UHRF1基因沉默对逆转人肺腺癌A549细胞顺铂耐药性的影响

Reverse effect of UHRF 1 gene silencing on cisplatin resistance of lung adenocarcinoma A549 cells

目的:检测泛素样含PHD和环指域1(ubiquitin-like with PHD and ringfinger domain 1,UHRF1)基因在人肺腺癌顺铂(cisplatin,DDP)耐药细胞株A549/DDP及其亲本细胞株A549中的表达差异,并探讨沉默UHRF1基因对逆转A549/DDP细胞对DDP耐药性的影响。方法:采用半定量RT-PCR和蛋白质印迹法检测UHRF1 m RNA和蛋白在A549及A549/DDP细胞中的表达差异。随后构建靶向沉默UHRF1基因的短发夹RNA(short hairpin RNA,sh RNA)质粒表达载体,并采用慢病毒感染法感染至A549/DDP细胞,同时设未进行感染的空白对照组和感染非特异性sh RNA的阴性对照组。采用蛋白质印迹法检测各组细胞中UHRF1蛋白的表达水平。采用MTT法检测各组细胞在DDP作用下的半数抑制浓度(half maximal inhibitory concentration,IC50)。采用FCM法检测细胞凋亡率。采用蛋白质印迹法检测凋亡调节因子Bcl-2和Bax的表达情况。结果:UHRF1 m RNA和蛋白在A549/DDP细胞中的表达水平显著高于亲代A549细胞(P<0.01)。靶向UHRF1基因的sh RNA明显下调A549/DDP细胞中UHRF1蛋白的表达水平(P<0.01)。在不同浓度DDP作用24 h后,UHRF1-sh RNA组A549/DDP细胞的IC50值明显低于空白对照组和阴性对照组,对DDP的敏感性显著提高(P值均<0.01)。DDP(6 mg/L)作用24 h后,UHRF1-sh RNA组细胞的凋亡率及促凋亡蛋白Bax的表达水平较空白对照组和阴性对照组明显增高,而抗凋亡蛋白Bcl-2的表达水平则明显下调(P值均<0.01)。结论 :UHRF1基因在人耐药肺腺癌细胞中呈现高表达,提示UHRF1参与肺腺癌耐药的形成;UHRF1-sh RNA可特异性下调UHRF1的表达,逆转A549/DDP细胞对DDP的耐药性,并通过调节凋亡相关基因的表达促进其凋亡。UHRF1基因可能成为逆转肺癌耐药性的一个新的分子靶点。

Objective： To examine the ubiquitin-like with PHD and ringfinger domain 1 （UHRF1）gene expression in cisplatin （DDP）-resistant lung adenocarcinoma A549/ DDP cells and parental A549 cells, and to investigate the reverse effect of UHRF1 gene silencing on DDP resistance of A549/DDP cells.Methods： The expression levels of UHRF1 mRNA and protein in A549 and A549/DDP cells were dectected by RT-PCR and Western blotting, respectively. The UHRFl-short hairpin RNA （shRNA） expression plasmid vectors were constructed and infected into A549/DDP cells by lentiviral infection approach. The A549/DDP cells infected with lentivirus containing negative control shRNA （NC-shRNA） or not were as the negative control and the blank control, respectively. The expression level of UHRF1 protein in each group was evaluated by Western blotting. The half maximal inhibitory concentration （IC50） of DDP was examined by MTT assay. The apoptosis rate was determined by flow cytometry （FCM）. The protein expression levels of apoptosis regulatory factors Bcf-2 and Bax were detected by Western blotting.Results： The expression levels of UHRF1 mRNA and protein in AS49/DDP cells were significantly elevated as compared with those of parental A549 cells （P 〈 0.01）. The shRNA targeting UHRF1 gene could down-regulate the protein expression of UHRF1 in A549/DDP cells （P 〈 0.01）. After treatment with different concentrations of DDP for 24 h, the ICso of DDP in UHRFI-shRNA group was significantly decreased, as compared with those in the negative control and the blank control groups （both P 〈 0.01）. After treatment with DDP （6 mg/L） for 24 h, the apoptosis rate and the expression of proapoptotic protein Bax in UHRF1- shRNA group were significantly increased, but the expression of antiapoptotic protein Bcl-2 was significantly decreased, as compared with those in the negative control and the blank control groups （all P 〈 0.01）.Conclusion： The over-expression of UHRF1 in DDP-resistant human lung adenocarcinoma cells suggests that UHRF1 might be involved in the chemoresistance of lung cancer. UHRF1- specific shRNA can down-regulate the expression of UHRF1, reverse the resistance to DDP in A549/DDP cells, and promote apoptosis through influencing the expressions of apoptosis regulatory factors. UHRF1 may be a new target for reversal of chemoresistance of lung cancer.