Epidermal growth factor in breast cancer

Identification and functional analysis of epidermal growth factor receptor (EGFR) from Scylla paramamosain: The first evidence of two EGFR genes in animal and their involvement in immune defense against pathogen infection

The epidermal growth factor receptor (EGFR) is a pleiotropic glycoprotein which plays a role in regulating cell proliferation, migration and differentiation. However, the genetic diversity of EGFR in crustaceans as well as its function, such as whether it is involved in immune regulation, remains obscure. In this study, two EGFR genes, including EGFR1 and EGFR2, and three transcripts were identified and characterized in Scylla Paramamosain for the first time. To our knowledge, this is the first time that more than one EGFR gene was identified in a single species. The complete open reading frames (ORFs) of SpEGFR1, SpEGFR2a and SpEGFR2b were 4377 bp, 4404 bp and 4341 bp encoding deduced proteins of 1458 amino acids (aa), 1467 aa and 1446 aa, respectively. All EGFR had a signal peptide region and two Recep_L_domain region, followed by a transmembrane region and a conserved tyrosine kinase domain (TyrKc), and phylogenetic analysis demonstrated three SpEGFRs clustered together with invertebrate EGFR branch. Tissue specific expression analysis depicted that all SpEGFRs presented similar transcription patterns. The expression levels of SpEGFR1 and SpEGFR2s in hepatopancreas and gills were significantly altered after the stimulation of bacterial and viral pathogens including Staphylococcus aureus, Vibrio alginolyticus, White spot syndromre virus and Polycytidylinic acid. The in vivo RNA interference assays demonstrated that expression levels of SpIKK, two members of NF-κB (SpRelish and SpDorsal) and six antimicrobial peptide (AMP) genes (SpCrustin and SpALF1-5) were significantly reduced when SpEGFR1 or SpEGFR2 was silenced, respectively. The transcription patterns of SpIKK, SpRelish, SpDorsal and AMPs exhibited similar down- or up-regulation trend when the primary cultured hemocytes were treated with EGFR antagonist or agonist for 24 h. These results suggested that SpEGFR might play an important role in innate immune responses to bacterial and viral infections by regulating the NF-κB pathway. It also provided a better understanding of the origin or evolution of EGFR in crustaceans and even invertebrates.

Development of ML390: A Human DHODH Inhibitor That Induces Differentiation in Acute Myeloid Leukemia

Homeobox transcription factor A9 (HoxA9) is overexpressed in 70% of patients diagnosed with acute myeloid leukemia (AML), whereas only a small subset of AML patients respond to current differentiation therapies. A cell line overexpressing HoxA9 was derived from the bone marrow of a lysozyme-GFP mouse. In this fashion, GFP served as an endogenous reporter of differentiation, permitting a high-throughput phenotypic screen against the MLPCN library. Two chemical scaffolds were optimized for activity yielding compound ML390, and genetic resistance and sequencing efforts identified dihydroorotate dehydrogenase (DHODH) as the target enzyme. The DHODH inhibitor brequinar works against these leukemic cells as well. The X-ray crystal structure of ML390 bound to DHODH elucidates ML390s binding interactions.

Effect of Antiestrogens on EGF-Mediated Movement of Human Breast Cancer Cells

In a previous study we compared the influence of several growth factors on breast cancer cells in culture and observed that epidermal growth factor (EGF) enhanced the invasiveness of estrogen receptor-positive breast cancer cells. The objective of the present study was to determine the influence of three unique antiestrogens on EGF-mediated movement of human breast cancer cells. The rate of movement of MCF-7 breast cancer cells was measured using time-lapse videomicroscopy (TLVM). The MCF-7 cells were pretreated with antiestrogen (either tamoxifen, ICI-182-780 (ICI) or 1,1-dichloro-cis-2,3-diarylcyclopropane (AII)) at 10(-6) mol/l for 4 days, and then treated with EGF (10(-10) mol/l) immediately prior to TLVM. EGF enhanced the motility of the MCF-7 cells at 30-90 min post-administration. However, EGF-mediated motility of the MCF-7 cells was inhibited by antiestrogen pretreatment, with TAM and ICI producing complete inhibition of EGF-induced motility. In conclusion, this study demonstrates that EGF enhances the rate of movement of MCF-7 breast cancer cells and that antiestrogen pretreatment inhibits EGF-mediated motility.

The angiogenic factors CXCL8 and VEGF in breast cancer: regulation by an array of pro-malignancy factors

The regulation of secretion of the angiogenic factors CXCL8 and Vascular Endothelial Growth Factors (VEGF) was determined in breast tumor cells and in monocytic cells (as host cells that contribute to breast cancer). CXCL8 secretion, and partly the secretion of VEGF, were up-regulated in monocytic cells, but not in breast tumor cells, by the CC chemokines CCL5 and CCL2. EGF potently up-regulated CXCL8 secretion by breast tumor cells, and its effect was promoted by a consecutive treatment of the cells by estrogen and progesterone. These findings provide evidence for a complex set of pro-malignancy factors that may control the expression of angiogenic mediators at breast tumor sites.

Serum levels of pantropic p53 protein and EGF-receptor, and detection of anti-p53 antibodies in former uranium miners (SDAG Wismut)

BACKGROUND

The oncogene product EGF-receptor (EGF-R), the tumor suppressor gene product p53, and anti-p53 antibodies are detectable in serum of certain cancer patients. Increased levels of some of these products were reported in lung cancer patients after occupational asbestos exposure, after exposure to polycyclic aromatic hydrocarbons or vinyl chloride. This molecular epidemiological study investigated the use of serum EGF-R, p53-protein, and anti-p53 antibodies as biomarkers for detection of effects of radon and its decay products.

METHODS

Serum EGF-R, p53-protein, and anti-53 antibodies were measured using ELISA in former uranium miners of SDAG Wismut without lung disease (n=106) and miners with Schneeberg lung cancer (n=22). They were compared with healthy subjects (n=23), patients with lung cancer not due to ionizing radiation (n=88), and patients with non-malignant lung or pleural diseases (n=50).

RESULTS

No significantly elevated or decreased serum values for p53 protein, EGF-R, or anti-p53 antibodies could be found. There was no correlation of these with Working Level Months (WLM).

CONCLUSIONS

p53 protein, EGF-R, or anti-p53 antibodies in serum are not useful as biomarkers for detection of lung cancer related to ionizing radiation (i.e., Schneeberg lung cancer).

Interaction of a monoclonal antibody against hEGF with a receptor site for EGF

Epidermal growth factor (EGF) has been detected by radioimmunoassay (RIA) in different body fluids such as serum, amniotic fluid, and urine. Human tumor tissues with EGF receptors (EGF-Rc) may be saturated with EGF, which may be of prognostic value. An RIA was envisaged to measure human epidermal growth factor (hEGF) levels using EGF-Rc as capture agent and a monoclonal antibody anti-hEGF (MAb anti-hEGF) labeled with 125Iodine as a marker for this binding. The purpose of this work was to study the feasibility of MAb anti-hEGF to detect the receptor binding sites and to investigate the interaction between MAb anti-hEGF and the EGF-Rc. Various binding experiments were performed to study possible interference and interactions in the complex MAb anti-hEGF and the receptor. Affinity constants were determined by means of Scatchard plot analysis to interpret the complex stability challenged with other compounds for a better understanding of the interaction process. Binding constants were of the same order for all the ligands tested separately involving the EGF-Rc, but were significantly higher (t = 15.7, p < 0.05) for hEGF in its binding to MAb anti-hEGF. It was possible with equilibrium studies and competition experiments to evaluate the interaction of EGF and MAb anti-hEGF with the EGF receptor. This observation makes the MAb anti-hEGF a potential tracer for the quantitation of receptors in vitro, and possibly for the detection of membrane receptors on tumor cells in vivo.

p53 protein, EGF receptor, and anti-p53 antibodies in serum from patients with occupationally derived lung cancer

The oncogene product epidermal growth factor receptor (EGF-R), the tumour suppressor gene product p53 and anti-p53 antibodies are detectable in the serum of certain cancer patients. Increased levels of some of these products were reported in lung cancer patients after occupational asbestos exposure and after exposure to polycyclic aromatic hydrocarbons or vinylchloride. In the first step, this study investigated the possible diagnostic value of serum EGF-R, p53-protein and anti-p53 antibodies, measured by an enzyme-linked immunosorbent assay, in lung tumour patients. In addition to being investigated on a molecular epidemiological basis, these parameters were examined as biomarkers of carcinogenesis, especially with regard to asbestos incorporation effects or of radon-induced lung cancers. Also, a possible effect of cigarette smoking and age dependence were studied. A total of 116 male patients with lung or pleural tumours were examined. The histological classification was four small-cell cancers, six large-cell cancers, 32 adenocarcinomas, 47 squamous carcinomas, 12 mixed lung carcinomas, five diffuse malignant mesotheliomas and ten lung metastasis of extrapulmonary tumours. Twenty-two lung cancers and all mesotheliomas were related to asbestos, 22 lung cancers were related to ionizing radiation and 61 patients had cigarette smoke-related lung cancer. Besides these patients 50 male patients with non-malignant lung or pleural diseases were included; of the latter eight subjects suffered from asbestosis. Controls were 129 male subjects without any lung disease. No significantly elevated or decreased serum values for p53 protein, EGF-R, or anti-p53 antibodies as a function of histological tumour type, age, or degree and type of exposure (asbestos, smoking, ionizing radiation) could be found. The utility of p53-protein, EGF-R and anti-p53 antibodies as routine biomarkers for screening occupationally derived lung cancers is limited.

Epidermal growth factor in NMU-induced mammary tumors in rats

In this work we analyze the hypothesis that tumors induced by i.p. N-nitroso-N-methylurea injection express EGF-like peptides and EGF receptors which could be involved in the response to hormone manipulation. EGF receptors (EGFR) were determined in the purified membrane fraction of tumors from control and ovariectomized (OVX) animals and no significant differences were found in either maximal binding capacities (Q) or dissociation constants (Kd) between them. Neither did we observe differences between tumors that regressed (HR) or continued growing (HU) after ovariectomy. In order to test the ability of EGFR to trigger a biological response we measured the production of second messengers inositol triphosphates (IP3) and cAMP levels; we found that EGF increases IP3 production in a dose-dependent way, while cAMP levels were not affected. In addition, EGF was able to induce in vitro cell proliferation in a concentration-dependent manner when tested in primary cultures of tumor cells by the clonogenic soft agar technique. EGF/TGF-alpha activity was determined by a radioreceptor assay in tumor cytosols from control and OVX rats. Results showed a trend to lower values in tumors from OVX rats, but no differences between HR and HU tumors. A positive correlation was found between EGF/TGF-alpha activity and progesterone receptor maximal binding capacity. When we tested the action of estradiol and EGF added together to primary cultures of tumor cells we found an additive effect on cell proliferation. The study of steady state mRNA levels showed that E2 increases PgR and c-myc mRNA levels in HR but not in HU tumors. In conclusion, the autocrine loop EGFR-EGF/TGF-alpha present in all tumors is hormonally regulated, possibly by Pg, but is not related to the tumor response to ovariectomy.

Thiol-bearing compounds selectively inhibit protein kinase C-dependent oxidative events and proliferation in human T cells

The aminothiol cysteamine at 10(-5) to 10(-4) M concentrations inhibited both the proliferation of mitogenically stimulated human peripheral mononuclear cells and the phorbol myristate acetate-mediated oxidation of 2',7'-dichlorofluorescein within these cells. Both 2',7'-dichlorofluorescein oxidation and the proliferative response were maximally sensitive to cysteamine-induced inhibition during the first 2 h of mitogenic stimulation. This period of sensitivity indicates that cysteamine preferentially arrests cells transiting from G0 to G1 and is the first such demonstration, of an early cell cycle site of arrest for this compound. 2,3-Dimercapto-1-propane-sulfonic acid and WR 1065 were found to be more effective than cysteamine in attenuating T cell replication but not N-acetylcysteine. Aminothiols preferentially inhibited the intracellular oxidation of 2',7'-dichlorofluorescein, rather than the activity of protein kinase C, which initiates the oxidation, indicating that oxidative events are one of a number of crucial and independent events required for the successful transition through G0-G1. Since aminothiols affect both lectin and PMA/ionomycin-directed proliferation, these aminothiol-sensitive events may serve to integrate and regulate common pathways in T cell activation.

Relationship between EGF-R, c-erbB-2 protein expression and Ki67 immunostaining in breast cancer and hormone sensitivity

The expression of the epidermal growth factor receptor (EGF-R), c-erbB-2 protein product and Ki67 have been evaluated in 105 breast cancers of known responsiveness to endocrine therapy using immunohistochemistry. EGF-R staining was observed in 62 of the tumours and was significantly associated with elevated rates of cell proliferation (%Ki67 positive cells) and loss of hormone sensitivity. In contrast, c-erbB-2 expression was not correlated with cell proliferation rates and was less strongly related to hormone insensitivity. Subdivision of the EGF-R data according to c-erbB-2 measurements revealed an association between c-erbB-2 immunostaining and worsened patient outlook and hormone insensitivity in moderately EGF-R-positive tumours. c-erbB-2 immunostaining in highly EGF-R-positive tumours did not further contribute to the already poor prognosis of these patients. These data confirm the prognostic importance of EGF-R measurements in breast cancer and may infer a functional interaction between this protein and the c-erbB-2 protein product in the aberrant growth of a subset of breast tumours.

Gonadotropins, estradiol, and growth factors regulate epithelial ovarian cancer cell growth

Indirect evidence suggests that gonadal steroids and gonadotropins may have a role in the genesis of epithelial ovarian cancer. In the studies reported herein, we established 17 beta-estradiol (E2) secreting cell cultures from an omental metastasis of an epithelial ovarian cancer. We demonstrate that human chorionic gonadotropin (hCG), human follicle-stimulating hormone, and epidermal growth factor (EGF) increased cell growth in a dose- and time-dependent manner, whereas E2 inhibited cell growth in the nanomolar range. Epidermal growth factor was able to partially block the negative effect of E2; a similar but quantitatively lesser effect was observed with hCG. These results provide direct evidence to support the view that gonadotropins, EGF, TGF beta (transforming growth factor), and estradiol may modulate growth of metastatic epithelial ovarian cancer cells.

Measurement of occupied and non-occupied epidermal growth factor receptor sites in 216 human breast cancer biopsies

The epidermal growth factor (EGF) is one of several growth factors involved in normal breast epithelial development and tumor proliferation. EGF and EGF-like peptide TGF alpha bind and activate the same membrane receptor protein. This receptor (EGF-R) has been recently studied in breast tumor biopsies and its detectability reported as a prognostic indicator. However, normal and tumor tissue themselves produce EGF and related peptides in variable amount. This suggests that the standard measurement of EGF-R by binding assay should reflect only the number of non-occupied receptor sites. Based on this observation, the presence of occupied sites (EGF-R2) has been assessed in 216 human mammary tumor biopsies simultaneously with the direct measurement of non occupied EGF receptor sites (EGF-R1) and the results compared to estrogen and progesterone receptor status (ER, PGR). EGF-R1 and EGF-R2 were evaluated by 2 separate (125I) EGF binding assays performed on 2 aliquots of tumor crude membrane fraction, the first one directly, the other after dissociation of the endogenously bound ligand. The validity of the method has been assessed on membrane fractions prepared from human placenta. It is shown that the dissociation does not modify the binding dissociation constant. ER and PGR were measured by the dextran coated charcoal method. Results greater than 10 fmol/mg of membrane or cytosol protein were considered as positive. It is found that EGF-R1 and EGF-R2 are detectable in 54 and 90% of the cases, indicating that EGF-R is masked by endogenous ligand in 36% of the tumors.(ABSTRACT TRUNCATED AT 250 WORDS)