BTG2对非小细胞肺癌放疗敏感性的影响及其机制

Effect of BTG2 on radiosensitivity of non-small cell lung cancer and its mechanism

目的研究BTG2在非小细胞肺癌(non-small cell lung cancer,NSCLC)中的表达及其对放疗敏感性的影响,并探索其可能机制。方法通过查阅Tumor IMmune Estimation Resource、Oncomine和TCGA数据库比较BTG2蛋白在NSCLC中的表达情况,分析BTG2表达水平与患者预后的相关性。通过Western blot实验检测BTG2在正常肺上皮细胞BEAS-2B和人肺腺癌细胞系H1975中的蛋白表达。H1975细胞分为对照组(转染pcDNA3.1-HA空载质粒)和过表达组(转染HA-BTG2质粒),MTT实验检测细胞增殖情况。通过MTT检测对照组或过表达组经不同剂量的X射线(0,2,4,6,8 Gy)照射后细胞的增殖情况。H1975细胞分为对照组(转染pcDNA3.1-HA空载质粒)、过表达组(转染HA-BTG2质粒)、照射组(转染pcDNA3.1-HA空载质粒+X射线4 Gy照射)和联合组(转染HA-BTG2质粒+X射线4 Gy照射),Western blot实验检测不同处理后P53和BRCA1的蛋白水平。结果与癌旁组织相比,NSCLC组织中BTG2的表达明显降低(P<0.05)。BTG2的表达较低时患者的预后较差(P<0.05)。与BEAS-2B细胞相比,H1975细胞中BTG2的表达降低(P<0.05)。过表达组H1975细胞培养96 h OD值较对照组降低(1.26±0.04 vs 1.76±0.05,P<0.05)。当X射线照射剂量为4 Gy时,过表达组H1975细胞OD值较对照组降低(0.64±0.05 vs 0.85±0.03,P<0.05)。与照射组和过表达组相比,联合组H1975细胞中P53蛋白表达升高,BRCA1蛋白表达降低(P<0.05)。结论BTG2在NSCLC组织中低表达,且可能是通过上调P53的表达、降低BRCA1的表达来干扰DNA的损伤修复过程,增强NSCLC对放疗的敏感性。

Objective To study the expression of BTG2 in non-small cell lung cancer(NSCLC)and its effect on radiotherapy sensitivity,and explore its possible mechanism.Methods The expression of BTG2 protein was detected in NSCLC based on Tumor IMmune Estimation Resource,Oncomine and TCGA databases,and the correlation between the expression and the prognosis was analyzed.Western blot was used to detect the protein expression of BTG2 in normal lung epithelial cells BEAS-2B and human lung adenocarcinoma cell line H1975.H1975 cells were divided into control group(transfected with pcDNA3.1-HA empty plasmid)and overexpression group(transfected with HA-BTG2 plasmid),and then MTT assay was used to detect the cell survival rate.MTT was also used to detect the cell proliferation after treated with different doses of X-rays(0,2,4,6,8 Gy)in control group and overexpression group.H1975 cells were divided into four groups:control group(transfected with pcDNA3.1-HA empty plasmid),overexpression group(transfected with HA-BTG2 plasmid),irradiation group(transfection of pcDNA3.1-HA empty plasmid+X-ray 4 Gy irradiation)and combination group(transfection of HA-BTG2 plasmid+X-ray 4Gy irradiation),and Western blot was used to detect the protein levels of P53 and BRCA1 after different treatment.Results Compared with adjacent tissues,the expression of BTG2 in NSCLC tissues was significantly reduced(P<0.05).Patients with low BTG2 expression had a poor prognosis(P<0.05).The protein expression of BTG2 in H1975 was significantly lower than that in BEAS-2B(P<0.05).The OD value of H1975 cells cultured for 96 h in overexpression group was lower than in control group(1.26±0.04 vs 1.76±0.05,P<0.05).The OD value was lower in overexpression group than in control group after treatment with 4 Gy irradiation(0.64±0.05 vs 0.85±0.03,P<0.05).Compared with irradiation group and overexpression group,the expression of P53 protein was increased and the expression of BRCA1 protein was decreased in combination group(P<0.05).Conclusion BTG2 is lowly expressed in NSCLC tissues.BTG2 can enhance the sensitivity of NSCLC to radiotherapy,which may be related to the DNA damage repair process by up-regulating the expression of P53 and reducing the expression of BRCA1.