Abstract:

Objective To detect the cell cycle and mRNA expression of Cyclin B1 and Cyclin D1 in human nasopharyngeal carcinoma cell line (CNE-2) with modeling intensity modulated radiation therapy (IMRT).  Methods CNE-2 cell lines were divided into acute irradiation therapy （ART） group and modeling IMRT group, and both groups were irradiated at 2, 4, 6 and 8Gy dose levels by 6 MV X-ray. The time of irradiation in ART group was 1 to 3 min, and that in IMRT group was 35 min. Besides, blank control group without irradiation was established. The distribution of cell cycle was analysed by flow cytometry, and RT-PCR was employed to detect the mRNA expression of Cyclin D1 and Cyclin B1.  Results Compared with ART group, the proportion of G2 phase of IMRT group was lower at each dose point, and gradually increased with the irradiation dose. There was no significant difference in the mRNA expression of Cyclin D1 at each dose point between these two groups (P＞0.05). The mRNA expression of Cyclin B1 of IMRT group was significantly higher than that of ART group at each dose point（P＜0.05）, and the mRNA expression of both groups were down-regulated in a dose-dependent manner.  Conclusion Modeling IMRT leads to relatively higher expression of Cyclin B1 and decreased radiation-induced G2 arrest.

Key words: human nasopharyngeal carcinoma cell line, modeling intensity modulated radiation therapy, cell cycle,
Cyclin B1, Cyclin D1