Stoichiometry,Kinetic and Binding Analysis of the Interaction between Epidermal Growth Factor (EGF) and the Extracellular Domain of the EGF Receptor

Abstract

The kinetics, binding equilibria and stoichiometry of the interaction between epidermal growth factor and the soluble extracellular domain of the epidermal growth factor receptor (sEGFR), produced in CHO cells using a bioreactor, have been studied by three methods: analytical ultracentrifugation, biosensor analysis using surface plasmon resonance detection (BIAcore 2000) and fluorescence anisotropy. These studies were performed with an sEGFR preparation purified in the absence of detergent using a mild two step chromatographic procedure employing anion exchange and size exclusion HPLC. The fluorescence anisotropy and analytical ultracentrifugation data indicated a 1:1 molar binding ratio between EGF and the sEGFR. Analytical ultracentrifugation further indicated that the complex comprised 2EGF: 2sEGFR, consistent with the model proposed recently by Lemmon et al. (1997). Global analysis of the BIAcore binding data showed that a simple Langmuirian interaction does not adequately describe the EGF: sEGFR interaction and that more complex interaction mechanisms are operative. Furthermore, analysis of solution binding data using either fluorescence anisotropy or the biosensor, to determine directly the concentration of free sEGFR in solution competition experiments, yielded Scatchard plots which were biphasic and Hill coefficients of less than unity. Taken together our data indicate that in solution there are two sEGFR populations; one which binds EGF with a K_D of 2–20 nM and the other with a K_D of 400–550 nM.     

Gab1 is essential for membrane translocation,activity and integrity of mTORCs after EGF stimulation in urothelial cell carcinoma

Urothelial carcinoma is the most common type of malignancy in long-term dialysis patients and kidney transplant recipients in Taiwan. mTORCs (mammalian target of rapamycin complexes) and EGF are important in urothelial carcinoma. To identify the regulation of mTORCs upon EGF stimulation is necessary. mTOR integrates signals from growth factors via mTOR Complex 1 (mTORC1) and mTOR Complex 2 (mTORC2). The mechanism of mTORC1 action has been widely studied; however, the regulation of mTORC2 has not been well studied. Here, we demonstrate that Gab1 is an important upstream regulator in EGF-mediated activation of mTORCs. In our study, we confirm that mTORCs translocate from the cytoplasm to the plasma membrane via the PH domain of Gab1 upon EGF stimulation. Moreover, Gab1 associates with mTORCs. This association stabilizes the integrity of mTORCs and induces mTORC activity. Compared to normal bladder tissue, the expression of Gab1 and activity of mTORCs are elevated in urothelial carcinoma. Collectively, our results suggest that Gab1 is an essential regulator of the EGF-mediated mTORC pathways and may potentially be used as a biomarker for urothelial carcinoma to predict diagnosis and drug response.     

Nouvelle perspective de traitement dans le cancer bronchique non à petites cellules (CBNPC). Place de l’afatinib : un inhibiteur oral et irréversible de la famille ErbB

Tyrosine kinase inhibitors (TKI) that block epidermal growth factor receptor (EGFR) pathway have demonstrated a clinical benefit for patients with non-small-cell lung cancer (NSCLC) harboring EGFR mutations. The currently available TKI (gefitinib and erlotinib) are EGFR reversible inhibitors. Afatinib is an oral, irreversible ErbB family blocker that covalently binds and blocks signaling from EGFR (ErbB1), HER2 (ErbB2) and ErbB4. The compound inhibits also the transphosphorylation of ErbB3. With this mode of action, afatinib is thought to have a mechanistic advantage over EGFR blockade alone, in that it provides a sustained, covalent inhibition of ErbB homo- and hetero-dimers. In the pivotal LUX-Lung 3 study, afatinib demonstrated a prolonged progression free survival over standard pemetrexed plus cisplatin chemotherapy (11.1 versus 6.9 months; HR = 0.58, 95% CI: 0.43–0.78; P = 0.001) in EGFR mutation positive NSCLC patients. The compound has recently been granted a marketing authorization (MA) for the treatment of patients with locally advanced or metastatic NSCLC with activating EGFR mutation(s) and EGFR TKI-naive. In this paper are summarized the efficacy and safety data in this indication.     

加味黑布膏对大鼠耳廓复合痤疮模型局部组织IL-2及EGF的影响

目的通过观察加味黑布膏对大鼠耳廓复合痤疮模型IL-2及EGF的影响,研究加味黑布膏对大鼠痤疮的干预机制。方法按随机数字表法将72只雌雄各半的Wistar大鼠平均分为6组,分别是:空白组、模型组、加味黑布膏高、中、低剂量组以及阳性对照组。除空白组外用Kligman法对大鼠耳廓进行造模,21 d后,随机抽取4只进行病理切片观察,提示造模成功后开始外用药物,空白组和模型组不给予药物治疗,黑布膏低、中、高剂量组分别给予不同剂量的加味黑布膏,外用1次/d,阳性对照组给予0.025%的维A酸乳膏,给药1次/d,连续用药4周,4周后对大鼠进行局部组织采样,并采用ELISA法检测样品中IL-2以及EGF的含量。结果经4周治疗后各组局部组织中IL-2以及EGF较模型组均有所下降(P<0.05),加味黑布膏中、低剂量组中所测因子与阳性对照组比较差异无统计意义(P>0.05),高剂量组与阳性对照组比较差异有统计学意义(P<0.01)。结论加味黑布膏治疗痤疮疗效明确,可能与加味黑布膏降低局部组织中IL-2及EGF有关。     

定坤丹联合炔诺酮治疗月经不调的临床研究

目的探讨定坤丹联合炔诺酮治疗月经不调的临床疗效。方法选取2017年3月—2019年3月在开封市人民医院治疗的月经不调患者92例,根据用药的差别分为对照组(46例)和治疗组(46例)。对照组口服炔诺酮片,2.5mg/次,4次/d;治疗组在对照组基础上口服定坤丹,7 g/次,2次/d。两组患者均经过3个月经周期治疗。观察两组患者临床疗效,同时比较治疗前后两组患者临床症候积分、性激素水平、月经失血图(PBAC)、中华生存质量量表(Ch QOL)、高温相评分(HPS)、匹茨堡睡眠质量指数量表(PSQI)评分以及血清细胞因子水平。结果治疗后,对照组临床有效率为82.61%,显著低于治疗组的97.83%,两组比较差异具有统计学意义(P0.05)。治疗后,两组患者症候积分明显下降(P0.05),且治疗组临床症候积分明显低于对照组(P0.05)。治疗后,两组血清孕酮(P)、雌二醇(E2)水平显著升高(P0.05),黄体生成激素(LH)、促卵泡成熟激素(FSH)水平显著下降(P0.05),且治疗组E2、P、LH和FSH水平明显好于对照组(P0.05)。治疗后,两组PBAC和PSQI评分显著下降(P0.05),Ch QOL和HPS评分显著升高(P0.05),且治疗组PBAC、PSQI、Ch QOL和HPS评分明显好于对照组(P0.05)。治疗后,两组患者血清表皮生长因子(EGF)、血管内皮生长因子(VEGF)水平均明显升高(P0.05),且治疗组EGF和VEGF水平明显高于对照组(P0.05)。结论定坤丹联合炔诺酮片治疗月经不调可有效改善患者临床症状,改善机体性激素水平,提高患者睡眠和生活质量。     

健脾益气法对结直肠炎病变后诱发结直肠癌小鼠的影响研究

目的:观察健脾益气中药对结直肠炎病变后诱发结直肠癌小鼠白细胞介素(Interleukin,IL)-6和表皮细胞生长因子(Epidermal Growth Factor,EGF)蛋白的影响。方法:将30只雄性C57BL/6小鼠随机分为对照组、模型组和治疗组,每组10只。采用偶氮氧化甲烷/葡聚糖硫酸钠方法建立结直肠炎相关结直肠癌小鼠模型,治疗组以加减四君子汤颗粒加蒸馏水配成溶液,药物质量浓度19.92%,3.32 g/kg灌胃,模型组以蒸馏水灌胃。4周后处死各组小鼠并留取血液和结直肠组织组织标本,酶联免疫吸附试验(Enzyme-linked immunosorbent method,ELISA)法检测血清IL-6浓度,苏木精-伊红染色法(Hematoxylin-eosin Staining,简称HE染色法)染色镜下观察小鼠结肠组织病理变化,Western-blot法检测EGF蛋白表达。结果:健脾益气治疗组小鼠的体质量较模型组明显增加,差异有统计学意义(P<0.01);治疗组小鼠血清IL-6表达量比模型组显著下降,差异有统计学意义(P<0.01);治疗组小鼠的EGF蛋白表达显著降低,与模型组比较,差异均有统计学意义(P<0.05)。结论:健脾益气中药能增加结直肠炎病变后诱发结直肠癌小鼠的体质量,减少炎症因子IL-6的表达和降低EGF蛋白表达,可为健脾益气中药抗结肠癌临床应用提供科学依据。     

PI3K/Akt/mTOR信号通路对大鼠肾小球系膜细胞增殖的调控作用探讨

目的:探讨磷脂酰肌醇-3(PI3K)/蛋白激酶(Akt)/哺乳动物雷帕霉素靶蛋白(m TOR)信号通路对大鼠肾小球系膜细胞(MC)增殖的调控作用。方法:体外培养大鼠MC,随机分为正常对照组、表皮生长因子(EGF)(10ng/m L)组、PI3K抑制剂LY294002组(2μg/m L)、EGF联合LY294002组。采用四甲基偶氮唑蓝(MTT)法检测4组MC的增殖,流式细胞术检测MC周期,免疫荧光法检测系膜细胞m TOR的表达。结果:与正常对照组相比,EGF组能显著促进大鼠MC增殖,G0/G1期细胞减少,S期及G2/M期细胞增加,且m TOR表达增加;LY294002组大鼠MC增殖受抑制,G0/G1期细胞增加,S期及G2/M期细胞减少,且m TOR表达降低;与EGF组比较,EGF联合LY294002干预组MC增殖受抑制,G0/G1期细胞增多,S期及G2/M期细胞减少,且m TOR表达降低。结论:m TOR信号通路参与了大鼠肾小球MC增殖的调控,抑制该信号通路的活化可显著抑制MC的增殖和MC周期的进程。     

Mutations in K-Ras linked to levels of osteoprotegerin and sensitivity to TRAIL-induced cell death in pancreatic ductal adenocarcinoma cells

Osteoprotegerin (OPG) is a soluble receptor expressed in the serum of patients with diabetes, arthritis and pancreatic cancer. While OPG has been considered a tumor survival factor for bone metastasizing breast and prostate cancers, the role of OPG in pancreatic cancer, which itself rarely metastasizes to bone, is not known. Pancreatic ductal adenocarcinoma (PDAC) cell lines were found to secrete OPG and the level of OPG production correlated with sensitivity to TRAIL-induced apoptosis. Silencing OPG sensitized cells to TRAIL-induced apoptosis. Interestingly, a positive correlation was noted between OPG production level and K-Ras mutation status. Earlier studies implicated K-Ras in conferring resistance to TRAIL-induced apoptosis in pancreatic cells and this study demonstrates that K-Ras mediated TRAIL resistance in pancreatic cancer cells occurs due to increased OPG production. Silencing K-Ras in pancreatic cancer cells decreased OPG levels and increased sensitivity to TRAIL-induced apoptosis. These observations indicate that OPG can play a role in both cell survival and in PDAC cell sensitivity to TRAIL-induced apoptosis, which may contribute to metastasis. Targeted inhibition of OPG binding to TRAIL may represent a therapeutic approach in the treatment of pancreatic cancer.     

Effects of D-Penicillamine and Prednisolone on Connective Tissue in Rats

The effects of D-penicillamine and prednisolone acetate on connective tissue were studied in rats using various techniques. Tensile strength of skin strips decreased even after 2 days' oral treatment with D-penicillamine. This effect was dose-related and was much more pronounced after 10 days' treatment. Injections of prednisolone acetate caused an increase of skin tensile strength which was antagonized by simultaneous treatment with D-penicillamine. In contrast to skin there was almost no influence of D-penicillamine in doses up to 300 mg/kg p.o. on tensile strength of femoral epiphyseal plates of rats. In addition, the antagonism against prednisolone was very small in epi- physeal cartilage.

D-penicillamine caused no effect on exudative inflammation (granuloma pouch) whereas prednisolone was very effective. Connective tissue proliferation measured as wet weight of glass rod granuloma was not influenced by D-penicillamine, whereas a significant weight reduction was found after prednisolone injections. In contrast to the lack of effect on wet weight, the breaking load of glass rod granuloma was considerably decreased by D-penicillamine. In spite of severe weight reduction by prednisolone treatment the tensile strength of granuloma tissue was slightly increased.     

Wound dressing composed of hyaluronic acid and collagen containing EGF or bFGF: comparative culture study

We developed a novel wound dressing composed of a hyaluronic acid (HA) and collagen (Col) spongy sheet containing epidermal growth factor (EGF) or basic fibrolast growth factor (bFGF) by freeze-drying method (EGF-wound dressing or bFGF-wound dressing, respectively). A wound dressing without any growth factor was prepared as a control in a similar manner as above (C-wound dressing). Intermolecular cross-linkage between Col molecules was induced by UV irradiation. The release behavior of free HA from the wound dressing was investigated using a C-wound dressing. The weight of C-wound dressing after 1 day, 3, 5, and 7?days of incubation on top of a Col gel sheet at the air–water interface (wound surface model) was 55, 36, 30, and 19% of the original weight, respectively. Most free HA and a part of Col was released from the cross-linked Col network in the wound dressing during incubation, as the original Col content in the wound dressing was 33%. Next, fibroblast proliferation was assessed in conventional culture medium preconditioned by immersion of a piece of C-, EGF-, or bFGF-wound dressing, i.e. C-conditioned medium, EGF-conditioned medium, or bFGF-conditioned medium. Cell proliferation in C-conditioned medium increased to approximately the same level as that in conventional medium. Cell proliferation in EGF- and bFGF-conditioned medium was 1.9 times and 2.6 times greater than that in conventional medium after 7?days of cultivation, respectively. Finally, cytokine production of fibroblasts was assessed in a wound surface model using a fibroblast-incorporating Col gel sheet (cultured dermal substitute [CDS]). CDS was elevated to the air–medium interface, on which each wound dressing was placed and cultured for 7?days. Fibroblasts in CDS covered with EGF-wound dressing released 3.6 times more vascular endothelial growth factor (VEGF) and 4.6 times more hepatocyte growth factor (HGF) when compared with the C-wound dressing. Fibroblasts in CDS covered with bFGF-wound dressing released 10.2 times more VEGF and 6.3 times more HGF when compared with the C-wound dressing. This finding indicates that bFGF-wound dressing can facilitate more effectively the VEGF and FGF production compared with EGF-wound dressing.