Dust ; Humans ; Pneumoconiosis ; etiology

Animals ; Antigens, Nuclear ; DNA ; genetics ; metabolism ; DNA Breaks, Double-Stranded ; DNA Repair ; DNA-Binding Proteins ; Humans ; Ku Autoantigen

Genomics ; Proteomics ; Toxicology

Animals ; DNA Damage ; DNA Repair ; DNA-Activated Protein Kinase ; Humans

Apoptosis ; Cell Cycle ; Cell Differentiation ; Cell Proliferation ; Humans ; Neoplastic Processes ; Proto-Oncogene Proteins c-jun ; genetics ; metabolism ; physiology

Dust ; Humans ; Occupational Exposure ; prevention & control ; Pneumoconiosis ; prevention & control

Attitude to Health ; China ; Dust ; prevention & control ; Humans ; Needs Assessment ; Occupational Exposure ; prevention & control ; Occupational Health Services ; Pneumoconiosis ; prevention & control ; Surveys and Questionnaires

China ; epidemiology ; Dust ; prevention & control ; Humans ; Silicon Dioxide ; chemistry ; Silicosis ; epidemiology ; prevention & control

OBJECTIVETo study the role of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) in silica-induced DNA double-strand break repair in human embryo lung fibroblasts (HELF).

METHODSTwo stable transfectants, HELF transfected with DNA-PKcs siRNA (HELF-PKcs) and with negative control siRNA (HELF-NC), were established. HELF cells were treated with 0, 25, 50, 100, 200, 300 and 400 microg/ml silica for 12 h and with 200 microg/ml silica for different times (0, 1, 2, 6, 12 and 24 h). HELF-PKcs and HELF-NC were treated with 200 microg/ml silica for 0, 12 and 24 h. The expression levels of DNA-PKcs and phosphor-H2AX (H2AX) were determined by Western blot. DNA double strand breaks were measured by neutral comet assay.

RESULTSAfter treatment with different doses of silica for 12 h, the levels of H2AX and the percentages of tail DNA increased in concentration-dependent manner. After treatment with 200 microg/ml silica for different times, the levels of H2AX increased in a time-dependent manner. The percentages of tail DNA increased significantly at 6 h, and reaching maximum at 12 h and then decreasing at 24 h. The expression level of DNA-PKcs was suppressed in HELF-PKcs. After treatment with silica at 12 h, the level of H2AX was lower in HELF-PKcs than in HELF-NC, and the percentages of tail DNA increased obviously in both HELF-PKcs and HELF-NC compared with non-treated cells, but no significant difference was found in the percentages of tail DNA between them. The percentages of tail DNA decreased markedly in silica-treated HELF-NC and was significantly lower than in HELF-PKcs at 24 h (P < 0.05).

CONCLUSIONSilica can induce DNA double strand breaks in human embryo lung fibroblasts. DNA-PKcs might play a major role in silica-induced DNA double strand break repair. Silica-induced histone H2AX phosphorylation was dependent on DNA-PKcs.

Cell Line ; DNA Breaks, Double-Stranded ; drug effects ; DNA Repair ; DNA-Activated Protein Kinase ; genetics ; metabolism ; Fibroblasts ; drug effects ; physiology ; Histones ; metabolism ; Humans ; Phosphorylation ; Silicon Dioxide ; pharmacology ; Transfection

OBJECTIVETo investigate the roles of cyclin D1 and CDK4 in the cell cycle changes of human embryonic lung fibroblasts (HELFs) exposed to silica.

METHODSHELFs were divided into 4 groups: control group, curcumin (20 µmol/L for 1 h) group, silica (200 µg/ml for 24 h) group and curcumin plus silica group, i.e. after exposure to 20 µmol/L curcumin for 1h, the HELFs were treated with 200 µg/ml silica for 24 h. Western blot and Immunofluorescence assays were utilized to detect the expression levels of cyclin D1, CDK4 and E2F1/4. Flow cytometry was used to detect the cell cycle progression, the RNA transfection technique was used to investigate the silica-induced signal pathway and the roles of which in silica-induced cell cycle changes.

RESULTSThe expression levels of cyclin D1 and CDK4 significantly increased and the expression level of E2F-4 decreased obviously, but the expression level of E2F-1 did not significantly change in silica group. The proportion of G1 phase cells obviously decreased and the proportion of S phase cells significantly increased in silica group, as compared with control group (P < 0.05). When suppressing the expression of cyclin D1 or CDK4, the proportions of cells in G1 phase in anti-D1 plus silica group and anti-K4 plus silica group did not obviously change, as compared with control group. When suppressing AP-1 activity, the cyclin D1 and CDK4 expression levels decreased and the E2F-4 expression level increased in curcumin plus silica group, as compared with silica group.

CONCLUSIONThe results of present suggested that 200 µg/ml silica could induce the high expression of cyclin D1 and CDK4 and the low expression of E2F-4, resulting in the cell cycle changes by AP-1/cyclin D1 pathway in HELFs.

Cell Cycle ; drug effects ; Cells, Cultured ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase 4 ; metabolism ; E2F4 Transcription Factor ; metabolism ; Fibroblasts ; cytology ; metabolism ; G1 Phase ; Humans ; Quartz ; adverse effects ; Transcription Factor AP-1 ; metabolism ; Transfection