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。     

Growth Differentiation Factor (GDF)-15 Blocks Norepinephrine-induced Myocardial Hypertrophy via a Novel Pathway Involving Inhibition of Epidermal Growth Factor Receptor Transactivation

Accumulating evidence suggests that growth differentiation factor 15 (GDF-15) is associated with the severity and prognosis of various cardiovascular diseases. However, the effect of GDF-15 on the regulation of cardiac remodeling is still poorly understood. In this present study, we demonstrate that GDF-15 blocks norepinephrine (NE)-induced myocardial hypertrophy through a novel pathway involving inhibition of EGFR transactivation. Both in vivo and in vitro assay indicate that NE was able to stimulate the synthesis of GDF-15. The up-regulation of GDF-15 feedback inhibits NE-induced myocardial hypertrophy, including quantitation of [³H]leucine incorporation, protein/DNA ratio, cell surface area, and ANP mRNA level. Further research shows that GDF-15 could inhibit the phosphorylation of EGF receptor and downstream kinases (AKT and ERK1/2) induced by NE. Clinical research also shows that serum GDF-15 levels in hypertensive patients were significant higher than in healthy volunteers and were positively correlated with the thickness of the posterior wall of the left ventricle, interventricular septum, and left ventricular mass, as well as the serum level of norepinephrine. In conclusion, NE induces myocardial hypertrophy and up-regulates GDF-15, and this up-regulation of GDF-15 negatively regulates NE-induced myocardial hypertrophy by inhibiting EGF receptor transactivation following NE stimulation.     

P2Y2 Nucleotide Receptors Mediate Metalloprotease-dependent Phosphorylation of Epidermal Growth Factor Receptor and ErbB3 in Human Salivary Gland Cells

The G protein-coupled receptor P2Y₂ nucleotide receptor (P2Y₂R) has been shown to be up-regulated in a variety of tissues in response to stress or injury. Recent studies have suggested that P2Y₂Rs may play a role in immune responses, wound healing, and tissue regeneration via their ability to activate multiple signaling pathways, including activation of growth factor receptors. Here, we demonstrate that in human salivary gland (HSG) cells, activation of the P2Y₂R by its agonist induces phosphorylation of ERK1/2 via two distinct mechanisms, a rapid, protein kinase C-dependent pathway and a slower and prolonged, epidermal growth factor receptor (EGFR)-dependent pathway. The EGFR-dependent stimulation of UTP-induced ERK1/2 phosphorylation in HSG cells is inhibited by the adamalysin inhibitor tumor necrosis factor-α protease inhibitor or by small interfering RNA that selectively silences ADAM10 and ADAM17 expression, suggesting that ADAM metalloproteases are required for P2Y₂R-mediated activation of the EGFR. G protein-coupled receptors have been shown to promote proteolytic release of EGFR ligands; however, neutralizing antibodies to known ligands of the EGFR did not inhibit UTP-induced EGFR phosphorylation. Immunoprecipitation experiments indicated that UTP causes association of the EGFR with another member of the EGF receptor family, ErbB3. Furthermore, stimulation of HSG cells with UTP induced phosphorylation of ErbB3, and silencing of ErbB3 expression inhibited UTP-induced phosphorylation of both ErbB3 and EGFR. UTP-induced phosphorylation of ErbB3 and EGFR was also inhibited by silencing the expression of the ErbB3 ligand neuregulin 1 (NRG1). These results suggest that P2Y₂R activation in salivary gland cells promotes the formation of EGFR/ErbB3 heterodimers and metalloprotease-dependent neuregulin 1 release, resulting in the activation of both EGFR and ErbB3.     

Epidermal Growth Factor and EGF Receptors are mainly expressed in the wound epidermis and proliferating ependyma of the regenerating tail of lizards

The presence of EGF and its receptor during tail regeneration in lizard has been assessed by immunoblotting and immunofluorescence to test whether this growth factor may be involved in the process. Immunolabelled bands at 8 and 42–46 kDa for EGF are detected in the regenerating tail. A main band at 45–50 kDa and other weaker bands at lower or higher molecular weight for the EGF receptor are also present. The results indicate that degraded forms of the protein are present although the specific nature of the different bands could not be determined. Immunofluorescence indicates that EGF-labelled cells and EGF receptor are especially seen in the wound epidermis and in the cytoplasm of ependymal cells. Numerous basal keratinocytes of the wound epidermis and apical epidermal peg contain labelled nuclei for EGFR, suggesting that activated receptor stimulates intense cell proliferation of the wound epidermis. Blastema and labelled myoblasts are occasionally detected in early differentiating muscles, but almost no labelled chondroblasts are present in the differentiating cartilaginous tube. The study indicates that EGF and its receptor are mainly present in epithelial cells in a form that allows them to regulate proliferation during tail regeneration.     

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)     

EGFR突变种类与临床疗效关联

癌组织中表皮生长因子受体（epidermal growth factor receptor,EGFR）基因突变是应用靶向药物EGFR酪氨酸激酶抑制剂（tyrosine kinase inhibitor,TKI）治疗的一个重要相关因素及预测指标。对其突变的检测可以指导TKI类药物（TKIs）的最佳应用。该种突变常出现在非小细胞肺癌（NSCLC）中,尤其是在亚洲女性、肺腺癌、非吸烟者中,与非小细胞肺癌患者对TKIs治疗的敏感性密切相关。本文旨在探讨利用EGFR基因的已知突变热点的相关知识选择适合不同分子遗传学背景的群体或/和个体的＂个体化＂治疗方案,最终达到延长肺癌患者生存时间和提高生活质量的双重目的。     

Transient Acceleration of Epidermal Growth Factor Receptor Dynamics Produces Higher-Order Signaling Clusters

Cell signaling depends on spatiotemporally regulated molecular interactions. Although the movements of signaling proteins have been analyzed with various technologies, how spatial dynamics influence the molecular interactions that transduce signals is unclear. Here, we developed a single-molecule method to analyze the spatiotemporal coupling between motility, clustering, and signaling. The analysis was performed with the epidermal growth factor receptor (EGFR), which triggers signaling through its dimerization and phosphorylation after association with EGF. Our results show that the few EGFRs isolated in membrane subdomains were released by an EGF-dependent increase in their diffusion area, facilitating molecular associations and producing immobile clusters. Using a two-color single-molecule analysis, we found that the EGF-induced state transition alters the properties of the immobile clusters, allowing them to interact for extended periods with the cytoplasmic protein, GRB2. Our study reveals a novel correlation between this molecular interaction and its mesoscale dynamics, providing the initial signaling node.     

靶向表皮生长因子受体的全新小分子配体筛选

肿瘤靶向分子的筛选一直是肿瘤治疗和早期诊断的研究热点 . 表皮生长因子受体 (EGFR) 在很多肿瘤细胞表面过量表达,是一个理想的药物输送靶点 . 选择了 EGFR 表面不同于表皮生长因子 (EGF) 结合位点的一个凹陷部位作为计算机模拟筛选的结合位点,然后使用 DOCK 软件包对 DTP-Plated 有机小分子数据库进行了两遍筛选,最后选择了 7 个有机小分子作为可能的靶向分子 . BIAcore 体外结合实验对所选择的小分子样品进行了进一步的验证,结果表明,小分子 NSC51186 能特异地与 EGFR 结合 . 小分子 NSC51186 和 EGFR 之间的动力学常数也得到进一步的测定 . 新的靶向分子和药物、纳米粒子或者基因载体相连,将有可能用于靶向于 EGFR 的肿瘤治疗和诊断 .     

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.     

Plasma Kallikrein Promotes Epidermal Growth Factor Receptor Transactivation and Signaling in Vascular Smooth Muscle through Direct Activation of Protease-activated Receptors

The kallikrein-kinin system, along with the interlocking renin-angiotensin system, is a key regulator of vascular contractility and injury response. The principal effectors of the kallikrein-kinin system are plasma and tissue kallikreins, proteases that cleave high molecular weight kininogen to produce bradykinin. Most of the cellular actions of kallikrein (KK) are thought to be mediated by bradykinin, which acts via G protein-coupled B1 and B2 bradykinin receptors on VSMCs and endothelial cells. Here, we find that primary aortic vascular smooth muscle but not endothelial cells possess the ability to activate plasma prekallikrein. Surprisingly, exposing VSMCs to prekallikrein leads to activation of the ERK1/2 mitogen-activated protein kinase cascade via a mechanism that requires kallikrein activity but does not involve bradykinin receptors. In transfected HEK293 cells, we find that plasma kallikrein directly activates G protein-coupled protease-activated receptors (PARs) 1 and 2, which possess consensus kallikrein cleavage sites, but not PAR4. In vascular smooth muscles, KK stimulates ADAM (a disintegrin and metalloprotease) 17 activity via a PAR1/2 receptor-dependent mechanism, leading sequentially to release of the endogenous ADAM17 substrates, amphiregulin and tumor necrosis factor-α, metalloprotease-dependent transactivation of epidermal growth factor receptors, and metalloprotease and epidermal growth factor receptor-dependent ERK1/2 activation. These results suggest a novel mechanism of bradykinin-independent kallikrein action that may contribute to the regulation of vascular responses in pathophysiologic states, such as diabetes mellitus.     

Mutations in the Polybasic Juxtamembrane Sequence of Both Plasma Membrane- and Endoplasmic Reticulum-localized Epidermal Growth Factor Receptors Confer Ligand-independent Cell Transformation

Deregulation of ErbB receptor-tyrosine kinases is a hallmark of many human cancers. Conserved in the ErbB family is a cluster of basic amino acid residues in the cytoplasmic juxtamembrane region. We found that charge-silencing mutagenesis within this juxtamembrane region of the epidermal growth factor receptor (EGFR) results in the generation of a mutant receptor (EGFR Mut R1-6) that spontaneously transforms NIH 3T3 cells in a ligand-independent manner. A similar mutant with one additional basic residue, EGFR Mut R1-5, fails to exhibit ligand-independent transformation. The capacity of EGFR Mut R1-6 to mediate this transformation is maintained when this mutant is retained in the endoplasmic reticulum via a single point mutation, L393H, which we describe. We show that EGFR Mut R1-6 with or without L393H exhibits enhanced basal tyrosine phosphorylation when ectopically expressed, and the ligand-independent transforming activity of EGFR Mut R1-6 is sensitive to inhibition of EGFR kinase activity and is particularly dependent on PI3K and mTOR activity. Similar to EGFR Mut R1-6/L393H in NIH 3T3 cells, EGFR variant type III, a highly oncogenic mutant form of EGFR linked to human brain cancers, confers transforming activity while it is wholly endoplasmic reticulum-retained in U87 cells. Our findings highlight the importance of the polybasic juxtamembrane sequence in regulating the oncogenic potential of EGFR signaling.     

表皮生长因子受体信号通路在维吾尔族妇女宫颈癌中的表达研究

目的:随着表皮生长因子受体(epidermal growth factor receptor,EGFR)靶点治疗药物在其它肿瘤治疗中的应用,能否在妇科肿瘤中应用并取得疗效,已经得到学者们的重视。但在临床应用之前,必须明确EGFR与妇科肿瘤发生发展的关系及其机制。因此,我们来探讨表皮生长因子受体EGFR信号通路在维吾尔族不同级别宫颈病变组织中的差异表达及其临床意义。方法:应用免疫组织化学方法检测EGFR、P-EGFR、ERK 1/2、P-ERK1/2在108例子宫颈癌,47例CIN,79例正常宫颈组织中的表达,并分析其与临床病理参数的关系。结果:EGFR在子宫颈癌、CIN及正常宫颈组织中的阳性表达率分别是74.10%、66%、27.80%(P0.01);P-EGFR在三组间的阳性表达率分别是55.60%、74.50%、20.30%(P0.01);ERK1/2在三组间的阳性表达率分别是60.10%、76.60%、25.30%(P0.01);P-ERK1/2在三组间的阳性表达率分别是44.40%、66%、24.10%(P0.01),其在宫颈癌中EGFR与与浸润深度、淋巴结转移有关;ERK与肿瘤的临床分期、远处转移有关,而且在宫颈癌中EGFR与P-EGFR、ERK 1/2、P-ERK1/2的表达成正相关(P0.05)。结论:EGFR、P-EGFR、ERK1/2、P-ERK1/2的表达与宫颈癌的发生、发展相关,促进宫颈癌的浸润和转移,抑制EGFR信号通路可能为多靶点联合治疗宫颈癌提供新的方向。     

A Pathophysiologic Role for Epidermal Growth Factor Receptor in Pemphigus Acantholysis

The pemphigus family of autoimmune bullous disorders is characterized by autoantibody binding to desmoglein 1 and/or 3 (dsg1/dsg3). In this study we show that EGF receptor (EGFR) is activated following pemphigus vulgaris (PV) IgG treatment of primary human keratinocytes and that EGFR activation is downstream of p38 mitogen-activated protein kinase (p38). Inhibition of EGFR blocked PV IgG-triggered dsg3 endocytosis, keratin intermediate filament retraction, and loss of cell-cell adhesion in vitro. Significantly, inhibiting EGFR prevented PV IgG-induced blister formation in the passive transfer mouse model of pemphigus. These data demonstrate cross-talk between dsg3 and EGFR, that this cross-talk is regulated by p38, and that EGFR is a potential therapeutic target for pemphigus. Small-molecule inhibitors and monoclonal antibodies directed against EGFR are currently used to treat several types of solid tumors. This study provides the experimental rationale for investigating the use of EGFR inhibitors in pemphigus.     

Prolidase Directly Binds and Activates Epidermal Growth Factor Receptor and Stimulates Downstream Signaling

Prolidase, also known as Xaa-Pro dipeptidase or peptidase D (PEPD), is a ubiquitously expressed cytosolic enzyme that hydrolyzes dipeptides with proline or hydroxyproline at the carboxyl terminus. In this article, however, we demonstrate that PEPD directly binds to and activates epidermal growth factor receptor (EGFR), leading to stimulation of signaling proteins downstream of EGFR, and that such activity is neither cell-specific nor dependent on the enzymatic activity of PEPD. In line with the pro-survival and pro-proliferation activities of EGFR, PEPD stimulates DNA synthesis. We further show that PEPD activates EGFR only when it is present in the extracellular space, but that PEPD is released from injured cells and tissues and that such release appears to result in EGFR activation. PEPD differs from all known EGFR ligands in that it does not possess an epidermal growth factor (EGF) motif and is not synthesized as a transmembrane precursor, but PEPD binding to EGFR can be blocked by EGF. In conclusion, PEPD is a ligand of EGFR and presents a novel mechanism of EGFR activation.     

花背蟾蜍胎肺发育中表皮生长因子受体的表达和定位作用

取花背蟾蜍(Bufo raddei)363、7、38、39期蝌蚪肺组织和幼蟾肺组织,进行常规石蜡切片,用免疫组化SP两步法检测EGFR的表达。观察了表皮生长因子受体(EGFR)在花背蟾蜍胎肺发育过程的表达特征,并探讨表皮生长因子(EGF)和转化生长因子α(TGF-α)通过与EGFR的作用,对花背蟾蜍胎肺形态发生和肺泡上皮成熟分化的作用。结果表明,36期,EGFR在肺网状隔膜上皮细胞处有表达;37期,肺网状隔膜处EGFR阳性表达很明显,在肺泡囊处表达呈弱阳性;38期,肺网状隔膜处EGFR的阳性表达变弱,在远端的肺泡囊上皮细胞处其阳性表达增强;39期,EGFR在肺泡囊上皮细胞处阳性表达最活跃,在网状隔膜处EGFR的表达很弱;幼蟾期,EGFR阳性反应主要定位在肺泡上皮细胞。结论是,在胎肺发育的不同时期,EGFR在上皮细胞的定位有迁移,免疫组化反应强弱也有差异,说明EGFR在胎肺不同发育阶段发挥不同的功能,它对肺泡上皮细胞的成熟分化有重要调节作用。     

50 Hz弱磁场诱导离体表皮生长因子受体聚集

利用原子力显微镜(atomic force microscope,AFM)观测到浓度为5滋g/mL离体表皮因子受体(epidermal growth factor receptor,EGFR)蛋白在50Hz磁场作用下发生聚集,其颗粒呈现倍数变大和变高趋势;利用透射电镜(transmission electronic microscope,TEM)也得到类似的蛋白变大趋势。结果表明,在AFM和TEM下观察到,磁场作用后蛋白聚集颗粒的平均半高宽(平均直径)由(21.7±2.2)nm(12.5nm)增大到(33.0±4.0)nm(23nm),最可几高度由(1.42±0.18)nm增加到(3.08±0.17)nm。这种由磁场引起的聚集效应呈时间依赖性。利用Alexa-488-EGF标记EGFR观察了磁场暴露对细胞上EGF受体表达的影响,提示EGF受体的表达可能稍有上调。上述结果提示50Hz磁场信号可能通过影响EGFR的膜上聚集状态来影响下游信号通路。这种对信号通路的影响可能是电磁场生物性效应的一种机制。     

阿霉素肾病大鼠表皮生长因子及其受体的表达

目的研究阿霉素肾病大鼠肾组织中表皮生长因子(EGF)及其受体EGFR的表达分布以及表达量与尿蛋白之间关系。方法选择第5天、14天、28天作为动态观察的时点,同期设立正常对照。采用荧光定量RT-PCR、免疫组织化学及计算机图像定量分析EGF mRNA以及EGF、EGFR蛋白在肾组织的表达,同时测定24 h尿蛋白定量。WT1和EGFR双重免疫组化确定EGFR在肾小球内确切细胞定位。结果阿霉素注射后第5天,EGFmRNA即较正常增高,28 d明显增高并高于5 d和14 d。正常对照组EGF阳性细胞主要分布于远曲小管和髓袢,阿霉素组EGF还在集合管和近曲小管上表达;EGF阳性表达范围和强度随尿蛋白增加而增加;EGFmRNA表达量以及EGF在肾小管中的表达强度与24 h尿蛋白量呈正相关。肾小管上皮细胞广泛表达EGFR,阿霉素组EGFR在小管表达均高于正常,但组间各时点差异无显著性;随尿蛋白增加EGFR在肾小球内表达逐渐增多。EGFR在肾小球和肾小管中的表达强度均与24 h尿蛋白量呈正相关。WT1和EGFR双重免疫组化显示阿霉素肾病组EGFR可在足突细胞上表达,正常组则无。结论阿霉素肾病大鼠的肾小球脏层上皮有EGFR的表达。EGF/EGFR可能参与了阿霉素肾病的发病过程以及蛋白尿的形成。     

表皮生长因子受体(EGFR)的细胞内信号传导

表皮生长因子受体（EGFR）是一种存在于细胞表面的多功能跨膜蛋白分子,具有酪氨酸蛋白激酶活性,EGFR与配体结合后启动细胞内信号传导通路,不同的通路之间存在交叉对话（Cross-talks）共同完成细胞生理功能.对EGFR的深入研究,不仅可阐明细胞生长和发育等重要的生命过程,而且在医药和工业上也将有广泛的应用.