Expression and mutation of p53 gene in the lung of mice intratracheal injected with crystalline silica

The genotoxic effect of crystalline silica (Qt) in the lung was studied to clarify that silicosis conferred a significant increase in risk subsequent lung cancer. C57BL/6N mice received a single tracheal injection of Qt at dose of 2 mg/mouse. Lung p53mRNA was suppressed significantly, but no change of p21mRNA 15 months after treatment. Mutation of p53 gene was not identified at 15 months in the Qt group. Silicotic lesions were observed in the lungs of Qt group, but silicosis with pulmonary neoplasia was no detected. These results indicated that genetic changes in the silicotic lung might lead to facilitation of carcinogenesis.