epidermal-growth-factor and Neuroendocrine-Tumors

Neuroendocrine tumors (NETs) are a heterogeneous group of neoplasms that arise from cells of the neuroendocrine system. NETs are characterized by being highly vascularized tumors that produce large amounts of proangiogenic factors. Due to their complexity and heterogeneity, progress in the development of successful therapeutic approaches has been limited. For instance, standard chemotherapy-based therapies have proven to be poorly selective for tumor cells and toxic for normal tissues. Considering the urge to develop an efficient therapy to treat NET patients, vascular targeting has been proposed as a new approach to block tumor growth. This review provides an update of the mechanisms regulating different components of vessels and their contribution to tumor progression in order to develop new therapeutic drugs. Following the description of classical anti-angiogenic therapies that target VEGF pathway, new angiogenic targets such as PDGFs, EGFs, FGFs and semaphorins are further explored. Based on recent research in the field, the combination of therapies that target multiple and different components of vessel formation would be the best approach to specifically target NETs and inhibit tumor growth.

Topics: Angiogenesis Inhibitors; Epidermal Growth Factor; Fibroblast Growth Factors; Gene Expression Regulation, Neoplastic; Genetic Heterogeneity; Humans; Neovascularization, Pathologic; Neuroendocrine Tumors; Neurosecretory Systems; Platelet-Derived Growth Factor; Semaphorins; Signal Transduction; Vascular Endothelial Growth Factor A

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) constitute a heterogeneous group of tumours associated with variable clinical presentations, growth rates, and prognoses. To improve the management of GEP-NENs, the WHO developed a classification system that enables tumours to be graded based on markers of cell proliferation in biopsy specimens. Indeed, histopathology has been a mainstay in the diagnosis of GEP-NENs, and the WHO grading system facilitates therapeutic decision-making; however, considerable intratumoural heterogeneity, predominantly comprising regional variations in proliferation rates, complicates the evaluation of tumour biology. The use of molecular imaging modalities to delineate the most-aggressive cell populations is becoming more widespread. In addition, molecular profiling is increasingly undertaken in the clinical setting, and genomic studies have revealed a number of chromosomal alterations in GEP-NENs, although the 'drivers' of neoplastic development have not been identified. Thus, our molecular understanding of GEP-NENs remains insufficient to inform on patient prognosis or selection for treatments, and the WHO classification continues to form the basis for management of this disease. Nevertheless, our increasing understanding of the molecular genetics and biology of GEP-NENs has begun to expose flaws in the WHO classification. We describe the current understanding of the molecular characteristics of GEP-NENs, and discuss how advances in molecular profiling measurements, including assays of circulating mRNAs, are likely to influence the management of these tumours.

Topics: Biomarkers, Tumor; Clinical Trials as Topic; DNA Methylation; Epidermal Growth Factor; Gastrointestinal Neoplasms; Gene Expression Regulation, Neoplastic; Genes, Neoplasm; Humans; Mutation; Neoplasm Proteins; Neovascularization, Pathologic; Neuroendocrine Tumors; Pancreatic Neoplasms; Phenotype; Phosphatidylinositol 3-Kinases; Receptors, Somatostatin; Signal Transduction; Somatomedins; TOR Serine-Threonine Kinases; Vascular Endothelial Growth Factor A

Pancreatic neuroendocrine tumors (NETs) are rare and account for about 7% of all cancers occurring in the pancreas. The epidermal growth factor family of receptors and their ligands play an important role in the growth and progression of tumors but their role in PNET development remains unknown. We hypothesized that functional single nucleotide polymorphisms (SNPs) in the EGF, EGFR, and HER2 genes might affect individual susceptibility to PNETs development and invasion like it was shown for various other tumors.. We genotyped 68 patients with unresectable PNETs and 300 controls to evaluate the association between EGF, EGFR, and HER2 polymorphisms and susceptibility to PNETs and presence of metastases.. Genotype analysis of three SNPs EGF +61A/G (rs4444903), EGFR +1562 G/A (rs11543848), and HER2 +1963 A/G (rs1136201) showed that carriers of EGFR +1562 AG genotype and AA/AG EGF +61/HER2 +1963 genotype combination are at risk of developing PNET. Furthermore, EGFR +1562 AA genotype could be associated with the susceptibility to insulinoma development.. Our results suggest involvement of EGFR signaling pathway in etiology of PNET development.

Topics: Epidermal Growth Factor; ErbB Receptors; Genes, erbB-2; Genetic Predisposition to Disease; Humans; Neuroectodermal Tumors, Primitive; Neuroendocrine Tumors; Pancreatic Neoplasms; Polymorphism, Single Nucleotide; Receptor, ErbB-2

Foregut neuroendocrine tumors [NETs] usually pursuit a benign course, but some show aggressive behavior. The treatment of patients with advanced NETs is marginally effective and new approaches are needed. In other tumors, transactivation of the EGF receptor (EGFR) by growth factors, gastrointestinal (GI) hormones and lipids can stimulate growth, which has led to new treatments. Recent studies show a direct correlation between NET malignancy and EGFR expression, EGFR inhibition decreases basal NET growth and an autocrine growth effect exerted by GI hormones, for some NETs. To determine if GI hormones can stimulate NET growth by inducing transactivation of EGFR, we examined the ability of EGF, TGFα and various GI hormones to stimulate growth of the human foregut carcinoid,BON, the somatostatinoma QGP-1 and the rat islet tumor,Rin-14B-cell lines. The EGFR tyrosine-kinase inhibitor, AG1478 strongly inhibited EGF and the GI hormones stimulated cell growth, both in BON and QGP-1 cells. In all the three neuroendocrine cell lines studied, we found EGF, TGFα and the other growth-stimulating GI hormones increased Tyr(1068) EGFR phosphorylation. In BON cells, both the GI hormones neurotensin and a bombesin analogue caused a time- and dose-dependent increase in EGFR phosphorylation, which was strongly inhibited by AG1478. Moreover, we found this stimulated phosphorylation was dependent on Src kinases, PKCs, matrix metalloproteinase activation and the generation of reactive oxygen species. These results raise the possibility that disruption of this signaling cascade by either EGFR inhibition alone or combined with receptor antagonists may be a novel therapeutic approach for treatment of foregut NETs/PETs.

Topics: Adenoma, Islet Cell; Animals; Blotting, Western; Cell Proliferation; Epidermal Growth Factor; ErbB Receptors; Gastrointestinal Hormones; Humans; Neuroendocrine Tumors; Pancreatic Neoplasms; Phosphorylation; Rats; Reactive Oxygen Species; Signal Transduction; Somatostatinoma; Transcriptional Activation; Transforming Growth Factor alpha; Tumor Cells, Cultured; Tyrosine

Fetal antigen 1 (FA1) is a glycoprotein containing six epidermal growth factor (EGF)-like repeats. It is closely similar to the protein translated from the human delta-like (dlk) cDNA and probably constitutes a proteolytically processed form of dlk. dlk is homologous to the Drosophila homeotic proteins delta and notch and to the murine preadipocyte differentiation factor Pref-1. These proteins participate in determining cell fate choices during differentiation. We now report that FA1 immunoreactivity is present in a number of neuroectodermally derived tumours as well as in pancreatic endocrine tumours. A negative correlation between FA1 and glucagon immunoreactants in these tumours prompted a reexamination of FA1 immunoreactants during fetal pancreatic development. At the earliest stages of development, FA1 was expressed by most of the non-endocrine parenchymal cells and, with ensuing development, gradually disappeared from these cells and became restricted to insulin-producing beta cells. Throughout development FA1 was not detected in endocrine glucagon, somatostatin or pancreatic polypeptide cells. Moreover, developing insulin cells that coexpressed glucagon were negative for FA1. Thus, there was a negative correlation between FA1 and glucagon both in tumours and during development. These results, together with FA1/dlk's similarity with homeotic proteins, point to a role of FA1 in islet cell differentiation.

Topics: Antibodies, Monoclonal; Endocrine Gland Neoplasms; Epidermal Growth Factor; Fetus; Fluorescent Antibody Technique; Glucagon; Glucagonoma; Glycoproteins; Humans; Insulin; Insulinoma; Neuroendocrine Tumors; Pancreas; Pheochromocytoma; Somatostatin; Tumor Cells, Cultured

The present paper describes the primary structure, glycosylation and tissue localization of fetal antigen 1 (FA1) isolated from second-trimester human amniotic fluid. FA1 is a single-chained, heterogeneous glycoprotein of 225-262 amino acid residues. FA1 has six well conserved epidermal-growth-factor motifs and contains up to ten O-glycosylation and N-glycosylation sites, six of which are differentially glycosylated. Alignment to the translated sequences of Mus. musculus dlk and human dlk revealed 86% and 99% identity, respectively, to a 259-amino-acid residue overlap, and this high similarity extends with minor corrections to the human adrenal-specific mRNA, pG2 as well. Immunohistochemical analysis demonstrated the presence of FA1 in 10 out of 14 lung tumors containing neuroendocrine elements, and in the placental villi where FA1 was exclusively seen in stromal cells in close contact to the vascular structure. In the pancreas, FA1 co-localized with insulin in the insulin secretory granules of the beta cells within the islets of Langerhans. Our findings suggest that FA1 is synthesized as a membrane anchored protein and released into the circulation after enzymic cleavage, and that circulating FA1 represents the post-translationally modified gene product of human dlk which, in turn, is identical to human adrenal-specific mRNA pG2.

Topics: Amino Acid Sequence; Amniotic Fluid; Animals; Carcinoid Tumor; Epidermal Growth Factor; Female; Glycoproteins; Glycosylation; Humans; Immunohistochemistry; Intracellular Signaling Peptides and Proteins; Membrane Proteins; Mice; Molecular Sequence Data; Neoplasm Proteins; Neuroendocrine Tumors; Pancreas; Placenta; Pregnancy; Pregnancy Trimester, Second; RNA, Messenger; Sequence Homology, Amino Acid