Growth factor receptor inhibitor

About: Growth factor receptor inhibitor is a research topic. Over the lifetime, 4730 publications have been published within this topic receiving 297500 citations.

Fibroblast growth factor receptor-mediated signals contribute to the malignant phenotype of non-small cell lung cancer cells: therapeutic implications and synergism with epidermal growth factor receptor inhibition

Abstract: Fibroblast growth factors (FGF) and their high-affinity receptors (FGFR) represent an extensive cellular growth and survival system. Aim of this study was to evaluate the contribution of FGF/FGFR-mediated signals to the malignant growth of non-small cell lung cancer (NSCLC) and to assess their potential as targets for therapeutic interventions. Multiple FGFR mRNA splice variants were coexpressed in NSCLC cells (n = 16) with predominance of FGFR1. Accordingly, both expression of a dominant-negative FGFR1 (dnFGFR1) IIIc-green fluorescent protein fusion protein and application of FGFR small-molecule inhibitors (SU5402 and PD166866) significantly reduced growth, survival, clonogenicity, and migratory potential of the majority of NSCLC cell lines. Moreover, dnFGFR1 expression completely blocked or at least significantly attenuated s.c. tumor formation of NSCLC cells in severe combined immunodeficient mice. Xenograft tumors expressing dnFGFR1 exhibited significantly reduced size and mitosis rate, enhanced cell death, and decreased tissue invasion. When FGFR inhibitors were combined with chemotherapy, antagonistic to synergistic in vitro anticancer activities were obtained depending on the application schedule. In contrast, simultaneous blockage of FGFR- and epidermal growth factor receptor-mediated signals exerted synergistic effects. In summary, FGFR-mediated signals in cooperation with those transmitted by epidermal growth factor receptor are involved in growth and survival of human NSCLC cells and should be considered as targets for combined therapeutic approaches.

Emergence of MCF-7 cells overexpressing a transfected epidermal growth factor receptor (EGFR) under estrogen-depleted conditions: Evidence for a role of EGFR in breast cancer growth and progression

Abstract: Overexpression of epidermal growth factor receptor (EGFR) is correlated with loss of estrogen receptor and poor prognosis in breast cancer. To investigate this phenomenon, we transfected a cytomegalovirus expression vector directing the expression of EGFR into estrogen receptor-positive MCF-7 breast cancer cells and into a clone of MCF-7 cells previously transfected with transforming growth factor alpha. Cells arising from single clones or pooled polyclonal populations maintained in charcoal-stripped calf serum, a medium devoid of estrogen, overexpressed EGFR. Switching these cells to a medium containing fetal calf serum or charcoal-stripped calf serum plus 17 beta-estradiol resulted in the emergence of a population expressing low EGFR levels. Loss of expression was not a consequence of nonspecific repression of the cytomegalovirus promoter, because expression of the fibroblast growth factor (FGF)-4 complementary DNA in a similar vector was not lost in fetal calf serum. While loss of EGFR overexpression in fetal calf serum was seen at both the protein and mRNA levels, Southern blotting shows that this was not due to loss of the transfected gene. Subclones of a cell population with low EGFR expression were capable of increasing expression upon estrogen withdrawal, demonstrating that the changes in EGFR expression were reversible and suggesting a growth advantage conferred by EGFR overexpression under these restrictive growth conditions. Overexpression of EGFR did not result in loss of ER expression. These results suggest a role for overexpression of EGFR in the growth of estrogen receptor-positive breast cancer cells in the absence of estrogen.

Identification of a determinant of epidermal growth factor receptor ligand-binding specificity using a truncated, high-affinity form of the ectodomain

Abstract: Murine and human epidermal growth factor receptors (EGFRs) bind human EGF (hEGF), mouse EGF (mEGF), and human transforming growth factor alpha (hTGF-alpha) with high affinity despite the significant differences in the amino acid sequences of the ligands and the receptors. In contrast, the chicken EGFR can discriminate between mEGF (and hEGF) and hTGF-alpha and binds the EGFs with approximately 100-fold lower affinity. The regions responsible for this poor binding are known to be Arg(45) in hEGF and the L2 domain in the chicken EGFR. In this study we have produced a truncated form of the hEGFR ectodomain comprising residues 1-501 (sEGFR501), which, unlike the full-length hEGFR ectodomain (residues 1-621, sEGFR621), binds hEGF and hTGF-alpha with high affinity (K(D) = 13-21 and 35-40 nM, respectively). sEGFR501 was a competitive inhibitor of EGF-stimulated mitogenesis, being almost 10-fold more effective than the full-length EGFR ectodomain and three times more potent than the neutralizing anti-EGFR monoclonal antibody Mab528. Analytical ultracentrifugation showed that the primary EGF binding sites on sEGFR501 were saturated at an equimolar ratio of ligand and receptor, leading to the formation of a 2:2 EGF:sEGFR501 dimer complex. We have used sEGFR501 to generate three mutants with single position substitutions at Glu(367), Gly(441), or Glu(472) to Lys, the residue found in the corresponding positions in the chicken EGFR. All three mutants bound hTGF-alpha and were recognized by Mab528. However, mutant Gly(441)Lys showed markedly reduced binding to hEGF, implicating Gly(441), in the L2 domain, as part of the binding site that recognizes Arg(45) of hEGF.