Radiation-induced apoptosis and cell cycle alterations in human carcinoma cell lines with different radiosensitivities.

Radiosensitivity of examined human neoplastic cell lines was assessed with the aid of MTT assay. Differences between radiosensitive and radioresistant human neoplastic cell lines were as follow: a) radiation-induced apoptosis detected by flow cytometry was apparent in the most radiosensitive (i.e. CH-1 ovarian carcinoma cell line), but not in the radioresistant (i.e. SKOV-3 ovarian carcinoma) cell lines, b) radiation-induced G2/M arrest appeared early after irradiation (6 hours) in both the radioresistant SKOV-3 cells and in the radiosensitive CH-1 human ovarian carcinoma cell line, but a different pattern was observed 24 hours after irradiation with 2 Gy dose with G2/M arrest only in radiosensitive cell line. The radiosensitivity and resistance to radiation-induced apoptosis in the radioresistant human breast carcinoma MDA-MB-231 cell line were similar to those observed in SKOV-3 cells. These data suggest that radiation-induced apoptosis and cell cycle alterations can predict radiosensitivity at least in some examined human malignant cells in vitro.