TP53 alterations in relation to the cell cycle-associated proteins p21, cyclin D1, CDK4, RB, MDM2, and EGFR in cancers of the uterine corpus

Abstract

In the present study, TP53 alterations have been analysed and compared with the expression of the proteins p21, cyclin D1, cdk4, RB, EGFR, and MDM2 in 53 cancers of the uterine corpus. TP53 gene mutations analysed by CDGE/DGGE and direct sequencing showed a TP53 gene mutation in 18 per cent of the cases. TP53 gene mutations were not significantly related to overexpression or down-regulation of any of the proteins. Immunohistochemically, there was an increased protein level of TP53 in 77 per cent, p21 in 36 per cent, cyclin D1 in 45 per cent, cdk4 in 77 per cent, EGFR in 8 per cent, and MDM2 in 32 per cent of the cases. Expression of RB protein was normal in all cancers. Significant association of protein expression was seen between TP53 and MDM2 (p=0.005) and p21 and MDM2 (p=0.001). Furthermore, there may be an association between TP53 and p21 (p=0. 038) and cyclin D1 and cdk4 (p=0.045). The results revealed increased levels of TP53 protein in all MDM2-positive cases that did not show TP53 mutations, indicating TP53 protein stabilization and inactivation by complex formation with MDM2. In summary, the high number of cases showing an increased level of TP53 and cdk4 proteins suggests that these proteins play an important role in the neoplastic process in cancers of the uterine corpus.