Role of DNA-dependent protein kinase catalytic subunit in silica-induced DNA double-strand break repair in human embryo lung fibroblasts / 中华劳动卫生职业病杂志
Chinese Journal of Industrial Hygiene and Occupational Diseases
; (12): 2-6, 2009.
Article
em Zh
| WPRIM
| ID: wpr-347259
Biblioteca responsável:
WPRO
ABSTRACT
<p><b>OBJECTIVE</b>To 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).</p><p><b>METHODS</b>Two 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.</p><p><b>RESULTS</b>After 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).</p><p><b>CONCLUSION</b>Silica 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.</p>
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Índice:
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Assunto principal:
Farmacologia
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Fosforilação
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Fisiologia
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Histonas
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Transfecção
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Linhagem Celular
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Dióxido de Silício
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Reparo do DNA
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Proteína Quinase Ativada por DNA
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Quebras de DNA de Cadeia Dupla
Limite:
Humans
Idioma:
Zh
Revista:
Chinese Journal of Industrial Hygiene and Occupational Diseases
Ano de publicação:
2009
Tipo de documento:
Article