Dysregulation of Fra1 expression by Wnt/β-catenin signalling promotes glioma aggressiveness through epithelial-mesenchymal transition

Netrin G1 Ligand is a new stromal immunomodulator that promotes pancreatic cancer

Understanding pancreatic cancer biology is fundamental for identifying new targets and for developing more effective therapies. In particular, the contribution of the stromal microenvironment to pancreatic cancer tumorigenesis requires further exploration. Here, we report the stromal roles of the synaptic protein Netrin G1 Ligand (NGL-1) in pancreatic cancer, uncovering its pro-tumor functions in cancer-associated fibroblasts and in immune cells. We observed that the stromal expression of NGL-1 inversely correlated with patients' overall survival. Moreover, germline knockout (KO) mice for NGL-1 presented decreased tumor burden, with a microenvironment that is less supportive of tumor growth. Of note, tumors from NGL-1 KO mice produced less immunosuppressive cytokines and displayed an increased percentage of CD8 + T cells than those from control mice, while preserving the physical structure of the tumor microenvironment. These effects were shown to be mediated by NGL-1 in both immune cells and in the local stroma, in a TGF-β-dependent manner. While myeloid cells lacking NGL-1 decreased the production of immunosuppressive cytokines, NGL-1 KO T cells showed increased proliferation rates and overall polyfunctionality compared to control T cells. CAFs lacking NGL-1 were less immunosuppressive than controls, with overall decreased production of pro-tumor cytokines and compromised ability to inhibit CD8 + T cells activation. Mechanistically, these CAFs downregulated components of the TGF-β pathway, AP-1 and NFAT transcription factor families, resulting in a less tumor-supportive phenotype. Finally, targeting NGL-1 genetically or using a functionally antagonistic small peptide phenocopied the effects of chemotherapy, while modulating the immunosuppressive tumor microenvironment (TME), rather than eliminating it. We propose NGL-1 as a new local stroma and immunomodulatory molecule, with pro-tumor roles in pancreatic cancer.

Statement of Significance

Here we uncovered the pro-tumor roles of the synaptic protein NGL-1 in the tumor microenvironment of pancreatic cancer, defining a new target that simultaneously modulates tumor cell, fibroblast, and immune cell functions. This study reports a new pathway where NGL-1 controls TGF-β, AP-1 transcription factor members and NFAT1, modulating the immunosuppressive microenvironment in pancreatic cancer. Our findings highlight NGL-1 as a new stromal immunomodulator in pancreatic cancer.

FOSL1's Oncogene Roles in Glioma/Glioma Stem Cells and Tumorigenesis: A Comprehensive Review

This review specifically examines the important function of the oncoprotein FOSL1 in the dimeric AP-1 transcription factor, which consists of FOS-related components. FOSL1 is identified as a crucial controller of invasion and metastatic dissemination, making it a potential target for therapeutic treatment in cancer patients. The review offers a thorough examination of the regulatory systems that govern the influence exerted on FOSL1. These include a range of changes that occur throughout the process of transcription and after the translation of proteins. We have discovered that several non-coding RNAs, such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play a significant role in regulating FOSL1 expression by directly interacting with its mRNA transcripts. Moreover, an investigation into the functional aspects of FOSL1 reveals its involvement in apoptosis, proliferation, and migration. This work involves a comprehensive analysis of the complex signaling pathways that support these diverse activities. Furthermore, particular importance is given to the function of FOSL1 in coordinating the activation of several cytokines, such as TGF-beta, and the commencement of IL-6 and VEGF production in tumor-associated macrophages (TAMs) that migrate into the tumor microenvironment. There is a specific emphasis on evaluating the predictive consequences linked to FOSL1. Insights are now emerging on the developing roles of FOSL1 in relation to the processes that drive resistance and reliance on specific treatment methods. Targeting FOSL1 has a strong inhibitory effect on the formation and spread of specific types of cancers. Despite extensive endeavors, no drugs targeting AP-1 or FOSL1 for cancer treatment have been approved for clinical use. Hence, it is imperative to implement innovative approaches and conduct additional verifications.

TRPM7 transactivates the FOSL1 gene through STAT3 and enhances glioma stemness

INTRODUCTION

We previously reported that TRPM7 regulates glioma cells' stemness through STAT3. In addition, we demonstrated that FOSL1 is a response gene for TRPM7, and the FOSL1 gene serves as an oncogene to promote glioma proliferation and invasion.

METHODS

In the present study, we determined the effects of FOSL1 on glioma stem cell (GSC) markers CD133 and ALDH1 by flow cytometry, and the maintenance of stem cell activity by extreme limiting dilution assays (ELDA). To further gain insight into the mechanism by which TRPM7 activates transcription of the FOSL1 gene to contribute to glioma stemness, we constructed a FOSL1 promoter and its GAS mutants followed by luciferase reporter assays and ChIP-qPCR in a glioma cell line and glioma patient-derived xenoline. We further examined GSC markers ALDH1 and TRPM7 as well as FOSL1 by immunohistochemistry staining (IHC) in brain tissue microarray (TMA) of glioma patients.

RESULTS

We revealed that FOSL1 knockdown reduces the expression of GSC markers CD133 and ALDH1, and FOSL1 is required to maintain stem cell activity in glioma cells. The experiments also showed that mutations of - 328 to - 336 and - 378 to - 386 GAS elements markedly reduced FOSL1 promoter activity. Constitutively active STAT3 increased while dominant-negative STAT3 decreased FOSL1 promoter activity. Furthermore, overexpression of TRPM7 enhanced while silencing of TRPM7 reduced FOSL1 promoter activity. ChIP-qPCR assays revealed that STAT3, present in nuclear lysates of glioma cells stimulated by constitutively activated STAT3, can bind to two GAS elements, respectively. We demonstrated that deacetylation of FOSL1 at the Lys-116 residue located within its DNA binding domain led to an increase in FOSL1 transcriptional activity. We found that the expression of TRPM7, ALDH1, and FOSL1 protein is associated with grades of malignant glioma, and TRPM7 protein expression correlates to the expression of ALDH1 and FOSL1 in glioma patients.

CONCLUSIONS

These combined results demonstrated that TRPM7 induced FOSL1 transcriptional activation, which is mediated by the action of STAT3, a mechanism shown to be important in glioma stemness. These results indicated that FOSL1, similar to GSC markers ALDH1 and TRPM7, is a diagnostic marker and potential drug target for glioma patients.

Expression and potential role of FOSB in glioma

Background

FOSB is reported to be an oncogene in a variety of tumors. However, the expression and role of FOSB in glioma remain obscure. In this study, we aimed to explore the expression of FOSB in glioma and its biological role in glioblastoma multiforme (GBM).

Methods

Western blot, immunohistochemical staining, and quantitative real-time polymerase chain reaction (RT-qPCR) were used to detect the expression of FOSB in clinical samples. FOSB was knocked down in cells to determine the effects of FOSB on the phenotypic changes of tumors by plate cloning, CCK-8 assay, and Transwell assay. Finally, subcutaneous tumorigenesis in nude mice was used to observe the tumorigenesis of glioma cell lines after the knockdown of the FOSB gene.

Results

FOSB expression was higher in glioma compared with normal brain tissue. After the downregulation of FOSB, the expression of cleaved caspase-3 increased. Plate cloning and CCK-8 experiments showed that the proliferation of glioma cell lines decreased. The Transwell assay demonstrated that the glioblastoma cell lines had lower migration ability after the knockdown of FOSB. Finally, the tumor volume of U87 glioma cells in group sh-FOSB was smaller than that in the control group. The TUNEL staining in vitro showed that the apoptosis of sh-FOSB glioma cells increased.

Conclusion

FOSB was highly expressed in glioma tissues. The viability of glioma cells decreased, and the ability of glioma cells to proliferate and migrate was reduced when FOSB was downregulated. Hence, FOSB may promote the development and migration of gliomas.

Transcriptomic Portraits and Molecular Pathway Activation Features of Adult Spinal Intramedullary Astrocytomas

In this study, we report 31 spinal intramedullary astrocytoma (SIA) RNA sequencing (RNA-seq) profiles for 25 adult patients with documented clinical annotations. To our knowledge, this is the first clinically annotated RNA-seq dataset of spinal astrocytomas derived from the intradural intramedullary compartment. We compared these tumor profiles with the previous healthy central nervous system (CNS) RNA-seq data for spinal cord and brain and identified SIA-specific gene sets and molecular pathways. Our findings suggest a trend for SIA-upregulated pathways governing interactions with the immune cells and downregulated pathways for the neuronal functioning in the context of normal CNS activity. In two patient tumor biosamples, we identified diagnostic KIAA1549-BRAF fusion oncogenes, and we also found 16 new SIA-associated fusion transcripts. In addition, we bioinformatically simulated activities of targeted cancer drugs in SIA samples and predicted that several tyrosine kinase inhibitory drugs and thalidomide analogs could be potentially effective as second-line treatment agents to aid in the prevention of SIA recurrence and progression.

The Fra-1/AP-1 Oncoprotein: From the "Undruggable" Transcription Factor to Therapeutic Targeting

The genetic and epigenetic changes affecting transcription factors, coactivators, and chromatin modifiers are key determinants of the hallmarks of cancer. The acquired dependence on oncogenic transcriptional regulators, representing a major determinant of cancer cell vulnerability, points to transcription factors as ideal therapeutic targets. However, given the unavailability of catalytic activities or binding pockets for small-molecule inhibitors, transcription factors are generally regarded as undruggable proteins. Among components of the AP-1 complex, the FOS-family transcription factor Fra-1, encoded by FOSL1, has emerged as a prominent therapeutic target. Fra-1 is overexpressed in most solid tumors, in response to the BRAF-MAPK, Wnt-beta-catenin, Hippo-YAP, IL-6-Stat3, and other major oncogenic pathways. In vitro functional analyses, validated in onco-mouse models and corroborated by prognostic correlations, show that Fra-1-containing dimers control tumor growth and disease progression. Fra-1 participates in key mechanisms of cancer cell invasion, Epithelial-to-Mesenchymal Transition, and metastatic spreading, by driving the expression of EMT-inducing transcription factors, cytokines, and microRNAs. Here we survey various strategies aimed at inhibiting tumor growth, metastatic dissemination, and drug resistance by interfering with Fra-1 expression, stability, and transcriptional activity. We summarize several tools aimed at the design and tumor-specific delivery of Fra-1/AP-1-specific drugs. Along with RNA-based therapeutics targeting the FOSL1 gene, its mRNA, or cognate regulatory circRNAs, we will examine the exploitation of blocking peptides, small molecule inhibitors, and innovative Fra-1 protein degraders. We also consider the possible caveats concerning Fra-1 inhibition in specific therapeutic contexts. Finally, we discuss a recent suicide gene therapy-based approach, aimed at selectively killing the Fra-1-overexpressing neoplastic cells.

IR-Surviving NSCLC Cells Exhibit Different Patterns of Molecular and Cellular Reactions Relating to the Multifraction Irradiation Regimen and p53-Family Proteins Expression

Simple Summary

For the first time, we demonstrated that the significant decrease in p63/p73 expression together with the absence of functional p53 could underlie an increase in the fraction of polyploid cells, transformation rates, and the glycolytic NAD(P)H production in multifraction X-ray radiation exposure (MFR)-surviving cancer cells, providing conditions for radioresistance associated with epithelial–mesenchymal transition (EMT)-like process activation. During radiation therapy (RT), the treatment dose, fractionation, and dose limits for organs at risk (OARs) do not change between patients and are still prescribed mainly based on the Tumor, Node, Metastasis (TNM) stage, performance status, and comorbidities, taking no account of the tumor biology. Our data once again emphasize that non-small cell lung cancer (NSCLC) therapy approaches should become more personalized according to RT regimen, tumor histology, and molecular status of critical proteins.

Abstract

Radiotherapy is a primary treatment modality for patients with unresectable non-small cell lung cancer (NSCLC). Tumor heterogeneity still poses the central question of cancer radioresistance, whether the presence of a particular cell population inside a tumor undergoing a selective outgrowth during radio- and chemotherapy give rise to metastasis and tumor recurrence. In this study, we examined the impact of two different multifraction X-ray radiation exposure (MFR) regimens, fraction dose escalation (FDE) in the split course and the conventional hypofractionation (HF), on the phenotypic and molecular signatures of four MFR-surviving NSCLC cell sublines derived from parental A549 (p53 wild-type) and H1299 (p53-null) cells, namely A549FR/A549HR, H1299FR/H1299HR cells. We demonstrate that sublines surviving different MFR regimens in a total dose of 60 Gy significantly diverge in their molecular traits related to irradiation regimen and p53 status. The observed changes regarding radiosensitivity, transformation, proliferation, metabolic activity, partial epithelial-to-mesenchymal transition (EMT) program activation and 1D confined migratory behavior (wound healing). For the first time, we demonstrated that MFR exposure led to the significant decrease in the expression of p63 and p73, the p53-family members, in p53null cells, which correlated with the increase in cell polyploidy. We could not find significant differences in FRA1 expression between parental cells and their sublines that survived after any MFR regimen regardless of p53 status. In our study, the FDE regimen probably causes partial EMT program activation in MFR-survived NSCLC cells through either Vimentin upregulation in p53null or an aberrant N-cadherin upregulation in p53wt cells. The HF regimen likely less influences the EMT activation irrespectively of the p53 status of MFR-survived NSCLC cells. Our data highlight that both MFR regimens caused overall higher cell transformation of p53null H1299FR and H1299HR cells than their parental H1299 cells. Moreover, our results indicate that the FDE regimen raised the radioresistance and transformation of MFR-surviving NSCLC cells irrespectively of their p53 status, though the HF regimen demonstrated a similar effect on p53null NSCLC cells only. Our data once again emphasize that NSCLC therapy approaches should become more personalized according to radiation therapy (RT) regimen, tumor histology, and molecular status of critical proteins.

Crosstalk between 17β-Estradiol and TGF-β Signaling Modulates Glioblastoma Progression

Epithelial–mesenchymal transition (EMT) is an essential mechanism contributing to glioblastoma multiforme (GBM) progression, the most common and malignant brain tumor. EMT is induced by signaling pathways that crosstalk and regulate an intricate regulatory network of transcription factors. It has been shown that downstream components of 17β-estradiol (E2) and transforming growth factor β (TGF-β) signaling pathways crosstalk in estrogen-sensitive tumors. However, little is known about the interaction between the E2 and TGF-β signaling components in brain tumors. We have investigated the relationship between E2 and TGF-β signaling pathways and their effects on EMT induction in human GBM-derived cells. Here, we showed that E2 and TGF-β negatively regulated the expression of estrogen receptor α (ER-α) and Smad2/3. TGF-β induced Smad2 phosphorylation and its subsequent nuclear translocation, which E2 inhibited. Both TGF-β and E2 induced cellular processes related to EMT, such as morphological changes, actin filament reorganization, and mesenchymal markers (N-cadherin and vimentin) expression. Interestingly, we found that the co-treatment of E2 and TGF-β blocked EMT activation. Our results suggest that E2 and TGF-β signaling pathways interact through ER-α and Smad2/3 mediators in cells derived from human GBM and inhibit EMT activation induced by both factors alone.

FRA1 is essential for the maintenance of the oncogenic phenotype induced by in vitro long-term arsenic exposure

Arsenic induces oncogenic effects activating stress-related signalling pathways. This can result in the over-activation of the AP-1 protein, specifically its FRA1 component. FRA1 is a transcription factor frequently overexpressed in epithelial tumors, where it can regulate the expression of different target genes. Accordingly, FRA1 could play an essential role in the in vitro cell transformation induced by arsenic. FRA1 levels were monitored in MEF cells throughout their transformation stages during 40 weeks of long-term 2 μM arsenic exposure. Interestingly, the results show a progressive FRA1 overexpression with time (60-fold and 11-fold for mRNA and pFRA/non-pFRA1, respectively, at week 40), which may be responsible for the observed altered expression in the FRA1 downstream target genes Pten, Pdcd4, Tpm1, Tgfb1, Tgfb2, Zeb1, Zeb2, and Twist. The levels of MAPKs (ERK, p38, and JNK) and other known players upstream from FRA1 were assessed at equivalent time-points, and ERK, p38 and RAS were pinpointed as potential candidates involved in arsenic-induced FRA1 activation. Furthermore, FRA1 stable knockdown under chronic arsenic exposure settings elicits a remarkable impact on the features relative to the cells' oncogenic phenotype. Notably, FRA1 knockdown cells present a 30% diminished proliferation rate, a 50% lowered migration and invasion potential, a 50% reduction in senescence, and a 30-60% reduced tumorsphere-forming ability. This work is the first to demonstrate the important role of FRA1 in the development and aggressiveness of the in vitro transformed phenotype induced by long-term arsenic exposure.

Multifaceted WNT Signaling at the Crossroads Between Epithelial-Mesenchymal Transition and Autophagy in Glioblastoma

Tumor cells can employ epithelial-mesenchymal transition (EMT) or autophagy in reaction to microenvironmental stress. Importantly, EMT and autophagy negatively regulate each other, are able to interconvert, and both have been shown to contribute to drug-resistance in glioblastoma (GBM). EMT has been considered one of the mechanisms that confer invasive properties to GBM cells. Autophagy, on the other hand, may show dual roles as either a GBM-promoter or GBM-suppressor, depending on microenvironmental cues. The Wingless (WNT) signaling pathway regulates a plethora of developmental and biological processes such as cellular proliferation, adhesion and motility. As such, GBM demonstrates deregulation of WNT signaling in favor of tumor initiation, proliferation and invasion. In EMT, WNT signaling promotes induction and stabilization of different EMT activators. WNT activity also represses autophagy, while nutrient deprivation induces β-catenin degradation via autophagic machinery. Due to the importance of the WNT pathway to GBM, and the role of WNT signaling in EMT and autophagy, in this review we highlight the effects of the WNT signaling in the regulation of both processes in GBM, and discuss how the crosstalk between EMT and autophagy may ultimately affect tumor biology.

Identifying collagen VI as a target of fibrotic diseases regulated by CREBBP/EP300

Fibrotic diseases remain a major cause of morbidity and mortality, yet there are few effective therapies. The underlying pathology of all fibrotic conditions is the activity of myofibroblasts. Using cells from freshly excised disease tissue from patients with Dupuytren's disease (DD), a localized fibrotic disorder of the palm, we sought to identify new therapeutic targets for fibrotic disease. We hypothesized that the persistent activity of myofibroblasts in fibrotic diseases might involve epigenetic modifications. Using a validated genetics-led target prioritization algorithm (Pi) of genome wide association studies (GWAS) data and a broad screen of epigenetic inhibitors, we found that the acetyltransferase CREBBP/EP300 is a major regulator of contractility and extracellular matrix production via control of H3K27 acetylation at the profibrotic genes, ACTA2 and COL1A1 Genomic analysis revealed that EP300 is highly enriched at enhancers associated with genes involved in multiple profibrotic pathways, and broad transcriptomic and proteomic profiling of CREBBP/EP300 inhibition by the chemical probe SGC-CBP30 identified collagen VI (Col VI) as a prominent downstream regulator of myofibroblast activity. Targeted Col VI knockdown results in significant decrease in profibrotic functions, including myofibroblast contractile force, extracellular matrix (ECM) production, chemotaxis, and wound healing. Further evidence for Col VI as a major determinant of fibrosis is its abundant expression within Dupuytren's nodules and also in the fibrotic foci of idiopathic pulmonary fibrosis (IPF). Thus, Col VI may represent a tractable therapeutic target across a range of fibrotic disorders.

Coronin 3 Promotes the Development of Oncogenic Properties in Glioma Through the Wnt/β-Catenin Signaling Pathway

PURPOSE

Evidence indicates that the actin-binding protein Coronin 3, which is aberrantly expressed in various cancers, is associated with cancer development and progression. However, little is known about the role of Coronin 3 in glioma tumorigenesis. Here, we aimed to explore the biological function and regulatory mechanism of Coronin 3 in glioblastoma (GBM).

MATERIALS AND METHODS

Coronin 3 level in human GBM clinical samples and cell lines was investigated. The shRNA knockdown strategy was used to assess the tumor characteristics of GBM cell lines. The role of β-catenin in Coronin 3-mediated oncogenic phenotypes was evaluated.

RESULTS

Coronin 3 was found to be highly upregulated in glioma cell lines. Furthermore, knockdown of Coronin 3 significantly inhibited the growth of glioma cells both in vivo and in vitro and suppressed the expression of Wnt/β-catenin pathway genes, including β-catenin, Cyclin D1, and c-Myc. Moreover, we demonstrated that Coronin 3 regulates the expression of β-catenin in glioma. Our results revealed that Coronin 3-stimulated tumor growth was β-catenin-dependent.

CONCLUSION

Our study reveals a new molecular mechanism of Coronin 3 in promoting glioma growth and development through regulating the Wnt/β-catenin signaling pathway.

Equine penile squamous cell carcinoma: expression of biomarker proteins and EcPV2

Equine penile squamous cell carcinoma (EpSCC) is a relatively common cutaneous neoplasm with a poor prognosis. In this study, we aimed to determine the protein expression and colocalisation of FRA1, c-Myc, Cyclin D1, and MMP7 in normal (NT), tumour (T), hyperplastic epidermis and/or squamous papilloma (Hyp/Pap), poorly-differentiated (PDSCC), or well-differentiated (WDSCC) EpSCC using a tissue array approach. Further objectives were to correlate protein expression to (i) levels of inflammation, using a convolutional neural network (ii) equine papillomavirus 2 (EcPV2) infection, detected using PCR amplification. We found an increase in expression of FRA1 in EpSCC compared to NT samples. c-Myc expression was higher in Hyp/Pap and WDSCC but not PDSCC whereas MMP7 was reduced in WDSCC compared with NT. There was a significant increase in the global intersection coefficient (GIC) of FRA1 with MMP7, c-Myc, and Cyclin D1 in EpSCC. Conversely, GIC for MMP7 with c-Myc was reduced in EpSCC tissue. Inflammation was positively associated with EcPV2 infection in both NT and EpSCC but not Hyp/Pap. Changes in protein expression could be correlated with EcPV2 for Cyclin D1 and c-Myc. Our results evaluate novel biomarkers of EpSCC and a putative correlation between the expression of biomarkers, EcPV2 infection and inflammation.

The nuclear oncoprotein Fra-1: a transcription factor knocking on therapeutic applications' door

Among the FOS-related members of the AP-1 dimeric complex, the transcription factor Fra-1, encoded by FOSL1, is crucially involved in human tumor progression and metastasis, thus representing a promising therapeutic target. Here we review the state of the art and discuss the emerging topics and perspectives on FOSL1 and its gene product. First, we summarize the present knowledge on the FOSL1 transcriptional and epigenetic controls, driving Fra-1 accumulation in a variety of human solid tumors. We also present a model on the regulatory interactions between Fra-1, p53, and miRNAs. Then, we outline the multiple roles of Fra-1 posttranslational modifications and transactivation mechanisms of select Fra-1 target genes. In addition to summarizing the Fra-1-dependent gene networks controlling proliferation, survival, and epithelial-mesenchymal transitions (EMT) in multiple cancer cell types, we highlight the roles played by Fra-1 in nonneoplastic cell populations recruited to the tumor microenvironment, and in mouse models of tumorigenesis. Next, we review the prognostic power of the Fra-1-associated gene signatures, and envisage potential strategies aimed at Fra-1 therapeutic inhibition. Finally, we discuss several recent reports showing the emerging roles of Fra-1 in the mechanisms of both resistance and addiction to targeted therapies.

Ubiquitin-Specific Protease 21 Promotes Colorectal Cancer Metastasis by Acting as a Fra-1 Deubiquitinase

Fos-related-antigen-1 (Fra-1), a member of the activator protein-1 (AP-1) transcription factor superfamily, has an essential role in cancer progress and metastasis and Fra-1 is considered a therapeutic target in metastatic cancer including metastatic colorectal cancer (mCRC). However, its regulation at protein level has not yet been clearly elucidated. We found that ubiquitin-specific protease 21 (USP21) increases Fra-1 stability by deubiquitinating Fra-1 and enhances the expression of Fra-1 target genes in colon cancer cells. We also showed that USP21 controlled Fra-1-dependent migration and invasion activities. The oncogenic property of USP21 was confirmed by a significant reduction in liver metastasis when USP21-knockdown cancer cells were injected intrasplenically into mice. Consistently, clinicopathological analysis of colorectal cancer patients revealed a correlation of USP21 expression with high-grade carcinoma and life span. These results demonstrate that USP21 enhances Fra-1 stability and AP-1 target gene expression by deubiquitinating Fra-1. Therefore, USP21 is considered an attractive therapeutic target in mCRC with high Fra-1 expression.

PELP1 promotes glioblastoma progression by enhancing Wnt/β-catenin signaling

Background

Glioblastoma (GBM) is a deadly neoplasm of the central nervous system. The molecular mechanisms and players that contribute to GBM development is incompletely understood.

Methods

The expression of PELP1 in different grades of glioma and normal brain tissues was analyzed using immunohistochemistry on a tumor tissue array. PELP1 expression in established and primary GBM cell lines was analyzed by Western blotting. The effect of PELP1 knockdown was studied using cell proliferation, colony formation, migration, and invasion assays. Mechanistic studies were conducted using RNA-seq, RT-qPCR, immunoprecipitation, reporter gene assays, and signaling analysis. Mouse orthotopic models were used for preclinical evaluation of PELP1 knock down.

Results

Nuclear receptor coregulator PELP1 is highly expressed in gliomas compared to normal brain tissues, with the highest expression in GBM. PELP1 expression was elevated in established and patient-derived GBM cell lines compared to normal astrocytes. Knockdown of PELP1 resulted in a significant decrease in cell viability, survival, migration, and invasion. Global RNA-sequencing studies demonstrated that PELP1 knockdown significantly reduced the expression of genes involved in the Wnt/β-catenin pathway. Mechanistic studies demonstrated that PELP1 interacts with and functions as a coactivator of β-catenin. Knockdown of PELP1 resulted in a significant increase in survival of mice implanted with U87 and GBM PDX models.

Conclusions

PELP1 expression is upregulated in GBM and PELP1 signaling via β-catenin axis contributes to GBM progression. Thus, PELP1 could be a potential target for the development of therapeutic intervention in GBM.

Hypoxia‑inducible factors in hepatocellular carcinoma (Review)

Maintenance of an appropriate oxygen concentration is essential for the function of the liver. However, in many pathological conditions, and particularly in the tumor microenvironment, cells and tissues are frequently in a hypoxic state. In the presence of hypoxia, the cells adapt to the low oxygen levels through the hypoxia-inducible factor (HIF) pathway. Overgrowth of tumor cells restricts the diffusion of oxygen in tumors, leading to insufficient blood supply and the creation of a hypoxic microenvironment, and, as a consequence, activation of the expression of HIFs. HIFs possess a wide range of target genes, which function to control a variety of signaling pathways; thus, HIFs modulate cellular metabolism, immune escape, angiogenesis, metastasis, extracellular matrix remodeling, cancer stem cells and other properties of the tumor. Given their crucial role in the occurrence and development of tumors, HIFs are expected to become new targets of precise treatment of hepatocellular carcinoma.

Expression and function of FRA1 protein in tumors

AP-1 is a dimeric complex that is composed of JUN, FOS, ATF and MAF protein families. FOS-related antigen 1 (FRA1) which encoded by FOSL1 gene, belongs to the FOS protein family, and mainly forms an AP-1 complex with the protein of the JUN family to exert an effect. Regulation of FRA1 occurs at levels of transcription and post-translational modification, and phosphorylation is the major post-translational modification. FRA1 is mainly regulated by the mitogen-activated protein kinases signaling pathway and is degraded by ubiquitin-independent proteasomes. FRA1 can affect biological functions, such as tumor proliferation, differentiation, invasion and apoptosis. Studies have demonstrated that FRA1 is abnormally expressed in many tumors and plays a relevant role, but the specific condition varies from the target organs. FRA1 is overexpressed in breast cancer, lung cancer, colorectal cancer, prostate cancer, nasopharyngeal cancer, thyroid cancer and other tumors. However, the expression of FRA1 is decreased in cervical cancer, and the expression of FRA1 in ovarian cancer and oral squamous cell carcinoma is still controversial. In this review, we present a detailed description of the regulatory factors and functions of FRA1, also, the expression of FRA1 in various tumors and its function in relative tumor.

RBM47-regulated alternative splicing of TJP1 promotes actin stress fiber assembly during epithelial-to-mesenchymal transition

Morphological and functional changes in cells during the epithelial-mesenchymal transition (EMT) process are known to be regulated by alternative splicing. However, only a few splicing factors involved in EMT have been reported and their underlying mechanisms remain largely unknown. Here, we showed that an isoform of tight junction protein 1 (TJP1) lacking exon 20 (TJP1-α-) is predominantly expressed in tumor tissues and in A549 cells during transforming growth factor-β (TGF-β)-induced EMT. RBM47 promoted the inclusion of exon 20 of TJP1, the alternative exon encoding the α-domain, by which RBM47 recognizes to (U)GCAUG in the downstream intronic region of exon 20. We also found that the first RNA recognition motif (RRM) domain of RBM47 is critical in the regulation of alternative splicing and its recognition to pre-mRNA of TJP1. Furthermore, we demonstrated that the TJP1-α- isoform enhances the assembly of actin stress fibers, thereby promoting cellular migration in a wound healing assay. Our results suggest the regulatory mechanism for the alternative splicing of TJP1 pre-mRNA by RBM47 during EMT, providing a basis for studies related to the modulation of EMT via alternative splicing.

SWIM tool application to expression data of glioblastoma stem-like cell lines, corresponding primary tumors and conventional glioma cell lines

BACKGROUND

It is well-known that glioblastoma contains self-renewing, stem-like subpopulation with the ability to sustain tumor growth. These cells - called cancer stem-like cells - share certain phenotypic characteristics with untransformed stem cells and are resistant to many conventional cancer therapies, which might explain the limitations in curing human malignancies. Thus, the identification of genes controlling the differentiation of these stem-like cells is becoming a successful therapeutic strategy, owing to the promise of novel targets for treating malignancies.

METHODS

Recently, we developed SWIM, a software able to unveil a small pool of genes - called switch genes - critically associated with drastic changes in cell phenotype. Here, we applied SWIM to the expression profiling of glioblastoma stem-like cells and conventional glioma cell lines, in order to identify switch genes related to stem-like phenotype.

RESULTS

SWIM identifies 171 switch genes that are all down-regulated in glioblastoma stem-like cells. This list encompasses genes like CAV1, COL5A1, COL6A3, FLNB, HMMR, ITGA3, ITGA5, MET, SDC1, THBS1, and VEGFC, involved in "ECM-receptor interaction" and "focal adhesion" pathways. The inhibition of switch genes highly correlates with the activation of genes related to neural development and differentiation, such as the 4-core OLIG2, POU3F2, SALL2, SOX2, whose induction has been shown to be sufficient to reprogram differentiated glioblastoma into stem-like cells. Among switch genes, the transcription factor FOSL1 appears as the brightest star since: it is down-regulated in stem-like cells; it highly negatively correlates with the 4-core genes that are all up-regulated in stem-like cells; the promoter regions of the 4-core genes harbor a consensus binding motif for FOSL1.

CONCLUSIONS

We suggest that the inhibition of switch genes in stem-like cells could induce the deregulation of cell communication pathways, contributing to neoplastic progression and tumor invasiveness. Conversely, their activation could restore the physiological equilibrium between cell adhesion and migration, hampering the progression of cancer. Moreover, we posit FOSL1 as promising candidate to orchestrate the differentiation of cancer stem-like cells by repressing the 4-core genes' expression, which severely halts cancer growth and might affect the therapeutic outcome. We suggest FOSL1 as novel putative therapeutic and prognostic biomarker, worthy of further investigation.

Loss of GINS2 inhibits cell proliferation and tumorigenesis in human gliomas

AIMS

In this study, we examined the expression of GINS2 in glioma and determined its role in glioma development.

METHODS

The protein expression of GINS2 was assessed in 120 human glioma samples via immunohistochemistry. Then, we suppressed the expression of GINS2 in glioma cell strains U87 and U251 using a short hairpin RNA lentiviral vector. In addition, RNA sequencing and bioinformatics analysis were performed on glioma cells before and after GINS2 knockdown. Subsequent co-immunoprecipitation and western blot experiments indicated possible downstream regulatory molecules.

RESULTS

The present results showed that GINS2 can accelerate the growth of glioma cells, whereas the suppression of GINS2 expression decreased the proliferation and tumorigenicity of glioma cells. Mechanism research experiments proved that GINS2 can block the cell cycle by regulating certain downstream molecules, such as MCM2, ATM, and CHEK2.

CONCLUSION

GINS2 is closely related to the occurrence and development of glioma, and is likely to become a prognostic marker for glioma patients, as well as a potential therapeutic target in the treatment of glioma.

The Role of Notch3 in Cancer

The Notch family is a highly conserved gene group that regulates cell-cell interaction, embryogenesis, and tissue commitment. This review article focuses on the third Notch family subtype, Notch3. Regulation via Notch3 signaling was first implicated in vasculogenesis. However, more recent findings suggest that Notch3 signaling may play an important role in oncogenesis, tumor maintenance, and resistance to chemotherapy. Its role is mainly oncogenic, although in some cancers it appears to be tumor suppressive. Despite the wealth of published literature, it remains relatively underexplored and requires further research to shed more light on its role in cancer development, determine its tissue-specific function, and elaborate novel treatment strategies. Herein we summarize the role of Notch3 in cancer, possible mechanisms of its action, and current cancer treatment strategies targeting Notch3 signaling.

IMPLICATIONS FOR PRACTICE

The Notch family is a highly conserved gene group that regulates cell-cell interaction, embryogenesis, and tissue commitment. This review summarizes the existing data on the third subtype of the Notch family, Notch3. The role of Notch3 in different types of cancers is discussed, as well as implications of its modification and new strategies to affect Notch3 signaling activity.

Developmentally regulated signaling pathways in glioma invasion

Malignant gliomas are the most common, infiltrative, and lethal primary brain tumors affecting the adult population. The grim prognosis for this disease is due to a combination of the presence of highly invasive tumor cells that escape surgical resection and the presence of a population of therapy-resistant cancer stem cells found within these tumors. Several studies suggest that glioma cells have cleverly hijacked the normal developmental program of neural progenitor cells, including their transcriptional programs, to enhance gliomagenesis. In this review, we summarize the role of developmentally regulated signaling pathways that have been found to facilitate glioma growth and invasion. Furthermore, we discuss how the microenvironment and treatment-induced perturbations of these highly interconnected signaling networks can trigger a shift in cellular phenotype and tumor subtype.

Decreased carbonyl reductase 1 expression promotes tumor growth via epithelial mesenchymal transition in uterine cervical squamous cell carcinomas

Purpose

Carbonyl reductase 1 (CBR1) is involved in cancer progression. Recently, the authors reported that the loss of CBR1 expression is associated with a poor prognosis in uterine cervical cancer. Here, we investigated whether the decreased CBR1 expression promotes cancer progression by inducing the epithelial mesenchymal transition (EMT).

Methods

Antisense constructs of CBR1 complementary DNA (antisense clones) and the empty vectors (control clones) were transfected into human uterine cervical squamous cell carcinoma cell lines (SKG II and SiHa) and the proliferation and EMT marker expression of these clones were analyzed in vitro. In an in vivo study, 10⁷ cells of the antisense and control clones were subcutaneously injected into nude mice and the tumorigenesis was observed for 8 weeks.

Results

With the decreased CBR1 expression, the proliferation of the antisense clones increased, accompanied by a decrease in epithelial markers (E-cadherin and cytokeratin) and an increase in mesenchymal markers (fibronectin, alpha-smooth muscle actin, and N-cadherin), which suggests EMT induction. In the in vivo study, the tumor volume in the antisense group was significantly larger than that in the control group.

Conclusion

Decreased CBR1 expression promotes tumor growth by inducing EMT in uterine cervical squamous cell carcinomas.

Melatonin attenuates hypoxia-induced epithelial-mesenchymal transition and cell aggressive via Smad7/ CCL20 in glioma

Tumor recurrence in gliomas is partly attributed to increased epithelial-mesenchymal transition (EMT) and enhanced tumor cell dissemination in the adjacent brain parenchyma. Thus, exploring effective strategies for against EMT-like changes in glioma invasion and recurrence will be important for glioma treatment. In this study, we investigated the roles of melatonin in hypoxia-induced EMT suppression, and found that melatonin could significantly suppress the release of the cytokine, CCL20, from cancer cells and antagonize glioma cell metastasis and invasion under hypoxic stress in glioma cells. Furthermore, our findings show that melatonin deregulates Smad7 expression to suppress TGFβ/Smad-mediated increase in CCL20 transcript levels and CCL20-induced EMT occurrence, suggesting a potential anti-EMT therapeutic role for melatonin in malignant transformation in gliomas.

Roles of Wnt Target Genes in the Journey of Cancer Stem Cells

The importance of Wnt/β-catenin signaling in cancer stem cells (CSCs) has been acknowledged; however, the mechanism through which it regulates the biological function of CSCs and promotes cancer progression remains elusive. Hence, to understand the intricate mechanism by which Wnt controls stemness, the specific downstream target genes of Wnt were established by analyzing the genetic signatures of multiple types of metastatic cancers based on gene set enrichment. By focusing on the molecular function of Wnt target genes, the biological roles of Wnt were interpreted in terms of CSC dynamics from initiation to metastasis. Wnt signaling participates in cancer initiation by generating CSCs from normal stem cells or non-CSCs and augmenting persistent growth at the primary region, which is resistant to anti-cancer therapy. Moreover, it assists CSCs in invading nearby tissues and in entering the blood stream, during which the negative feedback of the Wnt signaling pathway maintains CSCs in a dormant state that is suitable for survival. When CSCs arrive at distant organs, another burst of Wnt signaling induces CSCs to succeed in re-initiation and colonization. This comprehensive understanding of Wnt target genes provides a plausible explanation for how Wnt allows CSCs variation during cancer progression.