E1A基因对鼻咽癌细胞放射敏感性影响的初步实验研究

Effect of E1A gene on radiosensitivity of nasopharyngeal carcinoma cells

目的探讨E1A基因对鼻咽癌细胞放射增敏作用及相关机制。从而为提高鼻咽癌放射治疗疗效提供实验依据。方法经腺病毒介导，将E1A基因导入人鼻咽癌细胞系CNE2细胞。经RT-PCR鉴定，获得含E1A的阳性克隆。将未转染的CNE2细胞、转染对照空载体Ad-B-gal的CNE2细胞和转染Ad-E1A的CNE2细胞用6MVX线分别照射0、2、4、6、8Gy后进行成克隆分析并绘制细胞存活曲线，计算放射增敏比。流式细胞术和RT—PCR检测转染前后的细胞周期分布以及wtp53表达情况。结果转染后阳性克隆细胞RT—PCR结果说明E1A已整合到细胞基因组中并且稳定表达。细胞存活曲线结果显示转染E1A的CNE2细胞放射增敏比分别为1．37（D0值比）、1．95（Dq值比）、1．46（SF2值比）。未转染及空载体转染后的CNE2细胞照射后细胞存活曲线分析结果显示无差异，D0、Dq、SF2值分别为1．57Gy及1．53Gy、1．82Gy及1．78Gy、0．89及0．82。流式细胞术显示细胞周期出现G2＋M期阻滞，RT-PCR结果显示E1A基因能提高wtp53的表达。结论E1A基因能显著提高人鼻咽癌细胞的放射敏感性，其作用机制可能与E1A基因提高wtp53基因的表达和引起G2＋M期阻滞有关。

Objective To study the effect of E1A gene on the radiosensitivity of nasopharyngeal carcinoma （NPC） cells and its mechanism. Methods Ad-E1A gene was transfected into human NPC ceils （CNE2）, then the positive clones （CNE2-Ad-E1A） were identified by RT-PCR. CNE2 cells, CNE2 cells transfected with Ad-β-gal （CNE2-Ad -β-gal） and CNE2-Ad-E1A cells were irradiated with 0 Gy,2 Gy,4 Gy,6 Gy and 8 Gy respectively using 6 MV X-ray. Clone forming assays were carried out, cell survival curves were drawn and the sensitivity enhancing ratio （SER） was calculated. The redistributions of cell cycle were analyzed by flow cytometry. RT-PCR was used to detect the expression of wtp53. Results RT- PCR confirmed that E1A gene had been integrated into positively transfected cells and stably expressed. Cell survival curves showed that the SER of Do, Dq and SF2 value was 1.37, 1.95 and 1.46 in CNE2-Ad-E1A cells. The DO ,Dq and SF2 value was 1.57 Gy,1.82 Gy, 0.89 in CNE-2 cells and 1.53 Gy,1.78 Gy,0.82 in CNE2-Ad-lS-gal cells, respectively. The %/M arrest was shown in CNE2-Ad-E1A cells. Moreover, the expression of wtp53 gene was markedly enhanced in Ad-E1A-CNE2 cells. Conclusions E1A gene can effectively enhance the radiosensitivity of human NPC cells, which may be associated the enhancement of wtp53 expression and G2/M arrest.