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肺癌是全球发病率较高的恶性肿瘤,同时也是我国病死率增长较快的肿瘤,且发病年龄也呈年轻化趋势[1-2]。根据病理类型,肺癌可分为小细胞肺癌和非小细胞肺癌[3]。肺癌的发病原因还不十分清楚,有研究发现其与吸烟、长期遭受空气污染和职业中接触致癌物等密切相关[4-6]。放疗是肺癌治疗的重要手段之一[7-8],随着治疗的进程,肿瘤细胞会产生辐射耐受性,而加大放疗剂量势必给患者带来严重的不良反应及并发症,并严重影响患者的生活质量[9-10]。因此,寻找肺癌细胞产生耐辐射的机制,改变放射敏感性调节相关基因、miRNA等的表达水平和功能,靶向地增加肺癌细胞的放疗敏感性,从而提升患者的放疗疗效,一直是肺癌治疗基础研究的热点。
近年来,有研究发现miRNA能够通过调控某些基因的表达及信号通路来参与调节肿瘤细胞的放射敏感性[11-12]。miR-148a是近年来新发现的一种高度保守的miRNA,其前体序列位于人类第7号染色体短臂1区5带[13]。大量的研究结果表明,miR-148a的表达水平与肺癌的发生发展呈负相关[14-15]。miR-148a能够抑制肺癌细胞增殖,同时抑制非小细胞肺癌的浸润与迁移[16]。miR-148a可以通过抑制雌激素受体(estrogen receptor,ER)的表达水平,进而抑制乳腺癌的发生发展及迁移[17]。但有关miR-148a与ER在肺癌细胞中的关系,以及miR-148a是否能够调控肺癌细胞的放射敏感性,迄今为止尚不清楚。我们通过分析miR-148a过表达对肺癌A549、H460和H1299细胞系放射敏感性的影响,为探索肺癌放疗增敏的新途径提供实验依据和理论基础。
MiR-148a对肺癌细胞放射敏感性的影响
Effect of miR-148a on the radiosensitivity of lung cancer cells
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摘要:
目的探讨miR-148a对肺癌A549、H460以及H1299细胞放射敏感性的影响。 方法根据不同的处理方法,分别按以下方式将肺癌A549、H460和H1299细胞进行分组。(1)将肺癌A549和H460细胞分为3组:空白对照组、4 Gy γ射线照射组和8 Gy γ射线照射组。采用实时定量PCR检测miR-148a的表达水平;(2)将肺癌A549细胞分为2组:空白对照组、miR-148a转染组;同时,将肺癌H460细胞分为2组:空白对照组、anti-miR-148a转染组。分别对转染2组细胞进行不同剂量的γ射线照射,并采用克隆形成实验方法来检测细胞增殖;(3)将肺癌A549和H1299细胞分为3组:空白对照组、miR-148a单独处理组、miR-148a和雌激素受体(ER)共转染组。分别对3组细胞进行不同剂量的γ射线照射,并采用克隆形成实验方法检测细胞生长情况。采用Student t-test对数据进行统计学分析,P < 0.05表示差异有统计学意义。 结果实时定量PCR实验结果显示,γ射线照射能够显著下调肺癌A549和H460细胞中miR-148a的表达水平。克隆形成实验结果显示,与空白对照组相比,miR-148a转染能够显著增强肺癌A549细胞的放射敏感性,差异有统计学意义(t=12.16,P < 0.01),而anti-miR-148a转染能够显著降低肺癌H460细胞的放射敏感性,差异有统计学意义(t=11.93,P < 0.01)。同时,miR-148a过表达可以明显下调肺癌A549细胞中ER的mRNA及蛋白表达水平;而anti-miR-148a能够显著上调肺癌H460细胞中ER的mRNA及蛋白表达水平。另外,与miR-148a单独处理组相比,miR-148a和ER共转染组中miR-148a对肺癌A549和H1299细胞增殖的影响显著降低,差异有统计学意义(t=11.34、12.68,均P < 0.01)。 结论照射可以诱导miR-148a的表达水平降低,人为过表达miR-148a能够抑制ER的蛋白表达水平,进而降低肺癌A549和H1299细胞的增殖能力,同时增强其放射敏感性。 -
关键词:
- 肺肿瘤 /
- 辐射耐受性 /
- MiRNA-148a /
- 雌激素受体 /
- 细胞增殖
Abstract:ObjectiveTo explore the effects of miR-148a on the radiosensitivity of lung cancer cell lines A549, H460, and H1299. MethodsLung cancer cells were divided into various groups based on different treatment methods. (1) A549 and H460 cells were classified into three groups:control, 4 Gy γ-irradiation, and 8 Gy γ-irradiation groups. miR-148a expression levels were analyzed through qRT-PCR. (2) A549 cells were categorized into two groups:control and miR-148a transfection groups. H460 cells were also divided into two groups:control and anti-miR-148a transfection groups. The cells were treated with different doses of γ-irradiation, and cell proliferation was detected through a clonogenic assay. (3) A549 and H1299 cells were grouped into three:control, miR-148a transfection, and miR-148a+ER transfection groups. The cells were treated with different doses of γ-irradiation, and the proliferation of A549 and H1299 cells was detected via clonogenic assay. Statistical significance was determined with SPSS and analyzed with Student t test. P < 0.05 was considered statistically significant. ResultsqRT-PCR analysis revealed that the miR-148a expression in the A549 and H460 cells treated with γ-irradiation decreased significantly. Clonogenic assays showed that miR-148a could sensitize A549 cells exposed to irradiation compared with that of the control group (t=12.16, P < 0.01). H460 cells were more resistant to irradiation in the presence of anti-miR-148a (t=11.93, P < 0.01). miR-148a overexpression could also downregulate the mRNA and protein levels of estrogen receptor (ER) in A549 cells, but anti-miR-148a could increase the mRNA and protein levels of ER in H460 cells. The miR-148a and ER overexpression significantly decreased the effect of miR-148a on the proliferation of A549 and H1299 cells (t=11.34, 12.68, respectively, both P < 0.01). ConclusionsIrradiation could decrease miR-148a expression levels, and miR-148a overexpression could downregulate the ER level and suppress the proliferation of A549 and H1299 cells, thereby enhancing the radiosensitivity of lung cancer cells. -
Key words:
- Lung neoplasms /
- Radiation tolerance /
- MiRNA-148a /
- Estrogen receptor /
- Cell proliferation
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图 1 MiR-148a对肺癌A529和H460细胞放射敏感性的影响 图中,A:实时定量PCR结果显示,与空白对照组比较,4 Gy和8 Gy照射能够显著下调A549细胞中miR-148a的表达水平(**:t=10.18、11.66,均P < 0.01);B:与空白对照组比较,4 Gy γ射线照射对H460细胞中miR-148a表达水平无显著影响(t=3.17,P>0.05),但8 Gy γ射线照射能够显著下调H460细胞中miR-148a的表达水平(**:t= 10.95,P < 0.01);C、D:克隆形成实验结果显示,与空白对照组比较,miR-148a转染能够显著增强A549细胞的放射敏感性(**:t= 12.16,P < 0.01);同时,anti-miR-148a转染能够显著降低H460细胞的放射敏感性(**:t=11.93,P < 0.01)。PCR:聚合酶链反应。
Figure 1. The effect of miR-148a on the radiosensitivity of lung cancer A549 and H460 cells
图 2 MiR-148a对ER 3' UTR序列的靶向调控作用 图中,A:ER的3' UTR序列中受miR-148a直接调控的模序;B:ER-3' UTR序列突变示意图;C:MiR-148a能够抑制野生型ER-3' UTR的荧光素酶活性,差异有统计学意义(**:t=11.52、12.78,均P < 0.01),但对突变型ER-3' UTR的荧光素酶活性无显著影响,差异无统计学意义(*:t=1.97、2.32,均P>0.05);D:Anti-miR-148a能够增强野生型ER-3' UTR的荧光素酶活性(**:t=11.98、13.22,均P < 0.01),但对突变型ER-3' UTR的荧光素酶活性无显著影响,差异无统计学意义(*:t=2.11、2.42,均P>0.05)。ER:雌激素受体。
Figure 2. The direct regulation of miR-148a on the ER-3' UTR
图 3 MiR-148a或anti-miR-148a对肺癌A529和H460细胞中ER mRNA表达水平及蛋白表达水平的影响 图中,A:MiR-148a转染下调了A549细胞中ER的mRNA及蛋白表达水平;B:Anti-miR-148a转染上调了H460细胞中ER的mRNA及蛋白表达水平。**:MiR-148a及anti-miR-148a的转染差异有统计学意义(t=10.82、12.66、11.31、12.31,均P < 0.01)。ER:雌激素受体;GAPDH:甘油醛-3-磷酸脱氢酶。
Figure 3. The effects of miR-148a or anti-miR-148a on the expression of estrogen receptor at the mRNA and protein levels in A549 or H460 cells
图 4 MiR-148a和ER对肺癌细胞凋亡作用及放射敏感性的影响 图中,A:与空白对照组比较,miR-148a单独转染能够显著增强4 Gy γ射线照射对A549细胞的促凋亡作用,差异有统计学意义(**:t=13.38,P < 0.01);而与miR-148a单独转染组比较,共转染了miR-148a和ER的A549细胞中,4 Gy γ射线照射所导致的凋亡作用显著降低,差异有统计学意义(*:t=6.47,P < 0.05);B、C:与空白对照组比较,miR-148a单独转染能够显著提高肺癌A549和H1299细胞的放射敏感性,差异有统计学意义(**:t=12.91、13.44,均P < 0.01),而与miR-148a单独转染组比较,共转染了miR-148a和ER的肺癌A549和H1299细胞则出现明显放射敏感性下降,差异有统计学意义(**:t=11.34、12.68,均P < 0.01);D:与空白对照组比较,anti-miR-148a单独转染能够显著降低肺癌H460细胞的放射敏感性,差异有统计学意义(**:t=12.51,P < 0.01),而与anti-miR-148a单独转染组比较,共转染了anti-miR-148a和ER siRNA的肺癌H460细胞则出现明显放射敏感性升高,差异有统计学意义(**:t=10.96,P < 0.01)。ER:雌激素受体。
Figure 4. Effects of miR-148a and estrogen receptor on the apoptosis and radiosensitivity of lung cancer cells
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