Amplification and Overexpression of Cyclin D1 in Head and Neck Squamous Cell Carcinomas

Kim, Sang Hyun; Yeom, Bum Woo

Abstract

BACKGROUND: Overexpression of the cell cycle control gene, cyclin D1 may, at least in some tumor types, provide a prognostic marker. Cyclin D1 is expressed during the G1 phase of the cell cycle and becomes associated with its catalytic partner CDK4 or CDK6. This association may overcome the G1 arrest.
OBJECTIVES
To establish the frequency of cyclin D1 protein overexpression and to evaluate its correlation with cyclin D1 gene amplification and its correlation with clinico-pathologic variables that are used in clinical practice.
MATERIALS AND METHODS
The cyclin D1 gene amplification was estimated with the differential polymerase chain reaction(PCR) and cyclin D1 protein overexpression was evaluated with immunohistochemical study in 32 cases of resectable head and neck squamous cell carcinoma(SCC). The presence or absence of cyclin D1 protein overexpression was correlated with anatomical sites, T stage, nodal involvement, pathologic grade and survival rate.
RESULTS
Six SCC cases(18.7%) showed the amplification of cyclin D1 gene. A highly statistical correlation between cyclin D1 gene amplification and cyclin D1 protein overexpression was noted(p<0.05). However in seven cases(21.9%) there was cyclin D1 protein overexpression without gene amplification. There was no correlation between cyclin D1 protein overexpression and known clinicopathologic variables(T and N stages, pathologic grade)(p>0.05). But overexpression of cyclin D1 protein was associated with a poor survival of these cases(p<0.05).
CONCLUSIONS
Overexpression of cyclin D1 is the independent prognostic factor for the head and neck squamous cell carcinoma. The cyclin D1 gene amplification results in the overexpression of cyclin D1 protein. But additional genetic mechanisms are involved in the protein overexpression. Therefore, cyclin D1 oncogene may be important in tumorigenesis in the head and neck squamous cell carcinoma.