ETS transcription factor ESE1/ELF3 orchestrates a positive feedback loop that constitutively activates NF-κB and drives prostate cancer progression

Epigenome-wide impact of MAT2A sustains the androgen-indifferent state and confers synthetic vulnerability in ERG fusion-positive prostate cancer

Castration-resistant prostate cancer (CRPC) is a frequently occurring disease with adverse clinical outcomes and limited therapeutic options. Here, we identify methionine adenosyltransferase 2a (MAT2A) as a critical driver of the androgen-indifferent state in ERG fusion-positive CRPC. MAT2A is upregulated in CRPC and cooperates with ERG in promoting cell plasticity, stemness and tumorigenesis. RNA, ATAC and ChIP-sequencing coupled with histone post-translational modification analysis by mass spectrometry show that MAT2A broadly impacts the transcriptional and epigenetic landscape. MAT2A enhances H3K4me2 at multiple genomic sites, promoting the expression of pro-tumorigenic non-canonical AR target genes. Genetic and pharmacological inhibition of MAT2A reverses the transcriptional and epigenetic remodeling in CRPC models and improves the response to AR and EZH2 inhibitors. These data reveal a role of MAT2A in epigenetic reprogramming and provide a proof of concept for testing MAT2A inhibitors in CRPC patients to improve clinical responses and prevent treatment resistance.

Switch of ELF3 and ATF4 transcriptional axis programs the amino acid insufficiency-linked epithelial-to-mesenchymal transition

Epithelial-to-mesenchymal transition (EMT) that endows cancer cells with increased invasive and migratory capacity enables cancer dissemination and metastasis. This process is tightly associated with metabolic reprogramming acquired for rewiring cell status and signaling pathways for survival in dietary insufficiency conditions. However, it remains largely unclear how transcription factor (TF)-mediated transcriptional programs are modulated during the EMT process. Here, we reveal that depletion of a key epithelial TF, ELF3 (E74-like factor-3), triggers a transforming growth factor β (TGF-β) signaling activation-like mesenchymal transcriptomic profile and metastatic features linked to the aminoacyl-tRNA biogenesis pathway. Moreover, the transcriptome alterations elicited by ELF3 depletion perfectly resemble an ATF4-dependent weak response to amino acid starvation. Intriguingly, we observe an exclusive enrichment of ELF3 and ATF4 in epithelial and TGF-β-induced or ELF3-depletion-elicited mesenchymal enhancers, respectively, with rare co-binding on altered enhancers. We also find that the upregulation of aminoacyl-tRNA synthetases and some mesenchymal genes upon amino acid deprivation is diminished in ATF4-depleted cells. In sum, the loss of ELF3 binding on epithelial enhancers and the gain of ATF4 binding on the enhancers of mesenchymal factors and amino acid deprivation responsive genes facilitate the loss of epithelial cell features and the gain of TGF-β-signaling-associated mesenchymal signatures, which further promote lung cancer cell metastasis.

The function of the ELF3 gene and its mechanism in cancers

E74-like factor 3 (ELF3) is an important member of the E-twenty-six (ETS) transcription factor family. ELF3 is expressed in various types of cells and regulates a variety of biological behaviors, such as cell proliferation, differentiation, apoptosis, migration, and invasion, by binding to DNA to regulate the expression of other genes. In recent years, studies have shown that ELF3 plays an important role in the occurrence and development of many tumors and inflammation and immune related diseases. ELF3 has different functions and expression patterns in different tumors; it can function as a tumor suppressor gene or an oncogene, highlighting its dual effects of tumor promotion and inhibition. ELF3 also affects the levels of tumor immunity-related cytokines and is involved in the regulation and expression of multiple signaling pathways. In tumor therapy, ELF3 is a complex and multifunctional gene and has become a key focus of targeted treatment research. An in-depth study of the biological function of ELF3 can help to elucidate its role in biological processes and provide ideas and a basis for the development and clinical application of ELF3-related therapeutic methods. This review introduces the structure and physiological and cellular functions of the ELF3 gene, summarizes the mechanisms of action of ELF3 in different types of malignant tumors and its role in immune regulation, inflammation, etc., and discusses treatment methods for ELF3-related diseases, providing significant reference value for scholars studying the ELF3 gene and related diseases.

ELF3 plays an important role in defining TRAIL sensitivity in breast cancer by modulating the expression of decoy receptor 2 (DCR2)

BACKGROUND

TRAIL protein on binding to its cognate death receptors (DR) can induce apoptosis specifically in breast tumor cells sparing normal cells. However, TRAIL also binds to decoy receptors (DCR) thereby inhibiting the apoptotic pathways thus causing TRAIL resistance. Also, one of the barriers due to which TRAIL-based therapy could not become FDA-approved might be because of resistance to therapy. Therefore, in the current study we wanted to explore the role of transcription factors in TRAIL resistance with respect to breast cancer.

METHODS

Microarray data from TRAIL-sensitive (TS) and TRAIL-resistant (TR) MDA-MB-231 cells were reanalyzed followed by validation of the candidate genes using quantitative PCR (qPCR), immunoblotting and immunofluorescence technique. Overexpression of the candidate gene was performed in MDA-MB-231 and MCF7 cells followed by cell viability assay and immunoblotting for cleaved caspase-3. Additionally, immunoblotting for DCR2 was carried out. TCGA breast cancer patient survival was used for Kaplan-Meier (KM) plot.

RESULTS

Validation of the candidate gene i.e. ELF3 using qPCR and immunoblotting revealed it to be downregulated in TR cells compared to TS cells. ELF3 overexpression in MDA-MB-231 and MCF7 cells caused reversal of TRAIL resistance as observed using cell viability assay and cleaved caspase-3 immunoblotting. ELF3 overexpression also resulted in DCR2 downregulation in the MDA-MB-231 and MCF7 cells. Furthermore, KM analysis found high ELF3 and low DCR2 expression to show better patient survival in the presence of TRAIL.

CONCLUSION

Our study shows ELF3 to be an important factor that can influence TRAIL-mediated apoptosis in breast cancer. Also, ELF3 and DCR2 expression status should be taken into consideration while designing strategies for successful TRAIL-based therapy.

KLF5 Promotes Tumor Progression and Parp Inhibitor Resistance in Ovarian Cancer

One major characteristic of tumor cells is the aberrant activation of epigenetic regulatory elements, which remodel the tumor transcriptome and ultimately promote cancer progression and drug resistance. However, the oncogenic functions and mechanisms of ovarian cancer (OC) remain elusive. Here, super-enhancer (SE) regulatory elements that are aberrantly activated in OC are identified and it is found that SEs drive the relative specific expression of the transcription factor KLF5 in OC patients and poly(ADP-ribose) polymerase inhibitor (PARPi)-resistant patients. KLF5 expression is associated with poor outcomes in OC patients and can drive tumor progression in vitro and in vivo. Mechanistically, KLF5 forms a transcriptional complex with EHF and ELF3 and binds to the promoter region of RAD51 to enhance its transcription, strengthening the homologous recombination repair (HRR) pathway. Notably, the combination of suberoylanilide hydroxamic acid (SAHA) and olaparib significantly inhibits tumor growth and metastasis of PARPi-resistant OC cells with high KLF5. In conclusion, it is discovered that SEs-driven KLF5 is a key regulatory factor in OC progression and PARPi resistance; and potential therapeutic strategies for OC patients with PARPi resistance and high KLF5 are identified.

Emerging role of miR-320a in lung cancer: a comprehensive review

A specialized biomarker(s) for lung cancer is imperative owing to its high mortality. Continuing our earlier work demonstrating the role of miR-320a as a tumor suppressor, here we discuss the most recent updates on miR-320a in lung cancer pathogenesis. We found that miR-320a modulates levels of diverse cancer-associated molecules and signaling pathways, and is also involved in modulating the immune microenvironment of lung cancer during its pathogenesis. We also discuss how miR-320a encapsulated in exosomes inhibits invasive phenotypes of lung cancer. Therefore, based on the multimodal role of miR-320a in lung cancer development and progression, we believe that miR-320a may be utilized as a potential diagnostic/prognostic marker and therapeutic target for lung cancer patients.

Deciphering transcriptional mechanisms of maize internodal elongation by regulatory network analysis

The lengths of the basal internodes is an important factor for lodging resistance of maize (Zea mays). In this study, foliar application of coronatine (COR) to 10 cultivars at the V8 growth stage had different suppression effects on the length of the eighth internode, with three being categorized as strong-inhibition cultivars (SC), five as moderate (MC), and two as weak (WC). RNA-sequencing of the eighth internode of the cultivars revealed a total of 7895 internode elongation-regulating genes, including 777 transcription factors (TFs). Genes related to the hormones cytokinin, gibberellin, auxin, and ethylene in the SC group were significantly down-regulated compared to WC, and more cell-cycle regulatory factors and cell wall-related genes showed significant changes, which severely inhibited internode elongation. In addition, we used EMSAs to explore the direct regulatory relationship between two important TFs, ZmABI7 and ZmMYB117, which regulate the cell cycle and cell wall modification by directly binding to the promoters of their target genes ZmCYC1, ZmCYC3, ZmCYC7, and ZmCPP1. The transcriptome reported in this study will provide a useful resource for studying maize internode development, with potential use for targeted genetic control of internode length to improve the lodging resistance of maize.

Single cell transcriptomic analysis of HPV16-infected epithelium identifies a keratinocyte subpopulation implicated in cancer

Persistent HPV16 infection is a major cause of the global cancer burden. The viral life cycle is dependent on the differentiation program of stratified squamous epithelium, but the landscape of keratinocyte subpopulations which support distinct phases of the viral life cycle has yet to be elucidated. Here, single cell RNA sequencing of HPV16 infected compared to uninfected organoids identifies twelve distinct keratinocyte populations, with a subset mapped to reconstruct their respective 3D geography in stratified squamous epithelium. Instead of conventional terminally differentiated cells, an HPV-reprogrammed keratinocyte subpopulation (HIDDEN cells) forms the surface compartment and requires overexpression of the ELF3/ESE-1 transcription factor. HIDDEN cells are detected throughout stages of human carcinogenesis including primary human cervical intraepithelial neoplasias and HPV positive head and neck cancers, and a possible role in promoting viral carcinogenesis is supported by TCGA analyses. Single cell transcriptome information on HPV-infected versus uninfected epithelium will enable broader studies of the role of individual keratinocyte subpopulations in tumor virus infection and cancer evolution.

The ELF3 transcription factor is associated with an epithelial phenotype and represses epithelial-mesenchymal transition

BACKGROUND

Epithelial-mesenchymal plasticity (EMP) involves bidirectional transitions between epithelial, mesenchymal and multiple intermediary hybrid epithelial/mesenchymal phenotypes. While the process of epithelial-mesenchymal transition (EMT) and its associated transcription factors are well-characterised, the transcription factors that promote mesenchymal-epithelial transition (MET) and stabilise hybrid E/M phenotypes are less well understood.

RESULTS

Here, we analyse multiple publicly-available transcriptomic datasets at bulk and single-cell level and pinpoint ELF3 as a factor that is strongly associated with an epithelial phenotype and is inhibited during EMT. Using mechanism-based mathematical modelling, we also show that ELF3 inhibits the progression of EMT. This behaviour was also observed in the presence of an EMT inducing factor WT1. Our model predicts that the MET induction capacity of ELF3 is stronger than that of KLF4, but weaker than that of GRHL2. Finally, we show that ELF3 levels correlates with worse patient survival in a subset of solid tumour types.

CONCLUSION

ELF3 is shown to be inhibited during EMT progression and is also found to inhibit the progression of complete EMT suggesting that ELF3 may be able to counteract EMT induction, including in the presence of EMT-inducing factors, such as WT1. The analysis of patient survival data indicates that the prognostic capacity of ELF3 is specific to cell-of-origin or lineage.

Emerging Developments in ETS-Positive Prostate Cancer Therapy

Prostate cancer is a global health concern, which has a low survival rate in its advanced stages. Even though second-generation androgen receptor-axis inhibitors serve as the mainstay treatment options, utmost of the metastatic cases progress into castration-resistant prostate cancer after their initial treatment response with poor prognostic outcomes. Hence, there is a dire need to develop effective inhibitors that aim the causal oncogenes tangled in the prostate cancer initiation and progression. Molecular-targeted therapy against E-26 transformation-specific (ETS) transcription factors, particularly ETS-related gene, has gained wide attention as a potential treatment strategy. ETS rearrangements with the male hormone responsive transmembrane protease serine 2 promoter defines a significant number of prostate cancer cases and is responsible for cancer initiation and progression. Notably, inhibition of ETS activity has shown to reduce tumorigenesis, thus highlighting its potential as a clinical therapeutic target. In this review, we recapitulate the various targeted drug approaches, including small molecules, peptidomimetics, nucleic acids, and many others, aimed to suppress ETS activity. Several inhibitors have demonstrated ERG antagonist activity in prostate cancer, but further investigations into their molecular mechanisms and impacts on nontumor ETS-containing tissues is warranted.

MYB and ELF3 differentially modulate labor-inducing gene expression in myometrial cells

Spontaneous uterine contractions are initiated when smooth muscle cells (SMCs) within the uterine muscle, or myometrium, transition from a functionally dormant to an actively contractile phenotype at the end of the pregnancy period. We know that this process is accompanied by gestational time point-specific differences in the SMC transcriptome, which can be modulated by the activator protein 1 (AP-1), nuclear factor kappa beta (NF-κβ), estrogen receptor (ER), and progesterone receptor (PR) transcription factors. Less is known, however, about the additional proteins that might assist these factors in conferring the transcriptional changes observed at labor onset. Here, we present functional evidence for the roles of two proteins previously understudied in the SMC context-MYB and ELF3-which can contribute to the regulation of labor-driving gene transcription. We show that the MYB and ELF3 genes exhibit elevated transcript expression levels in mouse and human myometrial tissues during spontaneous term labor. The expression of both genes was also significantly increased in mouse myometrium during preterm labor induced by the progesterone antagonist mifepristone (RU486), but not during infection-simulating preterm labor induced by intrauterine infusion of lipopolysaccharide (LPS). Furthermore, both MYB and ELF3 proteins affect labor-driving gene promoter activity, although in surprisingly opposing ways: Gja1 and Fos promoter activation increases in the presence of MYB and decreases in the presence of ELF3. Collectively, our study adds to the current understanding of the transcription factor network that defines the transcriptomes of SMCs during late gestation and implicates two new players in the control of labor timing.

Role of Interleukin-1 family in bone metastasis of prostate cancer

Prostate cancer (PCa) is one of the most fatal diseases in male patients with high bone metastatic potential. Bone metastasis severely shortens overall survival and brings skeletal-related events (SREs) which reduces the life quality of patients, and this situation is currently regarded as irreversible and incurable. The progression and metastasis of PCa are found to be closely associated with inflammatory cytokines and chemokines. As pivotal members of inflammatory cytokines, Interleukin-1 (IL-1) family plays a crucial role in this process. Elevated expression of IL-1 family was detected in PCa patients with bone metastasis, and accumulating evidences proved that IL-1 family could exert vital effects on the progression and bone metastasis of many cancers, while some members have dual effects. In this review, we discuss the role of IL-1 family in the bone metastasis of PCa. Furthermore, we demonstrate that many members of IL-1 family could act as pivotal biomarkers to predict the clinical stage and prognosis of PCa patients. More importantly, we have elucidated the role of IL-1 family in the bone metastasis of PCa, which could provide potential targets for the treatment of PCa bone metastasis and probable directions for future research.

Loss of ATRX promotes aggressive features of osteosarcoma with increased NF-κB signaling and integrin binding

Osteosarcoma (OS) is a lethal disease with few known targeted therapies. Here, we show that decreased ATRX expression is associated with more aggressive tumor cell phenotypes, including increased growth, migration, invasion, and metastasis. These phenotypic changes correspond with activation of NF-κB signaling, extracellular matrix remodeling, increased integrin αvβ3 expression, and ETS family transcription factor binding. Here, we characterize these changes in vitro, in vivo, and in a data set of human OS patients. This increased aggression substantially sensitizes ATRX-deficient OS cells to integrin signaling inhibition. Thus, ATRX plays an important tumor-suppression role in OS, and loss of function of this gene may underlie new therapeutic vulnerabilities. The relationship between ATRX expression and integrin binding, NF-κB activation, and ETS family transcription factor binding has not been described in previous studies and may impact the pathophysiology of other diseases with ATRX loss, including other cancers and the ATR-X α thalassemia intellectual disability syndrome.

Hypoxia‐induced ELF3 promotes tumor angiogenesis through IGF1/IGF1R

Epithelial ovarian cancer (EOC) is one of the most lethal gynecological cancers despite a relatively low incidence. Angiogenesis, one of the hallmarks of cancer, is essential for the pathogenesis of EOC, which is related to the induction of angiogenic factors. We found that ELF3 was highly expressed in EOCs under hypoxia and functioned as a transcription factor for IGF1. The ELF3‐mediated increase in the secretion of IGF1 and VEGF promoted endothelial cell proliferation, migration, and EOC angiogenesis. Although this situation was much exaggerated under hypoxia, ELF3 silencing under hypoxia significantly attenuated angiogenic activity in endothelial cells by reducing the expression and secretion of IGF1 and VEGF. ELF3 silencing attenuated angiogenesis and tumorigenesis in ex vivo and xenograft mouse models. Consequently, ELF3 plays an important role in the induction of angiogenesis and tumorigenesis in EOC as a transcription factor of IGF1. A detailed understanding of the biological mechanism of ELF3 may both improve current antiangiogenic therapies and have anticancer effects for EOC.

Elevated NF-κB/SHh/GLI1 Signature Denotes a Worse Prognosis and Represent a Novel Potential Therapeutic Target in Advanced Prostate Cancer

Prostate cancer (PCa) is the second most frequent cancer in men worldwide. NF-κB seems to play a key role in cell survival, proliferation and invasion, sustaining the heterogeneous multifocal nature of PCa. In recent years, the Hedgehog (Hh) signaling pathway has attracted attention as a therapeutic target due to its implication in tumorigenesis and metastasis in several types of cancer, including PCa. Although it is well-known that Sonic Hedgehog (SHh) is a transcriptional target of NF-κB(p65), and that GLI1 is the effector of this crosstalk, the precise role played by this axis in PCa is still not completely clear. Here, we set out to explore the correlation between NF-κB activation and SHh pathways in PCa, investigating if the interplay between NF-κB(p65) and SHh-GLI1 in advanced PCa could be a prospective therapeutic target. Our findings demonstrate that a NF-κB-SHh-GLI1 gene signature is enriched in PCa patients featuring a higher Gleason score. Moreover, elevated levels of this signature are associated with worse prognosis, thus suggesting that this axis could provide a route to treat aggressive PCa.

ETS transcription factor ELF3 (ESE-1) is a cell cycle regulator in benign and malignant prostate

This study aimed to elucidate the role of ELF3, an ETS family member in normal prostate growth and prostate cancer. Silencing ELF3 in both benign prostate (BPH-1) and prostate cancer (PC3) cell lines resulted in decreased colony forming ability, inhibition of cell migration and reduced cell viability due to cell cycle arrest, establishing ELF3 as a cell cycle regulator. Increased ELF3 expression in more advanced prostate tumours was shown by immunostaining of tissue microarrays and from analysis of gene expression and genetic alteration studies. This study indicates that ELF3 functions as part of normal prostate epithelial growth but also as a potential oncogene in advanced prostate cancers.

What Do We Have to Know about PD-L1 Expression in Prostate Cancer? A Systematic Literature Review. Part 3: PD-L1, Intracellular Signaling Pathways and Tumor Microenvironment

The tumor microenvironment (TME) includes immune (T, B, NK, dendritic), stromal, mesenchymal, endothelial, adipocytic cells, extracellular matrix, and cytokines/chemokines/soluble factors regulating various intracellular signaling pathways (ISP) in tumor cells. TME influences the survival/progression of prostate cancer (PC), enabling tumor cell immune-evasion also through the activation of the PD-1/PD-L1 axis. We have performed a systematic literature review according to the PRISMA guidelines, to investigate how the PD-1/PD-L1 pathway is influenced by TME and ISPs. Tumor immune-escape mechanisms include suppression/exhaustion of tumor infiltrating cytotoxic T lymphocytes, inhibition of tumor suppressive NK cells, increase in immune-suppressive immune cells (regulatory T, M2 macrophagic, myeloid-derived suppressor, dendritic, stromal, and adipocytic cells). IFN-γ (the most investigated factor), TGF-β, TNF-α, IL-6, IL-17, IL-15, IL-27, complement factor C5a, and other soluble molecules secreted by TME components (and sometimes increased in patients' serum), as well as and hypoxia, influenced the regulation of PD-L1. Experimental studies using human and mouse PC cell lines (derived from either androgen-sensitive or androgen-resistant tumors) revealed that the intracellular ERK/MEK, Akt-mTOR, NF-kB, WNT and JAK/STAT pathways were involved in PD-L1 upregulation in PC. Blocking the PD-1/PD-L1 signaling by using immunotherapy drugs can prevent tumor immune-escape, increasing the anti-tumor activity of immune cells.

Overexpression of E74-like transformation-specific transcription factor 3 promotes cellular proliferation and predicts poor prognosis in ovarian cancer

E74-like E26 transformation-specific (ETS) transcription factor 3 (ELF3), is a member of the ETS transcription factor family, and has been characterized as an epithelial cell-specific transcription factor. The role of ELF3 in tumor progression remains to be elucidated. Previous studies have indicated that loss of ELF3 mRNA and protein expression was associated with poor outcomes in ovarian cancer (OC). By contrast, the present study demonstrated that ELF3 was upregulated in OC, using data from The Cancer Genome Atlas, and elevated expression levels of ELF3 were associated with a poor prognosis. ELF3 promoted OC cell proliferation in vitro and in vivo. The present study revealed that ELF3 inhibited apoptosis and reduced the cisplatin sensitivity of OC cells. Furthermore, the mTOR pathway was found to be activated by ELF3. Collectively, the results of the present study indicated the role of ELF3 in the development and pathogenesis of OC.

ELF3 activated by a superenhancer and an autoregulatory feedback loop is required for high-level HLA-C expression on extravillous trophoblasts

HLA-C arose during evolution of pregnancy in the great apes 10 to 15 million years ago. It has a dual function on placental extravillous trophoblasts (EVTs) as it contributes to both tolerance and immunity at the maternal-fetal interface. The mode of its regulation is of considerable interest in connection with the biology of pregnancy and pregnancy abnormalities. First-trimester primary EVTs in which HLA-C is highly expressed, as well as JEG3, an EVT model cell line, were employed. Single-cell RNA-seq data and quantitative PCR identified high expression of the transcription factor ELF3 in those cells. Chromatin immunoprecipitation (ChIP)-PCR confirmed that both ELF3 and MED1 bound to the proximal HLA-C promoter region. However, binding of RFX5 to this region was absent or severely reduced, and the adjacent HLA-B locus remained closed. Expression of HLA-C was inhibited by ELF3 small interfering RNAs (siRNAs) and by wrenchnolol treatment. Wrenchnolol is a cell-permeable synthetic organic molecule that mimics ELF3 and is relatively specific for binding to ELF3's coactivator, MED23, as our data also showed in JEG3. Moreover, the ELF3 gene is regulated by a superenhancer that spans more than 5 Mb, identified by assay for transposase-accessible chromatin using sequencing (ATAC-seq), as well as by its sensitivity to (+)-JQ1 (inhibitor of BRD4). ELF3 bound to its own promoter, thus creating an autoregulatory feedback loop that establishes expression of ELF3 and HLA-C in trophoblasts. Wrenchnolol blocked binding of MED23 to ELF3, thus disrupting the positive-feedback loop that drives ELF3 expression, with down-regulation of HLA-C expression as a consequence.

EZH2-induced lysine K362 methylation enhances TMPRSS2-ERG oncogenic activity in prostate cancer

The TMPRSS2-ERG gene fusion is the most frequent alteration observed in human prostate cancer. However, its role in disease progression is still unclear. In this study, we uncover an important mechanism promoting ERG oncogenic activity. We show that ERG is methylated by Enhancer of zest homolog 2 (EZH2) at a specific lysine residue (K362) located within the internal auto-inhibitory domain. Mechanistically, K362 methylation modifies intra-domain interactions, favors DNA binding and enhances ERG transcriptional activity. In a genetically engineered mouse model of ERG fusion-positive prostate cancer (Pb-Cre4 Pten^flox/floxRosa26-ERG, ERG/PTEN), ERG K362 methylation is associated with PTEN loss and progression to invasive adenocarcinomas. In both ERG positive VCaP cells and ERG/PTEN mice, PTEN loss results in AKT activation and EZH2 phosphorylation at serine 21 that favors ERG methylation. We find that ERG and EZH2 interact and co-occupy several sites in the genome forming trans-activating complexes. Consistently, ERG/EZH2 co-regulated target genes are deregulated preferentially in tumors with concomitant ERG gain and PTEN loss and in castration-resistant prostate cancers. Collectively, these findings identify ERG methylation as a post-translational modification sustaining disease progression in ERG-positive prostate cancers.

Although the TMPRSS2-ERG gene fusion is the most common alteration in human prostate cancer, its involvement in disease progression remains unclear. Here, the authors demonstrate that ERG is methylated by Enhancer of zest homolog 2 leading to enhanced transcriptional and oncogenic activity.

Transcriptomic analysis of castration, chemo-resistant and metastatic prostate cancer elucidates complex genetic crosstalk leading to disease progression

Prostate adenocarcinoma, with its rising numbers and high fatality rate, is a daunting healthcare challenge to clinicians and researchers alike. The mainstay of our meta-analysis was to decipher differentially expressed genes (DEGs), their corresponding transcription factors (TFs), miRNAs (microRNA) and interacting pathways underlying the progression of prostate cancer (PCa). We have chosen multiple datasets from primary, castration-resistant, chemo-resistant and metastatic prostate cancer stages for investigation. From our tissue-specific and disease-specific co-expression networks, fifteen hub genes such as ACTB, ACTN1, CDH1, CDKN1A, DDX21, ELF3, FLNA, FLNC, IKZF1, ILK, KRT13, KRT18, KRT19, SVIL and TRIM29 were identified and validated by molecular complex detection analysis as well as survival analysis. In our attempt to highlight hub gene-associated mutations and drug interactions, FLNC was found to be most commonly mutated and CDKN1A gene was found to have highest druggability. Moreover, from DAVID and gene set enrichment analysis, the focal adhesion and oestrogen signalling pathways were found enriched which indicates the involvement of hub genes in tumour invasiveness and metastasis. Finally by Enrichr tool and miRNet, we identified transcriptional factors SNAI2, TP63, CEBPB and KLF11 and microRNAs, namely hsa-mir-1-3p, hsa-mir-145-5p, hsa-mir-124-3p and hsa-mir-218-5p significantly controlling the hub gene expressions. In a nutshell, our report will help to gain a deeper insight into complex molecular intricacies and thereby unveil the probable biomarkers and therapeutic targets involved with PCa progression.

ELF3 Overexpression as Prognostic Biomarker for Recurrence of Stage II Colorectal Cancer

BACKGROUND/AIM

Adjuvant chemotherapy for high-risk Stage II colorectal cancer (CRC) is weakly recommended; however, no consensus exists on "high-risk" definition. Prognostic biomarker identification is important for selecting patients with poor prognosis who may benefit from adjuvant chemotherapy.

MATERIALS AND METHODS

Using Microarray data analyses, ELF3 was identified as a candidate gene highly expressed in Stage II CRC with distant recurrences. ELF3 mRNA expression in 168 Stage II CRC patients was subjected to quantitative RT-PCR analysis and ELF3 protein expression in 185 patients was quantified by immunohistochemical analysis. The relationship between mRNA and protein expression levels and patient characteristics were also investigated.

RESULTS

The overall recurrence rate and relapse-free survival were significantly poorer in the ELF3 high-expression than the low-expression group at the mRNA and protein levels. High ELF3 mRNA and protein expression levels were independent poor prognostic factors.

CONCLUSION

High ELF3 expression was associated with recurrence of Stage II.

FZD5 prevents epithelial-mesenchymal transition in gastric cancer

Background

Frizzled (FZD) proteins function as receptors for WNT ligands. Members in FZD family including FZD2, FZD4, FZD7, FZD8 and FZD10 have been demonstrated to mediate cancer cell epithelial-mesenchymal transition (EMT).

Methods

CCLE and TCGA databases were interrogated to reveal the association of FZD5 with EMT. EMT was analyzed by investigating the alterations in CDH1 (E-cadherin), VIM (Vimentin) and ZEB1 expression, cell migration and cell morphology. Transcriptional modulation was determined by ChIP in combination with Real-time PCR. Survival was analyzed by Kaplan–Meier method.

Results

In contrast to other FZDs, FZD5 was identified to prevent EMT in gastric cancer. FZD5 maintains epithelial-like phenotype and is negatively modulated by transcription factors SNAI2 and TEAD1. Epithelial-specific factor ELF3 is a downstream effecter, and protein kinase C (PKC) links FZD5 to ELF3. ELF3 represses ZEB1 expression, further guarding against EMT. Moreover, FZD5 signaling requires its co-receptor LRP5 and WNT7B is a putative ligand for FZD5. FZD5 and ELF3 are associated with longer survival, whereas SNAI2 and TEAD1 are associated with shorter survival.

Conclusions

Taken together, FZD5-ELF3 signaling blocks EMT, and plays a potential tumor-suppressing role in gastric cancer.

Deoxycholic Acid Upregulates Serum Golgi Protein 73 through Activating NF-κB Pathway and Destroying Golgi Structure in Liver Disease

Golgi protein 73 (GP73) is upregulated in a variety of liver diseases, yet the detailed mechanism is poorly characterized. We analyzed GP73 in a retrospective cohort including 4211 patients with chronic liver disease (CLD) or hepatocellular carcinoma (HCC). The effect of deoxycholic acid (DCA) and nuclear factor-kappa B (NF-κB) on expression and release of GP73 in Huh-7 and SMMC7721 cells were studied. A mouse study was used to confirm our findings in vivo. A positive correlation was found between serum GP73 and total bile acid (TBA) in cirrhotic patients (r = 0.540, p < 0.001), higher than that in non-cirrhotic CLD (r = 0.318, p < 0.001) and HCC (r = 0.353, p < 0.001) patients. In Huh-7 and SMMC7721 cells, DCA upregulated the expression and release of GP73 in a dose- and time-dependent manner. After overexpressing NF-κB p65, the promoter activity, GP73 messenger RNA (mRNA) level, and supernatant GP73 level were increased. The promotion effect of DCA on GP73 release was attenuated after inhibiting the NF-κB pathway. Mutating the binding sites of NF-κB in the sequence of the GP73 promoter led to a declined promoting effect of DCA on GP73. The upregulation role of DCA in GP73 expression through the NF-κB pathway was confirmed in vivo. In addition, exposure to DCA caused disassembly of Golgi apparatus. In summary, DCA upregulates the expression and release of GP73 via activating the NF-κB pathway and destroying the Golgi structure.

Single-cell RNA sequencing reveals heterogeneous tumor and immune cell populations in early-stage lung adenocarcinomas harboring EGFR mutations

Lung adenocarcinoma (LUAD) harboring EGFR mutations prevails in Asian population. However, the inter-patient and intra-tumor heterogeneity has not been addressed at single-cell resolution. Here we performed single-cell RNA sequencing (scRNA-seq) of total 125,674 cells from seven stage-I/II LUAD samples harboring EGFR mutations and five tumor-adjacent lung tissues. We identified diverse cell types within the tumor microenvironment (TME) in which myeloid cells and T cells were the most abundant stromal cell types in tumors and adjacent lung tissues. Within tumors, accompanied by an increase in CD1C+ dendritic cells, the tumor-associated macrophages (TAMs) showed pro-tumoral functions without signature gene expression of defined M1 or M2 polarization. Tumor-infiltrating T cells mainly displayed exhausted and regulatory T-cell features. The adenocarcinoma cells can be categorized into different subtypes based on their gene expression signatures in distinct pathways such as hypoxia, glycolysis, cell metabolism, translation initiation, cell cycle, and antigen presentation. By performing pseudotime trajectory, we found that ELF3 was among the most upregulated genes in more advanced tumor cells. In response to secretion of inflammatory cytokines (e.g., IL1B) from immune infiltrates, ELF3 in tumor cells was upregulated to trigger the activation of PI3K/Akt/NF-κB pathway and elevated expression of proliferation and anti-apoptosis genes such as BCL2L1 and CCND1. Taken together, our study revealed substantial heterogeneity within early-stage LUAD harboring EGFR mutations, implicating complex interactions among tumor cells, stromal cells and immune infiltrates in the TME.

E74-Like Factor 3 Is a Key Regulator of Epithelial Integrity and Immune Response Genes in Biliary Tract Cancer

The transcription factor E74-like factor 3 (ELF3) is inactivated in a range of cancers, including biliary tract cancer (BTC). Here, we investigated the tumor-suppressive role of ELF3 in bile duct cells by identifying several previously unknown direct target genes of ELF3 that appear to be implicated in biliary duct carcinogenesis. ELF3 directly repressed ZEB2, a key regulator of epithelial-mesenchymal transition, and upregulated the expression of CGN, an integral element in lumen formation. Loss of ELF3 led to decreased cell-cell junctions and enhanced cell motility. ALOX5 and CXCL16 were also identified as additional direct targets of ELF3; their corresponding proteins 5-lipoxygenase and CXCL16 play a role in the immune response. Conditioned medium from cells overexpressing ELF3 significantly enhanced the migration of natural killer cells and CD8⁺ T cells toward the conditioned medium. Gene expression profiling for BTC expressing high levels of ELF3 revealed significant enrichment of the ELF3-related genes. In a BTC xenograft model, activation of ELF3 increased expression of ELF3-related genes, enhanced the tubular structure of the tumors, and led to a loss of vimentin. Overall, our results indicate that ELF3 is a key regulator of both epithelial integrity and immune responses in BTC. SIGNIFICANCE: Thease finding shows that ELF3 regulates epithelial integrity and host immune responses and functions as a tumor suppressor in biliary tract cancer. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/2/489/F1.large.jpg.

LGR4 maintains HGSOC cell epithelial phenotype and stem-like traits

OBJECTIVE

High-grade serous ovarian cancer (HGSOC) is lethal mainly due to extensive metastasis. Cancer cell stem-like properties are responsible for HGSOC metastasis. LGR4, a G-protein-coupled receptor, is involved in the maintenance of stem cell self-renewal and activity in some human organs.

METHODS

TCGA and CCLE databases were interrogated for gene mRNA in ovarian cancer tissues and cell lines. Gain and loss of functions of LGR4, ELF3, FZD5 and WNT7B were performed to identify their roles in ovarian cancer cell epithelial phenotype and stem-like properties. In vivo experiments were performed to observe the effect of LGR4 on ovarian cancer cell growth and peritoneal seeding. The binding of ELF3 to LGR4 gene promoter was investigated by dual-luciferase reporter assays and ChIP.

RESULTS

LGR4 was shown to be overexpressed in HGSOCs and maintain the epithelial phenotype of HGSOC cells. LGR4 knockdown suppressed POU5F1, SOX2, PROM1 (CD133) and ALDH1A2 expression. Furthermore, LGR4 knockdown reduced CD133⁺ and ALDH⁺ subpopulations and impaired tumorisphere formation. To the contrary, LGR4 overexpression enhanced POU5F1 and SOX2 expression and tumorisphere formation capacity. LGR4 knockdown inhibited HGSOC cell growth and peritoneal seeding in xenograft models. Mechanistically, LGR4 and ELF3, an epithelium-specific transcription factor, formed a reciprocal regulatory loop, which was positively modulated by WNT7B/FZD5 ligand-receptor pair. Consistently, knockdown of ELF3, WNT7B, and FZD5, respectively, disrupted HGSOC cell epithelial phenotype and stem-like properties.

CONCLUSION

Together, these data demonstrate that WNT7B/FZD5-LGR4/ELF3 axis maintains HGSOC cell epithelial phenotype and stem-like traits; targeting this axis may prevent HGSOC metastasis.

Dynamic chromatin accessibility landscape changes following interleukin-1 stimulation

Dynamic modifications of chromatin allow rapid access of the gene regulatory machinery to condensed genomic regions facilitating subsequent gene expression. Inflammatory cytokine stimulation of cells can cause rapid gene expression changes through direct signalling pathway-mediated transcription factor activation and regulatory element binding.

Here we used the Assay for Transposase Accessible Chromatin with high-throughput sequencing (ATAC-seq) to assess regions of the genome that are differentially accessible following treatment of cells with interleukin-1 (IL-1). We identified 126,483 open chromatin regions, with 241 regions significantly differentially accessible following stimulation, with 64 and 177 more or less accessible, respectively. These differentially accessible regions predominantly correspond to regions of the genome marked as enhancers. Motif searching identified an overrepresentation of a number of transcription factors, most notably RelA, in the regions becoming more accessible, with analysis of ChIP-seq data confirmed RelA binding to these regions. A significant correlation in differential chromatin accessibility and gene expression was also observed.

Functionality in regulating gene expression was confirmed using CRISPR/Cas9 genome-editing to delete regions that became more accessible following stimulation in the genes MMP13, IKBKE and C1QTNF1. These same regions were also accessible for activation using a dCas9-transcriptional activator and showed enhancer activity in a cellular model.

Together, these data describe and functionally validate a number of dynamically accessible chromatin regions involved in inflammatory signalling.

Interleukin-1β and Cancer

Within a tumor, IL-1β is produced and secreted by various cell types, such as immune cells, fibroblasts, or cancer cells. The IL1B gene is induced after "priming" of the cells and a second signal is required to allow IL-1β maturation by inflammasome-activated caspase-1. IL-1β is then released and leads to transcription of target genes through its ligation with IL-1R1 on target cells. IL-1β expression and maturation are guided by gene polymorphisms and by the cellular context. In cancer, IL-1β has pleiotropic effects on immune cells, angiogenesis, cancer cell proliferation, migration, and metastasis. Moreover, anti-cancer treatments are able to promote IL-1β production by cancer or immune cells, with opposite effects on cancer progression. This raises the question of whether or not to use IL-1β inhibitors in cancer treatment.

miR-320/ELF3 axis inhibits the progression of breast cancer via the PI3K/AKT pathway

There is increasing evidence demonstrating that disorders affecting microRNAs (miRs) influence tumorigenesis and progression, which results in a poor prognosis in patients with breast cancer (BC). In the present study, the precise molecular mechanism underlying the role of miR-320 in the progression of BC was investigated. Reverse transcription-quantitative PCR was conducted to determine mRNA expression, and western blot analysis was used to test protein levels. An MTT assay was conducted to detect cell viability and Transwell assays were used to analyze cell migration and invasion abilities. Furthermore, E74-like factor 3 (ELF3) protein density was tested via immunohistochemistry. Tumor volume was detected by xenograft tumor formation assay. The current results indicated that miR-320 expression was downregulated in BC tissues and cells, and was associated with a poor prognosis of patients with BC. Overexpression of miR-320 inhibited cell proliferation, migration and invasion via inhibition of the epithelial-mesenchymal transition and the PI3K/AKT signaling pathway in BC cells. Furthermore, it was revealed that the tumor size and weight were smaller in nude mice that had been transfected to overexpress miR-320. The luciferase reporter assay demonstrated the direct binding of miR-320 to the 3′ untranslated region of ELF3 mRNA, which may further downregulate ELF3. Overall, the present results provided evidence that miR-320 may be a tumor suppressor in BC, and that the miR-320/ELF3 axis regulated tumor progression via the PI3K/AKT signaling pathway, which may represent a novel treatment strategy for BC.

The Transcription Factor Elf3 Is Essential for a Successful Mesenchymal to Epithelial Transition

The epithelial to mesenchymal transition (EMT) and the mesenchymal to epithelial transition (MET) are two critical biological processes that are involved in both physiological events such as embryogenesis and development and also pathological events such as tumorigenesis. They present with dramatic changes in cellular morphology and gene expression exhibiting acute changes in E-cadherin expression. Despite the comprehensive understanding of EMT, the regulation of MET is far from being understood. To find novel regulators of MET, we hypothesized that such factors would correlate with Cdh1 expression. Bioinformatics examination of several expression profiles suggested Elf3 as a strong candidate. Depletion of Elf3 at the onset of MET severely impaired the progression to the epithelial state. This MET defect was explained, in part, by the absence of E-cadherin at the plasma membrane. Moreover, during MET, ELF3 interacts with the Grhl3 promoter and activates its expression. Our findings present novel insights into the regulation of MET and reveal ELF3 as an indispensable guardian of the epithelial state. A better understanding of MET will, eventually, lead to better management of metastatic cancers.

Transcriptional Reprogramming and Novel Therapeutic Approaches for Targeting Prostate Cancer Stem Cells

Prostate cancer is the most common malignancy in men and the second cause of cancer-related deaths in western countries. Despite the progress in the treatment of localized prostate cancer, there is still lack of effective therapies for the advanced forms of the disease. Most patients with advanced prostate cancer become resistant to androgen deprivation therapy (ADT), which remains the main therapeutic option in this setting, and progress to lethal metastatic castration-resistant prostate cancer (mCRPC). Current therapies for prostate cancer preferentially target proliferating, partially differentiated, and AR-dependent cancer cells that constitute the bulk of the tumor mass. However, the subpopulation of tumor-initiating or tumor-propagating stem-like cancer cells is virtually resistant to the standard treatments causing tumor relapse at the primary or metastatic sites. Understanding the pathways controlling the establishment, expansion and maintenance of the cancer stem cell (CSC) subpopulation is an important step toward the development of more effective treatment for prostate cancer, which might enable ablation or exhaustion of CSCs and prevent treatment resistance and disease recurrence. In this review, we focus on the impact of transcriptional regulators on phenotypic reprogramming of prostate CSCs and provide examples supporting the possibility of inhibiting maintenance and expansion of the CSC pool in human prostate cancer along with the currently available methodological approaches. Transcription factors are key elements for instructing specific transcriptional programs and inducing CSC-associated phenotypic changes implicated in disease progression and treatment resistance. Recent studies have shown that interfering with these processes causes exhaustion of CSCs with loss of self-renewal and tumorigenic capability in prostate cancer models. Targeting key transcriptional regulators in prostate CSCs is a valid therapeutic strategy waiting to be tested in clinical trials.

ETS transcription factors as emerging drug targets in cancer

The ETS family of proteins consists of 28 transcription factors, many of which have been implicated in development and progression of a variety of cancers. While one family member, ERG, has been rigorously studied in the context of prostate cancer where it plays a critical role, other ETS factors keep emerging as potential hallmark oncodrivers. In recent years, numerous studies have reported initial discoveries of small molecule inhibitors of ETS proteins and opened novel avenues for ETS-directed cancer therapies. This review summarizes the state of the art data on therapeutic targeting of ETS family members and highlights the corresponding drug discovery strategies.

Downregulation of Pro-Inflammatory and Pro-Angiogenic Pathways in Prostate Cancer Cells by a Polyphenol-Rich Extract from Olive Mill Wastewater

Dietary phytochemicals are particularly attractive for chemoprevention and are able to modulate several signal transduction pathways linked with cancer. Olive oil, a major component of the Mediterranean diet, is an abundant source of phenolic compounds. Olive oil production is associated with the generation of a waste material, termed 'olive mill wastewater' (OMWW) that have been reported to contain water-soluble polyphenols. Prostate cancer (PCa) is considered as an ideal cancer type for chemopreventive approaches, due to its wide incidence but relatively long latency period and progression time. Here, we investigated activities associated with potential preventive properties of a polyphenol-rich olive mill wastewater extract, OMWW (A009), on three in vitro models of PCa. A009 was able to inhibit PCa cell proliferation, adhesion, migration, and invasion. Molecularly, we found that A009 targeted NF-κB and reduced pro-angiogenic growth factor, VEGF, CXCL8, and CXCL12 production. IL-6/STAT3 axis was also regulated by the extract. A009 shows promising properties, and purified hydroxytyrosol (HyT), the major polyphenol component of A009, was also active but not always as effective as A009. Finally, our results support the idea of repositioning a food waste-derived material for nutraceutical employment, with environmental and industrial cost management benefits.

ESE1 expression correlates with neuronal apoptosis in the hippocampus after cerebral ischemia/reperfusion injury

Epithelial-specific ETS-1 (ESE1), a member of the ETS transcription factor family, is widely expressed in multiple tissues and performs various functions in inflammation. During neuroinflammation, ESE1 promotes neuronal apoptosis; however, the expression and biological functions of ESE1 remain unclear after cerebral ischemia/reperfusion. We performed in vivo and in vitro experiments to explore the role of ESE1 in cerebral ischemic injury. A modified four vessel occlusion method was used in adult Sprague-Dawley rats. At 6, 12, 24, 48, and 72 hours after model induction, the hippocampus was collected for analysis. Western blot assays and immunohistochemistry showed that the expression of ESE1, phosphorylated p65 and active caspase-3 was significantly up-regulated after ischemia. Double immunofluorescence staining indicated that ESE1 and NeuN were mostly co-located in the hippocampus after ischemia. Furthermore, ESE1 was also co-expressed with active caspase-3. PC12 cells were stimulated with cobalt chloride (CoCl₂) to establish a chemical hypoxia model. After ESE1 knockdown by siRNA for 6 hours, cell viability was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assays. The levels of ESE1, phosphorylated p65 and active caspase-3 were also remarkably increased in PC12 cells after CoCl₂ stimulation. After ESE1 knockdown, PC12 cell viability was increased after hypoxia. siRNA knockdown of ESE1 decreased the level of p-p65 and active caspase-3 after CoCl₂ stimulation. These data reveal that ESE1 levels are elevated in the hippocampus after cerebral ischemia/reperfusion injury. This may play a role in neuronal apoptosis via activation of the nuclear factor-κB pathway.

Oncogenic ETS Factors in Prostate Cancer

Prostate cancer is unique among carcinomas in that a fusion gene created by a chromosomal rearrangement is a common driver of the disease. The TMPRSS2/ERG rearrangement drives aberrant expression of the ETS family transcription factor ERG in 50% of prostate tumors. Similar rearrangements promote aberrant expression of the ETS family transcription factors ETV1 and ETV4 in another 10% of cases. Together, these three ETS factors are thought to promote tumorigenesis in the majority of prostate cancers. A goal of precision medicine is to be able to apply targeted therapeutics that are specific to disease subtypes. ETS gene rearrangement positive tumors represent the largest molecular subtype of prostate cancer, but to date there is no treatment specific to this marker. In this chapter we will review the latest findings regarding the molecular mechanisms of ETS factor function in the prostate. These molecular details may provide a path towards new therapeutic targets for this subtype of prostate cancer. Further, we will describe efforts to target the oncogenic functions of ETS family transcription factors directly as well as indirectly.

ELF3, ELF5, EHF and SPDEF Transcription Factors in Tissue Homeostasis and Cancer

The epithelium-specific ETS (ESE) transcription factors (ELF3, ELF5, EHF and SPDEF) are defined by their highly conserved ETS DNA binding domain and predominant epithelial-specific expression profile. ESE transcription factors maintain normal cell homeostasis and differentiation of a number of epithelial tissues, and their genetic alteration and deregulated expression has been linked to the progression of several epithelial cancers. Herein we review the normal function of the ESE transcription factors, the mechanisms by which they are dysregulated in cancers, and the current evidence for their role in cancer progression. Finally, we discuss potential therapeutic strategies for targeting or reactivating these factors as a novel means of cancer treatment.

Inflammation and NF-κB Signaling in Prostate Cancer: Mechanisms and Clinical Implications

Prostate cancer is a highly prevalent form of cancer that is usually slow-developing and benign. Due to its high prevalence, it is, however, still the second most common cause of death by cancer in men in the West. The higher prevalence of prostate cancer in the West might be due to elevated inflammation from metabolic syndrome or associated comorbidities. NF-κB activation and many other signals associated with inflammation are known to contribute to prostate cancer malignancy. Inflammatory signals have also been associated with the development of castration resistance and resistance against other androgen depletion strategies, which is a major therapeutic challenge. Here, we review the role of inflammation and its link with androgen signaling in prostate cancer. We further describe the role of NF-κB in prostate cancer cell survival and proliferation, major NF-κB signaling pathways in prostate cancer, and the crosstalk between NF-κB and androgen receptor signaling. Several NF-κB-induced risk factors in prostate cancer and their potential for therapeutic targeting in the clinic are described. A better understanding of the inflammatory mechanisms that control the development of prostate cancer and resistance to androgen-deprivation therapy will eventually lead to novel treatment options for patients.

Identification of an IL-1-induced gene expression pattern in AR+ PCa cells that mimics the molecular phenotype of AR- PCa cells

BACKGROUND

In immunosurveillance, bone-derived immune cells infiltrate the tumor and secrete inflammatory cytokines to destroy cancer cells. However, cancer cells have evolved mechanisms to usurp inflammatory cytokines to promote tumor progression. In particular, the inflammatory cytokine, interleukin-1 (IL-1), is elevated in prostate cancer (PCa) patient tissue and serum, and promotes PCa bone metastasis. IL-1 also represses androgen receptor (AR) accumulation and activity in PCa cells, yet the cells remain viable and tumorigenic; suggesting that IL-1 may also contribute to AR-targeted therapy resistance. Furthermore, IL-1 and AR protein levels negatively correlate in PCa tumor cells. Taken together, we hypothesize that IL-1 reprograms AR positive (AR⁺ ) PCa cells into AR negative (AR^- ) PCa cells that co-opt IL-1 signaling to ensure AR-independent survival and tumor progression in the inflammatory tumor microenvironment.

METHODS

LNCaP and PC3 PCa cells were treated with IL-1β or HS-5 bone marrow stromal cell (BMSC) conditioned medium and analyzed by RNA sequencing and RT-QPCR. To verify genes identified by RNA sequencing, LNCaP, MDA-PCa-2b, PC3, and DU145 PCa cell lines were treated with the IL-1 family members, IL-1α or IL-1β, or exposed to HS-5 BMSC in the presence or absence of Interleukin-1 Receptor Antagonist (IL-1RA). Treated cells were analyzed by western blot and/or RT-QPCR.

RESULTS

Comparative analysis of sequencing data from the AR⁺ LNCaP PCa cell line versus the AR^- PC3 PCa cell line reveals an IL-1-conferred gene suite in LNCaP cells that is constitutive in PC3 cells. Bioinformatics analysis of the IL-1 regulated gene suite revealed that inflammatory and immune response pathways are primarily elicited; likely facilitating PCa cell survival and tumorigenicity in an inflammatory tumor microenvironment.

CONCLUSIONS

Our data supports that IL-1 reprograms AR⁺ PCa cells to mimic AR^- PCa gene expression patterns that favor AR-targeted treatment resistance and cell survival.

MiR-320a-3p/ELF3 axis regulates cell metastasis and invasion in non-small cell lung cancer via PI3K/Akt pathway

MicroRNAs (miRNAs) play important roles in tumorigenesis and tumor progression. In this study, we investigated the role of miR-320a-3p in non-small cell lung cancer (NSCLC). Expressions of miR-320a-3p were firstly determined in 80 NSCLC patients' cancer tissues and adjacent normal lung tissues by qRT-PCR. Then MTT assay, cell migration and invasion assays were performed in vitro. Potential binding sites on target gene of miR-320a-3p were predicted and luciferase reporter assay was used to identify the potential binding sites. Tumorigenesis assay were performed in nude mice by injecting A549 cells which stably express miR-320a-3p. Results indicated that high expression of miR-320a-3p suppresses cell proliferation, migration and invasion through the inactivation of PI3K/Akt signaling pathway in NSCLC cells. Smaller tumor size and lighter weight were also found in nude mice which had miR-320a-3p higher expressed. Furthermore, data from luciferase reporter assay proved the direct binding of miR-320a-3p on the 3'UTR region of ELF3 mRNA, this could further decrease ELF3 expression transcriptionally. We provided evidence that miR-320a-3p might work as a tumor suppressor in NSCLC both in vivo and in vitro.

Elf3 Contributes to Cartilage Degradation in vivo in a Surgical Model of Post-Traumatic Osteoarthritis

The E-74 like factor 3 (ELF3) is a transcription factor induced by inflammatory factors in various cell types, including chondrocytes. ELF3 levels are elevated in human cartilage from patients with osteoarthritis (OA), and ELF3 contributes to the IL-1β-induced expression of genes encoding Mmp13, Nos2, and Ptgs2/Cox2 in chondrocytes in vitro. Here, we investigated the contribution of ELF3 to cartilage degradation in vivo, using a mouse model of OA. To this end, we generated mouse strains with cartilage-specific Elf3 knockout (Col2Cre:Elf3^f/f) and Comp-driven Tet-off-inducible Elf3 overexpression (TRE-Elf3:Comp-tTA). To evaluate the contribution of ELF3 to OA, we induced OA in 12-week-old Col2Cre:Elf3^f/f and 6-month-old TRE-Elf3:Comp-tTA male mice using the destabilization of the medial meniscus (DMM) model. The chondrocyte-specific deletion of Elf3 led to decreased levels of IL-1β- and DMM-induced Mmp13 and Nos2 mRNA in vitro and in vivo, respectively. Histological grading showed attenuation of cartilage loss in Elf3 knockout mice compared to wild type (WT) littermates at 8 and 12 weeks following DMM surgery that correlated with reduced collagenase activity. Accordingly, Elf3 overexpression led to increased cartilage degradation post-surgery compared to WT counterparts. Our results provide evidence that ELF3 is a central contributing factor for cartilage degradation in post-traumatic OA in vivo.

ELF3 promotes epithelial-mesenchymal transition by protecting ZEB1 from miR-141-3p-mediated silencing in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers and currently the third leading cause of cancer-related deaths, worldwide. Epithelial-mesenchymal transition (EMT) plays a major role in HCC progression. In this study, we first found that the expression of E74-like ETS transcription factor 3 (ELF3), a member of the E-twenty-six family of transcription factors, was increased in HCC tissues, and that ELF3 overexpression was associated with poor prognoses for HCC patients. Gain-of-function and loss-of-function studies revealed that increased ELF3 expression promoted HCC cell proliferation, migration, and invasion, while these processes were inhibited when ELF3 was silenced. Additionally, ELF3 was found to promote EMT, which we demonstrated through decreased E-cadherin expression and increased N-cadherin and fibronectin expression. ELF3 knockdown reversed EMT via repressing ZEB1 expression through miR-141-3p upregulation. Chromatin immunoprecipitation assays revealed that ELF3 bound to the miR-141-3p promoter, suppressing miR-141-3p expression. Taken together, our data show that ELF3 repressed E-cadherin and promoted EMT in HCC cells by suppressing miR-141-3p, thereby activating ZEB1. Thus, ELF3 may be a potential prognostic biomarker and/or therapeutic target for HCC.

Overexpression of ELF3 facilitates cell growth and metastasis through PI3K/Akt and ERK signaling pathways in non-small cell lung cancer

ELF3 is one of the member of transcription factors from E-twenty-six family, its role varies in different types of cancer. However, the role and specific mechanisms of ELF3 in the development of non-small cell lung cancer (NSCLC) still remains largely unknown. In our study, ELF3 was observed to be upregulated in NSCLC tissues compared to the corresponding normal lung tissue at mRNA and protein levels, and its expression level was correlated with the overall survival of patients with NSCLC. Silencing of the ELF3 gene in NSCLC cells inhibited the proliferation and metastasis significantly in vitro and in vivo. Conversely, overexpression of ELF3 in NSCLC cells promoted cancer growth and metastasis in vitro. Mechanistically, ELF3 activated PI3K/AKT and ERK signaling pathways and its downstream effectors, thus regulating the cell cycle and epithelial-mesenchymal transition (EMT). Furthermore, the promotive effects of ELF3 on cellular proliferation and metastasis could be rescued by Ly294002 (inhibitor of PI3K) and U0126 (inhibitor of MEK1/2). The results show that ELF3 promotes cell growth and metastasis by regulating PI3K/Akt and ERK pathways in NSCLC and that it may be a promising new target for the treatment of NSCLC patients.

ESE-1/ELF3 mRNA expression associates with poor survival outcomes in HER2+ breast cancer patients and is critical for tumorigenesis in HER2+ breast cancer cells

ESE-1/Elf3 and HER2 appear to establish a positive feedback regulatory loop, but the precise role of ESE-1 in HER2⁺ breast tumorigenesis remains unknown. Analyzing public repositories, we found that luminal B and HER2 subtype patients with high ESE-1 mRNA levels displayed worse relapse free survival. We stably knocked down ESE-1 in HER2⁺ luminal B BT474 cells and HER2 subtype SKBR3 cells, which resulted in decreased cell proliferation, colony formation, and anchorage-independent growth in vitro. Stable ESE-1 knockdown inhibited HER2-dependent signaling in BT474 cells and inhibited mTOR activation in SKBR3 cells, but reduced Akt signaling in both cell types. Expression of a constitutively-active Myr-Akt partially rescued the anti-proliferative effect of ESE-1 knockdown in both cell lines. Furthermore, ESE-1 knockdown inhibited cyclin D1, resulting in a G1 delay in both cell lines. Finally, ESE-1 knockdown completely inhibited BT474 cell xenograft tumors in NOD/SCID female mice, which correlated with reduced in vitro tumorsphere formation. Taken together, these results reveal the ESE-1 controls transformation via distinct upstream signaling mechanisms in SKBR3 and BT474 cells, which ultimately impinge on Akt and cyclin D1 in both cell types to regulate cell proliferation. Particularly significant is that ESE-1 controls tumorigenesis and is associated with worse clinical outcomes in HER2 breast cancer.

The ETS family of oncogenic transcription factors in solid tumours

Findings over the past decade have identified aberrant activation of the ETS transcription factor family throughout all stages of tumorigenesis. Specifically in solid tumours, gene rearrangement and amplification, feed-forward growth factor signalling loops, formation of gain-of-function co-regulatory complexes and novel cis-acting mutations in ETS target gene promoters can result in increased ETS activity. In turn, pro-oncogenic ETS signalling enhances tumorigenesis through a broad mechanistic toolbox that includes lineage specification and self-renewal, DNA damage and genome instability, epigenetics and metabolism. This Review discusses these different mechanisms of ETS activation and subsequent oncogenic implications, as well as the clinical utility of ETS factors.

Ets1 and ESE1 reciprocally regulate expression of ZEB1/ZEB2, dependent on ERK1/2 activity, in breast cancer cells

The epithelial–mesenchymal transition (EMT) is a crucial morphological event that occurs during progression of epithelial tumors. We reported previously that levels of the δ‐crystallin/E2‐box factor 1 (δEF1) family proteins (Zinc finger E‐box binding homeobox 1 [ZEB1]/δEF1 and ZEB2/ Smad‐interacting protein 1), key regulators of the EMT, are positively correlated with EMT phenotypes and aggressiveness of breast cancer. Here, we show that Ets1 induces ZEB expression and activates the ZEB1 promoter, independently of its threonine 38 phosphorylation status. In the basal‐like subtype of breast cancer cells, siRNAs targeting Ets1 repressed expression of ZEBs and partially restored their epithelial phenotypes and sensitivity to antitumor drugs. Epithelium‐specific ETS transcription factor 1 (ESE1), a member of the Ets transcription factor family, was originally characterized as being expressed in an epithelial‐restricted pattern, placing it within the epithelium‐specific ETS subfamily. ESE1, highly expressed in the luminal subtype of breast cancer cells, was repressed by activation of the MEK–ERK pathway, resulting in induction of ZEBs through Ets1 upregulation. Conversely, Ets1, highly expressed in the basal‐like subtype, was repressed by inactivation of MEK–ERK pathway, resulting in reduction of ZEBs through ESE1 upregulation. These findings suggest that ESE1 and Ets1, whose expressions are reciprocally regulated by the MEK–ERK pathway, define the EMT phenotype through controlling expression of ZEBs in each subtype of breast cancer cells.

Gene regulatory network underlying the immortalization of epithelial cells

BACKGROUND

Tumorigenic transformation of human epithelial cells in vitro has been described experimentally as the potential result of spontaneous immortalization. This process is characterized by a series of cell-state transitions, in which normal epithelial cells acquire first a senescent state which is later surpassed to attain a mesenchymal stem-like phenotype with a potentially tumorigenic behavior. In this paper we aim to provide a system-level mechanistic explanation to the emergence of these cell types, and to the time-ordered transition patterns that are common to neoplasias of epithelial origin. To this end, we first integrate published functional and well-curated molecular data of the components and interactions that have been found to be involved in such cell states and transitions into a network of 41 molecular components. We then reduce this initial network by removing simple mediators (i.e., linear pathways), and formalize the resulting regulatory core into logical rules that govern the dynamics of each of the network components as a function of the states of its regulators.

RESULTS

Computational dynamic analysis shows that our proposed Gene Regulatory Network model recovers exactly three attractors, each of them defined by a specific gene expression profile that corresponds to the epithelial, senescent, and mesenchymal stem-like cellular phenotypes, respectively. We show that although a mesenchymal stem-like state can be attained even under unperturbed physiological conditions, the likelihood of converging to this state is increased when pro-inflammatory conditions are simulated, providing a systems-level mechanistic explanation for the carcinogenic role of chronic inflammatory conditions observed in the clinic. We also found that the regulatory core yields an epigenetic landscape that restricts temporal patterns of progression between the steady states, such that recovered patterns resemble the time-ordered transitions observed during the spontaneous immortalization of epithelial cells, both in vivo and in vitro.

CONCLUSION

Our study strongly suggests that the in vitro tumorigenic transformation of epithelial cells, which strongly correlates with the patterns observed during the pathological progression of epithelial carcinogenesis in vivo, emerges from underlying regulatory networks involved in epithelial trans-differentiation during development.

Stem cells and the role of ETS transcription factors in the differentiation hierarchy of normal and malignant prostate epithelium

Prostate cancer is the most common cancer of men in the UK and accounts for a quarter of all new cases. Although treatment of localised cancer can be successful, there is no cure for patients presenting with invasive prostate cancer and there are less treatment options. They are generally treated with androgen-ablation therapies but eventually the tumours become hormone resistant and patients develop castration-resistant prostate cancer (CRPC) for which there are no further successful or curative treatments. This highlights the need for new treatment strategies. In order to prevent prostate cancer recurrence and treatment resistance, all the cell populations in a heterogeneous prostate tumour must be targeted, including the rare cancer stem cell (CSC) population. The ETS transcription factor family members are now recognised as a common feature in multiple cancers including prostate cancer; with aberrant expression, loss of tumour suppressor function, inactivating mutations and the formation of fusion genes observed. Most notably, the TMPRSS2-ERG gene fusion is present in approximately 50% of prostate cancers and in prostate CSCs. However, the role of other ETS transcription factors in prostate cancer is less well understood. This review will describe the prostate epithelial cell hierarchy and discuss the evidence behind prostate CSCs and their inherent resistance to conventional cancer therapies. The known and proposed roles of the ETS family of transcription factors in prostate epithelial cell differentiation and regulation of the CSC phenotype will be discussed, as well as how they might be targeted for therapy.