Autophosphorylation sites on the epidermal growth factor receptor

The impact of nitric oxide on HER family post-translational modification and downstream signaling in cancer

The human epidermal growth factor receptor (HER) family consists of four members, activated by two families of ligands. They are known for mediating cell-cell interactions in organogenesis, and their deregulation has been associated with various cancers, including breast and esophageal cancers. In particular, aberrant epidermal growth factor receptor (EGFR) and HER2 signaling drive disease progression and result in poorer patient outcomes. Nitric oxide (NO) has been proposed as an alternative activator of the HER family and may play a role in this aberrant activation due to its ability to induce s-nitrosation and phosphorylation of the EGFR. This review discusses the potential impact of NO on HER family activation and downstream signaling, along with its role in the efficacy of therapeutics targeting the family.

Identification of epidermal growth factor receptor-tyrosine kinase inhibitor targeting the VP1 pocket of human rhinovirus

Screening a library of 1,200 preselected kinase inhibitors for anti-human rhinovirus 2 (HRV-2) activity in HeLa cells identified a class of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) as effective virus blockers. These were based on the 4-anilinoquinazoline-7-oxypiperidine scaffold, with the most potent representative AZ5385 inhibiting the virus with EC50 of 0.35 µM. Several structurally related analogs confirmed activity in the low µM range, while interestingly, other TKIs targeting EGFR lacked anti-HRV-2 activity. To further probe this lack of association between antiviral activity and EGFR inhibition, we stained infected cells with antibodies specific for activated EGFR (Y1068) and did not observe a dependency on EGFR-TK activity. Instead, consecutive passages of HRV-2 in HeLa cells in the presence of a compound and subsequent nucleotide sequence analysis of resistant viral variants identified the S181T and T210A alterations in the major capsid VP1 protein, with both residues located in the vicinity of a known hydrophobic pocket on the viral capsid. Further characterization of the antiviral effects of AZ5385 showed a modest virus-inactivating (virucidal) activity, while anti-HRV-2 activity was still evident when the inhibitor was added as late as 10 h post infection. The RNA copy/infectivity ratio of HRV-2 propagated in AZ5385 presence was substantially higher than that of control HRV indicating that the compound preferentially targeted HRV progeny virions during their maturation in infected cells. Besides HRV, the compound showed anti-respiratory syncytial virus activity, which warrants its further studies as a candidate compound against viral respiratory infections.

Osimertinib Covalently Binds to CD34 and Eliminates Myeloid Leukemia Stem/Progenitor Cells

Osimertinib is a third-generation covalent EGFR inhibitor that is used in treating non-small cell lung cancer. First-generation EGFR inhibitors were found to elicit pro-differentiation effect on acute myeloid leukemia (AML) cells in preclinical studies, but clinical trials yielded mostly negative results. Here, we report that osimertinib selectively induced apoptosis of CD34+ leukemia stem/progenitor cells but not CD34- cells in EGFR-negative AML and chronic myeloid leukemia (CML). Covalent binding of osimertinib to CD34 at cysteines 199 and 177 and suppression of Src family kinases (SFK) and downstream STAT3 activation contributed to osimertinib-induced cell death. SFK and STAT3 inhibition induced synthetic lethality with osimertinib in primary CD34+ cells. CD34 expression was elevated in AML cells compared with their normal counterparts. Genomic, transcriptomic, and proteomic profiling identified mutation and gene expression signatures of patients with AML with high CD34 expression, and univariate and multivariate analyses indicated the adverse prognostic significance of high expression of CD34. Osimertinib treatment induced responses in AML patient-derived xenograft models that correlated with CD34 expression while sparing normal CD34+ cells. Clinical responses were observed in two patients with CD34high AML who were treated with osimertinib on a compassionate-use basis. These findings reveal the therapeutic potential of osimertinib for treating CD34high AML and CML and describe an EGFR-independent mechanism of osimertinib-induced cell death in myeloid leukemia.

SIGNIFICANCE

Osimertinib binds CD34 and selectively kills CD34+ leukemia cells to induce remission in preclinical models and patients with AML with a high percentage of CD34+ blasts, providing therapeutic options for myeloid leukemia patients.

Loss of EGF receptor polarity enables homeostatic imbalance in epithelial-cell models

The polarized distribution of membrane proteins into apical and basolateral domains provides the basis for specialized functions of epithelial tissues. The EGF receptor (EGFR) plays important roles in embryonic development, adult-epithelial tissue homeostasis, and growth and survival of many carcinomas. Typically targeted to basolateral domains, there is also considerable evidence of EGFR sorting plasticity but very limited knowledge regarding domain-specific EGFR substrates. Here we have investigated effects of selective EGFR mistargeting because of inactive-basolateral sorting signals on epithelial-cell homeostatic responses to growth-induced stress in MDCK cell models. Aberrant EGFR localization was associated with multilayer formation, anchorage-independent growth, and upregulated expression of the intermediate filament-protein vimentin characteristically seen in cells undergoing epithelial-to-mesenchymal transition. EGFRs were selectively retained following their internalization from apical membranes, and a signaling pathway involving the signaling adaptor Gab1 protein and extracellular signal-regulated kinase ERK5 had an essential role integrating multiple responses to growth-induced stress. Our studies highlight the potential importance of cellular machinery specifying EGFR polarity in epithelial pathologies associated with homeostatic imbalance.

Structure-Based Virtual Screening, Molecular Docking, Molecular Dynamics Simulation of EGFR for the Clinical Treatment of Glioblastoma

Glioblastoma (GBM) is a WHO Grade IV tumor with poor visibility, a high risk of comorbidity, and exhibit limited treatment options. Resurfacing from second-rate glioma was originally classified as either mandatory or optional. Recent interest in personalized medicine has motivated research toward biomarker stratification-based individualized illness therapy. GBM biomarkers have been investigated for their potential utility in prognostic stratification, driving the development of targeted therapy and customizing therapeutic treatment. Due to the availability of a specific EGFRvIII mutational variation with a clear function in glioma-genesis, recent research suggests that EGFR has the potential to be a prognostic factor in GBM, while others have shown no clinical link between EGFR and survival. The pre-existing pharmaceutical lapatinib (PubChem ID: 208,908) with a higher affinity score is used for virtual screening. As a result, the current study revealed a newly screened chemical (PubChem CID: 59,671,768) with a higher affinity than the previously known molecule. When the two compounds are compared, the former has the lowest re-rank score. The time-resolved features of a virtually screened chemical and an established compound were investigated using molecular dynamics simulation. Both compounds are equivalent, according to the ADMET study. This report implies that the virtual screened chemical could be a promising Glioblastoma therapy.

A perspective of fluorescence microscopy for cellular structural biology with EGFR as witness

The epidermal growth factor receptor (EGFR) is a poster child for the understanding of receptor behaviour, and of paramount importance to cell function and human health. Cloned almost forty years ago, the interest in EGFR's structure/function relationships remains unabated, not least because changes in oncogenic EGFR mutants are key drivers of the formation of lung and brain tumours. The structure of the assemblies formed by EGFR have been comprehensibly investigated by techniques such as high-resolution X-ray crystallography, NMR and all-atom molecular dynamics (MD) simulations. However, the complexity embedded in the portfolio of EGFR states that are only possible in the physiological environment of cells has often proved refractory to cell-free structural methods. Conversely, some key inroads made by quantitative fluorescence microscopy and super-resolution have depended on exploiting the wealth of structures available. Here, a brief personal perspective is provided on how quantitative fluorescence microscopy and super-resolution methods have cross-fertilised with cell-free-derived EGFR structural information. I primarily discuss areas in which my research group has made a contribution to fill gaps in EGFR's cellular structural biology and towards developing new tools to investigate macromolecular assemblies in cells.

LRRK1 functions as a scaffold for PTP1B-mediated EGFR sorting into ILVs at the ER-endosome contact site

Proper control of epidermal growth factor receptor (EGFR) signaling is important for maintaining cellular homeostasis. Given that EGFR signaling occurs at the plasma membrane and endosomes following internalization, endosomal trafficking of EGFR spatiotemporally regulates EGFR signaling. In this process, leucine-rich repeat kinase 1 (LRRK1) has multiple roles in kinase activity-dependent transport of EGFR-containing endosomes and kinase-independent sorting of EGFR into the intraluminal vesicles (ILVs) of multivesicular bodies. Active, phosphorylated EGFR inactivates the LRRK1 kinase activity by phosphorylating Y944. In this study, we demonstrate that LRRK1 facilitates EGFR dephosphorylation by PTP1B (also known as PTPN1), an endoplasmic reticulum (ER)-localized protein tyrosine phosphatase, at the ER-endosome contact site, after which EGFR is sorted into the ILVs of endosomes. LRRK1 is required for the PTP1B-EGFR interaction in response to EGF stimulation, resulting in the downregulation of EGFR signaling. Furthermore, PTP1B activates LRRK1 by dephosphorylating pY944 on the contact site, which promotes the transport of EGFR-containing endosomes to the perinuclear region. These findings provide evidence that the ER-endosome contact site functions as a hub for LRRK1-dependent signaling that regulates EGFR trafficking.

Antitumor activity of a lectibody targeting cancer-associated high-mannose glycans

Aberrant protein glycosylation is a hallmark of cancer, but few drugs targeting cancer glycobiomarkers are currently available. Here, we showed that a lectibody consisting of the high-mannose glycan-binding lectin Avaren and human immunoglobulin G1 (IgG1) Fc (AvFc) selectively recognizes a range of cell lines derived from lung, breast, colon, and blood cancers at nanomolar concentrations. Binding of AvFc to the non-small cell lung cancer (NSCLC) cell lines A549 and H460 was characterized in detail. Co-immunoprecipitation proteomics analysis revealed that epidermal growth factor receptor (EGFR) and insulin-like growth factor 1 receptor (IGF1R) are among the lectibody's common targets in these cells. AvFc blocked the activation of EGFR and IGF1R by their respective ligands in A549 cells and inhibited the migration of A549 and H460 cells upon stimulation with EGF and IGF1. Furthermore, AvFc induced potent Fc-mediated cytotoxic effects and significantly restricted A549 and H460 tumor growth in severe combined immunodeficiency (SCID) mice. Immunohistochemistry analysis of primary lung tissues from NSCLC patients demonstrated that AvFc preferentially binds to tumors over adjacent non-tumor tissues. Our findings provide evidence that increased abundance of high-mannose glycans in the glycocalyx of cancer cells can be a druggable target, and AvFc may provide a new tool to probe and target this tumor-associated glycobiomarker.

Zinc Status Impacts the Epidermal Growth Factor Receptor and Downstream Protein Expression in A549 Cells

Zinc has been suggested to play a role in carcinogenesis and tumor progression. Serum zinc levels of lung cancer patients are for example lower than in healthy individuals. The activation and expression of the epidermal growth factor receptor (EGFR), which plays a role in tumor biology, are presumably influenced by zinc. EGFR activation influences cell adhesion and immune escape. This study provides insights into the impacts of zinc on the EGFR activation and expression of downstream proteins such as E-cadherin and PD-L1 in the alveolar carcinoma cell line A549. To model chronic changes in zinc homeostasis, A549 cells were cultured in media with different zinc contents. EGFR surface expression of unstimulated and stimulated A549 cells was determined by flow cytometry. EGFR phosphorylation as well as the protein expression of E-cadherin and PD-L1 were analyzed by Western blot. In our hands, chronic zinc deficiency led to increased EGFR surface expression, decreased E-cadherin protein expression and increased PD-L1 protein expression. Zinc supplementation decreased EGFR surface expression and PD-L1 protein expression. In summary, zinc-deficient A549 cells may display a more malignant phenotype. Thus, future clinical research should further focus on the possible benefits of restoring disturbed zinc homeostasis, especially in lung cancer patients.

Allosteric activation of preformed EGF receptor dimers by a single ligand binding event

Aberrant activation of the epidermal growth factor receptor (EGFR) by mutations has been implicated in a variety of human cancers. Elucidation of the structure of the full-length receptor is essential to understand the molecular mechanisms underlying its activation. Unlike previously anticipated, here, we report that purified full-length EGFR adopts a homodimeric form in vitro before and after ligand binding. Cryo-electron tomography analysis of the purified receptor also showed that the extracellular domains of the receptor dimer, which are conformationally flexible before activation, are stabilized by ligand binding. This conformational flexibility stabilization most likely accompanies rotation of the entire extracellular domain and the transmembrane domain, resulting in dissociation of the intracellular kinase dimer and, thus, rearranging it into an active form. Consistently, mutations of amino acid residues at the interface of the symmetric inactive kinase dimer spontaneously activate the receptor in vivo. Optical observation also indicated that binding of only one ligand activates the receptor dimer on the cell surface. Our results suggest how oncogenic mutations spontaneously activate the receptor and shed light on the development of novel cancer therapies.

The Epithelial-Mesenchymal Transition Influences the Resistance of Oral Squamous Cell Carcinoma to Monoclonal Antibodies via Its Effect on Energy Homeostasis and the Tumor Microenvironment

Oral squamous cell carcinoma (OSCC) is a major type of cancer that accounts for over 90% of all oral cancer cases. Recently developed evidence-based therapeutic regimens for OSCC based on monoclonal antibodies (mAbs), such as cetuximab, pembrolizumab, and nivolumab, have attracted considerable attention worldwide due to their high specificity, low toxicity, and low rates of intolerance. However, the efficacy of those three mAbs remains poor because of the low rate of responders and acquired resistance within a short period of time. The epithelial-mesenchymal transition (EMT) process is fundamental for OSCC growth and metastasis and is also responsible for the poor response to mAbs. During EMT, cancer cells consume abundant energy substrates and create an immunosuppressive tumor microenvironment to support their growth and evade T cells. In this review, we provide an overview of the complex roles of major substrates and signaling pathways involved in the development of therapeutic resistance in OSCC. In addition, we summarize potential therapeutic strategies that may help overcome this resistance. This review aims to help oral oncologists and researchers aiming to manage OSCC and establish new treatment modalities.

Epidermal growth factor receptor inhibitors as potential anticancer agents: An update of recent progress

Epidermal growth factor receptor (EGFR) is a vital intermediate in cell signaling pathway including cell proliferation, angiogenesis, apoptosis, and metastatic spread and also having four divergent members with similar structural features, such as EGFR (HER1/ErbB1), ErbB2 (HER2/neu), ErbB3 (HER3), and ErbB4 (HER4). Despite this, clinically exploited inhibitors of EGFR (including erlotinib, lapatinib, gefitinib, selumetinib, etc.) are not specific thus provoking unenviable adverse effects. Some of the paramount obstacles to generate and develop new lead molecules of EGFR inhibitors are drug resistance, mutation, and also selectivity which inspire medicinal chemists to generate novel chemotypes. The discovery of therapeutic agents that inhibit the precise stage in tumorous cells such as EGFR is one of the chief successful targets in many cancer therapies, including lung and breast cancers. This review aims to compile the various recent progressions (2016-2021) in the discovery and development of diverse epidermal growth factor receptor (EGFR) inhibitors belonging to distinct structural classes like pyrazoline, pyrazole, imidazole, pyrimidine, coumarin, benzothiazole, etc. We have summarized preclinical and clinical data, structure-activity relationships (SAR) containing mechanistic and in silico studies to provide proposals for the design and invention of new EGFR inhibitors with therapeutic significance. The detailed progress of the work in the field will provide inexorable scope for the development of novel drug candidates with greater selectivity and efficacy.

A Review: Discovering 1,3,4-oxadiazole and chalcone nucleus for cytotoxicity/EGFR inhibitory anticancer activity

INTRODUCTION

Cancer is reported to be one of the most life-threatening diseases. Major limitations of currently used anticancer agents are drug resistance, very small therapeutic index, and severe, multiple side effects.

OBJECTIVE

The current scenario necessitates developing new anticancer agents, acting on novel targets for effectively controlling cancer. The epidermal growth factor receptor is one such target, which is being explored for 1,3,4-oxadiazole and chalcone nuclei.

METHOD

Findings of different researchers working on these scaffolds have been reviewed and analyzed, and the outcomes were summarized. This review focuses on Structure-Activity Relationship studies (SARs) and computational studies of various 1,3,4-oxadiazole and chalcone hybrids/derivatives reported as cytotoxic/EGFR-TK inhibitory anticancer activity.

RESULT AND CONCLUSION

1,3,4-oxadiazole and chalcone hybrids/derivatives with varied substitutions are found to be effective pharmacophores in obtaining potent anticancer activity. Having done a thorough literature survey, we conclude that this review will surely provide firm and better insights to the researchers to design and develop potent hybrids/derivatives that inhibit EGFR.

Epidermal growth factor receptor and integrins meet redox signaling through P66shc and Rac1

This review examines the concerted role of Epidermal Growth Factor Receptor (EGFR) and integrins in regulating Reactive oxygen species (ROS) production through different signaling pathways. ROS as such are not always deleterious to the cells but they also act as signaling molecules, that regulates numerous indespensible physiological fuctions of life. Many adaptor proteins, particularly Shc and Grb2, are involved in mediating the downstream signaling pathways stimulated by EGFR and integrins. Integrin-induced activation of EGFR and subsequent tyrosine phosphorylation of a class of acceptor sites on EGFR leads to alignment and tyrosine phosphorylation of Shc, PLCγ, the p85 subunit of PI-3 K, and Cbl, followed by activation of the downstream targets Erk and Akt/PKB. Functional interactions between these receptors result in the activation of Rac1 via these adaptor proteins, thereby leading to Reactive Oxygen Species. Both GF and integrin activation can produce oxidants independently, however synergistically there is increased ROS generation, suggesting a mutual cooperation between integrins and GFRs for redox signalling. The ROS produced further promotes feed-forward stimulation of redox signaling events such as MAPK activation and gene expression. This relationship has not been reviewed previously. The literature presented here can have multiple implications, ranging from looking at synergistic effects of integrin and EGFR mediated signaling mechanisms of different proteins to possible therapeutic interventions operated by these two receptors. Furthermore, such mutual redox regulation of crosstalk between EGFR and integrins not only add to the established models of pathological oxidative stress, but also can impart new avenues and opportunities for targeted antioxidant based therapeutics.

mTOR-Rictor-EGFR axis in oncogenesis and diagnosis of glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the aggressive brain cancers with patients having less survival period upto 12-15 months. Mammalian target of rapamycin (mTOR) is a serine/threonine kinase, belongs to the phosphatidylinositol 3-kinases (PI3K) pathway and is involved in various cellular processes of cancer cells. Cancer metabolism is regulated by mTOR and its components. mTOR forms two complexes as mTORC1 and mTORC2. Studies have identified the key component of the mTORC2 complex, Rapamycin-insensitive companion of mammalian target of rapamycin (Rictor) plays a prominent role in the regulation of cancer cell proliferation and metabolism. Apart, growth factor receptor signaling such as epidermal growth factor signaling mediated by epidermal growth factor receptor (EGFR) regulates cancer-related processes. In EGFR signaling various other signaling cascades such as phosphatidyl-inositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR pathway) and Ras/Raf/mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) -dependent signaling cross-talk each other. From various studies about GBM, it is very well established that Rictor and EGFR mediated signaling pathways majorly playing a pivotal role in chemoresistance and tumor aggressiveness. Recent studies have shown that non-coding RNAs such as microRNAs (miRs) and long non-coding RNAs (lncRNAs) regulate the EGFR and Rictor and sensitize the cells towards chemotherapeutic agents. Thus, understanding of microRNA mediated regulation of EGFR and Rictor will help in cancer prevention and management as well as a future therapy.

Circular RNA-encoded oncogenic E-cadherin variant promotes glioblastoma tumorigenicity through activation of EGFR-STAT3 signalling

Activated EGFR signalling drives tumorigenicity in 50% of glioblastoma (GBM). However, EGFR-targeting therapy has proven ineffective in treating patients with GBM, indicating that there is redundant EGFR activation. Circular RNAs are covalently closed RNA transcripts that are involved in various physiological and pathological processes. Herein, we report an additional activation mechanism of EGFR signalling in GBM by an undescribed secretory E-cadherin protein variant (C-E-Cad) encoded by a circular E-cadherin (circ-E-Cad) RNA through multiple-round open reading frame translation. C-E-Cad is overexpressed in GBM and promotes glioma stem cell tumorigenicity. C-E-Cad activates EGFR independent of EGF through association with the EGFR CR2 domain using a unique 14-amino-acid carboxy terminus, thereby maintaining glioma stem cell tumorigenicity. Notably, inhibition of C-E-Cad markedly enhances the antitumour activity of therapeutic anti-EGFR strategies in GBM. Our results uncover a critical role of C-E-Cad in stimulating EGFR signalling and provide a promising approach for treating EGFR-driven GBM.

Deciphering the T790M/L858R-Selective Inhibition Mechanism of an Allosteric Inhibitor of EGFR: Insights from Molecular Simulations

Allosteric inhibitors have lately received great attention because of their unique advantages, representing a more suitable choice for combinatory therapeutics targeting resistance-relevant signaling cascades. Among the various inhibitors, an allosteric small-molecule inhibitor, JBJ-04-125-02, has been proven to be effective against EGFR^T790M/L858R mutant in vivo and in vitro. Herein, an in silico approach was adopted to shed light on the deep understanding of the higher selectivity of JBJ-04-125-02 against EGFR^T790M/L858R mutant than wild-type EGFR. Our results indicate that JBJ-04-125-02 prefers to bind with the EGFR^T790M/L858R mutant, stabilizes the inactive conformation, and further allosterically affects the conformations and dynamics of the interlobe cleft, including both the allosteric site and the ATP-binding site. Furthermore, docking results confirm that the binding of JBJ-04-125-02 at the allosteric site decreases the binding affinity of ANP (an ATP analogue) at the orthosteric site, especially for the Mut-holo one, which might further inhibit the function of EGFR. The present work provides a clear picture of the mutant-selective inhibition mechanism of an allosteric inhibitor of EGFR. The findings might pave the way for designing allosteric drugs targeting EGFR mutant lung cancer patients, which also takes a step forward in terms of drug resistance caused by protein mutations.

The Role of Epidermal Growth Factor Receptor Signaling Pathway during Bovine Herpesvirus 1 Productive Infection in Cell Culture

Accumulating studies have shown that the epidermal growth factor receptor (EGFR) signaling pathway plays an essential role in mediating cellular entry of numerous viruses. In this study, we report that bovine herpesvirus 1 (BoHV-1) productive infection in both the human lung carcinoma cell line A549 and bovine kidney (MDBK) cells leads to activation of EGFR, as demonstrated by the increased phosphorylation of EGFR at Tyr1068 (Y1068), which in turn plays important roles in virus infection. A time-of-addition assay supported that virus replication at post-entry stages was affected by the EGFR specific inhibitor Gefitinib. Interestingly, both phospholipase C-γ1 (PLC-γ1) and Akt, canonical downstream effectors of EGFR, were activated following virus infection in A549 cells, while Gefitinib could inhibit the activation of PLC-γ1 but not Akt. In addition, virus titers in A549 cells was inhibited by chemical inhibition of PLC-γ1, but not by the inhibition of Akt. However, the Akt specific inhibitor Ly294002 could significantly reduce the virus titer in MDBK cells. Taken together, our data suggest that PLC-γ1 is stimulated in part through EGFR for efficient replication in A549 cells, whereas Akt can be stimulated by virus infection independent of EGFR, and is not essential for virus productive infection, indicating that Akt modulates BoHV-1 replication in a cell type-dependent manner. This study provides novel insights on how BoHV-1 infection activates EGFR signaling transduction to facilitate virus replication.

Novel quinazoline-based EGFR kinase inhibitors: A review focussing on SAR and molecular docking studies (2015-2019)

The over expression of EGFR has been recognized as the driver mechanism in the occurrence and progression of carcinomas such as lung cancer, breast cancer, pancreatic cancer, etcetera. EGFR receptor was thus established as an important target for the management of solid tumors. The occurrence of resistance caused as a result of mutations in EGFR has presented a formidable challenge in the discovery of novel inhibitors of EGFR. This has resulted in the development of three generations of EGFR TKIs. Newer mutations like C797S cause failure of Osimertinib and other EGFR TKIs belonging to the third-generation caused by the development of resistance. In this review, we have summarized the work done in the last five years to overcome the limitations of currently marketed drugs, giving structural activity relationships of quinazoline-based lead compounds synthesized and tested recently. We have also highlighted the shortcomings of the currently used approaches and have provided guidance for circumventing these limitations. Our review would help medicinal chemists streamline and guide their efforts towards developing novel quinazoline-based EGFR inhibitors.

Perturbation biology links temporal protein changes to drug responses in a melanoma cell line

Cancer cells have genetic alterations that often directly affect intracellular protein signaling processes allowing them to bypass control mechanisms for cell death, growth and division. Cancer drugs targeting these alterations often work initially, but resistance is common. Combinations of targeted drugs may overcome or prevent resistance, but their selection requires context-specific knowledge of signaling pathways including complex interactions such as feedback loops and crosstalk. To infer quantitative pathway models, we collected a rich dataset on a melanoma cell line: Following perturbation with 54 drug combinations, we measured 124 (phospho-)protein levels and phenotypic response (cell growth, apoptosis) in a time series from 10 minutes to 67 hours. From these data, we trained time-resolved mathematical models that capture molecular interactions and the coupling of molecular levels to cellular phenotype, which in turn reveal the main direct or indirect molecular responses to each drug. Systematic model simulations identified novel combinations of drugs predicted to reduce the survival of melanoma cells, with partial experimental verification. This particular application of perturbation biology demonstrates the potential impact of combining time-resolved data with modeling for the discovery of new combinations of cancer drugs.

A non-hierarchical organization of tumorigenic NG2 cells in glioblastoma promoted by EGFR

Background

Expression of neuron-glial antigen 2 (NG2) identifies an aggressive malignant phenotype in glioblastoma (GBM). Mouse models have implicated NG2 in the genesis, evolution, and maintenance of glial cancers and have highlighted potential interactions between NG2 and epidermal growth factor receptor (EGFR). However, it is unknown whether the lineage relationship of NG2+ and NG2− cells follows a hierarchical or stochastic mode of growth. Furthermore, the interaction between NG2 and EGFR signaling in human GBM is also unclear.

Methods

Single GBM NG2+ and NG2− cells were studied longitudinally to assess lineage relationships. Short hairpin RNA knockdown of NG2 was used to assess the mechanistic role of NG2 in human GBM cells. NG2+ and NG2− cells and NG2 knockdown (NG2-KD) and wild type (NG2-WT) cells were analyzed for differential effects on EGFR signaling.

Results

Expression of NG2 endows an aggressive phenotype both at single cell and population levels. Progeny derived from single GBM NG2− or GBM NG2+ cells consistently establish phenotypic equilibrium, indicating the absence of a cellular hierarchy. NG2 knockdown reduces proliferation, and mice grafted with NG2-KD survive longer than controls. Finally, NG2 promotes EGFR signaling and is associated with EGFR expression.

Conclusions

These data support a dynamic evolution in which a bidirectional relationship exists between GBM NG2+ and GBM NG2− cells. Such findings have implications for understanding phenotypic heterogeneity, the emergence of resistant disease, and developing novel therapeutics.

Antiproliferative and apoptotic effects of indole derivative, N-(2-hydroxy-5-nitrophenyl (4'-methylphenyl) methyl) indoline in breast cancer cells

Indoline derivatives functions as an inhibitors of epidermal growth factor receptor (EGFR) with the anticancer potential against various cancers. We aim to investigate anti-breast cancer effects and mechanism of action of novel indoline derivatives. Molecular docking of seven indoline derivates with EGFR revealed, N-(2-hydroxy-5-nitrophenyl (4'-methylphenyl) methyl) indoline (HNPMI) as the top lead compound. RT-PCR analysis showed the downregulation of PI3K/S6K1 genes in breast cancer cells through the activation of EGFR with HNPMI. This compound found to have higher cytotoxicity than Cyclophosphamide, with the IC₅₀ of 64.10 μM in MCF-7 and 119.99 μM in SkBr3 cells. HNPMI significantly reduced the cell proliferation of MCF-7 and SkBr3 cells, without affecting non-cancerous cells, H9C2. Induction of apoptosis was analyzed by Caspase-3 and -9, DNA fragmentation, AO/EtBr staining and flow cytometry assays. A fold change of 0.218- and 0.098- for caspase-3 and 0.478- and 0.269- for caspase-9 in MCF7 and SkBr3 cells was observed, respectively. Caspase mediated apoptosis caused DNA fragmentation in breast cancer cells upon HNPMI treatment. The structural elucidation of HNPMI by QSAR model and ADME-Tox suggests, a bi-molecular interaction of HNPMI-EGFR which is related to antiproliferative and apoptotic activity. The data concludes that, HNPMI-induced the apoptosis via EGFR signaling pathway in breast cancer cells. Thus, HNPMI might serve as a scaffold for developing a potential anti-breast cancer therapeutic agent.

Male Breast Cancer: Results of the Application of Multigene Panel Testing to an Italian Cohort of Patients

Male breast cancer (MBC) is a rare tumor, accounting for less than 1% of all breast cancers. In MBC, genetic predisposition plays an important role; however, only a few studies have investigated in depth the role of genes other than BRCA1 and BRCA2. We performed a Next-Generation Sequencing (NGS) analysis with a panel of 94 cancer predisposition genes on germline DNA from an Italian case series of 70 patients with MBC. Moreover, we searched for large deletions/duplications of BRCA1/2 genes through the Multiplex Ligation-dependent Probe Amplification (MLPA) technique. Through the combination of NGS and MLPA, we identified three pathogenic variants in the BRCA1 gene and six in the BRCA2 gene. Besides these alterations, we found six additional pathogenic/likely-pathogenic variants in PALB2, CHEK2, ATM, RAD51C, BAP1 and EGFR genes. From our study, BRCA1 and BRCA2 emerge as the main genes associated with MBC risk, but also other genes seem to be associated with the disease. Indeed, some of these genes have already been implicated in female breast cancer predisposition, but others are known to be involved in other types of cancer. Consequently, our results suggest that novel genes could be involved in MBC susceptibility, shedding new light on their role in cancer development.

Exposure to mold proteases stimulates mucin production in airway epithelial cells through Ras/Raf1/ERK signal pathway

Environmental mold (fungus) exposure poses a significant threat to public health by causing illnesses ranging from invasive fungal diseases in immune compromised individuals to allergic hypertensive diseases such as asthma and asthma exacerbation in otherwise healthy people. However, the molecular pathogenesis has not been completely understood, and treatment options are limited. Due to its thermo-tolerance to the normal human body temperature, Aspergillus. fumigatus (A.fumigatus) is one of the most important human pathogens to cause different lung fungal diseases including fungal asthma. Airway obstruction and hyperresponsiveness caused by mucus overproduction are the hallmarks of many A.fumigatus induced lung diseases. To understand the underlying molecular mechanism, we have utilized a well-established A.fumigatus extracts (AFE) model to elucidate downstream signal pathways that mediate A.fumigatus induced mucin production in airway epithelial cells. AFE was found to stimulate time- and dose-dependent increase of major airway mucin gene expression (MUC5AC and MUC5B) partly via the elevation of their promoter activities. We also demonstrated that EGFR was required but not sufficient for AFE-induced mucin expression, filling the paradoxical gap from a previous study using the same model. Furthermore, we showed that fungal proteases in AFE were responsible for mucin induction by activating a Ras/Raf1/ERK signaling pathway. Ca2+ signaling, but ROS, both of which were stimulated by fungal proteases, was an indispensable determinant for ERK activation and mucin induction. The discovery of this novel pathway likely contributes to our understanding of the pathogenesis of fungal sensitization in allergic diseases such as fungal asthma.

Significance of desmoglein-2 on cell malignant behaviors via mediating MAPK signaling in cervical cancer

Desmoglein-2 (DSG2) is an integral component of desmosomes, maintaining cell-cell adhension in multiple cancers. It has been well studied in epithelial cells, cardiomyocytes and primary prostate cancer, colon cancer, skin squamous cell carcinoma, except for cervical cancer. Hence, we performed this study to examine the function of DSG2 in cervical cancer. We used TCGA and Oncomine databases to assess the expression level of DSG2 in cervical cancer cases. Kaplan-Meier method with log-rank test was utilized to plot overall survival (OS) curve. The reverse transcription-quantitative polymerase chain reaction (qRT-PCR) and western blotting were performed to detect the expression of DSG2 in cells. Cell Counting Kit-8 (CCK-8), wound-healing analysis, and transwell assay were carried out to examine proliferation, migration, and invasion of cells. A higher level of DSG2 in cervical cancer was associated with lower OS rate. Knockdown of DSG2 inhibited cervical cancer cell proliferation, migration, and invasion, while DSG2 enhancement promoted cell proliferation, migration, and invasion. Moreover, the proteins expression of p-MEK and p-ERK that are required for mitogen-activated protein kinases (MAPK) pathway were downregulated after reducing DSG2. In conclusion, these findings illustrated the importance of DSG2 in cervical cancer development and cell behaviors by mediating MAPK signaling pathway, suggesting DSG2 maybe a novel therapeutic target in control of cervical cancer.

ErbB1 and ErbB2 overexpression in patients with sinonasal inverted papilloma and inverted papilloma with squamous cell carcinoma in China

Background: Currently, the expression patterns of epidermal growth factor receptor (EGFR) family genes in sinonasal inverted papilloma (SNIP) and inverted papilloma with squamous cell carcinoma (IPwSCC) are not clear.Objective: This study aimed to investigate the expression of EGFR family members and their ligands in SNIP and IPwSCC and to analyze their correlations with SNIP histological grade and Krouse stage.Materials and methods: Data from 25 cases of inverted papilloma patients in China were collected and divided into 16 cases in the SNIP group and 9 in the IPwSCC group. In addition, eight cases of normal nasal mucosa (NNM) were collected and used as the control group. The expression levels of EGFR family members and their ligands in the NNM and SNIP groups and EGFR family members in the IPwSCC group were evaluated using immunohistochemistry and qRT-PCR. In addition, their correlations with the SNIP histological grade and Krouse stage were analyzed. The statistical analysis was performed using the GraphPad Prism 7.0 statistical software.Results: The ErbB1 and ErbB2 mRNA and protein expression levels were significantly higher in the SNIP group than in the NNM group (p < .01). The ErbB1 and ErbB2 protein expression levels were significantly higher in the IPwSCC group than those in the NNM and SNIP groups (p < .01). The ErbB1 and ErbB2 mRNA and protein expression levels in the SNIP group were positively correlated with the SNIP dysplasia grade.Conclusion: Upregulation of ErbB1 and ErbB2 expression may be associated with SNIP pathogenesis and carcinogenesis.

Dysregulated Expression of Phosphorylated Epidermal Growth Factor Receptor and Phosphatase and Tensin Homologue in Canine Cutaneous Papillomas and Squamous Cell Carcinomas

The molecular mechanisms contributing to the development of cutaneous papillomas (CPs) and cutaneous squamous cell carcinomas (CSCCs) are still poorly understood, limiting the ability to identify molecular suitable targets for the development of novel therapies. Persistent activation of the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signalling pathway is a component of epidermal carcinogenesis in dogs. The present study describes the immunohistochemical expression pattern of two key regulatory molecules involved in the PI3K/Akt/mTOR signalling pathway, phosphorylated epidermal growth factor receptor (pEGFR)^Tyr1068 and phosphatase and tensin homologue (PTEN), in samples of normal canine epidermis, CP, preneoplastic epidermis and CSCC using tissue microarrays to determine whether the deregulated activity of these molecules is involved in the pathogenesis of these relevant epidermal tumours of dogs. Expression of pEGFR and PTEN was dysregulated in most samples of CP, preneoplastic epidermis and CSCC. Overexpression of pEGFR, together with decreased expression of PTEN, may facilitate the progression of some canine CPs and CSCCs by deregulation of the key cellular functions in which the PI3K/Akt/mTOR signalling pathway is involved. These findings suggest that the PI3K/Akt/mTOR signalling molecules may be potential therapeutic targets for canine patients with CP and CSCC.

Mechanisms and Antitumor Activity of a Binary EGFR/DNA-Targeting Strategy Overcomes Resistance of Glioblastoma Stem Cells to Temozolomide

PURPOSE

Glioblastoma (GBM) is a fatal primary malignant brain tumor. GBM stem cells (GSC) contribute to resistance to the DNA-damaging chemotherapy, temozolomide. The epidermal growth factor receptor (EGFR) displays genomic alterations enabling DNA repair mechanisms in half of GBMs. We aimed to investigate EGFR/DNA combi-targeting in GBM.

EXPERIMENTAL DESIGN

ZR2002 is a "combi-molecule" designed to inflict DNA damage through its chlorethyl moiety and induce irreversible EGFR tyrosine kinase inhibition. We assessed its in vitro efficacy in temozolomide-resistant patient-derived GSCs, mesenchymal temozolomide-sensitive and resistant in vivo-derived GSC sublines, and U87/EGFR isogenic cell lines stably expressing EGFR/wild-type or variant III (EGFRvIII). We evaluated its antitumor activity in mice harboring orthotopic EGFRvIII or mesenchymal TMZ-resistant GSC tumors.

RESULTS

ZR2002 induced submicromolar antiproliferative effects and inhibited neurosphere formation of all GSCs with marginal effects on normal human astrocytes. ZR2002 inhibited EGF-induced autophosphorylation of EGFR, downstream Erk1/2 phosphorylation, increased DNA strand breaks, and induced activation of wild-type p53; the latter was required for its cytotoxicity through p53-dependent mechanism. ZR2002 induced similar effects on U87/EGFR cell lines and its oral administration significantly increased survival in an orthotopic EGFRvIII mouse model. ZR2002 improved survival of mice harboring intracranial mesenchymal temozolomide-resistant GSC line, decreased EGFR, Erk1/2, and AKT phosphorylation and was detected in tumor brain tissue by MALDI imaging mass spectrometry.

CONCLUSIONS

These findings provide the molecular basis of binary EGFR/DNA targeting and uncover the oral bioavailability, blood-brain barrier permeability, and antitumor activity of ZR2002 supporting potential evaluation of this first-in-class drug in recurrent GBM.

SGLT1 is required for the survival of triple-negative breast cancer cells via potentiation of EGFR activity

Sodium/glucose cotransporter 1 (SGLT1), an essential active glucose transport protein that helps maintain high intracellular glucose levels, was previously shown to interact with epidermal growth factor receptor (EGFR); the SGLT1-EGFR interaction maintains intracellular glucose levels to promote survival of cancer cells. Here, we explore the role of SGLT1 in triple-negative breast cancer (TNBC), which is the most aggressive type of breast cancer. We performed TCGA analysis coupled to in vitro experiments in TNBC cell lines as well as in vivo xenografts established in the mammary fat pad of female nude mice. Tissue microarrays of TNBC patients with information of clinical-pathological parameters were also used to investigate the expression and function of SGLT1 in TNBC. We show that high levels of SGLT1 are associated with greater tumour size in TNBC. Knockdown of SGLT1 compromises cell growth in vitro and in vivo. We further demonstrate that SGLT1 depletion results in decreased levels of phospho-EGFR, and as a result, the activity of downstream signalling pathways (such as AKT and ERK) is inhibited. Hence, targeting SGLT1 itself or the EGFR-SGLT1 interaction may provide novel therapeutics against TNBC.

Kaempferia parviflora Extract Inhibits STAT3 Activation and Interleukin-6 Production in HeLa Cervical Cancer Cells

Kaempferia parviflora (KP) has been reported to have anti-cancer activities. We previously reported its effects against cervical cancer cells and continued to elucidate the effects of KP on inhibiting the production and secretion of interleukin (IL)-6, as well as its relevant signaling pathways involved in cervical tumorigenesis. We discovered that KP suppressed epidermal growth factor (EGF)-induced IL-6 secretion in HeLa cells, and it was associated with a reduced level of Glycoprotein 130 (GP130), phosphorylated signal transducers and activators of transcription 3 (STAT3), and Mcl-1. Our data clearly showed that KP has no effect on nuclear factor kappa B (NF-κB) localization status. However, we found that KP inhibited EGF-stimulated phosphorylation of tyrosine 1045 and tyrosine 1068 of EGF receptor (EGFR) without affecting its expression level. The inhibition of EGFR activation was verified by the observation that KP significantly suppressed a major downstream MAP kinase, ERK1/2. Consistently, KP reduced the expression of Ki-67 protein, which is a cellular marker for proliferation. Moreover, KP potently inhibited phosphorylation of STAT3, Akt, and the expression of Mcl-1 in response to exogenous IL-6 stimulation. These data suggest that KP suppresses EGF-induced production of IL-6 and inhibits its autocrine IL-6/STAT3 signaling critical for maintaining cancer cell progression. We believe that KP may be a potential alternative anti-cancer agent for suppressing cervical tumorigenesis.

RUBCN/rubicon and EGFR regulate lysosomal degradative processes in the retinal pigment epithelium (RPE) of the eye

Macroautophagy/autophagy is an intracellular stress survival and recycling system whereas phagocytosis internalizes material from the extracellular milieu; yet, both pathways utilize lysosomes for cargo degradation. Whereas autophagy occurs in all cells, phagocytosis is performed by cell types such as macrophages and the retinal pigment epithelial (RPE) cells of the eye where it is supported by the noncanonical autophagy process termed LC3-associated phagocytosis (LAP). Autophagy and LAP are distinct pathways that use many of the same mediators and must compete for cellular resources, suggesting that cells may regulate both processes under homeostatic and stress conditions. Our data reveal that RPE cells promote LAP through the expression of RUBCN/Rubicon (RUN domain and cysteine-rich domain containing Beclin 1-interacting protein) and suppress autophagy through the activation of EGFR (epidermal growth factor receptor). In the morning when photoreceptor outer segments (POS) phagocytosis and LAP are highest, RUBCN expression is increased. At the same time, outer segment phagocytosis activates the EGFR resulting in MTOR (mechanistic target of rapamycin [serine/threonine kinase]) stimulation, the accumulation of SQSTM1/p62, and the phosphorylation of BECN1 (Beclin 1, autophagy related) on an inhibitory residue thereby suppressing autophagy. Silencing Rubcn, preventing EGFR activity or directly inducing autophagy in RPE cells by starvation inhibits phagocytic degradation of POS. Thus, RPE cells regulate lysosomal pathways during the critical period of POS phagocytosis to support retinal homeostasis.

Structure and Dynamics of the EGF Receptor as Revealed by Experiments and Simulations and Its Relevance to Non-Small Cell Lung Cancer

The epidermal growth factor receptor (EGFR) is historically the prototypical receptor tyrosine kinase, being the first cloned and the first where the importance of ligand-induced dimer activation was ascertained. However, many years of structure determination has shown that EGFR is not completely understood. One challenge is that the many structure fragments stored at the PDB only provide a partial view because full-length proteins are flexible entities and dynamics play a key role in their functionality. Another challenge is the shortage of high-resolution data on functionally important higher-order complexes. Still, the interest in the structure/function relationships of EGFR remains unabated because of the crucial role played by oncogenic EGFR mutants in driving non-small cell lung cancer (NSCLC). Despite targeted therapies against EGFR setting a milestone in the treatment of this disease, ubiquitous drug resistance inevitably emerges after one year or so of treatment. The magnitude of the challenge has inspired novel strategies. Among these, the combination of multi-disciplinary experiments and molecular dynamic (MD) simulations have been pivotal in revealing the basic nature of EGFR monomers, dimers and multimers, and the structure-function relationships that underpin the mechanisms by which EGFR dysregulation contributes to the onset of NSCLC and resistance to treatment.

A Brief History of Single-Particle Tracking of the Epidermal Growth Factor Receptor

Single-particle tracking (SPT) has been used and developed over the last 25 years as a method to investigate molecular dynamics, structure, interactions, and function in the cellular context. SPT is able to show how fast and how far individual molecules move, identify different dynamic populations, measure the duration and strength of intermolecular interactions, and map out structures on the nanoscale in cells. In combination with other techniques such as macromolecular crystallography and molecular dynamics simulation, it allows us to build models of complex structures, and develop and test hypotheses of how these complexes perform their biological roles in health as well as in disease states. Here, we use the example of the epidermal growth factor receptor (EGFR), which has been studied extensively by SPT, demonstrating how the method has been used to increase our understanding of the receptor’s organization and function, including its interaction with the plasma membrane, its activation, clustering, and oligomerization, and the role of other receptors and endocytosis. The examples shown demonstrate how SPT might be employed in the investigation of other biomolecules and systems.

EGFR as a clinical marker in glioblastomas and other gliomas

Epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein and a member of the tyrosine kinase superfamily receptor. Gliomas are tumors originating from glial cells, which show a range of aggressiveness depending on grade and stage. Many EGFR gene alterations have been identified in gliomas, especially glioblastomas, including amplifications, deletions and single nucleotide polymorphisms (SNPs). Glioblastomas are discussed as a separate entity due to their high correlation with EGFR mutants and the reported association of the latter with survival and response to treatment in this glioma subgroup. This review is a comprehensive report of EGFR gene alterations and their relations with several clinical factors in glioblastomas and other gliomas. It covers all EGFR gene alterations including point mutations, SNPs, methylations, copy number variations and amplifications, assessed with regard to different clinical variables, including response to therapy and survival. This review also discusses the current prognostic status of EGFR in glioblastomas and other gliomas, and highlights gaps in previous studies. This serves as an update for the medical community about the role of EGFR gene alterations in gliomas and specifically glioblastomas, as a means for targeted treatment and prognosis.

Allosteric regulation of epidermal growth factor (EGF) receptor ligand binding by tyrosine kinase inhibitors

The epidermal growth factor (EGF) receptor is a classical receptor tyrosine kinase with an extracellular ligand-binding domain and an intracellular kinase domain. Mutations in the EGF receptor have been shown to drive uncontrolled cell growth and are associated with a number of different tumors. Two different types of ATP-competitive EGF receptor tyrosine kinase inhibitors have been identified that bind to either the active (type I) or inactive (type II) conformation of the kinase domain. Despite the fact that both types of inhibitors block tyrosine kinase activity, they exhibit differential efficacies in different tumor types. Here, we show that in addition to inhibiting kinase activity, these inhibitors allosterically modulate ligand binding. Our data suggest that the conformations of the EGF receptor extracellular domain and intracellular kinase domain are coupled and that these conformations exist in equilibrium. Allosteric regulators, such as the small-molecule tyrosine kinase inhibitors, as well as mutations in the EGF receptor itself, shift the conformational equilibrium among the active and inactive species, leading to changes in EGF receptor-binding affinity. Our studies also reveal unexpected positive cooperativity between EGF receptor subunits in dimers formed in the presence of type II inhibitors. These findings indicate that there is strong functional coupling between the intracellular and extracellular domains of this receptor. Such coupling may impact the therapeutic synergy between small-molecule tyrosine kinase inhibitors and monoclonal antibodies in vivo.

Exposure of Barrett's and esophageal adenocarcinoma cells to bile acids activates EGFR-STAT3 signaling axis via induction of APE1

The development of Barret’s esophagus (BE) and its progression to esophageal adenocarcinoma (EAC) is highly linked to exposure to acidic bile salts due to chronic gastroesophageal reflux disease (GERD). In this study, we investigated the role of Apurinic/apyrimidinic endonuclease 1 /redox effector factor-1 (APE-1/REF-1) in STAT3 activation in response to EAC. Our results indicate that APE1 is constitutively overexpressed in EAC whereas its expression is transiently induced in response to acidic bile salts in non-neoplastic BE. Using overexpression or shRNA knockdown of APE1, we found that APE1 is required for phosphorylation, nuclear localization, and transcription activation of STAT3. By using an APE1 redox-specific mutant (C65A) and APE1 redox inhibitor (E3330), we demonstrate that APE1 activates STAT3 in a redox-dependent manner. By using pharmacologic inhibitors and genetic knockdown systems, we found that EGFR is a required link between APE1 and STAT3. EGFR phosphorylation (Y1068) was directly associated with APE1 levels and redox function. Co-immunoprecipitation and proximity ligation assays indicated that APE-1 coexists and interacts with the EGFR-STAT3 protein complex. Consistent with these findings, we demonstrated a significant induction in mRNA expression levels of STAT3 target genes (IL-6, IL-17A, BCL-xL, Survivin and c-Myc) in BE and EAC cells, following acidic bile salts treatment. ChIP assays indicated that acidic bile salts treatment enhances binding of STAT3 to the promoter of its target genes, Survivin and BCL-xL. Inhibition of APE1/REF-1 redox activity using E3330 abrogated STAT3 DNA binding and transcriptional activity. The induction of APE-1 - STAT3 axis in acidic bile salts conditions provided a survival advantage and promoted cellular proliferation. In summary, our study provides multiple pieces of evidence supporting a critical role for APE1 induction in activating the EGFR-STAT3 signaling axis in response to acidic bile salts, the main risk factors for Barrett’s carcinogenesis.

Identification of EGFR in pearl oyster (Pinctada fucata martensii) and correlation analysis of its expression and growth traits

Marine pearl production is directly influenced by the growth speed of Pinctada fucata martensii. However, the slow growth rate of this organism remains the main challenge in aquaculture production. Epidermal growth factor receptor (EGFR), an important receptor of tyrosine kinases in animals, plays versatile functions in development, growth and tissue regeneration. In this study, we described the characteristic and function of an EGFR gene identified from P. f. martensii (PmEGFR). PmEGFR possesses a typical EGFR structure and is expressed in all studied tissues, with the highest expression level in adductor muscle. PmEGFR expression level is significantly higher in the fast-growing group than that in the slow-growing one. Correlation analysis represents that shell height and shell weight show positive correlation with PmEGFR expression (p < 0.05), and total weight and tissue weight exhibit positive correlation with it (p < 0.01). This study indicates that PmEGFR is a valuable functional gene associated with growth traits.

Porcine Epidemic Diarrhea Virus-Induced Epidermal Growth Factor Receptor Activation Impairs the Antiviral Activity of Type I Interferon

Porcine epidemic diarrhea virus (PEDV) causes acute and devastating enteric disease in suckling piglets and results in huge economic losses in the pig industry worldwide. To establish productive infection, viruses must first circumvent the host innate immune response. In this study, we found that PEDV infection stimulated epidermal growth factor receptor (EGFR) activation, which has been linked to not only anticancer therapeutics, but also antiviral signaling. Therefore, we determined whether EGFR activation affected PEDV infection by using an activator or overexpression assay. The data showed that EGFR activation enhanced virus replication in both cases. We also found that specific inhibition of EGFR by either inhibitors or small interfering RNA (siRNA) led to a decrease in virus yields. Further analysis revealed that inhibition of EGFR produced augmentation of type I interferon genes. We next observed that the EGFR downstream cascade STAT3 was also activated upon PEDV infection. Similar to the case of EGFR, specific inhibition of STAT3 by either inhibitor or siRNA increased the antiviral activity of interferon and resulted in decreased PEDV RNA levels, and vice versa. The data on STAT3 depletion in combination with EGFR activation suggest that the attenuation of antiviral activity by EGFR activation requires activation of the STAT3 signaling pathway. Taken together, these data demonstrate that PEDV-induced EGFR activation serves as a negative regulator of the type I interferon response and provides a novel therapeutic target for virus infection.IMPORTANCE EGFR is a transmembrane tyrosine receptor that mediates various cellular events, as well as several types of human cancers. In this study, we investigated for the first time the role of EGFR in PEDV infection. We observed that PEDV infection induced EGFR activation. The role of EGFR activation is to impair the antiviral activity of type I interferon, which requires the involvement of the EGFR downstream signaling cascade STAT3. Our findings reveal a new mechanism evolved by PEDV to circumvent the host antiviral response, which might serve as a therapeutic target against virus infection.

Clinical Significance of Epidermal Growth Factor Receptor Content in Gastric Cancer

The objective of this work was to evaluate the epidermal growth factor receptor (EGFR) content in gastric cancer, its possible relationship with clinicopathological parameters of tumors and its prognostic significance. Membranous EGFR levels were examined by radioligand binding assays in 110 patients with gastric cancer. The mean follow-up period was 30.7 months. EGFR levels of tumors ranged widely, from 0.3 to 510 fmol/mg protein. EGFR levels were significantly higher (p<0.0005) in neoplastic tissue than in paired adjacent mucosa samples (median) (n= 84; 8.7 vs. 3.9 fmol/mg protein). Intratumoral EGFR levels were significantly correlated with tumor stage (p<0.05), and were higher in patients with stage III tumors (median) (7.6, 6.4, 12.3 and 7.5 fmol/mg protein for stages I, II, III and IV, respectively). In addition, the tumor/mucosa ratios of the EGFR content were significantly higher (p<0.05) in patients with stage III tumors (1, 1.8, 3.9, and 0.92, respectively). Although there was no significant relationship between EGFR levels of tumors and overall survival, the results suggest a role for EGFR in tumor progression of gastric cancer.

The Hippo transducer TAZ promotes cell proliferation and tumor formation of glioblastoma cells through EGFR pathway

TAZ, a WW-domain-containing transcriptional co-activator, is important for development of various tissues in mammals. Recently, TAZ has been found to be overexpressed in some types of human cancers. However, the role of TAZ in glioblastoma remains unclear. In this study, we found that TAZ was overexpressed in prognostically poor glioblastoma patients. Through knocking down or overexpressing TAZ in U87 and LN229 cells, the expression level of TAZ was found to be positively related to cell proliferation in vitro and tumor formation in vivo. Further investigation indicated that TAZ could significantly promote the acceleration of cell cycle. Moreover, the western blot for p-EGFR, p-AKT, p-ERK1/2, p21, cyclin E and CDK2 proteins, target genes of the EGFR pathway, indicated that TAZ significantly activated EGFR/AKT/ERK signaling. Additionally, the blockage of EGFR pathway resulted in a significantly inhibition of cell proliferation induced by TAZ. Taken together, these results demonstrate that TAZ can promote proliferation and tumor formation in glioblastoma cells by potentiating the EGFR/AKT/ERK pathway, and provide the evidence for promising target for the treatment of glioblastoma.

Identification of a novel fusion gene HMGA2-EGFR in glioblastoma

Glioblastoma is one of the most malignant forms of cancer, for which no effective targeted therapy has been found. Although The Cancer Genome Atlas has provided a list of fusion genes in glioblastoma, their role in progression of glioblastoma remains largely unknown. To search for novel fusion genes, we obtained RNA-seq data from TGS-01 human glioma-initiating cells, and identified a novel fusion gene (HMGA2-EGFR), encoding a protein comprising the N-terminal region of the high-mobility group AT-hook protein 2 (HMGA2) fused to the C-terminal region of epidermal growth factor receptor (EGFR), which retained the transmembrane and kinase domains of the EGFR. This fusion gene product showed transforming potential and a high tumor-forming capacity in cell culture and in vivo. Mechanistically, HMGA2-EGFR constitutively induced a higher level of phosphorylated STAT5B than EGFRvIII, an in-frame exon deletion product of the EGFR gene that is commonly found in primary glioblastoma. Forced expression of HMGA2-EGFR enhanced orthotopic tumor formation of the U87MG human glioma cell line. Furthermore, the EGFR kinase inhibitor erlotinib blocked sphere formation of TGS-01 cells in culture and inhibited tumor formation in vivo. These findings suggest that, in addition to gene amplification and in-frame exon deletion, EGFR signaling can also be activated by gene fusion, suggesting a possible avenue for treatment of glioblastoma.

Epidermal growth factor receptors containing a single tyrosine in their C-terminal tail bind different effector molecules and are signaling-competent

The EGF receptor is a classic receptor tyrosine kinase. It contains nine tyrosines in its C-terminal tail, many of which are phosphorylated and bind proteins containing SH2 or phosphotyrosine-binding (PTB) domains. To determine how many and which tyrosines are required to enable EGF receptor-mediated signaling, we generated a series of EGF receptors that contained only one tyrosine in their C-terminal tail. Assays of the signaling capabilities of these single-Tyr EGF receptors indicated that they can activate a range of downstream signaling pathways, including MAP kinase and Akt. The ability of the single-Tyr receptors to signal correlated with their ability to bind Gab1 (Grb2-associated binding protein 1). However, Tyr-992 appeared to be almost uniquely required to observe activation of phospholipase Cγ. These results demonstrate that multiply phosphorylated receptors are not required to support most EGF-stimulated signaling but identify Tyr-992 and its binding partners as a unique node within the network. We also studied the binding of the isolated SH2 domain of Grb2 (growth factor receptor-bound protein 2) and the isolated PTB domain of Shc (SHC adaptor protein) to the EGF receptor. Although these adapter proteins bound readily to wild-type EGF receptor, they bound poorly to the single-Tyr EGF receptors, even those that bound full-length Grb2 and Shc well. This suggests that in addition to pTyr-directed associations, secondary interactions between the tail and regions of the adapter proteins outside of the SH2/PTB domains are important for stabilizing the binding of Grb2 and Shc to the single-Tyr EGF receptors.

Design, Synthesis, and Antitumor Activity of Novel Quinazoline Derivatives

In an attempt to explore a new class of epidermal growth factor receptor (EGFR) inhibitors, novel 4-stilbenylamino quinazoline derivatives were synthesized through a Dimorth rearrangement reaction and characterized via IR, ¹H-NMR, ¹³C-NMR, and HRMS. Methoxyl, methyl, halogen, and trifluoromethyl groups on stilbeneamino were detected. These synthesized compounds were evaluated for antitumor activity in vitro against eight human tumor cell lines with an MTS assay. Most synthesized compounds exhibited more potent activity (IC₅₀ = ~2.0 μM) than gefitinib (IC₅₀ > 10.0 μM) against the A431, A549, and BGC-823 cell lines. Docking methodology of compound 6c and 6i binding into the ATP site of EGFR was carried out. The results showed that fluorine and trifluoromethyl played an important role in efficient cell activity.

Targeting epidermal growth factor receptor co-dependent signaling pathways in glioblastoma

The epidermal growth factor receptor (EGFR) is a transmembrane receptor tyrosine kinase (RTK) that is critical for normal development and function. EGFR is also amplified or mutated in a variety of cancers including in nearly 60% of cases of the highly lethal brain cancer glioblastoma (GBM). EGFR amplification and mutation reprogram cellular metabolism and broadly alter gene transcription to drive tumor formation and progression, rendering EGFR as a compelling drug target. To date, brain tumor patients have yet to benefit from anti-EGFR therapy due in part to an inability to achieve sufficient intratumoral drug levels in the brain, cultivating adaptive mechanisms of resistance. Here, we review an alternative set of strategies for targeting EGFR-amplified GBMs, based on identifying and targeting tumor co-dependencies shaped both by aberrant EGFR signaling and the brain's unique biochemical environment. These approaches may include highly brain-penetrant drugs from non-cancer pipelines, expanding the pharmacopeia and providing promising new treatments. We review the molecular underpinnings of EGFR-activated co-dependencies in the brain and the promising new treatments based on this strategy. WIREs Syst Biol Med 2018, 10:e1398. doi: 10.1002/wsbm.1398 This article is categorized under: Biological Mechanisms > Cell Signaling Laboratory Methods and Technologies > Genetic/Genomic Methods Translational, Genomic, and Systems Medicine > Translational Medicine.