Studies on the expression of endothelin, its receptor subtypes, and converting enzymes in lung cancer and in human bronchial epithelium.
ABSTRACT Lung cancer, particularly small cell lung cancer (SCLC), is characterized by production of numerous peptides and their resulting clinical syndromes. Such peptides can act as autocrine growth factors for these tumors. In this study, we investigated the role of endothelin (ET)-1 in lung cancer. Using reverse transcription/polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay, and immunocytochemistry, we screened a panel of lung cancer cell lines for ET-1, its receptors, and endothelin converting enzyme-1 (ECE-1), which generates the active form of ET-1. ET-1 messenger RNA was expressed in five of seven SCLC, four of four non-small cell lung cancer (NSCLC), and human bronchial epithelial (HBE) cells. The intracellular isoform of ECE-1, important in processing ET-1 if an autocrine growth loop is to function, was downregulated in the lung cancer cell lines as compared with expression of the extracellular isoform. Endothelin A receptor (ETAR), which mediates the mitogenic effects of ET-1 in prostate and ovarian cancer, was upregulated in HBE cells compared with expression in three of seven SCLC and two of four NSCLC cell lines. Endothelin B receptor (ETBR) was more widespread, being expressed in seven of seven SCLC, four of four NSCLC, and the HBE cells. We used flow cytometry to measure mobilization of intracellular calcium as a functional assay for the ETAR. These data concurred with the RT-PCR results, indicating that the ETAR was downregulated or was involved in an alternative signal transduction pathway in lung cancer, and no evidence of functional receptor mediating an autocrine growth loop was found. From our study, the data do not support the putative functional autocrine growth role of ET-1 in lung cancer. We propose instead that ET-1 may act as a paracrine growth factor for surrounding epithelial and endothelial cells via alternative pathways, promoting angiogenesis and stromal growth.
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ABSTRACT: The endothelin converting enzyme-1 (ECE-1) is a zinc binding protein involved in the generation of a 21 amino acid endothelin-1 (ET-1) peptide. The mitogenic action of ET-1 has been shown in several cell types and produced by several human cancer cell lines. We have used the ligand-based drug design methods to understand the structure–activity relationship for inhibitor design of this important multi-disease target. The molecular docking of thiol-based inhibitors into the active site of ECE-1 identified several nonbonding interactions that stabilize the protein-inhibitor complex. The S1 and S10 sub-sites could accommodate larger hydrophobic substitutions on the inhibitor with highest activity (molecule 16). From the 3DQSAR studies, the electrostatic and steric descriptors that correlate with the activity of the inhibitors were identified. In the best pharmacophore, the hydrogen bond donor feature at the electronegative sulfur atom of inhibitor indicates that chelation with the Zn-ion is essential in the S1 sub-site, besides the other features. Together, the results from these diverse methods are complementary to each other and provide guidelines for the design of better ECE-1 inhibitors.Medicinal Chemistry Research 01/2013; 22:4401-4409. · 1.61 Impact Factor
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ABSTRACT: The endothelins and their associated receptors are important controllers of vascular growth, inflammation and vascular tone. In cancer, they have roles in the control of numerous factors in cancer development and progression, including angiogenesis, stromal reaction, epithelial mesenchymal transitions, apoptosis, invasion, metastases and drug resistance. Also, we consider current information on the role of this signalling system in cancer and examine the state of the current cell, animal and clinical trials utilizing endothelin targeted drugs for cancer management. Although targeting the endothelin axis in cell lines and xenografts show some promise in retarding cellular growth, results from limited clinical trials in prostatic cancer are less encouraging and did not offer significant survival benefit. The ability to target both cancer cells and vasculature via endothelin is an important consideration that necessitates the further refining of therapeutic strategies as we continue to explore the possibilities of the endothelin axis in cancer treatment.Critical reviews in oncology/hematology 09/2013; · 5.27 Impact Factor
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ABSTRACT: Recent studies have highlighted the heterogeneity of gliomas and demonstrated that molecular and genetic analysis could help in their classification and in the design of treatment protocols. In a previous study we have identified a 4-gene signature highly correlated with survival of glioma patients. The aim of this study is to confirm and extend these findings by investigating the expression of these genes at the protein level and their association with outcome of patients with high grade gliomas. Immunohistochemical staining for EDN/RB, HJURP, p60/CAF-1 and PDLI4 was studied on archive materials from 96 patients (64 glioblastomas and 32 grade III gliomas). The levels of all four proteins differed significantly between grade III and grade IV tumours. The levels of the EDN/RB, HJURP and p60/CAF-1 proteins were strongly associated with overall survival (p<0.001, p<0.001 and p=0.002, respectively), whereas the one of PDLI4 was not (P=0.11). A risk criterion defined as high levels of at least two of the EDN/RB, HJURP and p60/CAF-1 proteins accurately predicted the prognosis of patients. Multivariate analysis confirmed that this criterion was an independent negative prognostic marker (hazard ratio = 2.225; 95% CI, 1.248 to 3.966, p=0.007). The expression of the EDN/RB, HJURP, p60/CAF-1 and PDLI4 proteins is disrupted in high grade gliomas and increases in the levels of these proteins are closely linked to tumour aggressiveness and poor outcome.PLoS ONE 01/2013; 8(9):e73332. · 3.73 Impact Factor