Expression of Cyclin D1 Protein in Breast Cancer and Its Correlation with Prognosis

Han, Se Hwan; Kim, Hong Yong; Park, Kyeong Mee; Lee, Myung Soo; Kim, Hong Joo; Kim, Young Duck

Abstract

BACKGROUND: Cyclin D1 is known to be a key regulator in the G1 to S transition of the cell cycle in numerous cases of human neoplasia. We performed immunohistochemical assay (IHC) for cyclin D1 expression in 67 breast cancer tissues to investigate its prognostic implication in breast cancer.
METHODS
Protein data for cyclin D1 expression obtained by IHC were merged with the clinical and the biological parameters of the patients, and the recurrence and the survival of the patients were analyzed according to the expression status of cyclin D1.
RESULTS
Of 67 breast cancers, 16 cases (23.9%) showed strong expression of cyclin D1 protein. Cyclin D1 expression was significantly increased in larger tumors (p=0.025) but there was no evident correlation between cyclin D1 expression and the clinical and the biological parameters of the studied patients. Although cyclin D1 is a cell cycle regulator essential for the G1 to S transition of the cell cycle, we could not identify any correlation between cyclin D1 expression and the S-phase or the G0/G1 fraction measured by flow cytometry. In the survival analyses, patients with increased expression of cyclin D1 protein had an increased incidence of recurrence and poorer survival than other patients. However, the difference was not statistically significant.
CONCLUSIONS
Increased expression of cyclin D1 protein was present in a certain proportion of breast cancer. Overexpression of cyclin D1 seemed to play a role in carcinogenesis and tumor growth. However, the clinical utility of cyclin D1 as a prognostic indicator in breast cancer patients have to be defined further by prospective studies with larger sample sizes.