ABSTRACT
BACKGROUND: Evidence suggests that small airways contribute to clinically significant processes in asthma. Cysteinyl leukotrienes (CysLTs) are considered to be pivotal mediators in the pathogenesis of asthma. Montelukast (MK), a specific CysLT1 receptor antagonist, is metabolized in two main hydroxylated metabolites (termed M5 and M6, respectively). OBJECTIVES: The aims of this study were to compare the responsiveness of small and large human bronchi to the three CysLTs, to evaluate the antagonist activity of MK, M5 and M6 in these preparations of human bronchi, and to characterize the CysLT receptors involved in the contractile response. METHODS AND RESULTS: In isolated small bronchus (i.d. 0.5-2 mm), the potencies (-log molar EC50) of LTC4, LTD4 and LTE4 were 9.3 (n=11), 9.1 (n=30) and 8.4 (n=14), respectively. The three CysLTs were about 30-fold more potent in small bronchi than in larger bronchi (i.d. 4-6 mm). In small bronchi, MK significantly shifted to the right the CysLT concentration-effect curves with pA2 values against LTC4, LTD4 and LTE4 of 9.1 (n=3), 9.0 (n=11) and 8.7 (n=5), respectively. The antagonist potencies of M6 and M5 were similar to MK and fivefold lower, respectively. A similar activity of MK against the three CysLTs suggested that CysLT1 receptors are involved in the contraction of human bronchus. Analysis by RT-PCR also indicated that human bronchus mainly expressed CysLT1 receptors. CONCLUSION: MK exerts a potent antagonist activity against the particularly potent constricting effects of CysLTs in isolated human small bronchi, which only expressed the CysLT1 receptor subtype. The metabolites of MK are also potent in vitro antagonists, but may not participate in the therapeutic activity of MK due to their low plasma concentrations in patients treated with the recommended dose of MK.
Subject(s)
Acetates/pharmacology , Bronchi/drug effects , Leukotriene Antagonists/pharmacology , Quinolines/pharmacology , Acetates/metabolism , Adult , Aged , Aged, 80 and over , Bronchial Hyperreactivity , Bronchial Provocation Tests , Cyclopropanes , Dose-Response Relationship, Drug , Female , Humans , In Vitro Techniques , Leukotriene Antagonists/metabolism , Leukotriene C4/antagonists & inhibitors , Leukotriene C4/pharmacology , Leukotriene D4/antagonists & inhibitors , Leukotriene D4/pharmacology , Leukotriene E4/antagonists & inhibitors , Leukotriene E4/pharmacology , Male , Middle Aged , Quinolines/metabolism , Reverse Transcriptase Polymerase Chain Reaction/methods , SulfidesABSTRACT
The E-cadherin-catenin complex, by mediating intercellular adhesion, regulates the architectural integrity of epithelia. Down-regulation of its expression is thought to contribute to invasion of carcinoma cells. To investigate the involvement of the E-cadherin-catenin adhesion system in the progression of human bronchopulmonary carcinomas, we compared the immunohistochemical distribution of E-cadherin, alpha-catenin, and beta-catenin in four human bronchial cancer cell lines with different invasive abilities and in 44 primary bronchopulmonary tumors. Although invasive bronchial cell lines did not express E-cadherin and alpha-catenin, complete down-regulation of cadherin-catenin complex expression was a rare event in vivo in bronchopulmonary carcinomas. Nevertheless, a spotty and cytoplasmic pattern of E-cadherin and catenins was observed in 32 primary tumors, only in invasive tumor clusters. Immunoprecipitation experiments showed that this redistribution was not related to a disruption of cadherin-catenin interaction but to down-regulated tyrosine phosphorylation of E-cadherin. We conclude that loss of E-cadherin and/or catenins is not a prominent early event in the invasive progression of human bronchopulmonary carcinomas in vivo. The decreased tyrosine phosphorylation of E-cadherin may reflect a loss of functionality of the complex and implicates a major role in tumor invasion.
Subject(s)
Cadherins/metabolism , Cytoskeletal Proteins/metabolism , Lung Neoplasms/metabolism , Trans-Activators , Tyrosine/metabolism , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Carcinoma, Bronchogenic/metabolism , Carcinoma, Bronchogenic/pathology , Carcinoma, Squamous Cell/metabolism , Carcinoma, Squamous Cell/pathology , Down-Regulation , Humans , Macromolecular Substances , Neoplasm Invasiveness , Phosphorylation , Tumor Cells, Cultured , alpha Catenin , beta CateninABSTRACT
BACKGROUND: Secondary solid tumors are rare events occurring in patients who underwent allogeneic marrow transplantation for aplastic anemia and Fanconi's anemia. Human herpes virus 8 (HHV8), Epstein-Barr virus (EBV), and human papillomaviruses (HPV) sequences have been found in squamous cell carcinoma (SCC) occurring in organ transplant recipients. The tumor suppressor gene p53 has been strongly linked to the occurrence of SCC in the nonimmunocompromised population. PATIENTS AND METHODS: In eight patients with SCC, we searched for HHV8, EBV, varicella zoster virus, adenovirus, and HPV sequences from DNA extracted from selected areas of SCC. We also looked for p53 expression in those specimens as well as the presence of anti-p53 antibodies in the serum of these patients at the onset of SCC. RESULTS: In one patient, we found the presence of both HHV8 and EBV sequences, and in another patient we found HPV16 sequences. All five tumors that could be studied disclosed evidence of p53 accumulation, but none of the eight patients had anti-p53 antibodies in the sera. CONCLUSION: SCC developing in marrow transplant recipients seems to occur via a multistep process. Genetic predisposition may be present, as in patients with Fanconi's anemia. Transplantation-related factors, such as irradiation and chronic graft-versus-host disease, also have a role. In this article, we add two more potent risk factors: p53 alteration(s) and in some cases the presence of oncogenic viruses.
