An experimental study on the association of cyclin D_1 oncoprotein with mutated p53 in progressive development of pulmonary tumors
WANG Xiaomei, SHAN Jun, CHEN Zhuohuai. Department of Pathology, Department of Radiology, Shenzhen People's Hospital, Shenzhen, Guangdong 518020, P.R.China
Objective To study the correlation of cyclin D-1 oncoprotein with a mutated p53 in pulmonary tumors progression. Methods Thirty-one male A/J strain mice were treated intraperitoneally with a single injection of 20-methylcholanthrene and sacirificed at various ages. A total of 292 lesions in various histological type were obtained. Immunohistochemical methods were employed to detect the expression of cyclin D-1 and p53 in paraffin-embeded tissues. Results Expression of cyclin D-1 oncoprotein was seen in 6 out of 7 (86%) in hyperplasias, 89 out of 102 (87%) in alveolar adenomas, 41 out of 56 (73%) in papillary adenomas, and 17 of 25 (68%) in papillary carcinomas. Cyclin D-1 expression did not correlate with the progression of the lung neoplasms, and tended to decrease in papillary carcinomas than in papillary adenomas, in alveolar adenomas and hyperplasias (χ 2=5.531, P=0.033). Expressions of p53 gene were obviously stronger in malignant lesions than in benign lesions (χ 2=41.77, P=0.000). The p53 showed positive staining in carcinoma and severe atypical cell population. Expression of p53 was seen in 16 out of 40 (40%) in papillary carcinomas, 6 out of 69 (9%) in papillary adenomas, and 4 out of 121 (3%) in alveolar adenoma. No positive p53 stain was observed in hyperplasias. Co-expressive rate of cyclin D-1 and p53 was highest in papillary carcinomas (26%), but did not show in alveolar adenomas and hyperplasias. Conclusion Cyclin D-1 oncoprotein may play an important role in the oncogenesis of lung neoplasms, especially in the early stage. p53 expression increases significantly as the histological grade advances, and may correlate with the progression of pulmonary tumors and the malignant potential of tumor.