Acute Regulation of the Epidermal Growth Factor Receptor in Response to Nerve Growth Factor

PC12 cells possess specific receptors for both nerve growth factor and epidermal growth factor, and by an unknown mechanism, nerve growth factor is able to attenuate the propagation of a mitogenic response to epidermal growth factor. The differentiation response of PC12 cells to nerve growth factor, therefore, predominates over the proliferative response to epidermal growth factor. We have observed that the addition of nerve growth factor to PC12 cells rapidly produces a decrease in surface 125I-epidermal growth factor binding capacity. Unlike previously described nerve growth factor effects on 125I-epidermal growth factor binding capacity, which required several days of nerve growth factor exposure, the decreases we report occur within minutes of nerve growth factor addition: A 50% decrease in 125I-epidermal growth factor binding capacity is evident at 10 min. This rapid nerve growth factor response is concentration dependent; inhibition of 125I-epidermal growth factor binding is detectable at nerve growth factor levels as low as 0.2 ng/ml and is maximal at approximately 50 ng/ml, consistent with known ranges of biological activity. No demonstrable differences in the rate of epidermal growth factor receptor synthesis or degradation were observed in cells acutely exposed to nerve growth factor. Scatchard analysis revealed that acute nerve growth factor treatment decreased the number of both high- and low-affinity 125I-epidermal growth factor binding sites, while the receptor affinity remained unchanged. We have also investigated the involvement of various potential intracellular mediators of nerve growth factor action and of known intracellular modulatory systems of the epidermal growth factor receptor for their capacity to participate in this nerve growth factor activity.     

肺癌EGFR突变与酪氨酸激酶抑制剂临床敏感性的关系

表皮生长因子受体(EGFR)酪氨酸激酶抑制剂(TKI)是近年来在临床中使用的一类新的小分子靶向药物,主要用于晚期非小细胞肺癌(NSCLC)的治疗,然而并非所有的NSCLC患者对TKI敏感。近期研究发现,在NSCLC治疗过程中,EGFR突变与TKI临床敏感性密切相关,通过检测肺癌EGFR突变状况可以预测TKI治疗的效果。     

Schwannoma-Derived Growth Factor Interacts with the Epidermal Growth Factor Receptor

Abstract: Schwannoma-derived growth factor (SDGF) is a potent mitogen and neuronal differentiation factor. Because of its relationship to epidermal growth factor (EGF) and the heregulins, it was asked if SDGF interacts with the EGF receptor or HER2/neu. SDGF binds to and causes the phosphorylation on tyrosine of the EGF receptor but not HER2/neu.     

表皮生长因子及受体在甲状腺肿瘤中的表达

目的:研究表皮生长因子(Epidermal Growth Factor,EGF)及受体(Epidermal Growth Factor Receptor,EGFR)及在甲状腺肿瘤中的表达。方法:应用免疫组织化学法检测91例甲状腺病变组织中EGFR和EGF的表达情况。结果:结节性甲状腺肿、甲状腺腺瘤、分化型甲状腺癌标本中EGFR表达的阳性率分别为15%、25%、68.62%,EGF表达的阳性率分别为10%、15%、68.62%,其中EGFR、EGF在分化型甲状腺癌与其余两组间差异均有统计学意义(P<0.05)。EGFR和EGF在甲状腺乳头状癌中的表达与性别、年龄、肿瘤大小、淋巴结转移、临床分期等临床因素无明显相关。结论:EGF和EGFR的表达可作为鉴别甲状腺肿瘤良恶性的一个指标。     

成纤维细胞生长因子与其受体相互作用及其抑制剂的研究进照

成纤维细胞生长因子(FGF)有许多重要的生理功能,并与肿瘤的形成有关.为了弄清FGF与成纤维细胞生长因子受体(FGFR)相互作用的机制,人们对FGF和RGFR的各个结合结构域进行了深入、细致的研究,定位了aFGF、bFGF的肝素结合区、bFGF的受体结合区、FGF受体的肝素结合区、配体结合区和FGF受体相互结合区,提出了两个FGF与FGFR相互作用的模型,在此基础上设计了FGF的核酸类、糖类和多肽类抑制剂,为寻找新一代抗癌药物打下了理论基础.     

Recent Development of the Second and Third Generation Irreversible Epidermal Growth Factor Receptor Inhibitors

Recent reports suggested that essential directions for new lung cancer, breast carcinoma therapies, as well as the roomier realm of targeted cancer therapies were provided through targeting the epidermal growth factor receptor (EGFR). Patients who carrying non‐small cell lung carcinoma (NSCLC) with activating mutations in EGFR initially respond well to the EGFR inhibitors erlotinib and gefitinib, which were located the active site of the EGFR kinase and designed to act as competitive inhibitors of combining with the ATP. However, patients who were treated with the erlotinib and gefitinib will relapse because of the emergence of drug‐resistant mutations, with T790M mutations accounting for approximately 60% of all resistance. In order to overcome drug resistance, Pharmaceutical chemistry experts recently devoted great endeavors to the development of second‐generation irreversible selective inhibitors which covalently modify Cys797 or Cys773 at the ATP binding cleft. Nevertheless, these inhibitors have not reached ideal effect of experts in patients with T790M positive mutation and apparently because of the dose‐limiting toxicities associated with inhibition of wild type EGFR. A novel class of ‘third generation’ EGFR TKIs have been developed that is sensitising and T790M mutant‐specific whilst sparing WT EGFR, representing a significant breakthrough in the treatment in NSCLC patients with acquired resistance harboring these genotypes. Herein, we provides an overview of the second and third generation inhibitors currently approved, in clinical trial and also encompasses novel structures of discovery. This review mainly focuses on drug resistance, their mechanisms of action, development of structure–activity relationships and binding modes.     

Quantitative Biomarkers for Prediction of Epidermal Growth Factor Receptor Mutation in Non-Small Cell Lung Cancer

OBJECTIVES: To predict epidermal growth factor receptor (EGFR) mutation status using quantitative radiomic biomarkers and representative clinical variables. METHODS: The study included 180 patients diagnosed as of non-small cell lung cancer (NSCLC) with their pre-therapy computed tomography (CT) scans. Using a radiomic method, 485 features that reflect the heterogeneity and phenotype of tumors were extracted. Afterwards, these radiomic features were used for predicting epidermal growth factor receptor (EGFR) mutation status by a least absolute shrinkage and selection operator (LASSO) based on multivariable logistic regression. As a result, we found that radiomic features have prognostic ability in EGFR mutation status prediction. In addition, we used radiomic nomogram and calibration curve to test the performance of the model. RESULTS: Multivariate analysis revealed that the radiomic features had the potential to build a prediction model for EGFR mutation. The area under the receiver operating characteristic curve (AUC) for the training cohort was 0.8618, and the AUC for the validation cohort was 0.8725, which were superior to prediction model that used clinical variables alone. CONCLUSION: Radiomic features are better predictors of EGFR mutation status than conventional semantic CT image features or clinical variables to help doctors to decide who need EGFR tyrosine kinase inhibitor (TKI) treatment.     

Intracellular Transactivation of the Insulin-like Growth Factor I Receptor by an Epidermal Growth Factor Receptor

Growth factor receptors may be transactivated not only by homologous receptors, but also by heterologous receptors. We have investigated this possibility, using for this purpose R⁻/EGFR cells, which are mouse embryo cells devoid of IGF-I receptors, but overexpressing the EGF receptor. At variance with mouse embryo cells with a wild-type number of IGF-I receptors and overexpressing the EGF receptor, R⁻/EGFR cells cannot grow in EGF only, nor can they form colonies in soft agar. However, if a wild type human IGF-I receptor is stably transfected into R⁻/EGFR cells, growth in EGF and colony formation in soft agar are restored. To determine a possible interaction between the two receptors, we transfected into R⁻/EGFR cells a number of IGF-I receptor mutants with different impaired functions. The only IGF-I receptor that cannot reverse the growth phenotype of R⁻/EGFR cells is a receptor with a point mutation at the ATP-binding site. All other mutant receptors, even when incapable of responding to IGF-I with a mitogenic signal, made R⁻/EGFR cells fully capable of responding with growth to EGF stimulation. IGF-I receptor mutants that are mitogenic but not transforming made R⁻/EGFR cells grow in EGF only, but were incapable of inducing the transformed phenotype. The mutant IGF-I receptors are activated (tyrosyl phosphorylation of IRS-1) in response to EGF. These experiments indicate that certain IGF-I receptor mutants with loss of function can be reactivated intracellularly by an overexpressed EGF receptor and confirm that the C-terminus of the IGF-IR is required for its transforming activity.     

Baseline and Trend of Lymphocyte-to-Monocyte Ratio as Prognostic Factors in Epidermal Growth Factor Receptor Mutant Non-Small Cell Lung Cancer Patients Treated with First-Line Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors

Background

Patients with early-stage lung cancer who have a high baseline lymphocyte-to-monocyte ratio (LMR) have a favorable prognosis. However, the prognostic significance of LMR in patients with advanced-stage EGFR-mutant non-small cell lung cancer (NSCLC) receiving first-line epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has not been established. We conducted a retrospective analysis to investigate the influence of LMR on clinical outcomes including progression-free survival (PFS) and overall survival (OS) in EGFR-mutant patients with NSCLC.

Materials and Methods

Of 1310 lung cancer patients diagnosed between January 2011 and October 2013, 253 patients receiving first-line EGFR-TKIs for EGFR-mutant NSCLC were included. The cut-off values for baseline and the 1-month-to-baseline ratio of LMR (MBR), determined by using receiver operating characteristic curves, were 3.29 and 0.63, respectively. Patients were divided into 3 prognostic groups: high LMR and MBR, high LMR or MBR, and low LMR and MBR.

Results

The mean patient age was 65.2 years, and 41% were men. The median PFS and OS were 10.3 and 22.0 months, respectively. The PFS in patients with high LMR and MBR, high LMR or MBR, and low LMR and MBR were 15.4, 7.1, and 2.0 months, respectively (p < 0.001), whereas the OS were 32.6, 13.7, and 5.1 months, respectively (p < 0.001).

Conclusion

A combination of baseline and trend of LMR can be used to identify patients with a high mortality risk in EGFR-mutant NSCLC patients receiving first-line EGFR-TKIs.     

The Constitutive Activity of Epidermal Growth Factor Receptor vIII Leads to Activation and Differential Trafficking of Wild-type Epidermal Growth Factor Receptor and erbB2

A constitutively active epidermal growth factor receptor (EGFR) mutant, EGFR variant III (EGFRvIII), has been detected at high frequencies in certain human cancers. This study evaluated transactivation and trafficking of erbB family members as a result of constitutive EGFR activity in a cancer cell line. Expression of EGFRvIII modulated erbB family members through different mechanisms; the erbB3 mRNA level was reduced, whereas wild-type EGFR (wtEGFR) and erbB2 protein levels were diminished, with no change in their mRNA levels, and there was no change in the erbB4 expression level. Both EGFR and erbB2 were internalized as a result of EGFRvIII''s activity and redistributed to the cell surface upon addition of AG1478, an inhibitor of wtEGFR/EGFRvIII catalytic activity. Acute activation of EGFRvIII by removing AG1478 from cells increased phosphorylation of both wtEGFR and erbB2 and caused differential trafficking of EGFRvIII''s activation partners; wtEGFR was directed primarily to lysosomal compartments and partially to recycling compartments, whereas erbB2 was directed primarily to recycling compartments and partially to lysosomal compartments. Our data demonstrate that the constitutive activity of EGFRvIII is sufficient to trigger endocytosis and trafficking of wtEGFR and erbB2, which may play a role in activating signaling pathways that are triggered during receptor endocytosis. (J Histochem Cytochem 58:529–541, 2010)     

Epidermal Growth Factor Receptor in Prostate Cancer Derived Exosomes

Exosomes proteins and microRNAs have gained much attention as diagnostic tools and biomarker potential in various malignancies including prostate cancer (PCa). However, the role of exosomes and membrane-associated receptors, particularly epidermal growth factor receptor (EGFR) as mediators of cell proliferation and invasion in PCa progression remains unexplored. EGFR is frequently overexpressed and has been associated with aggressive forms of PCa. While PCa cells and tissues express EGFR, it is unknown whether exosomes derived from PCa cells or PCa patient serum contains EGFR. The aim of this study was to detect and characterize EGFR in exosomes derived from PCa cells, LNCaP xenograft and PCa patient serum. Exosomes were isolated from conditioned media of different PCa cell lines; LNCaP xenograft serum as well as patient plasma/serum by differential centrifugation and ultracentrifugation on a sucrose density gradient. Exosomes were confirmed by electron microscopy, expression of exosomal markers and NanoSight^™ analysis. EGFR expression was determined by western blot analysis and ELISA. This study demonstrates that exosomes may easily be derived from PCa cell lines, serum obtained from PCa xenograft bearing mice and clinical samples derived from PCa patients. Presence of exosomal EGFR in PCa patient exosomes may present a novel approach for measuring of the disease state. Our work will allow to build on this finding for future understanding of PCa exosomes and their potential role in PCa progression and as minimal invasive biomarkers for PCa.     

Plakophilin-2 Promotes Activation of Epidermal Growth Factor Receptor

While growth factor-driven dimerization of receptor tyrosine kinases (RTKs) is a simple and intuitive mechanism of activating RTKs, K.-I. Arimoto et al. (Mol. Cell. Biol. 34:3843–3854, 2014, doi:10.1128/MCB.00758-14) describe a novel means of promoting the activity of RTKs. Namely, plakophilin-2 (PKP2) associates with the epidermal growth factor receptor (EGFR) and enhances its ligand-dependent and ligand-independent activity. This discovery suggests that antagonizing PKP2 may be a new therapeutic opportunity to combat tumors in which activation of EGFR contributes to pathogenesis.     

Conformational Analysis of the Phosphorylated Epidermal Growth Factor Receptor

Phosphorylation-induced conformational changes have been well documented with different receptor tyrosine kinases. However, the susceptible epitopes and the tyrosine residue(s) involved in particular structural alteration mostly remain to be determined. Using a conformation-specific anti-peptide antibody, we have not only identified one such domain in the C-terminal tail of the EGF receptor but also identified the phosphate acceptor sites that are involved in the conformational change.     

人EGFR显性负性突变体负调控内源性EGFR功能的机制分析

通过定向克隆法构建真核表达载体pEGFPN1-DNEGFR,脂质体介导下转染体外培养的SGC-7901细胞,应用Western blotting检测DNEGFR-EGFP蛋白的表达,激光共聚焦显微镜对DNEGFR-EGFP亚细胞结构定位检测;并经RT-PCR、Western blotting检测DNEGFR-EGFP对内源性EGFRmRNA水平、蛋白及磷酸化水平的影响.成功检测到DNEGFR-EGFP蛋白的表达,DNEGFR-EGFP蛋白主要定位于细胞膜,DNEGFR-EGFP能降低内源性EGFR蛋白磷酸化水平,而对内源性EGFRmRNA水平及蛋白水平无影响.研究证明DNEGFR通过降低内源性EGFR蛋白磷酸化水平负调控EGFR功能,为靶向EGFR显性负性策略在肿瘤生物治疗中的进一步研究打下基础.     

Comprehensive Mapping of the Human Kinome to Epidermal Growth Factor Receptor Signaling

Disregulation of epidermal growth factor receptor (EGFR) signaling directly promotes bypass of proliferation and survival restraints in a high frequency of epithelia-derived cancer. As such, much effort is currently focused on decoding the molecular architecture supporting EGFR activation and function. Here, we have leveraged high throughput reverse phase protein lysate arrays, with a sensitive fluorescent nanocrystal-based phosphoprotein detection assay, together with large scale siRNA-mediated loss of function to execute a quantitative interrogation of all elements of the human kinome supporting EGF-dependent signaling. This screening platform has captured multiple novel contributions of diverse protein kinases to modulation of EGFR signal generation, signal amplitude, and signal duration. As examples, the prometastatic SNF1/AMPK-related kinase hormonally upregulated Neu kinase was found to support EGFR activation in response to ligand binding, whereas the enigmatic kinase MGC16169 selectively supports coupling of active EGFR to ERK1/2 regulation. Of note, the receptor tyrosine kinase MERTK and the pyrimidine kinase UCK1 were both found to be required for surface accumulation of EGFR and subsequent pathway activation in multiple cancer cell backgrounds and may represent new targets for therapeutic intervention.     

Mechanisms for Kinase-mediated Dimerization of the Epidermal Growth Factor Receptor

We study a mechanism by which dimerization of the EGF receptor (EGFR) cytoplasmic domain is transmitted to the ectodomain. Therapeutic and other small molecule antagonists to the kinase domain that stabilize its active conformation, but not those that stabilize an inactive conformation, stabilize ectodomain dimerization. Inhibitor-induced dimerization requires an asymmetric kinase domain interface associated with activation. EGF and kinase inhibitors stimulate formation of identical dimer interfaces in the EGFR transmembrane domain, as shown by disulfide cross-linking. Disulfide cross-linking at an interface in domain IV in the ectodomain was also stimulated similarly; however, EGF but not inhibitors stimulated cross-linking in domain II. Inhibitors similarly induced noncovalent dimerization in nearly full-length, detergent-solubilized EGFR as shown by gel filtration. EGFR ectodomain deletion resulted in spontaneous dimerization, whereas deletion of exons 2–7, in which extracellular domains III and IV are retained, did not. In EM, kinase inhibitor-induced dimers lacked any well defined orientation between the ectodomain monomers. Fab of the therapeutic antibody cetuximab to domain III confirmed a variable position and orientation of this domain in inhibitor-induced dimers but suggested that the C termini of domain IV of the two monomers were in close proximity, consistent with dimerization in the transmembrane domains. The results provide insights into the relative energetics of intracellular and extracellular dimerization in EGFR and have significance for physiologic dimerization through the asymmetric kinase interface, bidirectional signal transmission in EGFR, and mechanism of action of therapeutics.     

成纤维细胞生长因子与其受体相互作用及其抑制剂的研究进展

成纤维细胞生长因子（FGF）有许多重要的生理功能，并与肿瘤的形成有关.为了弄清FGF与成纤维细胞生长因子受体(FGFR)相互作用的机制，人们对FGF和FGFR的各个结合结构域进行了深入、细致的研究，定位了aFGF、bFGF的肝素结合区、bFGF的受体结合区、FGF受体的肝素结合区、配体结合区和FGF受体相互结合区，提出了两个FGF与FGFR相互作用的模型，在此基础上设计了FGF的核酸类、糖类和多肽类抑制剂，为寻找新一代抗癌药物打下了理论基础.     

Aging Affects Epidermal Growth Factor Receptor Phosphorylation and Traffic Kinetics

With increasing donor age, cultured human fibroblasts express fewer epidermal growth factor receptors and display decreased mitogenic responsiveness to epidermal growth factor. To determine age-associated differences in epidermal growth factor receptor phosphorylation and traffic kinetics, we studied in fibroblasts derived from donors of different ages autophosphorylation of the receptor after ligand binding and trafficking of the receptor–ligand complexes. We now report an age-associated delay in the rate of receptor phosphorylation after epidermal growth factor stimulation. Furthermore, receptor/ligand trafficking is affected by aging. There is an age-associated decrease and delay in the number of occupied receptors that are transported intracellularly and in their rate of clearance from the plasma membrane. Our data show that aging affects receptor/ligand activation and processing and suggest that the decreased cellular mitogenic response with aging may be, at least in part, the result of decrements in receptor activation and processing.     

Role for the Epidermal Growth Factor Receptor in Chemotherapy-Induced Alopecia

Treatment of cancer patients with chemotherapeutics like cyclophosphamide often causes alopecia as a result of premature and aberrant catagen. Because the epidermal growth factor receptor (EGFR) signals anagen hair follicles to enter catagen, we hypothesized that EGFR signaling may be involved in cyclophosphamide-induced alopecia. To test this hypothesis, skin-targeted Egfr mutant mice were generated by crossing floxed Egfr and Keratin 14 promoter-driven Cre recombinase mice. Cyclophosphamide treatment of control mice resulted in alopecia while Egfr mutant skin was resistant to cyclophosphamide-induced alopecia. Egfr mutant skin entered catagen normally, as indicated by dermal papilla condensation and decreased follicular proliferation, but did not progress to telogen as did Egfr wild type follicles. Egfr mutant follicles responded with less proliferation, apoptosis, and fewer p53-positive cells after cyclophosphamide. Treatment of control mice with the EGFR inhibitors erlotinib or gefitinib similarly suppressed alopecia and catagen progression by cyclophosphamide. Secondary analysis of clinical trials utilizing EGFR-targeted therapies and alopecia-inducing chemotherapy also revealed evidence for involvement of EGFR in chemotherapy-induced alopecia. Taken together, our results demonstrated the involvement of EGFR signaling in chemotherapy-induced alopecia, which will help in the design of novel therapeutic regimens to minimize chemotherapy-induced alopecia.