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

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. 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. 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-x(L) 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.