ovarian cancer.
Gynecol Oncol. 2014; 133(3):568-74 [PubMed] Related Publications
OBJECTIVE: To determine the role of miR-378 as a biomarker for anti-angiogenic therapy response in ovarian cancer.
METHODS: Expression of miR-378 was analyzed in ovarian cancer cell lines and human tumors vs. normal ovarian epithelial cells by qRT-PCR. After miR-378 transfection in SKOV3 cells, dysregulated genes were identified using microarray. Data from The Cancer Genome Atlas (TCGA) was utilized to correlate miR-378 expression with progression-free survival (PFS) among patients treated with anti-angiogenic therapy by using Kaplan-Meier and Cox proportional hazards.
RESULTS: MiR-378 was overexpressed in ovarian cancer cells and tumors vs. normal ovarian epithelial cells. Overexpressing miR-378 in ovarian cancer cells altered expression of genes associated with angiogenesis (ALCAM, EHD1, ELK3, TLN1), apoptosis (RPN2, HIPK3), and cell cycle regulation (SWAP-70, LSM14A, RDX). In the TCGA dataset, low vs. high miR-378 expression was associated with longer PFS in a subset of patients with recurrent ovarian cancer treated with bevacizumab (9.2 vs. 4.2months; p=0.04). On multivariate analysis, miR-378 expression was an independent predictor for PFS after anti-angiogenic treatment (HR=2.04, 95% CI: 1.12-3.72; p=0.02). Furthermore, expression levels of two miR-378 targets (ALCAM and EHD1) were associated with PFS in this subgroup of patients who received anti-angiogenic therapy (9.4 vs. 4.2months, p=0.04 for high vs. low ALCAM; 7.9 vs. 2.3months, p<0.01 for low vs. high EHD1).
CONCLUSIONS: Our data suggest that miR-378 is overexpressed in ovarian cancer cells and tumors vs. normal ovarian epithelial cells. MiR-378 and its downstream targets may serve as markers for response to anti-angiogenic therapy.

Patki M, Chari V, Sivakumaran S, et al.
The ETS domain transcription factor ELK1 directs a critical component of growth signaling by the androgen receptor in prostate cancer cells.
J Biol Chem. 2013; 288(16):11047-65 [PubMed] Free Access to Full Article Related Publications
The androgen receptor (AR) is essential for diverse aspects of prostate development and function. Molecular mechanisms by which prostate cancer (PC) cells redirect AR signaling to genes that primarily support growth are unclear. A systematic search for critical AR-tethering proteins led to ELK1, an ETS transcription factor of the ternary complex factor subfamily. Although genetically redundant, ELK1 was obligatory for AR-dependent growth and clonogenic survival in both hormone-dependent PC and castration-recurrent PC cells but not for AR-negative cell growth. AR required ELK1 to up-regulate a major subset of its target genes that was strongly and primarily enriched for cell growth functions. AR functioned as a coactivator of ELK1 by association through its A/B domain, bypassing the classical mechanism of ELK1 activation by phosphorylation and without inducing ternary complex target genes. The ELK1-AR synergy per se was ligand-independent, although it required ligand for nuclear localization of AR as targeting the AR A/B domain to the nucleus recapitulated the action of hormone; accordingly, Casodex was a poor antagonist of the synergy. ELK3, the closest substitute for ELK1 in structure/function and genome recognition, did not interact with AR. ELK1 thus directs selective and sustained gene induction that is a substantial and critical component of growth signaling by AR in PC cells. The ELK1-AR interaction offers a functionally tumor-selective drug target.

Sloan KA, Marquez HA, Li J, et al.
Increased PEA3/E1AF and decreased Net/Elk-3, both ETS proteins, characterize human NSCLC progression and regulate caveolin-1 transcription in Calu-1 and NCI-H23 NSCLC cell lines.
Carcinogenesis. 2009; 30(8):1433-42 [PubMed] Free Access to Full Article Related Publications
Caveolin-1 protein has been called a 'conditional tumor suppressor' because it can either suppress or enhance tumor progression depending on cellular context. Caveolin-1 levels are dynamic in non-small-cell lung cancer, with increased levels in metastatic tumor cells. We have shown previously that transactivation of an erythroblastosis virus-transforming sequence (ETS) cis-element enhances caveolin-1 expression in a murine lung epithelial cell line. Based on high sequence homology between the murine and human caveolin-1 promoters, we proposed that ETS proteins might regulate caveolin-1 expression in human lung tumorigenesis. We confirm that caveolin-1 is not detected in well-differentiated primary lung tumors. Polyoma virus enhancer activator 3 (PEA3), a pro-metastatic ETS protein in breast cancer, is expressed at low levels in well-differentiated tumors and high levels in poorly differentiated tumors. Conversely, Net, a known ETS repressor, is expressed at high levels in the nucleus of well-differentiated primary tumor cells. In tumor cells in metastatic lymph node sites, caveolin-1 and PEA3 are highly expressed, whereas Net is now expressed in the cytoplasm. We studied transcriptional regulation of caveolin-1 in two human lung cancer cell lines, Calu-1 (high caveolin-1 expressing) and NCI-H23 (low caveolin-1 expressing). Chromatin immunoprecipitation-binding assays and small interfering RNA experiments show that PEA3 is a transcriptional activator in Calu-1 cells and that Net is a transcriptional repressor in NCI-H23 cells. These results suggest that Net may suppress caveolin-1 transcription in primary lung tumors and that PEA3 may activate caveolin-1 transcription in metastatic lymph nodes.

Li B, Ni P, Zhu Q, et al.
Growth inhibitory effect of the ternary complex factor Net on human pancreatic carcinoma cell lines.
Tohoku J Exp Med. 2008; 216(2):139-47 [PubMed] Related Publications
Pancreatic carcinoma is one of the most aggressive malignancies and carries the most dismal prognoses of all cancers. A better understanding of the genes involving in tumor development may allow us to tackle this rapidly progressive disease. The Net gene belongs to the ternary complex transcription factor (TCF) family and is regulated by the Ras/mitogen-activated protein kinase-signaling pathway. Under basal conditions, Net shows strong repressing function on transcription of proto-oncogene gene c-fos. Moreover, the lower expression of Net has been noted in some carcinoma cells, such as cervical cancer. To study the effect of Net on c-fos expression and its potential role in the growth of pancreatic carcinoma, we developed a recombinant plasmid, a pEGFP-N1-Net, which codes for Net-EGFP fusion proteins, and stably transfected it into BxPC-3 human pancreatic carcinoma cells. Using stable transformants, we were able to show that overexpression of Net decreased the expression of c-fos and inhibited pancreatic cancer cell proliferation. Cell cycle analysis demonstrated that Net overexpression inhibited cell cycle progression. These findings suggested that loss of Net repression could augment c-fos expression and further trigger neoplastic cell proliferation, which was involved in the pathogenesis of pancreatic cancer. Therefore, Net might be a potential target for the treatment of c-fos-positive pancreatic cancer.

Wasylyk C, Zheng H, Castell C, et al.
Inhibition of the Ras-Net (Elk-3) pathway by a novel pyrazole that affects microtubules.
Cancer Res. 2008; 68(5):1275-83 [PubMed] Related Publications
Net (Elk-3/SAP-2/Erp) is a transcription factor that is phosphorylated and activated by the Ras-extracellular signal-regulated kinase (Erk) signaling pathway and is involved in wound healing, angiogenesis, and tumor growth. In a cell-based screen for small molecule inhibitors of Ras activation of Net transcriptional activity, we identified a novel pyrazole, XRP44X. XRP44X inhibits fibroblast growth factor 2 (FGF-2)-induced Net phosphorylation by the Ras-Erk signaling upstream from Ras. It also binds to the colchicine-binding site of tubulin, depolymerizes microtubules, stimulates cell membrane blebbing, and affects the morphology of the actin skeleton. Interestingly, Combretastin-A4, which produces similar effects on the cytoskeleton, also inhibits FGF-2 Ras-Net signaling. This differs from other classes of agents that target microtubules, which have either little effect (vincristine) or no effect (docetaxel and nocodazole) on the Ras-Net pathway. XRP44X inhibits various cellular properties, including cell growth, cell cycle progression, and aortal sprouting, similar to other molecules that bind to the tubulin colchicine site. XRP44X has the potentially interesting property of connecting two important pathways involved in cell transformation and may thereby represent an interesting class of molecules that could be developed for cancer treatment.

He J, Pan Y, Hu J, et al.
Profile of Ets gene expression in human breast carcinoma.
Cancer Biol Ther. 2007; 6(1):76-82 [PubMed] Related Publications
BACKGROUND: Ets genes encode a family of transcription factors that play key roles in cell proliferation, differentiation and apoptosis. Fusions of Ets genes with other targets have been described in Ewing's sarcoma, chronic myelomonocytic leukemia and more recently prostate carcinoma. Ets expression in breast carcinoma has not been comprehensively studied, and is the focus of this study.
METHODS: RT-Q-PCR was used to determine the expression of Ets genes in a panel of ten common breast cancer cell lines, two immortalized normal breast epithelial cell lines, and one primary culture of human mammary epithelial cells. Ets with altered expression in cancer cell lines were verified in primary breast tumors.
RESULTS: Transcripts of 21 of the 27 Ets genes were detected in either normal or cancer cells. Of the 21 detectable genes, 14 were expressed at a similar level in both normal and breast cancer cell lines. Four genes, Ehf, Elf3, Elf5 and Pdef, were expressed at higher levels in breast cancer cells than normal epithelials. Surprisingly, the expression of Elk3, Etsl and Flil was repressed in breast cancer cells. The protein status of Ehf, Elf3, Pdef, Elk3, Etsl and Flil, strongly correlated with the transcript data, suggesting that Ets expression is regulated primarily at the transcriptional level. Similarly, Elf3, Pdef and Tel2 were overexpressed, while Elk3, Etsl and Flil were under-expressed in primary breast tumor specimens in comparison with normal mammary tissues.
CONCLUSIONS: Our study identified a subset of Ets genes with altered expression in breast carcinoma, implicating their roles in mammary tumorigenesis. While the Ets over-expression pattern is useful to uncover recurrent genetic alterations involving Ets genes, the repressed expression of several Ets genes suggests that some Ets proteins may play suppressor roles during breast cancer progression. Our results warrant detailed studies of individual Ets activity during mammary gland neoplasia.

Kim SJ, Lee SY, Lee C, et al.
Differential expression profiling of genes in a complete hydatidiform mole using cDNA microarray analysis.
Gynecol Oncol. 2006; 103(2):654-60 [PubMed] Related Publications
OBJECTIVES: To gain a better understanding of the genes involved in the pathogenesis of gestational trophoblastic diseases, we evaluated the genome-wide expression levels of genes in complete hydatidiform mole (H-mole) as compared to normal placenta using cDNA microarray technique.
METHODS: The expression profiles of complete H-mole tissues were compared with those of normal placenta using cDNA microarray technique. The data obtained from 10,305 human genes were normalized by the print-tip-based LOWESS method. Significance analysis of microarray (SAM) was used to identify genes with statistically significant changes in expression. The expression levels of genes which showed significant differences between normal early placenta and complete H-mole tissues were further confirmed by RT-PCR.
RESULTS: A cDNA microarray analysis consisting of 10,305 human genes revealed significant changes in the expression of 213 genes, with 91 genes being upregulated and 122 being downregulated. SAM revealed significant changes in gene expression, including those associated with signal transduction, cell structure, transcription, and apoptosis. Further RT-PCR analysis of altered gene expression in mole tissues supported the microarray analysis results. We confirmed the upregulation of TLE4, CAPZA1, PRSS25, RNF130, and USP1 in complete H-mole tissues. Moreover, our study provides the first evidence that ELK3, LAMA3, LNK, STAT2, and TNFRSF25 are downregulated in complete H-mole compared to normal early placenta tissues.
CONCLUSIONS: These findings provide a large body of information regarding gene expression profiles associated with complete H-mole tumorigenesis and allow the identification of potential targets for tumor prevention or therapy.

Erin N, Zhao W, Bylander J, et al.
Capsaicin-induced inactivation of sensory neurons promotes a more aggressive gene expression phenotype in breast cancer cells.
Breast Cancer Res Treat. 2006; 99(3):351-64 [PubMed] Related Publications
Capsaicin-induced inactivation of sensory neurons has been reported to enhance metastasis of a murine breast cancer cell line, specifically enhancing myocardial metastases. Here we characterized changes in gene expression patterns in primary tumors which developed in capsaicin-treated vs. control mice. We identified a small cohort of genes (17) which all showed significant decreases in expression levels. All of the identified genes have been linked to cell growth, differentiation, and/or cancer progression. Three representative genes, Caspase-7 (an executor of apoptosis), ADAM-10 (A Disintegrin and Metalloprotease), and Elk-3 (a transcriptional repressor of the ternary factor subfamily of the Ets factors) were further investigated. All three showed dramatic downregulation at the protein level in primary tumors from capsaicin-treated animals compared with control (vehicle-treated) animals, and their expression was also lost in cell culture. Elk-3 and Caspase-7 were not expressed in vitro in cultured cell lines, suggesting that their expression was induced by the tumor microenvironment. Loss of Caspase-7 expression can be expected to result in loss of function of apoptotic pathways. At first glance, loss of ADAM-10 expression would be expected to result in decreased invasive capability, due to loss of matrix metalloprotease activity. However, just the opposite appears to be true. We found that ADAM-10 actually hydrolyzes Substance P. Specifically ADAM-10 produces the same growth-inhibitory products from Substance P (i.e., SP (1-7)) that Neprilysin does, so that loss of ADAM-10 expression actually results in loss of production of growth inhibitory peptides from Substance P. Similarly, ADAM-10 also efficiently hydrolyzes Calcitonin Gene-Related Peptide, which may act in concert with Substance P. Finally, overactivity of Ets transcriptional suppressor functions has been linked to inhibition of tumorigenesis (e.g., Erf and Mef), and in addition loss of Elk-3 expression might also be be linked to tumorigenesis via loss of its putative anti-inflammatory activities. There is anecdotal evidence in the literature to indicate that the rest of the down-regulated genes may also contribute to development of a more aggressive phenotype in this breast cancer model.

Skov K, Adomat H, Bowden M, et al.
Hypoxia in the androgen-dependent Shionogi model for prostate cancer at three stages.
Radiat Res. 2004; 162(5):547-53 [PubMed] Related Publications
The objective of this study was to investigate a possible relationship between androgen status and hypoxia in the Shionogi murine prostate tumor model, which is widely used to study the effects of androgen withdrawal on hormone resistance and radiation response. Binding of the nitroimidazole hypoxia marker EF5 was assessed using the Cy3-tagged monoclonal antibody ELK3-51. Three hours after injection of EF5 (30 mg/kg), tumors from the following three stages were excised: androgen-dependent, regressed tumors 7 days after castration, and androgen-independent. Half of each tumor was disaggregated for analysis by flow cytometry and the remainder was flash frozen. Statistically significant differences (P < 0.01) were found between androgen-dependent, regressed and androgen-dependent tumors: approximately 30, approximately 2 and approximately 50% hypoxic cells, respectively. Frozen sections from androgen-dependent tumors exhibited highly variable EF5 binding; regressed tumors showed very little or no binding; each section from androgen-dependent tumors showed high levels and uniformly distributed binding of EF5. There was no correlation between the degree of hypoxia and tumor weight (P > 0.1). The results from this preliminary study indicate that hypoxia may play an important role with respect to the timing of irradiation in prostate cancer treatments and possibly may be a useful prognostic tool. In addition, hypoxia may also be relevant to progression in this disease after androgen ablation.

Cao D, Hustinx SR, Sui G, et al.
Identification of novel highly expressed genes in pancreatic ductal adenocarcinomas through a bioinformatics analysis of expressed sequence tags.
Cancer Biol Ther. 2004; 3(11):1081-9; discussion 1090-1 [PubMed] Related Publications
In most microarray experiments, a significant fraction of the differentially expressed mRNAs identified correspond to expressed sequence tags (ESTs) and are generally discarded from further analyses. We used careful bioinformatics analyses to characterize those ESTs that were found to be highly overexpressed in a series of pancreatic adenocarcinomas. cDNA was prepared from 60 non-neoplastic samples (normal pancreas [n = 20], normal colon [n = 10], or normal duodenal mucosal [n = 30]) and from 64 pancreatic cancers (resected cancers [n = 50] or cancer cell lines [n = 14]) and hybridized to the complete Affymetrix Human Genome U133 GeneChip(R) set (arrays U133A and B) for simultaneous analysis of 45,000 fragments corresponding to 33,000 known genes and 6,000 ESTs. The GeneExpress(R) software system Fold Change Analysis Tool was used and 60 ESTs were identified that were expressed at levels at least 3-fold greater in the pancreatic cancers as compared to normal tissues. Searches against the human genomic sequence and comparative genomic analysis of human and mouse genomes was carried out using basic local alignment search tools (BLAST), BLASTN, and BLASTX, for identifying protein coding genes corresponding to the ESTs. Subsequently, in order to pick the most relevant candidate genes for a more detailed analysis, we looked for domains/motifs in the open reading frames using SMART and Pfam programs. We were able to definitively map 43 of the 60 ESTs to known or novel genes, and 15 of the ESTs could be localized in close proximity to a gene in the human genome although we were unable to establish that the EST was indeed derived from those genes. The differential expression of a subset of genes was confirmed at the protein level by immunohistochemical labeling of tissue microarrays (inhibin beta A [INHBA] and CD29) and/or at the transcript level by RT-PCR (INHBA, AKAP12, ELK3, FOXQ1, EIF5A2, and EFNA5). We conclude that bioinformatics tools can be used to characterize differentially overexpressed ESTs, and that some of these ESTs may represent diagnostically and therapeutically useful targets that might be missed using data solely from currently annotated databases.

Mohr S, Bottin MC, Lannes B, et al.
Microdissection, mRNA amplification and microarray: a study of pleural mesothelial and malignant mesothelioma cells.
Biochimie. 2004; 86(1):13-9 [PubMed] Related Publications
The studies of molecular alterations in tumor cells with microarrays are often hampered by inherent tissue heterogeneity. The emergence of Laser Capture Microdissection (LCM) allowed us to overcome this challenge since it gives selective access to cancer cells that are isolated from their native tissue environment. In this report, we microdissected mesothelial cells and malignant mesothelioma cells of ex vivo resected specimens using LCM. Amplified RNA from mesothelial and mesothelioma microdissected cells allowed us to measure global gene expression with 10 K-microarrays in four independent experiments. We screened 9850 annotated human genes, 1275 of which have satisfied our data analysis requirements. They included 302 overexpressed genes and 160 downregulated genes in mesothelioma microdissected cells as compared to mesothelial microdissected cells. Among them, the expression levels of eight genes, namely BF, FTL, IGFBP7, RARRES1, RARRES2, RBP1, SAT, and TXN according to HUGO nomenclature, were increased, whereas six: ALOX5AP, CLNS1A, EIF4A2, ELK3, REQ and SYPL, were found to be underexpressed in mesothelioma microdissected cells. The ferritin light polypeptide (FTL) gene overexpression was confirmed by real time quantitative PCR. Our approach allowed a comprehensive in situ examination of mesothelioma and provided an accurate way to find new marker genes that may be useful for diagnosis and treatment of malignant pleural mesothelioma.

Kanda K, Nakayama T, Onizuka S, et al.
Expression of the Ets-1 proto-oncogene is linked to cell differentiation of human hepatocellular carcinoma.
Hepatogastroenterology. 2002 May-Jun; 49(45):747-51 [PubMed] Related Publications
BACKGROUND/AIMS: Ets-1 regulates the expression of a number of genes related to remodeling of the extracellular matrix. Ets-1 is associated with the occurrence of invasive processes, proliferation and differentiation. Less is known about the biological functions of Ets-1 in human hepatocellular carcinoma. In an attempt at elucidation, we examined immunohistochemically hepatocellular carcinoma followed by application of genetic techniques.
METHODOLOGY: We performed immunohistochemical analysis on tissue from 59 Japanese patients undergoing surgical resection of hepatocellular carcinoma using the antibody against human Ets-1. We compared Ets-1 expression in relation to clinicopathological findings. In situ hybridization and reverse transcription-polymerase chain reaction were also performed to confirm the expression of Ets-1 messenger RNA in hepatocellular carcinoma tissues.
RESULTS: In specimens from 59 patients with hepatocellular carcinoma, 41 (70%) showed positive staining for Ets-1 protein. The expression of Ets-1 messenger RNA was also observed in hepatocellular carcinoma tissues by in situ hybridization and reverse transcription-polymerase chain reaction. The expression of Ets-1 correlated with histological differentiation of hepatocellular carcinoma (P < 0.05). Ets-1 was positive in 2 (50%) of the 4 well-differentiated hepatocellular carcinomas and in 28 (64%) of the 44 moderately differentiated hepatocellular carcinomas, whereas all the 11 poorly differentiated hepatocellular carcinomas were positive for Ets-1 staining. Ets-1 protein was expressed more strongly at the peripheral than the central area of the tumor. Otherwise, no particular correlation was evident in terms of clinicopathological factors.
CONCLUSIONS: We found Ets-1 to be expressed in human hepatocellular carcinoma, particularly at the peripheral area of the tumor. As this expression is linked to cell differentiation, this gene may yield biological information relative to this malignant tumor of the liver.

Karkkainen MJ, Alitalo K
Lymphatic endothelial regulation, lymphoedema, and lymph node metastasis.
Semin Cell Dev Biol. 2002; 13(1):9-18 [PubMed] Related Publications
Vascular endothelial growth factor receptor-3 (VEGFR-3) mediates lymphatic endothelial cell (LEC) growth, migration, and survival by binding VEGF-C and VEGF-D. Recent studies have revealed new regulators of the lymphatic endothelium, such as the transcription factor Prox1, and the cell surface proteins podoplanin and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1). Furthermore, the isolation of LECs now allows detailed molecular studies of the factors regulating the lymphatic vasculature. These studies are aimed at targeting the lymphatic vasculature in the treatment of various diseases, such as tumour metastasis and lymphoedema.

Mavrothalassitis G, Ghysdael J
Proteins of the ETS family with transcriptional repressor activity.
Oncogene. 2000; 19(55):6524-32 [PubMed] Related Publications
ETS proteins form one of the largest families of signal-dependent transcriptional regulators, mediating cellular proliferation, differentiation and tumorigenesis. Most of the known ETS proteins have been shown to activate transcription. However, four ETS proteins (YAN, ERF, NET and TEL) can act as transcriptional repressors. In three cases (ERF, NET and TEL) distinct repression domains have been identified and there are indications that NET and TEL may mediate transcription via Histone Deacetylase recruitment. All four proteins appear to be regulated by MAPKs, though for YAN and ERF this regulation seems to be restricted to ERKs. YAN, ERF and TEL have been implicated in cellular proliferation although there are indications suggesting a possible involvement of YAN and TEL in differentiation as well. Other ETS-domain proteins have been shown to repress transcription in a context specific manner, and there are suggestions that the ETS DNA-binding domain may act as a transcriptional repressor. Transcriptional repression by ETS domain proteins adds an other level in the orchestrated regulation by this diverse family of transcription factors that often recognize similar if not identical binding sites on DNA and are believed to regulate critical genes in a variety of biological processes. Definitive assessment of the importance of this novel regulatory level will require the identification of ETS proteins target genes and the further analysis of transcriptional control and biological function of these proteins in defined pathways.

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