E1AF promotes breast cancer cell cycle progression via upregulation of Cyclin D3 transcription

Identification and characterization of novel ETV4 splice variants in prostate cancer

ETV4, one of ETS proteins overexpressed in prostate cancer, promotes migration, invasion, and proliferation in prostate cells. This study identifies a series of previously unknown ETV4 alternatively spliced transcripts in human prostate cell lines. Their expression has been validated using several unbiased techniques, including Nanopore sequencing. Most of these transcripts originate from an in-frame exon skipping and, thus, are expected to be translated into ETV4 protein isoforms. Functional analysis of the most abundant among these isoforms shows that they still bear an activity, namely a reduced ability to promote proliferation and a residual ability to regulate the transcription of ETV4 target genes. Alternatively spliced genes are common in cancer cells: an analysis of the TCGA dataset confirms the abundance of these novel ETV4 transcripts in prostate tumors, in contrast to peritumoral tissues. Since none of their translated isoforms have acquired a higher oncogenic potential, such abundance is likely to reflect the tumor deranged splicing machinery. However, it is also possible that their interaction with the canonical variants may contribute to the biology and the clinics of prostate cancer. Further investigations are needed to elucidate the biological role of these ETV4 transcripts and of their putative isoforms.

Bioinformatics screening of ETV4 transcription factor oncogenes and identifying small-molecular anticancer drugs

This bioinformatics study aimed to identify ETV4 transcription factor oncogenes and outline anticancer drugs for these genes. First, we collected known 61 ETV4 cancer targets that were framed as two classes of queries to screen against the multiomics resources in GeneMANIA. This method accessed and added functionally similar 20 genes to each set. These data were interpreted by hub genes, network clustering, gene ontology, and pathway analyses, and the results confirmed that all resultant genes were cancer promoters. The ETS-binding motifs were identified from the promoter regions of these genes. Thus, 23 ETV4 targets were figured and those involved in oncogenesis were filtered as the following 16 putative nodes: MMP8, MMP14, KDR, BRIP1, CXCR1, GRB14, SHC2, SHC4, SH2B1, SH2B2, INPPL1, PTPN3, GNG12, SEMA4D, RHOA, and SPSB2. The transcriptional regulation of these oncogenes was coordinated by an extensive miRNA network that found to deregulate many cancer pathways. Using DgIb database, the high quality 6 oncogene-drug combinations (MMP8-CHEMBL1231240, MMP8-Aminomethylamide, CXCR1-Reparixin, SEMA4D-Pepinemab, RHOA-Clausine E, and SPSB2-CHEMBL175296) were proposed. These findings may advance our understanding of novel neoplastic gene nexus of ETV4 and design treatment strategies for its modulation.

Biological and prognostic value of ETV5 in high-grade serous ovarian cancer

Background

ETS transcription factors are known to act as either positive or negative regulators of the expression of genes involved in various biological processes. It was reported that ETS variant transcription factor 5 (ETV5), a key member of the ETS family, mainly plays a role as an potential oncogene in various malignant tumors. However, the role and mechanism of ETV5 in high-grade serous ovarian cancer (HGSOC) have not been elucidated.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used to detect ETV5 messenger ribonucleic acid (mRNA) expression in 87 HGSOC tissues and 35 normal fallopian tube tissues. Western blotting and qRT-PCR were used to detect the protein and mRNA expression of ETV5 in six ovarian cancer (OC) and human embryonic cell lines. Knockdown or overexpression of ETV5 in HGSOC cell lines, Cell Counting Kit-8, colony formation, and transwell assays were used to detect HGSOC cell proliferation, invasion, and migration capabilities. The chi-square test was used to analyze the clinicopathological characteristics of HGSOC patients. Survival analysis was performed using the Kaplan-Meier method, and the log-rank test was used to analyze the correlation between ETV5 expression and HGSOC patient prognosis. Univariate and multivariate analyses using the Cox regression model were conducted to determine the independent significance of relevant clinical covariates.

Results

Bioinformatic analysis demonstrated that ETV5 expression was significantly upregulated in OC (p < 0.05). qRT-PCR showed that ETV5 was significantly overexpressed in HGSOC tissues than in fallopian tube tissues (p < 0.05). qRT-PCR and western blotting assays demonstrated that ETV5 was relatively highly expressed in OC cell lines. ETV5 overexpression was positively associated with poor survival in HGSOC patients, therefore making it a high-risk factor for HGSOC progression. Furthermore, ETV5 promoted the proliferation, migration, and invasion capabilities of HGSOC cells.

Conclusion

ETV5 has a carcinogenic effect in HGSOC and can be used as a clinically effective biomarker to determine the prognosis of HGSOC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00899-6.

ETV4 promotes breast cancer cell stemness by activating glycolysis and CXCR4-mediated sonic Hedgehog signaling

Cancer stem cells (CSCs) are a major cause of tumor treatment resistance, relapse and metastasis. Cancer cells exhibit reprogrammed metabolism characterized by aerobic glycolysis, which is also critical for sustaining cancer stemness. However, regulation of cancer cell metabolism rewiring and stemness is not completely understood. Here, we report that ETV4 is a key transcription factor in regulating glycolytic gene expression. ETV4 loss significantly inhibits the expression of HK2, LDHA as well as other glycolytic enzymes, reduces glucose uptake and lactate release in breast cancer cells. In human breast cancer and hepatocellular carcinoma tissues, ETV4 expression is positively correlated with glycolytic signaling. Moreover, we confirm that breast CSCs (BCSCs) are glycolysis-dependent and show that ETV4 is required for BCSC maintenance. ETV4 is enriched in BCSCs, its knockdown and overexpression suppresses and promotes breast cancer cell stem-like traits, respectively. Mechanistically, on the one hand, we find that ETV4 may enhance glycolysis activity to facilitate breast cancer stemness; on the other, ETV4 activates Sonic Hedgehog signaling by transcriptionally promoting CXCR4 expression. A xenograft assay validates the tumor growth-impeding effect and inhibition of CXCR4/SHH/GLI1 signaling cascade after ETV4 depletion. Together, our study highlights the potential roles of ETV4 in promoting cancer cell glycolytic shift and BCSC maintenance and reveals the molecular basis.

Molecular profiles of response to neoadjuvant chemoradiotherapy in oesophageal cancers to develop personalized treatment strategies

Identification of molecular predictive markers of response to neoadjuvant chemoradiation could aid clinical decision‐making in patients with localized oesophageal cancer. Therefore, we subjected pretreatment biopsies of 75 adenocarcinoma (OAC) and 16 squamous cell carcinoma (OSCC) patients to targeted next‐generation DNA sequencing, as well as biopsies of 85 OAC and 20 OSCC patients to promoter methylation analysis of eight GI‐specific genes, and subsequently searched for associations with histopathological response and disease‐free (DFS) and overall survival (OS). Thereby, we found that in OAC, CSMD1 deletion (8%) and ETV4 amplification (5%) were associated with a favourable histopathological response, whereas SMURF1 amplification (5%) and SMARCA4 mutation (7%) were associated with an unfavourable histopathological response. KRAS (15%) and GATA4 (7%) amplification were associated with shorter OS. In OSCC, TP63 amplification (25%) and TFPI2 (10%) gene promoter methylation were associated with an unfavourable histopathological response and shorter DFS (TP63) and OS (TFPI2), whereas CDKN2A deletion (38%) was associated with prolonged OS. In conclusion, this study identified candidate genetic biomarkers associated with response to neoadjuvant chemoradiotherapy in patients with localized oesophageal cancer.

ETV4 promotes late development of prostatic intraepithelial neoplasia and cell proliferation through direct and p53-mediated downregulation of p21

BACKGROUND

ETV4 is one of the ETS proteins overexpressed in prostate cancer (PC) as a result of recurrent chromosomal translocations. In human prostate cell lines, ETV4 promotes migration, invasion, and proliferation; however, its role in PC has been unclear. In this study, we have explored the effects of ETV4 expression in the prostate in a novel transgenic mouse model.

METHODS

We have created a mouse model with prostate-specific expression of ETV4 (ETV4 mice). By histochemical and molecular analysis, we have investigated in these engineered mice the expression of p21, p27, and p53. The implications of our in vivo findings have been further investigated in human cells lines by chromatin-immunoprecipitation (ChIP) and luciferase assays.

RESULTS

ETV4 mice, from two independent transgenic lines, have increased cell proliferation in their prostate and two-thirds of them, by the age of 10 months, developed mouse prostatic intraepithelial neoplasia (mPIN). In these mice, cdkn1a and its p21 protein product were reduced compared to controls; p27 protein was also reduced. By ChIP assay in human prostate cell lines, we show that ETV4 binds to a specific site (-704/-696 bp upstream of the transcription start) in the CDKN1A promoter that was proven, by luciferase assay, to be functionally competent. ETV4 further controls CDKN1A expression by downregulating p53 protein: this reduction of p53 was confirmed in vivo in ETV4 mice.

CONCLUSIONS

ETV4 overexpression results in the development of mPIN but not in progression to cancer. ETV4 increases prostate cell proliferation through multiple mechanisms, including downregulation of CDKN1A and its p21 protein product: this in turn is mediated through direct binding of ETV4 to the CDKN1A promoter and through the ETV4-mediated decrease of p53. This multi-faceted role of ETV4 in prostate cancer makes it a potential target for novel therapeutic approaches that could be explored in this ETV4 transgenic model.

Knockdown of P3H4 inhibits proliferation and invasion of bladder cancer

The prolyl 3-hydroxylase family member 4 (P3H4) (alias SC65) is implicated in a variety of physiological and pathological processes. However, little is known about the role of P3H4 in tumors. This study aimed to investigate the role of P3H4 in bladder cancer (BC) and the regulatory mechanisms that influence its expression. P3H4 was highly expressed in BC tissues. Knockdown of P3H4 inhibited BC cell proliferation, cell cycle, migration and invasion in vitro, and inhibited BC growth in vivo. We also found that ETV4 bound directly to the promoter region of P3H4 and activated its transcription. Furthermore, overexpression of ETV4 rescued the inhibition of proliferation and invasion induced by PH4 silencing. ETV4 was significantly overexpressed in the BC tissues. In conclusion, P3H4 functioned an oncogene role in BC progression, and ETV4 bound directly to the P3H4 promoter region to regulate its transcription.

ETV4 overexpression promotes progression of non-small cell lung cancer by upregulating PXN and MMP1 transcriptionally

ETS variant 4 (ETV4), together with ETV1 and ETV5, constitute the PEA3 subfamily of ETS transcription factors, which are implicated in the progression of many cancers. However, the clinicopathologic significance and molecular events regulated by ETV4 in lung cancer are still poorly understood, especially in squamous cell carcinoma of the lung. Here, we aimed to identify functional targets involved in ETV4-driven lung tumorigenesis. Microarray analysis and validation data revealed that ETV4 was the most preponderant PEA3 factor, which was significantly related to the advanced stage, lymph node metastasis, and poor prognosis of non-small cell lung cancers (NSCLCs; all P < .001). Reduced ETV4 expression suppressed the growth and metastasis of NSCLC both in vivo and in vitro. Microarray, gain, or loss of function and luciferase report assays revealed the direct regulatory effect of ETV4 on the expression of focal adhesion gene PXN and matrix metalloproteinase 1 (MMP1), and PXN and/or MMP1 inhibition partially abolished cell proliferation and migration induced by ETV4. Kaplan-Meier analysis indicated that ETV4 and PXN or MMP1 co-overexpression is associated with poor prognosis in human NSCLCs. In conclusion, the ETV4-PXN and ETV4-MMP1 axes are useful biomarkers of tumor progression and worse outcomes in NSCLCs.

Critical role of the MCAM-ETV4 axis triggered by extracellular S100A8/A9 in breast cancer aggressiveness

Metastatic breast cancer is the leading cause of cancer-associated death in women. The progression of this fatal disease is associated with inflammatory responses that promote cancer cell growth and dissemination, eventually leading to a reduction of overall survival. However, the mechanism(s) of the inflammation-boosted cancer progression remains unclear. In this study, we found for the first time that an extracellular cytokine, S100A8/A9, accelerates breast cancer growth and metastasis upon binding to a cell surface receptor, melanoma cell adhesion molecule (MCAM). Our molecular analyses revealed an important role of ETS translocation variant 4 (ETV4), which is significantly activated in the region downstream of MCAM upon S100A8/A9 stimulation, in breast cancer progression in vitro as well as in vivo. The MCAM-mediated activation of ETV4 induced a mobile phenotype called epithelial-mesenchymal transition (EMT) in cells, since we found that ETV4 transcriptionally upregulates ZEB1, a strong EMT inducer, at a very high level. In contrast, downregulation of either MCAM or ETV4 repressed EMT, resulting in greatly weakened tumor growth and lung metastasis. Overall, our results revealed that ETV4 is a novel transcription factor regulated by the S100A8/A9-MCAM axis, which leads to EMT through ZEB1 and thereby to metastasis in breast cancer cells. Thus, therapeutic strategies based on our findings might improve patient outcomes.

Steroid receptor coactivator-1 regulates glioma angiogenesis through polyomavirus enhancer activator 3 signaling

Steroid receptor coactivator 1 (SRC-1) is a transcriptional coactivator for steroid receptors and other transcription factors. SRC-1 has been shown to play an important role in the progression of breast cancer and prostate cancer. However, its role in glioma progression remains unknown. Here, in this study, we report that SRC-1 is upregulated in the vessels of human glioma and exerts important regulatory functions. Specifically, SRC-1 expression significantly enhanced basic fibroblast growth factor (bFGF)-mediated angiogenesis in vivo. Downregulating of SRC-1 expression suppressed endothelial cell migration and tube formation in vitro and upregulated the expression of pro-angiogenic factors, including vascular endothelial growth factor (VEGF) and matrix metallopeptidase (MMP)-9 in glioma cells. These SRC-1-mediated effects were dependent on the activation of polyomavirus enhancer activator 3 (PEA3) transcriptional activity. VEGF and VEGF inducer GS4012 induced the direct binding of SRC-1 and PEA3 in glioma cells, and PEA3 could directly bind with VEGF and MMP-9 promoter under GS4012 treatment in glioma cell. The expression of pro-angiogenic factors induced by SRC-1 was abrogated by sh-PEA3 knockdown. Taken together, these novel outcomes indicated that SRC-1 modulated endothelial cell (EC) function and facilitated a pro-angiogenic microenvironment through PEA3 signaling. Moreover, a combination of targeting SRC-1 and PEA3 signaling in glioma could be a promising strategy for suppressing tumor angiogenesis.

ETV4 transcription factor and MMP13 metalloprotease are interplaying actors of breast tumorigenesis

BACKGROUND

The ETS transcription factor ETV4 is involved in the main steps of organogenesis and is also a significant mediator of tumorigenesis and metastasis, such as in breast cancer. Indeed, ETV4 is overexpressed in breast tumors and is associated with distant metastasis and poor prognosis. However, the cellular and molecular events regulated by this factor are still misunderstood. In mammary epithelial cells, ETV4 controls the expression of many genes, MMP13 among them. The aim of this study was to understand the function of MMP13 during ETV4-driven tumorigenesis.

METHODS

Different constructs of the MMP13 gene promoter were used to study the direct regulation of MMP13 by ETV4. Moreover, cell proliferation, migration, invasion, anchorage-independent growth, and in vivo tumorigenicity were assayed using models of mammary epithelial and cancer cells in which the expression of MMP13 and/or ETV4 is modulated. Importantly, the expression of MMP13 and ETV4 messenger RNA was characterized in 456 breast cancer samples.

RESULTS

Our results revealed that ETV4 promotes proliferation, migration, invasion, and anchorage-independent growth of the MMT mouse mammary tumorigenic cell line. By investigating molecular events downstream of ETV4, we found that MMP13, an extracellular metalloprotease, was an ETV4 target gene. By overexpressing or repressing MMP13, we showed that this metalloprotease contributes to proliferation, migration, and anchorage-independent clonogenicity. Furthermore, we demonstrated that MMP13 inhibition disturbs proliferation, migration, and invasion induced by ETV4 and participates to ETV4-induced tumor formation in immunodeficient mice. Finally, ETV4 and MMP13 co-overexpression is associated with poor prognosis in breast cancer.

CONCLUSION

MMP13 potentiates the effects of the ETV4 oncogene during breast cancer genesis and progression.

ETV4 Facilitates Cell-Cycle Progression in Pancreatic Cells through Transcriptional Regulation of Cyclin D1

The ETS family transcription factor ETV4 is aberrantly expressed in a variety of human tumors and plays an important role in carcinogenesis through upregulation of relevant target gene expression. Here, it is demonstrated that ETV4 is overexpressed in pancreatic cancer tissues as compared with the normal pancreas, and is associated with enhanced growth and rapid cell-cycle progression of pancreatic cancer cells. ETV4 expression was silenced through stable expression of a specific short hairpin RNA (shRNA) in two pancreatic cancer cell lines (ASPC1 and Colo357), while it was ectopically expressed in BXPC3 cells. Silencing of ETV4 in ASPC1 and Colo357 cells reduced the growth by 55.3% and 38.9%, respectively, while forced expression of ETV4 in BXPC3 cells increased the growth by 46.8% in comparison with respective control cells. Furthermore, ETV4-induced cell growth was facilitated by rapid transition of cells from G₁- to S-phase of the cell cycle. Mechanistic studies revealed that ETV4 directly regulates the expression of Cyclin D1 CCND1, a protein crucial for cell-cycle progression from G₁- to S-phase. These effects on the growth and cell cycle were reversed by the forced expression of Cyclin D1 in ETV4-silenced pancreatic cancer cells. Altogether, these data provide the first experimental evidence for a functional role of ETV4 in pancreatic cancer growth and cell-cycle progression.Implications: The functional and mechanistic data presented here regarding ETV4 in pancreatic cancer growth and cell-cycle progression suggest that ETV4 could serve as a potential biomarker and novel target for pancreatic cancer therapy. Mol Cancer Res; 16(2); 187-96. ©2017 AACR.

Cyclin D3 predicts disease-free survival in breast cancer

Background

Cyclin D3, which induces progression through the G1 phase of the cell cycle, is a regulator of Cyclin-dependent kinases 4 and 6. Previous studies revealed that abnormal expression of Cyclin D3 was found in many different cancers. However, the role of Cyclin D3 in breast cancer (BC) remains unknown. The aim of this study is to examine the expression pattern of Cyclin D3 in BC and to evaluate its biological role and clinical significance in prognosis prediction. The mechanism involved is also evaluated.

Methods

Immunohistochemical staining was used to detect the expression of Cyclin D3. qRT-PCR was used to detect the mRNA level of Cyclin D3 in BC tissues and BC cell lines. Transwell assay was used to examine the role of Cyclin D3 in the migration and invasion of BC cells. Mass Spectrometry was used to search for the interacting protein with Cyclin D3. Co-Immunoprecipitation assay and GST-Pull Down assay were used to validate the interaction of Cyclin D3 and its interaction protein.

Results

Through detecting Cyclin D3 expression in 243 breast cancer patients’ tissue array, we found Cyclin D3 expression was correlated with ER status (p = 0.000), PR status (p = 0.001), HER2 status (p = 0.002) and tumor differentiation (p = 0.045). The Kaplan–Meier survival curves indicated that the disease free survival (DFS) was significantly poor in high Cyclin D3 expression BC patients (p = 0.004). Furthermore, expression of Cyclin D3 was significantly associated with BC prognosis and was shown to be an independent prognostic marker in breast cancer (p = 0.028). By IHC staining and qPCR detection, Cyclin D3 expression was found to be down-regulated both in BC tissues and in BC cell lines compared with the corresponding normal controls. Further investigation showed Cyclin D3 was involved in the metastasis of BC cells and physically interacted with actin in vivo and in vitro.

Conclusion

Our studies revealed that Cyclin D3 was upregulated in breast cancer and represented a novel predictor of BC prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-015-0245-6) contains supplementary material, which is available to authorized users.

ETS-related transcription factors ETV4 and ETV5 are involved in proliferation and induction of differentiation-associated genes in embryonic stem (ES) cells

The pluripotency and self-renewal capacity of embryonic stem (ES) cells is regulated by several transcription factors. Here, we show that the ETS-related transcription factors Etv4 and Etv5 (Etv4/5) are specifically expressed in undifferentiated ES cells, and suppression of Oct3/4 results in down-regulation of Etv4/5. Simultaneous deletion of Etv4 and Etv5 (Etv4/5 double knock-out (dKO)) in ES cells resulted in a flat, epithelial cell-like appearance, whereas the morphology changed into compact colonies in a 2i medium (containing two inhibitors for GSK3 and MEK/ERK). Expression levels of self-renewal marker genes, including Oct3/4 and Nanog, were similar between wild-type and dKO ES cells, whereas proliferation of Etv4/5 dKO ES cells was decreased with overexpression of cyclin-dependent kinase inhibitors (p16/p19, p15, and p57). A differentiation assay revealed that the embryoid bodies derived from Etv4/5 dKO ES cells were smaller than the control, and expression of ectoderm marker genes, including Fgf5, Sox1, and Pax3, was not induced in dKO-derived embryoid bodies. Microarray analysis demonstrated that stem cell-related genes, including Tcf15, Gbx2, Lrh1, Zic3, and Baf60c, were significantly repressed in Etv4/5 dKO ES cells. The artificial expression of Etv4 and/or Etv5 in Etv4/5 dKO ES cells induced re-expression of Tcf15 and Gbx2. These results indicate that Etv4 and Etv5, potentially through regulation of Gbx2 and Tcf15, are involved in the ES cell proliferation and induction of differentiation-associated genes in ES cells.

Loss of a negative feedback loop involving pea3 and cyclin d2 is required for pea3-induced migration in transformed mammary epithelial cells

The Ets family transcription factor Pea3 (ETV4) is involved in tumorigenesis especially during the metastatic process. Pea3 is known to induce migration and invasion in mammary epithelial cell model systems. However, the molecular pathways regulated by Pea3 are still misunderstood. In the current study, using in vivo and in vitro assays, Pea3 increased the morphogenetic and tumorigenic capacity of mammary epithelial cells by modulating their cell morphology, proliferation, and migration potential. In addition, Pea3 overexpression favored an epithelial-mesenchymal transition (EMT) triggered by TGF-β1. During investigation for molecular events downstream of Pea3, Cyclin D2 (CCND2) was identified as a new Pea3 target gene involved in the control of cellular proliferation and migration, a finding that highlights a new negative regulatory loop between Pea3 and Cyclin D2. Furthermore, Cyclin D2 expression was lost during TGF-β1-induced EMT and Pea3-induced tumorigenesis. Finally, restored Cyclin D2 expression in Pea3-dependent mammary tumorigenic cells decreased cell migration in an opposite manner to Pea3. As such, these data demonstrate that loss of the negative feedback loop between Cyclin D2 and Pea3 contributes to Pea3-induced tumorigenesis.

IMPLICATIONS

This study reveals molecular insight into how the Ets family transcription factor Pea3 favors EMT and contributes to tumorigenesis via a negative regulatory loop with Cyclin D2, a new Pea3 target gene.

Translational repression of cyclin D3 by a stable G-quadruplex in its 5' UTR: implications for cell cycle regulation

cyclin D3 (CCND3) is one of the three D-type cyclins that regulate the G1/S phase transition of the cell cycle. Expression of CCND3 is observed in nearly all proliferating cells; however, the presence of high levels of CCND3 has been linked to a poor prognosis for several types of cancer. Therefore, further mechanistic studies on the regulation of CCND3 expression are urgently needed to provide therapeutic implications. In this study, we report that a conserved RNA G-quadruplex-forming sequence (hereafter CRQ), located in the 5' UTR of mammalian CCND3 mRNA, is able to fold into an extremely stable, intramolecular, parallel G-quadruplex in vitro. The CRQ G-quadruplex dramatically reduces the activity of a reporter gene in human cell lines, but it has little impact on its mRNA level, indicating a translational repression. Moreover, the CRQ sequence in its natural context inhibits translation of CCND3. Disruption of the G-quadruplex structure by G/U-mutation or deletion results in an elevated expression of CCND3 and an increased phosphorylation of Rb, a downstream target of CCND3, which promotes progression of cells through the G1 phase. Our results add to the growing understanding of the regulation of CCND3 expression and provide a potential therapeutic target for cancer treatment.

Overexpression of ETV4 is oncogenic in prostate cells through promotion of both cell proliferation and epithelial to mesenchymal transition

The discovery of translocations that involve one of the genes of the ETS family (ERG, ETV1, ETV4 and ETV5) has been a major advance in understanding the molecular basis of prostate cancer (PC). Each one of these translocations results in deregulated expression of one of the ETS proteins. Here, we focus on the mechanism whereby overexpression of the ETV4 gene mediates oncogenesis in the prostate. By siRNA technology, we show that ETV4 inhibition in the PC3 cancer cell line reduces not only cell mobility and anchorage-independent growth, but also cell proliferation, cell cycle progression and tumor growth in a xenograft model. Conversely, ETV4 overexpression in the nonmalignant human prostate cell line (RWPE) increases anchorage-independent growth, cell mobility and cell proliferation, which is probably mediated by downregulation of p21, producing accelerated progression through the cell cycle. ETV4 overexpression is associated with changes in the pattern of E-cadherin and N-cadherin expression; the cells also become spindle-shaped, and these changes are characteristic of the so-called epithelial to mesenchymal transition (EMT). In RWPE cells overexpressing ETV4 EMT results from a marked increase in EMT-specific transcription factors such as TWIST1, SLUG1, ZEB1 and ZEB2. Thus, whereas ETV4 shares with the other ETS proteins (ERG, ETV5 and ETV1) a major role in invasiveness and cell migration, it emerges as unique in that it increases at the same time also the rate of proliferation of PC cells. Considering the wide spectrum in the clinical course of patients with PC, it may be highly relevant that ETV4 is capable of inducing most and perhaps all of the features that make a tumor aggressive.

PEA3/ETV4-related transcription factors coupled with active ERK signalling are associated with poor prognosis in gastric adenocarcinoma

Background:

Transcription factors often play important roles in tumourigenesis. Members of the PEA3 subfamily of ETS-domain transcription factors fulfil such a role and have been associated with tumour metastasis in several different cancers. Moreover, the activity of the PEA3 subfamily transcription factors is potentiated by Ras-ERK pathway signalling, which is itself often deregulated in tumour cells.

Methods:

Immunohistochemical patterns of PEA3 expression and active ERK signalling were analysed and mRNA expression levels of PEA3, ER81, MMP-1 and MMP-7 were determined in gastric adenocarcinoma samples.

Results:

Here, we have studied the expression of the PEA3 subfamily members PEA3/ETV4 and ER81/ETV1 in gastric adenocarcinomas. PEA3 is upregulated at the protein level in gastric adenocarcinomas and both PEA3/ETV4 and ER81/ETV1 are upregulated at the mRNA level in gastric adenocarcinoma tissues. This increased expression correlates with the expression of a target gene associated with metastasis, MMP-1. Enhanced ERK signalling is also more prevalent in late-stage gastric adenocarcinomas, and the co-association of ERK signalling and PEA3 expression also occurs in late-stage gastric adenocarcinomas. Furthermore, the co-association of ERK signalling and PEA3 expression correlates with decreased survival rates.

Conclusions:

This study shows that members of the PEA3 subfamily of transcription factors are upregulated in gastric adenocarcinomas and that the simultaneous upregulation of PEA3 expression and ERK pathway signalling is indicative of late-stage disease and a poor survival prognosis.

The ERK MAP kinase-PEA3/ETV4-MMP-1 axis is operative in oesophageal adenocarcinoma

BACKGROUND

Many members of the ETS-domain transcription factor family are important drivers of tumourigenesis. In this context, their activation by Ras-ERK pathway signaling is particularly relevant to the tumourigenic properties of many ETS-domain transcription factors. The PEA3 subfamily of ETS-domain transcription factors have been implicated in tumour metastasis in several different cancers.

RESULTS

Here, we have studied the expression of the PEA3 subfamily members PEA3/ETV4 and ER81/ETV1 in oesophageal adenocarcinomas and determined their role in oesophageal adenocarcinoma cell function. PEA3 plays an important role in controlling both the proliferation and invasive properties of OE33 oesophageal adenocarcinoma cells. A key target gene is MMP-1. The ERK MAP kinase pathway activates PEA3 subfamily members and also plays a role in these PEA3 controlled events, establishing the ERK-PEA3-MMP-1 axis as important in OE33 cells. PEA3 subfamily members are upregulated in human adenocarcinomas and expression correlates with MMP-1 expression and late stage metastatic disease. Enhanced ERK signaling is also more prevalent in late stage oesophageal adenocarcinomas.

CONCLUSIONS

This study shows that the ERK-PEA3-MMP-1 axis is upregulated in oesophageal adenocarcinoma cells and is a potentially important driver of the metastatic progression of oesophageal adenocarcinomas.

Phosphatidylinositol-3-kinase-AKT pathway, phospho-JUN and phospho-JNK expression in spontaneously arising bovine urinary bladder tumours

The aetiopathogenesis of urinary bladder tumours in cattle involves prolonged ingestion of bracken fern and infection by bovine papillomavirus types 1 or 2 (BPV-1/2). E5, the major BPV-1/2 oncoprotein, binds to the activated platelet-derived growth factor beta receptor (pPDGF-betaR), inducing cell transformation in vitro and spontaneously arising urinary bladder tumours. The aim of this study was to assess whether the 85 kDa regulatory subunit (p85) of the phosphatidylinositol-3-kinase (PI3K)-AKT pathway and other transforming signals phospho-JUN (pJUN) and phospho-JUN N-terminal kinases (pJNK) may be important in the development of BPV-associated urothelial carcinomas. A physical interaction between the pPDGF-betaR and PI3K was shown in four tumours and two samples of normal bladder tissue by co-immunoprecipitation and western blotting. There was greater expression of the PI3K-AKT-cyclin D3 molecular pathway downstream to the activation of pPDGF-betaR in neoplastic compared with normal tissue. pJNK and pJUN were overexpressed in samples of tumour compared with normal mucosal tissue. These findings provide new insights into the aetiopathogenic mechanisms underlying naturally occurring bovine urothelial carcinogenesis and contribute to understanding of the role of E5 oncoprotein in naturally occurring tumorigenesis.

Pea3 transcription factors and wnt1-induced mouse mammary neoplasia

The role of the PEA3 subfamily of Ets transcription factors in breast neoplasia is controversial. Although overexpression of PEA3 (E1AF/ETV4), and of the related factors ERM (ETV5) and ER81 (ETV1), have been observed in human and mouse breast tumors, PEA3 factors have also been ascribed a tumor suppressor function. Here, we utilized the MMTV/Wnt1 mouse strain to further interrogate the role of PEA3 transcription factors in mammary tumorigenesis based on our previous observation that Pea3 is highly expressed in MMTV/Wnt1 mammary tumors. Pea3 expression in mouse mammary tissues was visualized using a Pea3^NLSlacZ reporter strain. In normal mammary glands, Pea3 expression is predominantly confined to myoepithelial cells. Wnt1 transgene expression induced marked amplification of this cell compartment in nontumorous mammary glands, accompanied by an apparent increase in Pea3 expression. The pattern of Pea3 expression in MMTV/Wnt1 mammary glands recapitulated the cellular profile of activated β-catenin/TCF signaling, which was visualized using both β-catenin immunohistochemistry and the β-catenin/TCF-responsive reporter Axin2^NLSlacZ. To test the requirement for PEA3 factors in Wnt1-induced tumorigenesis, we employed a mammary-targeted dominant negative PEA3 transgene, ΔNPEA3En. Expression of ΔNPEA3En delayed early-onset tumor formation in MMTV/Wnt1 virgin females (P = 0.03), suggesting a requirement for PEA3 factor function for Wnt1-driven tumor formation. Consistent with this observation, expression of the ΔNPEA3En transgene was profoundly reduced in mammary tumors compared to nontumorous mammary glands from bigenic MMTV/Wnt1, MMTV/ΔNPEA3En mice (P = 0.01). Our data provide the first description of Wnt1-mediated expansion of the Pea3-expressing myoepithelial compartment in nontumorous mammary glands. Consistent with this observation, mammary myoepithelium was selectively responsive to Wnt1. Together these data suggest the MMTV/Wnt1 strain as a potential model of basal breast cancer. Furthermore, this study provides evidence for a protumorigenic role of PEA3 factors in breast neoplasia, and supports targeting the PEA3 transcription factor family in breast cancer.

Reduced tumorigenesis in mouse mammary cancer cells following inhibition of Pea3- or Erm-dependent transcription

Pea3 and Erm are transcription factors expressed in normal developing branching organs such as the mammary gland. Deregulation of their expression is generally associated with tumorigenesis and particularly breast cancer. By using RNA interference (RNAi) to downregulate the expression of Pea3 and/or Erm in a mammary cancer cell line, we present evidence for a role of these factors in proliferation, migration and invasion capacity of cancer cells. We have used different small interfering RNAs (siRNAs) targeting pea3 and erm transcripts in transiently or stably transfected cells, and assessed the physiological behavior of these cells in in vitro assays. We also identified an in vivo alteration of tumor progression after injection of cells that overexpress pea3 and/or erm short hairpin RNAs (shRNAs) in immunodeficient mice. Using transcriptome profiling in Pea3- or Erm-targeted cells, two largely independent gene expression programs were identified on the basis of their shared phenotypic modifications. A statistically highly significant part of both sets of target genes had previously been already associated with the cellular signaling pathways of the ;proliferation, migration, invasion' class. These data provide the first evidence, by using endogenous knockdown, for pivotal and complementary roles of Pea3 and Erm transcription factors in events crucial to mammary tumorigenesis, and identify sets of downstream target genes whose expression during tumorigenesis is regulated by these transcription factors.

Identification of E1AF as a target gene of E2F1-induced apoptosis in response to DNA damage

Transcription factor E1AF plays critical roles in neuronal development and tumour metastasis and is regulated by a number of signalling cascades, including the mitogen-activated protein kinase pathways. Accumulated evidence indicted that E1AF might contribute to cell survival in response to environment factors. Here, we provided evidence the cell cycle and apoptosis regulator E2F1 induces E1AF expression at the transcriptional level. DNA damage by etoposide causes E2F1-dependent induction of E1AF expression at transcriptional level. Furthermore, disruption of E1AF expression by E1AF RNAi decreased E2F1-induced apoptosis in response to etoposide. Thus, we conclude that activation of E1AF provides a means for E2F1 to induce cell apoptosis in response to DNA damage.

E1AF promotes mithramycin A-induced Huh-7 cell apoptosis depending on its DNA-binding domain

Transcription factor E1AF is widely known to play critical roles in tumor metastasis via directly binding to the promoters of genes involved in tumor migration and invasion. Here, we reported for the first time the pro-apoptotic role of E1AF in tumor cells. The expression of E1AF at protein level was obviously increased during Huh-7 and Hep3B cells apoptosis induced by the anticancer agent mithramycin A. E1AF overexpression markedly enhanced mithramycin A-induced Huh-7 cell apoptosis and the expression of pro-apoptotic protein Bax depending on its DNA-binding domain. And, reduction of E1AF inhibited mithramycin A-induced Huh-7 cell apoptosis. Furthermore, reducing the expression of Bax significantly inhibited E1AF-increased Huh-7 cell apoptosis induced by mithramycin A. Taken together, E1AF increases mithramycin A-induced Huh-7 cells apoptosis and Bax expression depending on its DNA-binding domain, indicating that E1AF might contribute to the therapeutic efficiency of mithramycin A for hepatoma.