Cyclin D1 overexpression associates with radiosensitivity in oral squamouscell carcinoma

Overexpression of cyclin D1, a G1 cell cycle regulator, is often found in m any different tumor types, including oral squamous cell carcinomas (SCC). R ecent laboratory experiments have demonstrated that cyclin D1 levels can in fluence radiosensitivity in various cell lines. This study evaluated the re lationship between cyclin D1 expression levels and radiosensitivity in nine oral SCC cell lines (HSC2, HSC3, HSC4, SCC15, SCC25, SCC66, SCC111, Ca9-22 , and NAN2) and 41 clinical patients with oral SCC who underwent preoperati ve radiation therapy. Radiosensitivity of the nine oral SCC cell lines diff ered greatly in their response to radiation, assessed by a standard colony formation assay. Likewise, the expression of cyclin D1 varied, and the magn itude of the cyclin D1 expression correlated with increased tumor radiosens itivity. The similar significant association between the response to preope rative radiation therapy and cyclin D1 overexpression was observed in the o ral SCC patients who were treated with preoperative radiation therapy. Thes e results suggest that cyclin D1 expression levels correlate to radiosensit ivity and could be used to predict the effectiveness of radiation therapy o n oral SCC. (C) 2001 Wiley-Liss, Inc.