OVEREXPRESSION OF P53 PROTEIN IN INTERSTITIAL LUNG-DISEASES

The p53 gene is well known as a tumour suppressor gene. In addition, t he mutated p53 gene is detected in a variety of human cancers includin g lung cancer, and is considered as an oncogene. Lung cancer is also f requently associated with interstitial lung diseases. Therefore. it ma y be possible to hypothesize that there might be some abnormality of p 53 gene in interstitial lung diseases. This work examined the relation ship between the p53 protein and gene in lung tissues of 28 patients w ith interstitial lung diseases. Among 28 patients, 13 cases were patho logically diagnosed to have usual interstitial pneumonia (UIP), 12 cas es were diagnosed as having collagen vascular lung diseases, and three cases were diagnosed to have a non-specific interstitial pneumonia. T wenty-three tissue samples were obtained by open lung biopsy and five samples were taken by autopsy. Paraffin-embedded tissues were treated by microwave, and stained with an anti-p53 antibody (DO7) by the Avidi n-Biotin-Peroxidase (ABC) method. In selected patients, mutations in e xons 5-8 of the p53 gene were also examined by single-strand conformat ion polymorphism (SSCP) analysis and DNA sequence. In addition, the pr esence of anti-p53 antibodies in patients' sera was screened for by EL ISA. Fifteen samples (53.6%) revealed overexpression of the p53 protei n in the nuclei of alveolar epithelial cells. However, SSCP or sequenc e analysis, which was performed in 13 tissues, showed no mutations in exons 5-8 of the p53 gene. In conclusion, p53 proteins were overexpres sed in interstitial lung diseases, and the expressed p53 protein was c onsidered to be wild-type. This wild-type p53 protein may play a role in blocking the transformation of proliferative epithelial cells.