The role of constitutive and inducible processes in the response of human squamous cell carcinoma cell lines to ionizing radiation.

The inherent radiation sensitivity of the cells within a tumor is thought to contribute to the success or failure of radiation therapy. In vitro studies have shown that differences in the radiation sensitivity of squamous cell carcinoma cell lines reflect alterations in DNA repair. These alterations result from constitutive changes in chromosome organization, not radiation-inducible processes. While inducible responses may play some role in the radiation response of tumor cells, there is no evidence for their involvement in inherent differences in tumor cell radiosensitivity or in the success or failure of radiotherapy of squamous cell carcinomas.