Quantitative analysis of the cyclin expression in human esophageal cancer cell lines

To study the altered mechanisms of cell cycle regulation in esophageal cancer, the expressions of cyclins involved in G1/S transition were analyzed in a series of 26 human esophageal cancer cell lines. To evaluate and compare the levels of cyclin expression, flow cytometric analysis was performed using human lymphocytes as control. Increased expressions of cyclin A, D1, D3 and E were found in 23.1% (6/26), 65.4% (17/26), 15.4% (4/26) and 57.7% (15/26) of the cell lines, respectively. All cell lines studied expressed less cyclin D2 than lymphocytes and the majority of the cell lines expressed cyclin D3 at levels similar to those of lymphocytes. Five cell lines expressed exceptionally high levels of cyclin E. Expressions of cyclin D1 and E were significantly elevated as compared to those of cyclin A, D2 and D3. These results suggest that increased expressions of the positive cell cycle regulators cyclin D1 and E may play an important role in esophageal carcinogenesis.