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目的:观察不同放疗剂量对食管癌细胞EC9706耐药基因MDR1表达水平的影响,同时分析其对细胞化疗耐药性的作用。方法:对食管癌细胞分别按常规剂量组(2 Gy/d.f)和小剂量组(1 Gy/d.f)进行分次外照射,共20次。采用实时定量PCR(QRT-PCR)和Western blot对外照射前后处于缺氧培养下的食管癌细胞MDR1表达水平进行检测。MTT实验评估化疗细胞抑制率。结果:照射前缺氧培养下的食管癌细胞MDR1表达水平即较对照组明显升高(P<0.05)。接受20次2 Gy/d.f照射后食管癌细胞的MDR1表达水平明显高于单纯缺氧培养组(P<0.05),但小剂量照射组的MDR1表达则明显减低(P<0.05),同时其耐药指数亦明显下降(P<0.05)。结论:同缺氧条件下进行常规剂量分次外照射相比,小剂量分次外照射可以缓解食管癌细胞的耐药程度,推测其辅助化疗疗效应较好。
OBJECTIVE: To observe the effects of different radiation doses on the expression of MDR1 gene in esophageal cancer cell line EC9706, and to analyze its role in cell chemoresistance. METHODS: Esophageal cancer cells were irradiated with external irradiation in conventional dose (2 Gy/d.f) and low dose (1 Gy/d.f) groups for 20 times. Real-time quantitative PCR (QRT-PCR) and Western blot were used to detect the expression of MDR1 in esophageal cancer cells before and after exposure to hypoxia. The MTT assay evaluates the inhibition rate of chemotherapy cells. RESULTS: The expression of MDR1 in esophageal cancer cells before the irradiation was significantly higher than that in the control group (P<0.05). The expression of MDR1 in esophageal cancer cells after 20 times of 2 Gy/df irradiation was significantly higher than that in the hypoxic group alone (P<0.05), but the expression of MDR1 in the low dose group was significantly decreased (P<0.05). The drug index also decreased significantly (P<0.05). Conclusion: Compared with conventional doses of external irradiation under hypoxic conditions, low-dose fractionated external irradiation can relieve the degree of drug resistance of esophageal cancer cells, and it is speculated that adjuvant chemotherapy should be effective.