ABSTRACT
Lung cancer is currently the leading cause of cancer-related death in the world. Signal transducers and activators of transcription 3 (STAT3) is a major oncogenic transcription factor involved in the development and progression of a number of human tumors including lung denocarcinoma. Gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) is known to functionally interact with STAT3 and inhibit its transcriptional activity. Decreased expression of GRIM-19 has been reported in tumors including those from kidney, prostate, colon and cervix, indicating that loss of GRIM-19 may be involved in the tumorigenesis through activation of the STAT3 pathway. In this study, we determined that GRIM-19 was significantly reduced at the mRNA and protein levels in lung adenocarcinoma tissues. Moreover, STAT3 was increased in these tumors and corresponding changes in the expression of its downstream target genes was observed. Overexpression of GRIM-19 was also found to suppress lung adenocancinoma tumor growth both in vitro and in vivo. Taken together, these findings will likely contribute to the future development of GRIM-19-based gene therapy approaches to treat lung adenocancinoma.
Subject(s)
Adenocarcinoma/genetics , Apoptosis Regulatory Proteins/metabolism , Cell Proliferation , Growth Inhibitors/metabolism , NADH, NADPH Oxidoreductases/metabolism , STAT3 Transcription Factor/metabolism , Adenocarcinoma/pathology , Adenocarcinoma/therapy , Animals , Apoptosis Regulatory Proteins/genetics , Cell Line, Tumor , Female , Gene Expression Regulation, Neoplastic , Growth Inhibitors/genetics , Humans , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/therapy , Mice , Mice, Inbred BALB C , Mice, Nude , NADH, NADPH Oxidoreductases/genetics , Protein Binding/genetics , STAT3 Transcription Factor/genetics , Signal Transduction/genetics , Transcriptional Activation/genetics , Transgenes/genetics , Tumor Burden/genetics , Xenograft Model Antitumor AssaysABSTRACT
BACKGROUND AND OBJECTIVE: Gene associated with retinoid-interferon-induced mortality-19 (GRIM-19) is one of the death-related genes. Its overexpression could suppress proliferation and promote apoptosis of tumor cells. This study was to investigate the expression and clinical significance of GRIM-19 in primary non-small cell lung cancer (NSCLC). METHODS: The expression of GRIM-19 in 49 specimens of NSCLC with corresponding adjacent normal lung tissues was examined by immunohistochemistry. The cellular distribution of GRIM-19 was observed under laser scanning confocal microscope. RESULTS: GRIM-19 was dominantly located in the cytoplasm of normal lung cells but enriched in the nuclei of cancer cells. The result was verified by laser scanning confocal microscopy. The positive rate of GRIM-19 was significantly higher in normal lung tissues than in NSCLC (93.8% vs. 55.1%, P<0.05). The protein level of GRIM-19 in NSCLC was reduced by 24.3% of that in normal lung tissues (0.22+/-0.01 vs. 0.29+/-0.02, P<0.05). The positive rates of GRIM-19 were 78.6% in stage I NSCLC, 48.1% in stage II NSCLC, and 12.5% in stages III-IV NSCLC. The expression of GRIM-19 was negatively correlated to clinical stage (rs=-0.428, P<0.05). CONCLUSION: GRIM-19 expression is down-regulated along the clinical development of NSCLC, and transfers from cytoplasm to nucleus.
Subject(s)
Apoptosis Regulatory Proteins/metabolism , Carcinoma, Non-Small-Cell Lung/metabolism , Lung Neoplasms/metabolism , NADH, NADPH Oxidoreductases/metabolism , Adult , Aged , Carcinoma, Non-Small-Cell Lung/pathology , Cell Nucleus/metabolism , Cytoplasm/metabolism , Down-Regulation , Female , Humans , Immunohistochemistry , Lung/metabolism , Lung/pathology , Lung Neoplasms/pathology , Lymphatic Metastasis , Male , Microscopy, Confocal , Middle Aged , Neoplasm StagingABSTRACT
AIMS: Glucocorticoids (GCs) are frequently used to treat various pulmonary diseases, which are typically accompanied by hypoxia. Whether hypoxia influences the effects of GCs on human airway cells remains unclear. The aim of the present study was to characterize changes in the expression levels of two isoforms of the glucocorticoid receptor (GR) and to evaluate the anti-inflammatory actions of GCs under hypoxic conditions in A549 cells. MAIN METHODS: A549 cells were exposed to normoxic or hypoxic conditions for 24, 48 and 72 h. Morphological alterations of cells were captured using a differential interference contrast microscope (DIC), and cell cycle distribution was estimated by flow cytometry. Real-time quantitative polymerase chain reaction and western blot were used to determine the mRNA and protein expression levels of GRalpha and GRbeta. Radioimmunoassay (RIA) for interleukin (IL)-8 was used to assess the anti-inflammatory actions of GCs after cells were stimulated with lipopolysaccharide (LPS). KEY FINDINGS: After cells were exposed to hypoxic conditions for 48 h, visible morphological alterations in the cells were observed. Cell cycle analysis showed that the number of cells in G1 phase increased significantly under hypoxia compared to the normoxic conditions. Hypoxia caused a time-dependent decrease in both mRNA and protein expression levels for GRalpha, but not GRbeta. Furthermore, when exposed to hypoxia for 48 h, the inhibitory effects of dexamethasone on LPS-stimulated IL-8 release were attenuated. SIGNIFICANCE: These results indicate that hypoxia impairs the anti-inflammatory actions of GCs in A549 cells, which could be attributed to down-regulation of GRalpha expression under hypoxic conditions.
