Ability to undergo apoptosis does not correlate with the intrinsic radiosensitivity (SF2) of human cervix tumor cell lines.
OBJECTIVE
To investigate the relationship between radiation-induced apoptosis and clonogenic cell kill in 9 cervical cancer cell lines.


METHODS
Cells were irradiated with 0, 2, 8, and 30 Gy. The level of apoptosis was evaluated using flow cytometry (Annexin-V binding), light microscropy (morphology), gel electrophoresis (DNA ladder formation), and TUNEL assay. Cell survival was measured using a clonogenic assay.


RESULTS
Of the 9 cervical carcinoma cell lines analyzed, 3 underwent radiation-induced apoptosis: CaSki, HT3, and 778. The levels of apoptosis, obtained 72 h after a dose of 30 Gy, were 49%, 28%, and 26%, respectively. All cell lines exhibited some level of background apoptosis measured by Annexin-V binding (mean = 2.6%+/-0.8; range, 0.2-6.9%) that correlated with the level of radiation-induced apoptosis (r = 0.92, p = 0.001). In 6 of the 9 lines, necrosis was the dominant form of cell death. A significant inverse relationship was found between the level of radiation-induced apoptosis and necrosis after 30 Gy (r = -0.87, p = 0.002). No relationship was found between radiation-induced apoptosis and intrinsic radiosensitivity measured, using a clonogenic assay, as surviving fraction at 2 Gy (SF2).


CONCLUSIONS
Cervical carcinoma cells do not readily undergo radiation-induced apoptosis in vitro. There is no relationship between ability to undergo apoptosis and intrinsic radiosensitivity measured using a clonogenic assay.
Sheridan
M T
MT
CRC Experimental Radiation Oncology Group, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, United Kingdom.
West
C M
CM
D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects*; D016923:Cell Death / Q000528:radiation effects; D005260:Female; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D009336:Necrosis; D011836:Radiation Tolerance / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000473:pathology* / Q000532:radiotherapy