[Determination of the repair half-time of human nasopharyngeal carcinoma cell lines CNE1, CNE2, HONE1 and C666-1].
OBJECTIVE
To determine the repair half-time (T1/2), a speed parameter of sub-lethal damage repair (SLDR), of human nasopharyngeal carcinoma (NPC) cell lines CNE1, HONE1, C666-1 and CNE2.


METHODS
A total radiation dose of 8 Gy divided into 4+4 Gy was delivered to the cell lines at the interval of 0 s, 15 s, 30 s, 1 h, 2 h, 4 h or 6 h. The cell survival fractions were determined using the standard cell clonogenic assay. The curves of the changes in the surviving cell fraction after a total dose of 8 Gy, as a function of the interval between the two doses of 4 Gy, were fitted manually, and the T1/2 of each cell line was calculated according to the curves.


RESULTS
The T1/2 of CNE1, HONE1, C666-1 and CNE2 were 18 s, 22 s, 29 s and 27 s, respectively.


CONCLUSIONS
The speed of SLDR of NPC cells is quite rapid, indicating that the fraction delivery time longer than 20 s might decrease the effect of radiotherapy.
Wang
Wen-jun
WJ
Department of Radiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. 40809773@qq.com
Zheng
Xiao-kang
XK
Liu
Jia-bin
JB
Yuan
Ya-wei
YW
Chen
Long-hua
LH
Sun
Heng-wen
HW
D045744:Cell Line, Tumor; D002470:Cell Survival / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D011832:Radiation Injuries / Q000517:prevention & control*; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated