吉西他滨对非小细胞肺癌细胞放射增敏的实验研究

In vitro Gemcitabine radiosensitization of human non-small cell lung cancer cell line A549 (wtp53)

目的 研究低浓度吉西他滨对非小细胞肺癌细胞系A5 4 9(wtp5 3)的放射增敏作用、并探讨用药后最佳放射时间。方法 ①以不同浓度的吉西他滨与A5 4 9细胞作用 2 4h ,MTT法选择生长抑制率≤ 10 %的药物浓度 (IC10 )。②将细胞分为对照组 (Ct)、单纯用药组 (Ch)、单纯照射组 (R1、R2 )、未弃药照射组 (CR)及弃药后照射组 (DCR1、DCR2 )。R1组行单纯60 Co2Gy照射 ;Ch组单纯用药 ;CR组及DCR1组均用IC10 浓度作用 2 4h ,CR组于 2 4h末、DCR1分别于弃药后 30min、1、3、6、12及 2 4h予60 Co2Gy照射。比较细胞存活分数 ,选择最佳弃药时间 (T)。③用IC10 药物浓度作用DCR2 2 4h ,于弃药后T时间经60 Co0 .5、1.0、2 .0、4 .0、6 .0、8.0Gy剂量照射 ,绘制细胞存活曲线 ;与R2 组 (同剂量单纯照射 )比较 ,计算增敏比 (D0 值比和Dq 值比 )。结果 IC10 浓度吉西他滨的放射增敏作用在弃药后 3h最为明显 [增敏比分别为 1.88(D0 值比 )、1.90 (Dq 值比 ) ];弃药 6h后与对照组比较差异无显著性意义 (P >0 .0 5 ) ;这种增敏作用在照射剂量较低时 ( 0 .5、1.0Gy)即已明显表现出来。结论 低浓度吉西他滨对离体非小细胞肺癌A5 4 9(wtp5 3)细胞系具有较好的放射增敏作用 ,且最佳照射时间为弃药后 3h。

Objective To investigate the ability of non-cytotoxic in vitro dFdC (Gemcitabine) radiosensitization of human non-small cell lung cancer (NSCLC)cell line A549 (wtp53) and the optimal radiation time. Methods 1. A549 cells were exposed to various concentrations of Gemcitabine for 24 hours. The optimal concentration giving ≤ 10% inhibition concentration (IC 10 ) by MTT assay was selected. 2. The cells were divided into 5 groups: chemotherapy alone (Ch group), radiotherapy alone (R 1 group, R 2 group), radiation at the end of chemotherapy (CR group), chemotherapy followed by radiotherapy (DCR 1 group, DCR 2 group) and control (Ct group) group. Cells in DCR 1, CR and Ch groups were exposed to Gemcitabine for 24 hours. 2?Gy of irradiation was delivered to R 1 group. In DCR 1 group, after 2?Gy of irradiation, the cells were exposed to Gemcitabine immediately, in 30 ?min, 1, 3, 6, 12, and 24 hours. In CR group cells were irradiated at the end of chemotherapy. After having been cultured for 14 days, the cells survival fraction and the plating efficiency were evaluated and compared in these groups in order to select the optimal radiation-time (T). 3. DCR 2 group had been exposed to Gemcitabine for 24 hours, followed by irradiation at T time with various doses: 0.5 ,1.0,2.0,4.0, 6.0 ,8.0?Gy. After 14 days, the cell-clonogenic survival curves and the SER were evaluated. Results The radiosensitivity enhancement of non-cytotoxic dFdC relied on the exposure time. It was most significantly obvious when radiation was delivered after exposure to Gemcitabine for 3 hours (P<0.01). After exposure for 6 hours, the plating efficiency increased and was almost equivalent to R 1 groups (P>0.05). Even in a low dose of radiation, remarkable sensitization was also shown (0.5,1.0?Gy) (P<0.01). Conclusions It is suggested that Gemcitabine enhances the radiosensitivity of NSCLC-A549 cell line in vitro (SER = 1.88). The enhancement depends on the exposure time to the drug. The optimal radiation-time should be 3 hour after exposure. Over 6 hours gives no significant difference.