ABSTRACT
OBJECTIVE: Malignant pleural mesothelioma is notoriously refractory to aggressive multimodality therapy. Epidermal growth factor receptor expression has been observed on malignant pleural mesothelioma cells. Epidermal growth factor receptor-mediated signaling promotes tumorigenesis and metastasis of cancer cells. The purpose of this study is to evaluate the ability of the epidermal growth factor receptor tyrosine kinase inhibitor PD153035 to abrogate the expression of prometastasis phenotypes in malignant pleural mesothelioma cells in vitro. METHODS: Epidermal growth factor receptor expression of malignant pleural mesothelioma cells and primary normal cells was quantitated by means of flow cytometry. PD153035-mediated growth inhibition was determined by means of 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan and clonogenic assays. Cell motility and invasion of extracellular matrix was evaluated with in vitro wound-healing and Matrigel invasion assays, respectively. Vascular epidermal growth factor levels in conditioned media were measured by using enzyme-linked immunosorbent assay. RESULTS: Epidermal growth factor receptor expression was detected on all 6 cultured malignant pleural mesothelioma cells, with 4 of 6 having normal receptor expression and 2 of 6 overexpressing the receptor. PD153035 suppressed cell motility and cell invasion through a Matrigel membrane, regardless of the baseline epidermal growth factor receptor expression. Decreased vascular epidermal growth factor production and significant inhibition of growth only occurred in malignant pleural mesothelioma cells that overexpress epidermal growth factor receptor. CONCLUSIONS: Epidermal growth factor receptor tyrosine kinase inhibitor PD153035 significantly inhibited motility and invasion in malignant pleural mesothelioma cells in vitro, regardless of their epidermal growth factor receptor expression levels. Inhibition of epidermal growth factor receptor-dependent signaling might be a useful strategy to diminish malignant pleural mesothelioma recurrence after aggressive cytoreductive surgery.
Subject(s)
Antineoplastic Agents/therapeutic use , ErbB Receptors/antagonists & inhibitors , Gene Expression Regulation, Neoplastic/drug effects , Mesothelioma/drug therapy , Pleural Neoplasms/drug therapy , Quinazolines/therapeutic use , Tumor Cells, Cultured/drug effects , Antineoplastic Agents/pharmacology , Cell Movement/drug effects , Cell Proliferation/drug effects , Cocarcinogenesis , Collagen , Dose-Response Relationship, Drug , Drug Combinations , Drug Screening Assays, Antitumor , Enzyme-Linked Immunosorbent Assay , ErbB Receptors/analysis , ErbB Receptors/genetics , Flow Cytometry , Fluorescent Antibody Technique, Indirect , Gene Expression Regulation, Neoplastic/genetics , Humans , Laminin , Neoplasm Invasiveness , Neoplasm Metastasis/genetics , Neoplasm Metastasis/prevention & control , Phenotype , Proteoglycans , Quinazolines/pharmacokinetics , Signal Transduction/drug effects , Signal Transduction/genetics , Tumor Cells, Cultured/physiology , Tumor Stem Cell Assay , Vascular Endothelial Growth Factor A/analysis , Vascular Endothelial Growth Factor A/drug effectsABSTRACT
OBJECTIVE: Histone deacetylase inhibitors mediate a potent growth-inhibitory effect in cancer cells through induction of cell-cycle arrest and apoptosis. Moreover, these agents significantly induce transcriptional activation of nuclear factor kappaB, as well as p21 regulated by protein kinase C, and are thought to negatively influence the ability of histone deacetylase inhibitor to effectively mediate apoptosis. This study aimed to evaluate the effect of calphostin C (a protein kinase C inhibitor) on trichostatin A (a histone deacetylase inhibitor)-mediated upregulation of nuclear factor kappaB and p21 promotor transcriptional activity, as well as induction of apoptosis in lung and esophageal cancer cells. METHODS: Cultured lung and esophageal cancer cells were treated with calphostin C and trichostatin A. Nuclear factor kappaB transcriptional activity was quantitated by using the nuclear factor kappaB-luciferase assay. Transcription of p21 gene and p21 protein levels was evaluated by using the p21 promoter-luciferase assay and the p21 enzyme-linked immunoassay, respectively. Apoptosis was evaluated by using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-based ApoBrdU assay. Levels of expression of nuclear factor kappaB-dependent antiapoptotic and proapoptotic proteins were evaluated by means of Western blotting. RESULTS: Exposure of lung or esophageal cancer cells to trichostatin A resulted in a dose- and cell-dependent 2-fold to greater than 20-fold increase of nuclear factor kappaB and p21 transcriptional activity. Treatment with trichostatin A and calphostin C led to a 50% to 90% decrease of trichostatin A- mediated upregulation of nuclear factor kappaB and p21 activation. Inhibition of nuclear factor kappaB activity resulted in significant reduction (30% to >99%) of trichostatin A- mediated activation of not only nuclear factor kappaB transcription but also p21 promotor activity. Importantly, 90% to 96% of thoracic cancer cells under-went apoptosis after exposure to the combination of trichostatin A plus calphostin C. CONCLUSION: Inhibition of protein kinase C abrogates trichostatin A-mediated upregulation of nuclear factor kappaB transcriptional activity and p21 expression that is associated with profound induction of apoptosis in lung or esophageal cancer cells. Protein kinase C might be a novel target for enhancing the efficacy of histone deacetylase inhibitor in cancer therapy.
Subject(s)
Apoptosis/drug effects , Hydroxamic Acids/pharmacology , NF-kappa B/metabolism , Naphthalenes/pharmacology , Oncogene Protein p21(ras)/metabolism , Blotting, Western , Cell Proliferation/drug effects , Cell Survival/drug effects , Drug Therapy, Combination , Esophageal Neoplasms/drug therapy , Esophageal Neoplasms/pathology , Histone Deacetylase Inhibitors , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/pathology , NF-kappa B/drug effects , Oncogene Protein p21(ras)/drug effects , Probability , Protein Kinase C/antagonists & inhibitors , Risk Factors , Sensitivity and Specificity , Tumor Cells, Cultured , Up-RegulationABSTRACT
BACKGROUND: Cancer cells frequently exhibit resistance to the cytotoxic effect of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Pretreatment of TRAIL-resistant cells with cisplatin sensitizes them to this ligand. Cisplatin also has been shown to enhance adenoviral transgene expression. OBJECTIVE: This study aims to evaluate the ability of cisplatin to enhance the expression and the cytotoxic effect of the tumor-specific adenoviral vector Ad/gTRAIL, which expresses a green fluorescent protein-TRAIL fusion protein. METHODS: Cultured cancer cells and normal human cells were infected with Ad/gTRAIL with or without cisplatin pretreatment. Adenoviral transgene expression was determined by using flow cytometry to measure green fluorescent protein fluorescence. Cytotoxicity was measured by using thiazolyl blue tetrazolium bromide assays and an apoptosis enzyme-linked immunosorbent assay kit. RESULTS: Green fluorescent protein-TRAIL fusion protein expression was significantly enhanced by cisplatin pretreatment in cancer cells. Cisplatin treatment before Ad/gTRAIL infection resulted in a 2- to 12-fold increase in green fluorescent protein fluorescence intensity across cancer lines. Although Ad/gTRAIL induced mild cytotoxicity in all cancer lines (inhibitory concentration of 50% values of >500 pfu/cell), pretreatment with cisplatin resulted in a dose-dependent enhancement of Ad/gTRAIL-mediated cytotoxicity, as indicated by the drastic reduction of inhibitory concentration of 50% values to 4 to 42 pfu/cell in all cell lines. There was no cytotoxicity noted in normal cells treated with both cisplatin and Ad/gTRAIL. CONCLUSION: Cisplatin pretreatment enhances Ad/gTRAIL cytotoxicity in malignant cells while not affecting normal cells. The mechanisms underlying this effect might include both enhancement of the susceptibility of cisplatin-treated cells to TRAIL and cisplatin-mediated enhancement of TRAIL expression in Ad/gTRAIL infected cells. These findings provide a rationale for development of Ad/gTRAIL-based therapy for thoracic malignancies.
