Gene Summary

Gene:ELK1; ETS transcription factor ELK1
Summary:This gene is a member of the Ets family of transcription factors and of the ternary complex factor (TCF) subfamily. Proteins of the TCF subfamily form a ternary complex by binding to the the serum response factor and the serum response element in the promoter of the c-fos proto-oncogene. The protein encoded by this gene is a nuclear target for the ras-raf-MAPK signaling cascade. This gene produces multiple isoforms by using alternative translational start codons and by alternative splicing. Related pseudogenes have been identified on chromosomes 7 and 14. [provided by RefSeq, Mar 2012]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:ETS domain-containing protein Elk-1
Source:NCBIAccessed: 29 August, 2019


What does this gene/protein do?
Show (19)
Pathways:What pathways are this gene/protein implicaed in?
Show (24)

Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 29 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • RNA Interference
  • MAP Kinase Signaling System
  • Breast Cancer
  • Cell Division
  • Cancer Gene Expression Regulation
  • Prostate Cancer
  • Promoter Regions
  • Phosphorylation
  • Messenger RNA
  • X Chromosome
  • Cell Movement
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Transcriptional Activation
  • siRNA
  • Hep G2 Cells
  • Proto-Oncogene Proteins
  • Disease Progression
  • Base Sequence
  • Neoplastic Cell Transformation
  • Transfection
  • ELK1
  • DNA-Binding Proteins
  • Western Blotting
  • Cell Proliferation
  • Oligonucleotide Array Sequence Analysis
  • Transcription Factors
  • ets-Domain Protein Elk-1
  • Molecular Sequence Data
  • Tetradecanoylphorbol Acetate
  • Up-Regulation
  • Signal Transduction
  • Transcription
  • MicroRNAs
  • Gene Expression Profiling
  • Apoptosis
  • Binding Sites
  • Antineoplastic Agents
  • Cell Cycle
  • Mutation
Tag cloud generated 29 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ELK1 (cancer-related)

Yue CH, Liu JY, Chi CS, et al.
Myeloid Zinc Finger 1 (MZF1) Maintains the Mesenchymal Phenotype by Down-regulating IGF1R/p38 MAPK/ERα Signaling Pathway in High-level MZF1-expressing TNBC cells.
Anticancer Res. 2019; 39(8):4149-4164 [PubMed] Related Publications
BACKGROUND/AIM: Signaling regulation of myeloid zinc finger 1 (MZF1) has been implicated in the progression of many human malignancies; however, the mechanistic action of MZF1 in triple-negative breast cancer (TNBC) progression remains elusive. In this study, the aim was to investigate the molecular mechanisms of MZF1 and its functional role in TNBC cellular migration and invasion.
MATERIALS AND METHODS: Hs578T and MDA-MB-231 cells were transfected to stably express the acidic domain of MZF1 (MZF1
RESULTS: Herein, we found that MZF1 in high-level MZF1-expressing TNBC cells is associated with cell migration, invasion, and mesenchymal phenotype. MZF1 interacted with the promoter region of insulin-like growth factor 1 receptor (IGF1R) to drive invasion and metastasis of high-level MZF1-expressing TNBC cells. Exogenous expression of the acidic domain of MZF1 repressed the binding of endogenous MZF1 to IGF1R promoter via blocking the interaction with ETS-like gene 1 (ELK1). This blockage not only caused MZF1 protein degradation, but also restrained ELK1 nuclear localization in high-level MZF1-expressing TNBC cells. MZF1, but not ELK1, was necessary for the retention of mesenchymal phenotype by repressing IGF1R promoter activity in TNBC cells expressing high levels of MZF1. Activation of the IGF1R-driven p38MAPK-ERα-slug-E-cadherin signaling axis mediated the conversion of mesenchymal cell to epithelial phenotype, caused by MZF1 destabilization. These results suggest that MZF1 is an oncogenic inducer.
CONCLUSION: Blocking of the MZF1/ELK1 interaction to reduce MZF1 protein stability by saturating the endogenous MZF1/ELK1 binding domains might be a promising therapeutic strategy for the treatment of high-level MZF1-expressing TNBC.

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

Rodriguez-Aguayo C, Bayraktar E, Ivan C, et al.
PTGER3 induces ovary tumorigenesis and confers resistance to cisplatin therapy through up-regulation Ras-MAPK/Erk-ETS1-ELK1/CFTR1 axis.
EBioMedicine. 2019; 40:290-304 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Inflammatory mediator prostaglandin E2-prostaglandin E2 receptor EP3 (PTGER3) signaling is critical for tumor-associated angiogenesis, tumor growth, and chemoresistance. However, the mechanism underlying these effects in ovarian cancer is not known.
METHODS: An association between higher tumoral expression of PTGER3 and shorter patient survival in the ovarian cancer dataset of The Cancer Genome Atlas prompted investigation of the antitumor effects of PTGER3 downmodulation. PTGER3 mRNA and protein levels were higher in cisplatin-resistant ovarian cancer cells than in their cisplatin-sensitive counterparts.
FINDINGS: Silencing of PTGER3 via siRNA in cancer cells was associated with decreased cell growth and less invasiveness, as well as cell-cycle arrest and increased apoptosis, mediated through the Ras-MAPK/Erk-ETS1-ELK1/CFTR1 axis. Furthermore, sustained PTGER3 silencing with multistage vector and liposomal 2'-F-phosphorodithioate-siRNA-mediated silencing of PTGER3 combined with cisplatin resulted in robust antitumor effects in cisplatin-resistant ovarian cancer models.
INTERPRETATION: These findings identify PTGER3 as a potential therapeutic target in chemoresistant ovarian cancers expressing high levels of this oncogenic protein. FUND: National Institutes of Health/National Cancer Institute, USA.

Dun S, Gao L
Tanshinone I attenuates proliferation and chemoresistance of cervical cancer in a KRAS-dependent manner.
J Biochem Mol Toxicol. 2019; 33(4):e22267 [PubMed] Related Publications
Chemoresistance is a common occurrence during advanced or recurrent cervical cancer therapy when treated by conventional treatment, platinum-based chemotherapy. This study aimed to investigate the effect and underlying mechanism of tanshinone I on attenuating proliferation and chemoresistance of cervical cancer cells. In cervical cancer cells, cell proliferation was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), cell count, and soft-agar colony-formation assay. rVista analysis and luciferase reporter assay were used to explore the upstream regulator of KRAS, and the expression levels of key genes were also detected. Western blot analysis showed that tanshinone I significantly suppressed KRAS expression and inhibited AKT phosphorylation. rVista analysis and luciferase reporter assay demonstrated that ELK1 can binds directly to KRAS promoter and positively regulates KRAS expression. MTT assay showed that KRAS or ELK1 overexpression significantly attenuated the suppressive effects of tanshinone I on HeLa cells proliferation. In addition, tanshinone I recovered the cisplatin sensitivity of HeLa CR cells, whereas KRAS or ELK1 overexpression significantly inhibited this phenomenon. Our results suggested that tanshinone I had anticancer effects on cervical cancer cells via inhibiting ELK1 and downregulating KRAS-AKT axis, which subsequently suppressed the proliferation and cisplatin resistance of cervical cancer cells.

Fan HX, Feng YJ, Zhao XP, et al.
MiR-185-5p suppresses HBV gene expression by targeting ELK1 in hepatoma carcinoma cells.
Life Sci. 2018; 213:9-17 [PubMed] Related Publications
AIMS: To investigate the role and underlying mechanism of miR-185-5p in hepatitis B virus (HBV) expression and replication.
MAIN METHODS: The relative levels of hepatitis B surface antigen and hepatitis B e antigen were detected by enzyme-linked immunosorbent assay (ELISA). The HBV DNA copies in the cultures medium were measured by RT-qPCR. The HBV large surface antigen promoter (S1p) activity was analyzed by luciferase reporter assay. The target relationship between miR-185-5p and ELK1 was identified by bioinformatics analysis and EGFP fluorescent reporter assay. The ELK1 expression was determined by RT-qPCR and Western blot.
KEY FINDINGS: miR-185-5p significantly decreased HBV large surface antigen promoter activity and subsequently the production of HBV proteins and HBV DNA copies in vitro. Further, we identified the ETS transcription factor ELK1 is a target of miR-185-5p. Overexpression and knockdown experiments showed overexpression of ELK1 stimulated HBV large surface antigen promoter activity and promoted the production of HBV proteins and HBV DNA copies, whereas knockdown of ELK1 has the opposite effects. Moreover, the rescue of ELK1 expression reversed the suppression of miR-185-5p on HBV replication and gene expression. Further mechanistic study showed that the ETS binding sites within the HBV large surface antigen promoter are required for the repression effect of miR-185-5p on HBV.
SIGNIFICANCE: There are few reports about the interaction between miRNAs and the transcription from HBV S1p, we found that miR-185-5p decreases HBV S1p activity by targeting ELK1, which may provide a promising therapeutic strategy for HBV infection.

Hu Z, Tie Y, Lv G, et al.
Transcriptional activation of miR-320a by ATF2, ELK1 and YY1 induces cancer cell apoptosis under ionizing radiation conditions.
Int J Oncol. 2018; 53(4):1691-1702 [PubMed] Related Publications
MicroRNAs (miRNAs or miRs) play important roles in numerous cellular processes, including development, proliferation, tumorigenesis and apoptosis. It has been reported that miRNA expression is induced by ionizing radiation (IR) in cancer cells. However, the underlying molecular mechanisms are not yet fully understood. In this study, endogenous miR‑320a and its primary precursor (pri‑miR‑320a) were assayed by reverse transcription‑quantitative PCR (RT‑qPCR). Luciferase activities were measured using a dual‑luciferase reporter assay system. Western blot analysis was used to determine the protein expressions of upstream and downstream genes of miR‑320a. Cell apoptosis was evaluated by Annexin V apoptosis assay and cell proliferation was measured using the trypan blue exclusion method. The results revealed that miR‑320a expression increased linearly with the IR dose and treatment duration. Three transcription factors, activating transcription factor 2 (ATF2), ETS transcription factor (ELK1) and YY1 transcription factor (YY1), were activated by p38 mitogen‑activated protein kinase (MAPK) and mitogen‑activated protein kinase 8 (JNK) and by upregulated miR‑320a expression under IR conditions. In addition, it was identified that X‑linked inhibitor of apoptosis (XIAP) was an miR‑320a target gene during the IR response. By targeting XIAP, miR‑320a induced apoptosis and inhibited the proliferation of the cancer cells. On the whole, the results of this study demonstrated that miRNA‑320a, regulated by the p38 MAPK/JNK pathway, enhanced the radiosensitivity of cancer cells by inhibiting XIAP and this may thus prove to be a potential therapeutic approach with which to overcome radioresistance in cancer treatment.

Wei X, Yu L, Jin X, et al.
Identification of open chromosomal regions and key genes in prostate cancer via integrated analysis of DNase‑seq and RNA‑seq data.
Mol Med Rep. 2018; 18(2):2245-2252 [PubMed] Related Publications
Prostate cancer is a type of adenocarcinoma arising from the peripheral zone of the prostate gland, and metastasized prostate cancer is incurable with the current available therapies. The present study aimed to identify open chromosomal regions and differentially expressed genes (DEGs) associated with prostate cancer development. The DNase sequencing data (GSE33216) and RNA sequencing data (GSE22260) were downloaded from the Gene Expression Omnibus database. DNase I hypersensitive sites were detected and analyzed. Subsequently, DEGs were identified and their potential functions were enriched. Finally, upstream regulatory elements of DEGs were predicted. In LNCaP cells, following androgen receptor activation, 244 upregulated and 486 downregulated open chromosomal regions were identified. However, only 1% of the open chromosomal regions were dynamically altered. The 41 genes with upregulated open chromosomal signals within their promoter regions were primarily enriched in biological processes. Additionally, 211 upregulated and 150 downregulated DEGs were identified in prostate cancer, including eight transcription factors (TFs). Finally, nine regulatory elements associated with prostate cancer were predicted. In particular, inhibitor of DNA binding 1 HLH protein (ID1) was the only significantly upregulated TF which exhibited motif enrichment in the promoter regions of upregulated genes. CCCTC‑binding factor (CTCF) and ELK1 ETS transcription factor (ELK1), enriched in the open promoter regions of downregulated genes, were potential upstream regulatory elements. Furthermore, reverse transcription‑quantitative polymerase chain reaction analysis confirmed that ID1 expression was significantly upregulated in LNCaP cells and 5α‑dihydrotestosterone (DHT)‑treated LNCaP cells compared with that in BPH1 cells, while CTCF and ELK1 expression was significantly downregulated in LNCaP cells and DHT‑treated LNCaP cells. In conclusion, ID1, CTCF and ELK1 may be associated with prostate cancer, and may be potential therapeutic targets for the treatment of this disease.

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.

Sheng K, Lu J, Zhao H
ELK1-induced upregulation of lncRNA HOXA10-AS promotes lung adenocarcinoma progression by increasing Wnt/β-catenin signaling.
Biochem Biophys Res Commun. 2018; 501(3):612-618 [PubMed] Related Publications
In recent years, increasing number of lncRNAs have been studied in lung adenocarcinoma (LAD). LncRNA HOXA10-AS was found to be upregulated in LAD tissues. Based on the data of TCGA database, HOXA10-AS was a prognostic factor for lung adenocarcinoma. This study aims to reveal the biological function of HOXA10-AS in LAD. qRT-PCR was applied to test expression levels of HOXA10-AS in both LAD tissues and cell lines. Next, transcription factor ELK1 was demonstrated to upregulate HOXA10-AS in LAD cells through performing bioinformatics analysis and dual luciferase activity. Loss of function assays were performed in two different LAD cell lines. Silenced HOXA10-AS was proved to inhibit LAD progression by affecting cell proliferation, cell apoptosis and cell metastasis and EMT progress. Western blot analysis revealed that HOXA10-AS increased Wnt/β-catenin signaling in LAD cell lines. Finally, rescue assays were carried out to identify the biological function of HOXA10-AS-Wnt/β-catenin signaling in LAD progression. In conclusion, ELK1-induced upregulation of HOXA10-AS improved LAD progression through increasing Wnt/β-catenin signaling.

Zhao Y, Min L, Xu C, et al.
Construction of disease-specific transcriptional regulatory networks identifies co-activation of four gene in esophageal squamous cell carcinoma.
Oncol Rep. 2017; 38(1):411-417 [PubMed] Related Publications
Even though various molecules may serve as biomarkers, little is known concerning the mechanisms underlying the carcinogenesis of ESCC, particularly the transcriptional regulatory network. Thus, in the present study, paired ESCC and non-cancerous (NC) tissues were assayed by Affymetrix microarray assays. Passing Attributes between Networks for Data Assimilation (PANDA) was used to construct networks between transcription factors (TFs) and their targets. AnaPANDA program was applied to compare the regulatory networks. A hypergeometric distribution model-based target profile similarity analysis was utilized to find co-activation effects using both TF-target networks and differential expression data. There were 1,116 genes upregulated and 1,301 genes downregulated in ESCC compared with NC tissues. In TF-target networks, 16,970 ESCC-specific edges and 9,307 NC-specific edges were identified. Edge enrichment analysis by AnaPANDA indicated 17 transcription factors (NFE2L2, ELK4, PAX6, TLX1, ESR1, ZNF143, TP53, REL, ELF5, STAT1, TBP, NHLH1, FOXL1, SOX9, STAT3, ELK1, and HOXA5) suppressed in ESCC and 5 (SPIB, BRCA1, MZF1, MAFG and NFE2L1) activated in ESCC. For SPIB, MZF1, MAFG and NFE2L1, a strong and significant co-activation effect among them was detected in ESCC. In conclusion, the construction of transcriptional regulatory networks found SPIB, MZF1, MAFG and NFE2L1 co-activated in ESCC, which provides distinctive insight into the carcinogenesis mechanism of ESCC.

Jin X, Chen X, Hu Y, et al.
LncRNA-TCONS_00026907 is involved in the progression and prognosis of cervical cancer through inhibiting miR-143-5p.
Cancer Med. 2017; 6(6):1409-1423 [PubMed] Free Access to Full Article Related Publications
Our previous long noncoding RNA (lncRNA) microarray revealed that lncRNA-TCONS_00026907 is aberrantly expressed between cervical cancer tissues and adjacent tissues. This study aims to explore the potential role of TCONS_00026907 in the development of cervical cancer. The expression levels of TCONS_00026907 in cervical cancer tissues and adjacent tissues from 83 patients of cervical cancer were detected by quantitative real-time polymerase chain reaction and the survival rate was analyzed. In vitro, HeLa and SiHa cells were transfected with small hairpin RNA (shRNA)-TCONS_00026907, then cell proliferation, cycle distribution, apoptosis, migration and invasion were measured. To confirm TCONS_00026907 regulates expression of ELK1 through inhibiting miR-143-5p, overexpression of miR-143-5p and silencing of ELK1 were, respectively, performed in HeLa and SiHa cells. Results showed that TCONS_00026907 level was significantly higher in cervical cancer tissues compared to noncancerous tissues and the survival rate was lower in the high expression group. Silencing of TCONS_00026907, overexpression of miR-143-5p and silencing of ELK1 inhibited cervical cell cycle, proliferation, migration, and invasion, but promoted apoptosis, respectively. Furthermore, silencing of TCONS_00026907 suppressed the growth of cervical tumors and altered the expression of ELK1, p-ELK1, C-fos, Cyclin D1 and Bcl-2 in vivo. Our study identifies TCONS_00026907 as a potent proto-oncogene and indicates that TCONS_00026907/miR143-5p/ELK1 regulatory pathway plays an important role in cervical cancer.

Ohguchi H, Harada T, Sagawa M, et al.
KDM6B modulates MAPK pathway mediating multiple myeloma cell growth and survival.
Leukemia. 2017; 31(12):2661-2669 [PubMed] Free Access to Full Article Related Publications
Recent studies have delineated cancer-type-specific roles of histone 3 lysine 27 (H3K27) demethylase KDM6B/JMJD3 depending on its H3K27 demethylase activity. Here we show that KDM6B is expressed in multiple myeloma (MM) cells; and that shRNA-mediated knockdown and CRISPR-mediated knockout of KDM6B abrogate MM cell growth and survival. Tumor necrosis factor-α or bone marrow stromal cell culture supernatants induce KDM6B, which is blocked by IKKβ inhibitor MLN120B, suggesting that KDM6B is regulated by NF-κB signaling in MM cells. RNA-seq and subsequent ChIP-qPCR analyses reveal that KDM6B is recruited to the loci of genes encoding components of MAPK signaling pathway including ELK1 and FOS, and upregulates expression of these genes without affecting H3K27 methylation level. Overexpression of catalytically inactive KDM6B activates expression of MAPK pathway-related genes, confirming its function independent of demethylase activity. We further demonstrate that downstream targets of KDM6B, ELK1 and FOS, confer MM cell growth. Our study therefore delineates KDM6B function that links NF-κB and MAPK signaling pathway mediating MM cell growth and survival, and validates KDM6B as a novel therapeutic target in MM.

Maicas M, Vázquez I, Alis R, et al.
The MDS and EVI1 complex locus (MECOM) isoforms regulate their own transcription and have different roles in the transformation of hematopoietic stem and progenitor cells.
Biochim Biophys Acta Gene Regul Mech. 2017; 1860(6):721-729 [PubMed] Related Publications
Transcriptional activation of the EVI1 oncogene (3q26) leads to aggressive forms of human acute myeloid leukemia (AML). However, the mechanism of EVI1-mediated leukemogenesis has not been fully elucidated. Previously, by characterizing the EVI1 promoter, we have shown that RUNX1 and ELK1 directly regulate EVI1 transcription. Intriguingly, bioinformatic analysis of the EVI1 promoter region identified the presence of several EVI1 potential binding sites. Thus, we hypothesized that EVI1 could bind to these sites regulating its own transcription. In this study, we show that there is a functional interaction between EVI1 and its promoter, and that the different EVI1 isoforms (EVI1-145kDa, EVI1-Δ324 and MDS1-EVI1) regulate the transcription of EVI1 transcripts through distinct promoter regions. Moreover, we determine that the EVI1-145kDa isoform activates EVI1 transcription, whereas EVI1-Δ324 and MDS1-EVI1 act as repressors. Finally, we demonstrate that these EVI1 isoforms are involved in cell transformation; functional experiments show that EVI1-145kDa prolongs the maintenance of hematopoietic stem and progenitor cells; conversely, MDS1-EVI1 repressed hematopoietic stem and progenitor colony replating capacity. We demonstrate for the first time that EVI1 acts as a regulator of its own expression, highlighting the complex regulation of EVI1, and open new directions to better understand the mechanisms of EVI1 overexpressing leukemias.

Shuang T, Wang M, Zhou Y, et al.
NF-κB1, c-Rel, and ELK1 inhibit miR-134 expression leading to TAB1 upregulation in paclitaxel-resistant human ovarian cancer.
Oncotarget. 2017; 8(15):24853-24868 [PubMed] Free Access to Full Article Related Publications
The mechanism by which the transcription factors inhibit the miRNA expression in ovarian cancer chemoresistance is unclear. The present study investigated the mechanism underlying the transcriptional repression of miR-134 in chemoresistant serous epithelial ovarian cancer. The results demonstrate that NF-κB1, c-Rel, and ELK1 are involved as transcription factors in repressing miR-134 expression in paclitaxel-resistant ovarian cancer cells. Knockdown of these transcription factors led to increased miR-134 expression, resulting in increased apoptosis and inhibition of proliferation in SKOV3-TR30 cells. NF-κB1, c-Rel, and ELK1 mRNA expression was upregulated in chemoresistant specimens and negatively correlated with miR-134 expression. Kaplan-Meier analysis revealed that high nuclear expressions of NF-κB1, c-Rel, ELK1 were significantly associated with short survival in serous epithelial ovarian cancer patients. Finally, TAB1 was identified as a functional target of miR-134, and the expression of TAB1 was increased by the transcription factors of NF-κB1, c-Rel, and ELK1 via miR-134. Taken together, these results provide an insight into the mechanism of repressed miR-134 expression in chemoresistance of serous epithelial ovarian cancer.

Bullock M, Lim G, Li C, et al.
Thyroid transcription factor FOXE1 interacts with ETS factor ELK1 to co-regulate TERT.
Oncotarget. 2016; 7(52):85948-85962 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Although FOXE1 was initially recognized for its role in thyroid organogenesis, more recently a strong association has been identified between the FOXE1 locus and thyroid cancer. The role of FOXE1 in adult thyroid, and in particular regarding cancer risk, has not been well established. We hypothesised that discovering key FOXE1 transcriptional partners would in turn identify regulatory pathways relevant to its role in oncogenesis.
RESULTS: In a transcription factor-binding array, ELK1 was identified to bind FOXE1. We confirmed this physical association in heterologously transfected cells by IP and mammalian two-hybrid assays. In thyroid tissue, endogenous FOXE1 was shown to bind ELK1, and using ChIP assays these factors bound thyroid-relevant gene promoters TPO and TERT in close proximity to each other. Using a combination of electromobility shift assays, TERT promoter assays and siRNA-silencing, we found that FOXE1 positively regulated TERT expression in a manner dependent upon its association with ELK1. Treating heterologously transfected thyroid cells with MEK inhibitor U0126 inhibited FOXE1-ELK1 interaction, and reduced TERT and TPO promoter activity.
METHODOLOGY: We investigated FOXE1 interactions within in vitro thyroid cell models and human thyroid tissue using a combination of immunoprecipitation (IP), chromatin IP (ChIP) and gene reporter assays.
CONCLUSIONS: FOXE1 interacts with ELK1 on thyroid relevant gene promoters, establishing a new regulatory pathway for its role in adult thyroid function. Co-regulation of TERT suggests a mechanism by which allelic variants in/near FOXE1 are associated with thyroid cancer risk.

Kent OA, Sandí MJ, Burston HE, et al.
An oncogenic KRAS transcription program activates the RHOGEF ARHGEF2 to mediate transformed phenotypes in pancreatic cancer.
Oncotarget. 2017; 8(3):4484-4500 [PubMed] Free Access to Full Article Related Publications
Activating mutations of KRAS are nearly ubiquitous in pancreatic adenocarcinomas occurring in greater than 90% of cases. Cellular transformation by oncogenic RAS requires the RHO guanine exchange factor ARHGEF2 (also known as GEF-H1) for tumor growth and survival. Here, we find oncogenic KRAS activates ARHGEF2 through a minimal RAS responsive promoter. We have determined the endogenous ARHGEF2 promoter is positively regulated by the transcription factors ELK1, ETS1, SP1 and SP3 and negatively regulated by the RAS responsive element binding protein (RREB1). We find that the panel of ARHGEF2-regulating transcription factors modulates RAS transformed phenotypes including cellular viability, anchorage-independent growth and invasion-migration of pancreatic cancer cells. RREB1 knockdown activates the amplitude and duration of RHOA via increased ARHGEF2 expression. By relieving the negative regulation of RREB1 on the ARHGEF2 promoter, we determined that ETS1 and SP3 are essential for the normal expression of ARHGEF2 and contribute to the migratory behavior of pancreatic cancer cells. Furthermore, enforced expression of ARHGEF2 rescues loss of SP3 driven invasion-migration and anchorage-independent growth defective phenotypes through restored activation of RHOA. Collectively, our results identify a transcription factor program required for RAS transformation and provide mechanistic insight into the highly metastatic behavior of pancreatic cancer.

Rosati R, Patki M, Chari V, et al.
The Amino-terminal Domain of the Androgen Receptor Co-opts Extracellular Signal-regulated Kinase (ERK) Docking Sites in ELK1 Protein to Induce Sustained Gene Activation That Supports Prostate Cancer Cell Growth.
J Biol Chem. 2016; 291(50):25983-25998 [PubMed] Free Access to Full Article Related Publications
The ETS domain transcription factor ELK1 is in a repressive association with growth genes and is transiently activated through phosphorylation by ERK1/2. In prostate cancer (PCa) cells the androgen receptor (AR) is recruited by ELK1, via its amino-terminal domain (A/B), as a transcriptional co-activator, without ELK1 hyper-phosphorylation. Here we elucidate the structural basis of the interaction of AR with ELK1. The ELK1 polypeptide motifs required for co-activation by AR versus those required for activation of ELK1 by ERK were systematically mapped using a mammalian two-hybrid system and confirmed using a co-immunoprecipitation assay. The mapping precisely identified the two ERK-docking sites in ELK1, the D-box and the DEF (docking site for ERK, FXFP) motif, as the essential motifs for its cooperation with AR(A/B) or WTAR. In contrast, the transactivation domain in ELK1 was only required for activation by ERK. ELK1-mediated transcriptional activity of AR(A/B) was optimal in the absence of ELK1 binding partners, ERK1/2 and serum-response factor. Purified ELK1 and AR bound with a dissociation constant of 1.9 × 10

Wu X, Xia M, Chen D, et al.
Profiling of downregulated blood-circulating miR-150-5p as a novel tumor marker for cholangiocarcinoma.
Tumour Biol. 2016; 37(11):15019-15029 [PubMed] Related Publications
Altered microRNA (miRNA) expression plays a role in cholangiocarcinoma (CCA) development; thus, detection of blood-circulating miRNAs could be useful as CCA markers. This study profiled serum miRNA levels in patients with primary sclerosing cholangitis (PSC) and CCA and then assessed the role of miR-150-5p in CCA progression in vitro. Three samples were randomly selected from each of 50 sera of healthy controls, 30 PSC sera, and 28 CCA sera with matched bile samples for miRNA microarray profiling. The dysregulated miRNAs were confirmed using qRT-PCR, and miR-150-5p was selected for further in vitro and ex vivo studies. The miRNA microarray identified three dysregulated miRNAs in both CCA and PSC samples, while miR-150-5p level was consistently lower in CCA sera, bile, and tissues than in normal control and PSC sera (P < 0.05). Furthermore, levels of miR-150-5p were associated with serum carbohydrate antigen 19-9 (CA19-9) levels and CCA pathological grade. Bioinformatic Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses showed that miR-150-5p could regulate hand-full gene pathways, including cancer pathway (P < 0.01). However, overexpression of miR-150-5p inhibited proliferation, migration, and invasion capability of CCA cells (P < 0.05). Luciferase reporter assay showed that miR-150-5p bound to an oncogene Ets including gene-1 (ELK1), and Western blot data confirmed that miR-150-5p suppressed ELK1 expression in CCA cell lines. These results suggest that reduced miR-150-5p expression could contribute to CCA development and progression due to uncontrolled ELK1 expression. Thus, further study could evaluate miR-150-5p as a novel target and predictor for CCA prevention and treatment.

Kamrani Moghaddam L, Ramezani Paschepari S, Zaimy MA, et al.
The inhibition of epidermal growth factor receptor signaling by hexagonal selenium nanoparticles modified by SiRNA.
Cancer Gene Ther. 2016; 23(9):321-5 [PubMed] Related Publications
The aim of this study was to investigate the effect of hexagonal selenium nanoparticles modified by SiRNA (HSNM-SiRNA) to inhibit epidermal growth factor receptor (EGFR) signaling in Human non-small-cell lung cancer (NSCLC). After synthesis, HSNM-SiRNA and HSNs were separately exposed to NSCLC cell lines (A549, H1299, H520, and H1975), and incubated for 6 h at 37 °C. Next, the expression of NFKB, MYC, STAT, ELK1, and GAPDH was evaluated by western blot and real-time PCR. The percentage of apoptotic cells and cell cycle progression were measured when exposed to HSNM-SiRNA and HSNs. Both western blot and real-time PCR results showed that HSNM-SiRNA could down-regulate the expression of all EGFR signaling genes. The percentage of apoptotic cells was significantly increased in all cell lines when exposed to HSNM-SiRNA (P>0.05). HSNM-SiRNA in A549 and H1299 cells significantly increased the proportion of cells in G1/G0 phase and significantly decreased the proportion of cells in S phase.

Deng Y, Wang Z, Zhang F, et al.
A Blockade of IGF Signaling Sensitizes Human Ovarian Cancer Cells to the Anthelmintic Niclosamide-Induced Anti-Proliferative and Anticancer Activities.
Cell Physiol Biochem. 2016; 39(3):871-88 [PubMed] Related Publications
BACKGROUND/AIMS: Ovarian cancer is the most lethal gynecologic malignancy, and there is an unmet clinical need to develop new therapies. Although showing promising anticancer activity, Niclosamide may not be used as a monotherapy. We seek to investigate whether inhibiting IGF signaling potentiates Niclosamide's anticancer efficacy in human ovarian cancer cells.
METHODS: Cell proliferation and migration are assessed. Cell cycle progression and apoptosis are analyzed by flow cytometry. Inhibition of IGF signaling is accomplished by adenovirus-mediated expression of siRNAs targeting IGF-1R. Cancer-associated pathways are assessed using pathway-specific reporters. Subcutaneous xenograft model is used to determine anticancer activity.
RESULTS: We find that Niclosamide is highly effective on inhibiting cell proliferation, cell migration, and cell cycle progression, and inducing apoptosis in human ovarian cancer cells, possibly by targeting multiple signaling pathways involved in ELK1/SRF, AP-1, MYC/MAX and NFkB. Silencing IGF-1R exert a similar but weaker effect than that of Niclosamide's. However, silencing IGF-1R significantly sensitizes ovarian cancer cells to Niclosamide-induced anti-proliferative and anticancer activities both in vitro and in vivo.
CONCLUSION: Niclosamide as a repurposed anticancer agent may be more efficacious when combined with agents that target other signaling pathways such as IGF signaling in the treatment of human cancers including ovarian cancer.

Duan Q, Pang C, Chang N, et al.
Overexpression of PAD4 suppresses drug resistance of NSCLC cell lines to gefitinib through inhibiting Elk1-mediated epithelial-mesenchymal transition.
Oncol Rep. 2016; 36(1):551-8 [PubMed] Related Publications
It is reported that epithelial-to-mesenchymal transition (EMT) could induce resistance in tumor cells, and knockdown of peptidylarginine deiminase IV (PAD4) induces the activity of EMT. However, the role of PAD4 in gefitinib‑acquired resistance in non-small cell lung cancer (NSCLC) remains unclear. In this study, we aimed to investigate the role of PAD4 in the resistance of NSCLC to gefitinib. The cells resistant to gefitinib were established in accordance with the literature, and were derived from NSCLC cell lines HCC827 and H1650. Real-time quantitative PCR and western blot results showed that PAD4 was obviously downregulated in the cells resistant to gefitinib. Overexpression of PAD4 distinctly inhibited gefitinib resistance, whereas PAD4 downregulation had the opposite effect. Further data indicated that PAD4 upregulation could restrain EMT activity via controlling the expression of ETS-domain containing protein (Elk1). Conversely, inhibition of PAD4 showed the reverse function compared with PAD4 upregulation. Above all, our study showed that overexpression of PAD4 constrains the activity of EMT via suppressing Elk1 expression, and inhibits resistance of NSCLC to gefitinib.

Kawahara T, Aljarah AK, Shareef HK, et al.
Silodosin inhibits prostate cancer cell growth via ELK1 inactivation and enhances the cytotoxic activity of gemcitabine.
Prostate. 2016; 76(8):744-56 [PubMed] Related Publications
BACKGROUND: Biological significance of ELK1, a transcriptional factor whose phosphorylation is necessary for c-fos proto-oncogene activation, in prostate cancer remains far from fully understood. In this study, we aim to investigate the role of ELK1 in tumor growth as well as the efficacy of a selective α1A-adrenergic blocker, silodosin, in ELK1 activity in prostate cancer cells.
METHODS: We first immunohistochemically determined the levels of phospho-ELK1 (p-ELK1) expression in radical prostatectomy specimens. We then assessed the effects of ELK1 knockdown via short hairpin RNA and silodosin on cell proliferation, migration, and invasion in prostate cancer lines.
RESULTS: The levels of p-ELK1 expression were significantly higher in carcinoma than in benign (P < 0.001) or high-grade prostatic intraepithelial neoplasia (HGPIN) (P = 0.002) as well as in HGPIN than in benign (P < 0.001). Kaplan-Meier and log-rank tests revealed that moderate-strong positivity of p-ELK1 in carcinomas tended to correlate with biochemical recurrence after radical prostatectomy (P = 0.098). In PC3 and DU145 expressing ELK1 (mRNA/protein) but no androgen receptor (AR), ELK1 silencing resulted in considerable decreases in the expression of c-fos as well as in cell migration/invasion and matrix metalloproteinase-2 expression, but not in cell viability. Silodosin treatment reduced the expression/activity of ELK1 in these cells as well as the viability of AR-positive LNCaP and C4-2 cells and the migration of both AR-positive and AR-negative cells, but not the viability of AR-negative or ELK1-negative cells. Interestingly, silodosin significantly increased sensitivity to gemcitabine, but not to cisplatin or docetaxel, even in AR-negative cells.
CONCLUSIONS: ELK1 is likely to be activated in prostate cancer cells and promote tumor progression. Furthermore, silodosin that inactivates ELK1 in prostate cancer cells not only inhibits their growth but also enhances the cytotoxic activity of gemcitabine. Thus, ELK1 inhibition has the potential of being a therapeutic approach for prostate cancer.

Hollander D, Donyo M, Atias N, et al.
A network-based analysis of colon cancer splicing changes reveals a tumorigenesis-favoring regulatory pathway emanating from ELK1.
Genome Res. 2016; 26(4):541-53 [PubMed] Free Access to Full Article Related Publications
Splicing aberrations are prominent drivers of cancer, yet the regulatory pathways controlling them are mostly unknown. Here we develop a method that integrates physical interaction, gene expression, and alternative splicing data to construct the largest map of transcriptomic and proteomic interactions leading to cancerous splicing aberrations defined to date, and identify driver pathways therein. We apply our method to colon adenocarcinoma and non-small-cell lung carcinoma. By focusing on colon cancer, we reveal a novel tumor-favoring regulatory pathway involving the induction of the transcription factor MYC by the transcription factor ELK1, as well as the subsequent induction of the alternative splicing factor PTBP1 by both. We show that PTBP1 promotes specific RAC1,NUMB, and PKM splicing isoforms that are major triggers of colon tumorigenesis. By testing the pathway's activity in patient tumor samples, we find ELK1,MYC, and PTBP1 to be overexpressed in conjunction with oncogenic KRAS mutations, and show that these mutations increase ELK1 levels via the RAS-MAPK pathway. We thus illuminate, for the first time, a full regulatory pathway connecting prevalent cancerous mutations to functional tumor-inducing splicing aberrations. Our results demonstrate our method is applicable to different cancers to reveal regulatory pathways promoting splicing aberrations.

Liu CY, Hu MH, Hsu CJ, et al.
Lapatinib inhibits CIP2A/PP2A/p-Akt signaling and induces apoptosis in triple negative breast cancer cells.
Oncotarget. 2016; 7(8):9135-49 [PubMed] Free Access to Full Article Related Publications
We tested the efficacy of lapatinib, a dual tyrosine kinase inhibitor which interrupts the HER2 and epidermal growth factor receptor (EGFR) pathways, in a panel of triple-negative breast cancer (TNBC) cells, and examined the drug mechanism. Lapatinib showed an anti-proliferative effect in HCC 1937, MDA-MB-468, and MDA-MB-231 cell lines. Lapatinib induced significant apoptosis and inhibited CIP2A and p-Akt in a dose and time-dependent manner in the three TNBC cell lines. Overexpression of CIP2A reduced lapatinib-induced apoptosis in MDA-MB-468 cells. In addition, lapatinib increased PP2A activity (in relation to CIP2A inhibition). Moreover, lapatinib-induced apoptosis and p-Akt downregulation was attenuated by PP2A antagonist okadaic acid. Furthermore, lapatinib indirectly decreased CIP2A transcription by disturbing the binding of Elk1 to the CIP2A promoter. Importantly, lapatinib showed anti-tumor activity in mice bearing MDA-MB-468 xenograft tumors, and suppressed CIP2A as well as p-Akt in these xenografted tumors. In summary, inhibition of CIP2A determines the effects of lapatinib-induced apoptosis in TNBC cells. In addition to being a dual tyrosine kinase inhibitor of HER2 and EGFR, lapatinib also inhibits CIP2A/PP2A/p-Akt signaling in TNBC cells.

Kent OA, Mendell JT, Rottapel R
Transcriptional Regulation of miR-31 by Oncogenic KRAS Mediates Metastatic Phenotypes by Repressing RASA1.
Mol Cancer Res. 2016; 14(3):267-77 [PubMed] Free Access to Full Article Related Publications
UNLABELLED: Activating KRAS mutations are nearly ubiquitous in pancreatic cancer occurring in more than 95% of clinical cases. miRNAs are small noncoding RNAs that regulate gene expression by binding sequences within the 3'UTRs of target mRNAs. An integral role for miRNAs in cancer pathogenesis is well established; however, the role of miRNAs in KRAS-mediated tumorigenesis is poorly characterized. Here it is demonstrated that expression of miR-31 is coupled to the expression of oncogenic KRAS and activity of the MAPK pathway. miR-31 is highly expressed in patient-derived xenografts and a panel of pancreatic and colorectal cancer cells harboring activating KRAS mutations. The miR-31 host gene is a large noncoding RNA that correlates with miR-31 expression and enabled identification of the putative miR-31 promoter. Using luciferase reporters, a minimal RAS-responsive miR-31 promoter was found to drive robust luciferase activity dependent on expression of mutant KRAS and the transcription factor ELK1. Furthermore, ELK1 interacts directly with the endogenous miR-31 promoter in a MAPK-dependent manner. Expression of enforced miR-31 significantly enhanced invasion and migration of multiple pancreatic cancer cells resulting from the activation of RhoA through regulation of the miR-31 target gene RASA1. Importantly, acute knockdown of RASA1 phenocopied enforced miR-31 expression on the migratory behavior of pancreatic cancer cells through increased RhoA activation.
IMPLICATIONS: Oncogenic KRAS can activate Rho through the miR-31-mediated regulation of RASA1 indicating miR-31 acts as a KRAS effector to modulate invasion and migration in pancreatic cancer.

Cea M, Cagnetta A, Adamia S, et al.
Evidence for a role of the histone deacetylase SIRT6 in DNA damage response of multiple myeloma cells.
Blood. 2016; 127(9):1138-50 [PubMed] Free Access to Full Article Related Publications
Multiple myeloma (MM) is characterized by a highly unstable genome, with aneuploidy observed in nearly all patients. The mechanism causing this karyotypic instability is largely unknown, but recent observations have correlated these abnormalities with dysfunctional DNA damage response. Here, we show that the NAD(+)-dependent deacetylase SIRT6 is highly expressed in MM cells, as an adaptive response to genomic stability, and that high SIRT6 levels are associated with adverse prognosis. Mechanistically, SIRT6 interacts with the transcription factor ELK1 and with the ERK signaling-related gene. By binding to their promoters and deacetylating H3K9 at these sites, SIRT6 downregulates the expression of mitogen-activated protein kinase (MAPK) pathway genes, MAPK signaling, and proliferation. In addition, inactivation of ERK2/p90RSK signaling triggered by high SIRT6 levels increases DNA repair via Chk1 and confers resistance to DNA damage. Using genetic and biochemical studies in vitro and in human MM xenograft models, we show that SIRT6 depletion both enhances proliferation and confers sensitization to DNA-damaging agents. Our findings therefore provide insights into the functional interplay between SIRT6 and DNA repair mechanisms, with implications for both tumorigenesis and the treatment of MM.

Luo X, Yang L, Xiao L, et al.
Grifolin directly targets ERK1/2 to epigenetically suppress cancer cell metastasis.
Oncotarget. 2015; 6(40):42704-16 [PubMed] Free Access to Full Article Related Publications
Grifolin, a secondary metabolite isolated from the fresh fruiting bodies of the mushroom Albatrellus confluens, has been reported by us and others to display potent antitumor effects. However, the molecular target of grifolin has not been identified and the underlying mechanism of action is not fully understood. Here, we report that the ERK1/2 protein kinases are direct molecular targets of grifolin. Molecular modeling, affinity chromatography and fluorescence quenching analyses showed that grifolin directly binds to ERK1/2. And in vitro and ex vivo kinase assay data further demonstrated that grifolin inhibited the kinase activities of ERK1/2. We found that grifolin suppressed adhesion, migration and invasion of high-metastatic cancer cells. The inhibitory effect of grifolin against tumor metastasis was further confirmed in a metastatic mouse model. We found that grifolin decreased phosphorylation of Elk1 at Ser383, and the protein as well as the mRNA level of DNMT1 was also down-regulated. By luciferase reporter and ChIP assay analyses, we confirmed that grifolin inhibited the transcription activity of Elk1 as well as its binding to the dnmt1 promoter region. Moreover, we report that significant increases in the mRNA levels of Timp2 and pten were induced by grifolin. Thus, our data suggest that grifolin exerts its anti-tumor activity by epigenetic reactivation of metastasis inhibitory-related genes through ERK1/2-Elk1-DNMT1 signaling. Grifolin may represent a promising therapeutic lead compound for intervention of cancer metastasis, and it may also be useful as an ERK1/2 kinase inhibitor as well as an epigenetic agent to further our understanding of DNMT1 function.

Khan FH, Pandian V, Ramraj S, et al.
Reorganization of metastamiRs in the evolution of metastatic aggressive neuroblastoma cells.
BMC Genomics. 2015; 16:501 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: MetastamiRs have momentous clinical relevance and have been correlated with disease progression in many tumors. In this study, we identified neuroblastoma metastamiRs exploiting unique mouse models of favorable and high-risk metastatic human neuroblastoma. Further, we related their deregulation to the modulation of target proteins and established their association with clinical outcomes.
RESULTS: Whole genome miRNA microarray analysis identified 74 metastamiRs across the manifold of metastatic tumors. RT-qPCR on select miRNAs validated profile expression. Results from bio-informatics across the ingenuity pathway, miRCancer, and literature data-mining endorsed the expression of these miRNAs in multiple tumor systems and showed their role in metastasis, identifying them as metastamiRs. Immunoblotting and TMA-IHC analyses revealed alterations in the expression/phosphorylation of metastamiRs' targets, including ADAMTS-1, AKT1/2/3, ASK1, AURKβ, Birc1, Birc2, Bric5, β-CATENIN, CASP8, CD54, CDK4, CREB, CTGF, CXCR4, CYCLIN-D1, EGFR, ELK1, ESR1, CFOS, FOSB, FRA, GRB10, GSK3β, IL1α, JUND, kRAS, KRTAP1, MCP1, MEGF10, MMP2, MMP3, MMP9, MMP10, MTA2, MYB, cMYC, NF2, NOS3, P21, pP38, PTPN3, CLEAVED PARP, PKC, SDF-1β, SEMA3D, SELE, STAT3, TLR3, TNFα, TNFR1, and VEGF in aggressive cells ex vivo and in a manifold of metastatic tumors in vivo. miRNA mimic (hsa-miR-125b, hsa-miR-27b, hsa-miR-93, hsa-miR-20a) and inhibitor (hsa-miR-1224-3p, hsa-miR-1260) approach for select miRNAs revealed the direct influence of the altered metastamiRs in the regulation of identified protein targets. Clinical outcome association analysis with the validated metastamiRs' targets corresponded strongly with poor overall and relapse-free survival.
CONCLUSIONS: For the first time, these results identified a comprehensive list of neuroblastoma metastamiRs, related their deregulation to altered expression of protein targets, and established their association with poor clinical outcomes. The identified set of distinctive neuroblastoma metastamiRs could serve as potential candidates for diagnostic markers for the switch from favorable to high-risk metastatic disease.

Vivacqua A, De Marco P, Santolla MF, et al.
Estrogenic gper signaling regulates mir144 expression in cancer cells and cancer-associated fibroblasts (cafs).
Oncotarget. 2015; 6(18):16573-87 [PubMed] Free Access to Full Article Related Publications
MicroRNAs (miRNAs) are small non coding RNA molecules that play a crucial role in several pathophysiological conditions, including cancer. The stimulation of hormone-sensitive tumors by estrogens are mediated by estrogen receptor (ER)α and G protein estrogen receptor (GPER). Previous studies have reported that ERα regulates miRNA expression, while this ability of GPER remains to be elucidated. Here, we demonstrate that in SkBr3 breast cancer and HepG2 hepatocarcinoma cells, 17β-estradiol (E2) and the selective GPER ligand G-1 induce miR144 expression through GPER and the involvement of the PI3K/ERK1/2/Elk1 transduction pathway. Moreover, we show that E2 and G-1 down-regulate through miR144 the onco-suppressor Runx1 and increase cell cycle progression. The capability of E2 and G-1 in triggering the induction of miR144 and the down-regulation of Runx1 was also confirmed in cancer-associated fibroblasts (CAFs) that are main components of the tumor microenvironment driving cancer progression. Further confirming these results, Runx1 protein levels were found decreased in tumor xenografts upon G-1 treatment. On the basis of our findings miR144 and Runx1 may be included among the oncotargets of GPER action. Moreover, the present data provide new insights regarding the ability of estrogens to trigger the GPER/miR144/Runx1 transduction pathway toward the stimulation of cancer progression.

Yue CH, Huang CY, Tsai JH, et al.
MZF-1/Elk-1 Complex Binds to Protein Kinase Cα Promoter and Is Involved in Hepatocellular Carcinoma.
PLoS One. 2015; 10(5):e0127420 [PubMed] Free Access to Full Article Related Publications
In this study, the molecular mechanism of protein kinase C alpha (PKCα) gene regulation in hepatocellular carcinoma (HCC) involving Ets-like protein-1 (Elk-1) and myeloid zinc finger-1 (MZF-1) was investigated. The luciferase reporter assay results revealed that the presence of both MZF-1 and Elk-1 significantly contributed to the upregulation of PKCα gene transcription activity, and the transcriptional activity decreased when the transfection included a DNA-binding-deficient (∆DBD) gene vector of either MZF-1 or Elk-1 DNA-binding deficiency (MZF-1∆DBD or Elk-1∆DBD), thereby indicating that the enhanced expression of PKCα was caused by the binding of MZF-1 and/or Elk-1 with the PKCα promoter. We investigated MZF-1 and Elk-1 to determine whether they bind to each other. The results of immunoprecipitation (IP), Co-IP, chromatin IP (ChIP), and Re-ChIP analyses indicated that Elk-1 can directly bind to the N-terminal region of MZF-1 and MZF-1 can directly bind to the C-terminal region of Elk-1 to form a complex before attaching to the PKCα promoter. Furthermore, when MZF-1∆DBD or Elk-1∆DBD was added to the cells, PKCα expression decreased, and cell proliferation, migration, invasion, and tumorigenicity also decreased. These findings suggest that PKCα expression in HCC could be stimulated by the formation of MZF-1/Elk-1 complex, which directly binds to the PKCα promoter.

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Cite this page: Cotterill SJ. ELK1, Cancer Genetics Web: http://www.cancer-genetics.org/ELK1.htm Accessed:

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