Autocrine and paracrine growth regulation of human breast cancer

Summary We consider the hypothesis that estrogen control of hormone dependent breast cancer is mediated by autocrine and paracrine growth factors secreted by the breast cancer cells themselves. Though we show direct, unmediated effects of estrogen on specific cell functions, we also provide evidence that human breast cancer cells secrete a collection of growth factors (IGF-I, TGF, TGF, a PDGF-like competency factor, and at least one new epithelial colony stimulating factor). Some of these are estrogen-regulated in hormone dependent cells, and are constitutively increased in cells which acquire independence either spontaneously or byras transfection. Collectively, the secreted growth factors are capable of promoting tumor formation by MCF-7 cells in nude mice, though not to the same extent as estrogens. There would seem to be potential for clinical intervention in the autocrine and paracrine control of breast cancer cells, including some cells which are no longer dependent on estrogens.     

EGF对小鼠角质形成细胞中组织型纤溶酶原激活剂表达的调节

目的 探讨小鼠表皮角质形成细胞（KC）中,EGF对组织型纤溶酶原激活剂（tPA)表达的影响。方法 应用免疫组化及原位杂交技术, 结合图像分析,定性及定量检测在EGF作用下的小鼠表皮角质形成细胞中,tPA mRNA/蛋白质的表达。结果 小鼠表皮KC经EGF处理12、24、48、72h后,tPAmRNA/蛋白质的量均增加（P＜0．01）,tPAmRNA的表达的 高峰出现于EGF作用24h时,tPA蛋白质表达的高峰则出现于EGF作用48h时。EGF联合0．5、1．0、1．5mmol/L Ca^2 作用小鼠表皮KC48h,与EGF单独作用小鼠表皮KC48h时,tPAmRNAA／蛋白质的表达,均显著降低（P＜0．001）。结论 小鼠表皮KC中,EGF可以时间依赖方式促进 tPAmRNA／蛋白质的表达,但受Ca^2 浓度的影响。     

EGF、bFGF对兔自体穿透角膜移植伤口愈合的影响

目的 观察表皮生长因子（EGF）、碱性成纤维细胞生长因子（bFGF）对自体家兔穿透性角膜移植（PKP）术后伤口愈合的影响。方法 利用家兔自体穿透性角膜移植模型,采用测量伤口愈合强度、液闪计数、AgNORs染色、VG染色和电镜等方法,观察家兔PKP术后伤口愈合情况。结果 （1）EGF、bFGF、EGF bFGF点眼均能增加伤口所能承受的极限压力和∧3H-TdR的掺入率。（2）bFGF和EGF bFGF点眼能刺激伤口处成纤维细胞及其所分泌的胶原纤维呈比较规则的排列。结论 （1）EGF、bFGF、EGF bFGF点眼均能增加PKP术后伤口愈合的强度,增加伤口愈合时DNA的合成。（2）术后14d以后EGF和bFGF联合点眼对伤口愈合的促进作用仅相当于单独用bFGF点眼的水平。（3）bFGF能提高PKP术后伤口愈合的质量。     

膀胱肿瘤患者中表皮生长因子水平临床意义

目的 :对 12 7例不同年龄结构的正常人群和 2 8例膀胱肿瘤患者尿中 EGF水平进行测定。 方法 :采用I1 2 5 - EGF的放射免疫法测定 EGF水平。 结果 :小儿组 (15例 ) EGF浓度 (31.19± 7.46 ) μg/L;正常人群组 (92例 )EGF浓度 (16 .5 2± 1.6 9)μg/L ;膀胱肿瘤组 (2 8例 ) EGF浓度 (14.6 4± 1.86 )μg/L ;前列腺增生组 (BPH,2 0例 ) EGF浓度 (7.91± 1.11)μg/L。膀胱肿瘤组与正常人群组比较有统计学差异 (P <0 .0 5 ) ;年龄的变化也有统计学差异 (P<0 .0 5 )。 结论 :EGF与年龄有相关性 ;EGF是一个较可靠、灵敏的指标有助于膀胱肿瘤的早期诊断     

Specific inhibition of epidermal growth factor receptor tyrosine kinase by 4-anilinoquinazolines

Summary Since the mitogenic action of EGF is mediated by ligand-induced autophosphorylation of the EGF receptor (EGFR), and EGFR is commonly overexpressed in solid human tumours, inhibitors of receptor tyrosine kinase activity (RTK) could prove to be effective antitumour agents. Screening of a compound library using an EGF-RTK enzyme prepared from human tumour derived A431 cells identified a series of potent (IC₅₀<1µM) enzyme inhibitors. These inhibitors are quinazolines bearing a variety of substituted anilines at the 4-position. The most potent 4-anilinoquinazolines (IC₅₀ 20nM) have small non-polar meta substituents on the aniline ring, and are competitive with ATP and non-competitive with substrate. The growth inhibitory activity of these agents was assessed in vitro using KB cells (human oral squamous tumour) grown in the absence or presence of EGF. A selected compound, 4-(3-chloroanilino)quinazoline (CAQ), inhibited EGF-stimulated growth in a concentration dependent manner and complete blockade was observed at concentrations (1–10 µM) which had no effect on basal growth. Selectivity of growth inhibition by CAQ was further exemplified in IGF1-stimulated KB cells where no effect was detected at concentrations which completely blocked EGF-stimulated growth. Similarly, CAQ blocked TGF-stimulated growth in MCF-7 human breast cancer cells without affecting insulin-stimulated growth. These studies define a novel class of EGF-RTK inhibitors which are also potent and selective inhibitors of EGF-stimulated human tumour cell growthin vitro. Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb.     

The significance ofheregulin in breast cancer tumor progression and drug resistance

Summary TheerbB-2 receptor plays an important role in the prognosis of breast cancer and is expressed at high levels in nearly 30% of tumors in breast cancer patients. While evidence accumulates to support the relationship betweenerbB-2 overexpression and poor overall survival in human breast cancer, understanding of the biological consequence(s) oferbB-2 overexpression remains elusive. The discovery ofheregulin has allowed us to identify a number of related but distinct biological endpoints which appear responsive to signal transduction through theerbB-2/4 receptor. These endpoints of growth, invasiveness, and differentiation have clear implications for the emergence, maintenance, and/or control of malignancy, and represent established endpoints in the assessment of malignant progression in human breast cancer. Preliminary studiesin vitro have shown thatheregulin induces a biphasic growth effect on cells witherbB-2 overexpression. Interestingly, we observed that expression ofheregulin correlates with a more aggressive/invasive, vimentin-positive phenotype in breast cancer cells lines. Therefore, we have postulated thatheregulin is involved in breast cancer tumor progression. We have shown thatheregulin inducesin vitro chemoinvasion and chemotaxis of breast cancer cells as well as growth in an anchorage dependent and independent manner. Interestingly, aheregulin neutralizing antibody inhibits chemotaxis and results in cell growth inhibition and blockade of the invasive phenotype. Strikingly, genetically engineered cells which constitutively expressheregulin demonstrate critical phenotypic changes that are associated with a more aggressive phenotype. Specifically, these cells are no longer dependent on estrogen for growth and are resistant to tamoxifenin vitro andin vivo, and moreover these cells metastasize to lymph nodes in athymic nude mice. These tumors appear to have lostbcl-2 expression as compared with the control tumors. In addition, presumably by activation/regulation of topoisomerase II, theheregulin-transfected cells become exquisitely sensitive to doxorubicin and VP-16. Clearly, mechanistic aspects of theerbB-2/4 andheregulin interaction need to be understood from a therapeutic standpoint which could provide additional insights into synergistic treatments for certain patients, or improve treatment regimens for a large number of women. The study ofheregulin and its co-expression witherbB-2/4 receptor and the assessment of its involvement in the progression from the in situ stage of breast tumors to the invasive one will additionally increase the relevance ofheregulin as a prognostic/diagnostic factor. We believe that our studies provide new insights into breast cancer diagnosis, prognosis, and treatment.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb.     

Inhibition of signaling from Type 1 receptor tyrosine kinases via intracellular expression of single-chain antibodies

Summary Members of the Type I / epidermal growth factor receptor (EGFR)-related family of receptor tyrosine kinases have been implicated in the development of human cancer. We have taken a novel approach using the intracellular expression of single chain antibodies (scFv) to specifically inhibit thein vivo action of these receptors. A scFv is a recombinant protein analogous to an Fv domain which is the smallest high affinity binding portion of an antibody. We report here on the expression in mammalian cells of cDNAs encoding scFv-225 and scFv-FRP5 directed against the extracellular domain of, respectively, human EGFR and human ErbB-2. The scFvs were provided with a signal peptide which directs them to the secretory pathway of the cell. scFv-225, which competes with EGF for binding, functions in an autocrine fashion to inhibit EGF-dependent cell growth. scFv-FRP5 was also provided with an endoplasmic reticulum (ER) retention signal and inactivates ErbB-2 in an intracrine fashion, by preventing its appearance on the cell surface.Presented at the symposium "New Approaches in the Therapy of Breast Cancer", Georgetown University Medical Center, Washington DC, October 1994, generously supported by an education grant from Bristol-Myers Squibb.     

慢性胃炎脾胃湿热证患者胃窦粘膜内EGF和TFF1表达的意义

探讨EGF和TFF1在慢性胃炎脾胃湿热患者胃窦粘膜内表达,采用免疫细胞化学的方法,选择慢性浅表性胃炎脾胃湿热证患者20例,与同病脾胃气虚证患者32例和健康人5例对照,结果脾胃湿热组和脾胃气虚组患者的EGF和TFF1的表达与正常对照组相比,有显著性差异(P<0．01和P<0．05);2组患者间EGF表达有显著性差异(P<0．01),TFF1在2组患者间无统计学意义(P>0．05),但脾胃湿热组TFF1阳性低于脾胃气虚组;脾胃湿热组患者Hp感染率高于脾胃气虚组,有显著性差异(P<0．01)。说明慢性胃炎脾胃湿热组EGF表达低于脾胃气虚组,可能与Hp感染有关;而TFF1的表达低于脾胃气虚组,可能与胃粘膜损伤程度有关。     

A high-density PEG interfacial layer alters the response to an EGF tethered polydimethylsiloxane surface

Previously, epidermal growth factor (EGF)-modified surfaces have shown promise in supporting cellular growth and adhesion on synthetic polymeric substrates. Surfaces prepared using a novel modification technique were investigated in the current work for their ability to support corneal epithelialization, important to the integration of a synthetic artificial cornea. EGF could be tethered to PDMS surfaces via a high-density, hetero-bifunctional PEG-NSC linking layer with a tunable surface concentration of up to 300 ng/cm². Only a small fraction of the EGF on these surfaces could be removed with SDS rinsing, indicative of covalent tethering. Studies with human corneal epithelial cells suggest a relatively linear increase in the number of corneal epithelial cells with increasing EGF concentration at all times. However, confluence was not achieved at any time point. It is believed that the presence of the non-adsorbent PEG layer, useful for preventing non-specific adsorption of proteins, may limit the cellular response by minimizing the adsorption of adhesion molecules. The effects of the EGF alone are clearly not sufficient to result in epithelialization of an artificial cornea surface. Altering both the adhesion and growth of corneal epithelial cells in a controlled manner may be necessary for epithelialization of an artificial cornea.     

EGF receptor tyrosine kinase inhibitors in the treatment of brain metastases from non-small-cell lung cancer

The incidence of brain metastasis (BM) is high in patients with non-small-cell lung cancer. Available standard therapeutic options, such as whole-brain radiation therapy and systemic chemotherapy, provide a slight improvement in local control, overall survival and symptom relief. Novel agents, such as EGF receptor (EGFR) tyrosine kinase inhibitors (TKIs), have now been included in standard non-small-cell lung cancer treatments. In a small subset of patients harboring EGFR-activating mutations, erlotinib and gefitinib administration was followed by a response rate of 70–80%, and a longer progression-free and overall survival than those obtained with standard chemotherapeutic regimens. However, since most of the larger studies on these agents have excluded BM patients from their series, few prospective data are available on the efficacy of these agents in this setting. In recent years, however, several authors have reported a growing number of cases of partial and complete response in BM patients treated with EGFR TKIs. Data from retrospective series and Phase II studies also suggest that a response can be obtained using EGFR TKI treatment for patients with BM, especially those harboring EGFR mutations.