Expression of Cyclin D1, CDK4, p16 and Rb Proteins in Human Soft Tissue Sarcomas

ABSTRACT

BACKGROUND: Altered cell cycle regulation may underlie the development and/or progression of human malignancies. The purpose of this study is to determine if the oncogenesis of soft tissue sarcomas could be better explained by examining the components involved in G1 phase progression. METHODS: Sixty-seven soft tissue sarcomas were studied for the immunohistochemical expression of cdk4, cyclin D1, retinoblastoma (Rb) and p16 proteins. For Rb and p16, samples showing either negative or heterogeneous (<80% of tumor cells) staining were considered to be altered. RESULTS: The cdk4 protein was observed in 64 cases (95.5%). Cyclin D1 was expressed in 14 cases (20.9%). The Rb expression was altered in 48 (71.6%). Sixty-three (94%) sarcomas demonstrated altered p16 expressions. All of the samples displayed altered expressions of either Rb or p16. A high percentage of the tumors with altered Rb were observed in relapsed patients (p<0.05). CONCLUSIONS: Disturbance in the cell cycle regulatory system involving the Rb/p16/cdk4/cyclin D1 pathway appears to be relatively frequent in soft tissue sarcomas and may play an important role in the tumorigenesis of these tumors. It is noteworthy that the reduced Rb expression correlates with tumor relapse, suggesting its prognostic significance.