Interrelation of Cyclin D1, Cyclin E, and p27Kip1 Expression on Tissue Arrays of Breast Cancer

To evaluate the clinical impact of the altered expression of cell cycle regulators in stage I and II breast cancers.

The interaction between cyclin D1/E and p27Kip1 expressions were analyzed using tissue microarray (TMA) technology in 133 breast cancers. Data from the immunohistochemical assays of 3 molecules were merged, and analyzed, with a Ki67 labeling index of the same tumors.

Cyclin D1 was expressed in 72 breast carcinomas (54.1%) and cyclin E in 60 (45.1%) out of the 133 breast carcinomas. Expressions of cyclin D1 and cyclin E were inversely related to each other, and significantly associated with the estrogen receptor (ER) expression and differentiation of the breast carcinoma. The expression of cyclin E was significantly decreased in tumors expressing cyclin D1 (p=0.022). There was a trend for cyclin D1 expression to increase in tumors expressing p27Kip1 (p=0.053), but the expression of cyclin E did not correlate with p27Kip1 expression. The Ki67 labeling index was markedly increased in tumors expressing cyclin E, whereas it was significantly decreased in the cyclin D1 or p27Kip1 expressing-tumors. From survival analysis, cyclin E expression was the only significant variable for the prediction of poor survival.

The abnormal expressions of cell cycle regulatory molecules are prevalent, and interrelated with each other in breast cancer. Integration of TMA technology allowed a high-throughput analysis for correlating molecular the in situ findings, with the clinico-pathologic information. Among the three molecules studied, the cyclin E had a prognostic implication for stage I and II breast cancer.