Radiotherapy response in oral squamous carcinoma cell lines: Evaluation of apoptotic proteins as prognostic factors

Background. In this study, we investigated the importance of apoptosis for cell death after radiotherapy, and whether the expression of pro‐ and anti‐apoptotic proteins has any correlation to the radiosensitivity. Methods. Three oral squamous cell carcinoma cell lines, UT‐SCC‐2, UT‐SCC‐9 and UT‐SCC‐24A, were subjected to radiotherapy. After irradiation, viable and dead cells were counted to determine radiation sensitivity and apoptosis was analyzed by measurement of caspase‐3 activity. The expressions of pro‐ and anti‐apoptotic proteins were assessed using western blot analyses. Results and Conclusion. After irradiation, apoptotic morphology and caspase‐3 activity were only detected in cell lines exhibiting high or moderate radiosensitivity. Western blot analysis indicates that survivin, epidermal growth factor receptor, cyclooxygenase‐2, and Bcl‐xL are critical components in irradiation resistance of the investigated cell lines. Moreover, our results suggest that apoptotic cell death and the balance between pro‐ and anti‐apoptotic proteins are of importance for the outcome of radiotherapy. © 2006 Wiley Periodicals, Inc. Head Neck, 2007.