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

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

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

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

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

OBJECTIVETo study the role of p53 in silica-induced cell cycle alternation and DNA double strand breaks repair in human embryo lung fibroblasts (HELF).

METHODSNeutral comet assay was applied to detect silica-induced DNA double strand breaks. According to the neutral comet experimental result, the DNA repair competence was calculated. The expression levels and phosphorylation of protein in HELF were determined by Western blot. Cell cycle changes were identified by flow cytometry in HELF.

RESULTSAfter treatment with 200 microg/ml silica for different times (0, 1, 2, 6, 12 and 24 h), the expression levels and phosphorylation of p53 increased in a time-dependent manner, reaching maximum at 12 h and then decreasing at 24 h. After treatment with 0, 25, 50, 100, 200, 300 and 400 microg/ml silica for 12 h, the expression levels and phosphorylation of p53 increased in concentration-dependent manner. After p53 expression was inhibited, silica-induced DNA damage repair competence was markedly increased (DRC = 87.68%), compared with the negative control cell induced by silica (DRC = 57.19%). Silica increased the percentage of S phase (31.8 +/- 1.1)% compared with the controls (24.3 +/- 3.8)% (P < 0.05). When p53 expression was inhibited, the number of S phase cells was significantly increased, (41.4 +/- 0.6)% compared with the controls (25.4 +/- 1.9)% (P < 0.05).

CONCLUSIONThe silica dramatically increases the expression levels and phosphorylation of p53. The increased expression of p53 mediates silica-induced cell cycle change and inhibits silica-induced DNA double strand breaks repair.

Cell Cycle ; Cell Line ; Comet Assay ; DNA Breaks, Double-Stranded ; DNA Damage ; DNA Repair ; Fibroblasts ; cytology ; metabolism ; Humans ; Lung ; cytology ; Silicon Dioxide ; toxicity ; Tumor Suppressor Protein p53 ; metabolism