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肝细胞癌为全球性健康问题[1],其发病率在全球排名第五,死亡率排名第二[2]。由于肝细胞癌早期无特征性临床表现,因此在发病早期难以发现,往往在病人就诊时已处于疾病晚期,失去了手术治疗的最佳时间[3]。因此,深入研究肝细胞癌的发病机制及发现新的治疗手段有重大意义。随着肿瘤免疫治疗突飞猛进,新型细胞免疫治疗技术得到飞速发展。近年来,在肿瘤免疫治疗研究中发现程序性死亡受体-1(programmed death receptor-1, PD-1) /程序性死亡配体-1(programmed death ligand-1,PD-L1/B7-H1) 信号通路的激活可以诱导发生肿瘤免疫逃逸,促进肿瘤快速生长, 在免疫耐受调节中扮演重要角色[4]。但目前尚未见文献报道有关PD-L1在肿瘤细胞自身增殖能力方面的研究。既往研究[5-12]表明,PD-L1在多种恶性肿瘤中呈高表达状态,如骨肉瘤、乳腺癌、非小细胞肺癌、结肠癌、淋巴瘤、胰腺癌、脑胶质瘤、鳞状细胞癌等。并且最近有研究[13]表明,PD-L1在肝细胞癌中同样呈高表达状态。本研究应用RNA干扰技术下调肝细胞癌细胞中PD-L1基因,观察下调PD-L1基因对肝癌细胞迁移、侵袭、增殖能力的影响,为肝细胞肝癌免疫治疗提供前期实验基础。现作报道。
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Western blotting结果显示,siRNA-PD-L1组、siRNA-NC组和空白对照组PD-L1蛋白表达量间差异有统计学意义(P<0.01),其中siRNA-PD-L1组均明显低于siRNA-NC组和空白对照组(P<0.01),而siRNA-NC组和空白对照组差异无统计学意义(P>0.05)(见图 1、表 1)。
分组 PD-L1蛋白 F P MS组内 siRNA-PD-L1组 0.332±0.011 siRNA-NC组 0.779±0.032** 439.64 <0.01 0.001 空白对照组 0.831±0.044** q检验:与siRNA-PD-L1组比较**P<0.01 表 1 各组细胞PD-L1蛋白表达量比较(x±s)
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荧光定量PCR结果显示,siRNA-PD-L1组、siRNA-NC组和空白对照组PD-L1蛋白表达量间差异有统计学意义(P<0.01),其中siRNA-PD-L1组均明显低于siRNA-NC组和空白对照组(P<0.01),而siRNA-NC组和空白对照组差异无统计学意义(P>0.05)(见表 2)。
分组 PD-L1mRNA F P MS组内 siRNA-PD-L1组 0.421±0.065 siRNA-NC组 1.243±0.201** 219.62 <0.01 0.001 空白对照组 1** q检验:与siRNA-PD-L1组比较**P<0.01 表 2 各组细胞PD-L1mRNA相对表达量比较(x±s)
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MTT实验结果显示,siRNA转染HepG2细胞后24、48 h,3组细胞增殖率差异均无统计学意义(P>0.05);转染后72 h,siRNA-PD-L1组细胞增殖率均明显低于siRNA-NC组和空白对照组(P<0.01)(见表 3)。
分组 n 24 h 48 h 72 h siRNA-PD-L1组 6 0.610±0.011 0.653±0.045 0.705±0.053 siRNA-NC组 6 0.628±0.029 0.710±0.029 0.901±0.034** 空白对照组 6 0.602±0.044 0.699±0.069 0.904±0.059** F — 1.10 2.16 31.44 P — >0.05 >0.05 <0.01 MS组内 — 0.001 0.003 0.003 q检验:与siRNA-PD-L1组比较**P<0.01 表 3 siRNA转染后不同时点各组细胞增殖率比较(x±s)
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Transwell侵袭实验结果显示,3组细胞侵袭能力间差异有统计学意义(P<0.01),其中siRNA-PD-L1组穿膜细胞数均明显低于siRNA-NC组和空白对照组(P<0.01),而siRNA-NC组和空白对照组差异无统计学意义(P>0.05)(见图 2、表 4)。
分组 穿膜细胞数 F P MS组内 siRNA-PD-L1组 40.21±3.02 siRNA-NC组 105.31±3.03** 535.04 <0.01 17.340 空白对照组 110.62±5.78** q检验:与siRNA-PD-L1组比较**P<0.01 表 4 各组细胞侵袭能力比较(x±s)
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细胞划痕实验结果显示,3组细胞迁移能力间差异有统计学意义(P<0.01),其中siRNA-PD-L1组均明显低于siRNA-NC组和空白对照组(P<0.01),而siRNA-NC组和空白对照组差异无统计学意义(P>0.05)(见图 3、表 5)。
分组 细胞迁移/% F P MS组内 siRNA-PD-L1组 12.30±2.00 siRNA-NC组 63.00±2.81** 441.71 <0.01 6.220 空白对照组 66.00±3.04** q检验:与siRNA-PD-L1组比较**P<0.01 表 5 各组细胞迁移能力比较(x±s)
PD-L1对肝细胞癌细胞增殖、侵袭及迁移的影响
Effect of PD-L1 on the proliferation,invasion and migration of hepatocellular carcinoma cells
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摘要:
目的 探讨程序性死亡配体(PD-L1)在肝癌细胞增殖、侵袭、迁移中的作用。 方法 转染有效的PD-L1基因siRNA干扰片段进入人肝细胞癌HepG2细胞中,下调细胞中PD-L1表达。采用荧光定量PCR法检测HepG2细胞中PD-L1基因表达情况,采用Western blotting法检测HepG2细胞中PD-L1蛋白表达情况。通过MTT实验观察其对HepG2细胞增殖能力的影响,采用细胞划痕实验检测细胞融合率,采用Transwell小室进行侵袭实验,观察其对HepG2细胞迁移及侵袭能力影响。 结果 下调PD-L1后,HepG2细胞PD-L1基因表达量、PD-L1蛋白表达量和细胞增殖能力、迁移能力及侵袭能力均明显低于阴性对照组和空白对照组(P<0.01),阴性对照组和正常对照组上述指标差异均无统计学意义(P>0.05)。 结论 下调PD-L1后,肝癌细胞的增殖、迁移、侵袭能力有一定程度下降,PD-L1可能成为肝细胞肝癌免疫治疗中的一个新基因靶位。 Abstract:ObjectiveTo investigate the effects of PD-L1 in the proiferation, invasion and migration of hepatacellular carcinorma cells. MethodsThe effective PD-L1 gene siRNA interference fragment was transfected into the human hepatocellular carcinoma HepG2 cells to down-regulate PD-L1 expression.The expression levels of PD-L1 gene and protein in HepG2 cells were detected using the real-time PCR and Western blotting, resepctively.The cells proliferation and fusion rate of HepG2 cells were observed using the MTT assay and cell scratch test, respectively.The invasion experiment was implemented using Transwell chamber, and the migration and invasion ability of HepG2 cells were observed. ResultsAfter the expression level of PD-L1 gene was down-regulated, the expression levels of PD-L1 gene and protein in HepG2 cells, and proliferation, migration and invasion abilities of HepG2 cells in PD-L1 interference group were significantly lower than those in negative control group and blank control group(P<0.01), and there was no statistical significance in the above indicators between the negative control group and normal control group(P>0.05). ConclusionsAfter the down-regulation of PD-L1, the proliferation, migration and invasion abilities of the human hepatocellular carcinoma cells decrease to a certain extent, and PD-L1 may become a new gene target in the immunotherapy of hepatocellular carcinoma. -
Key words:
- hepatocellular neoplasms /
- PD-L1 /
- invasion /
- migration /
- proliferation
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表 1 各组细胞PD-L1蛋白表达量比较(x±s)
分组 PD-L1蛋白 F P MS组内 siRNA-PD-L1组 0.332±0.011 siRNA-NC组 0.779±0.032** 439.64 <0.01 0.001 空白对照组 0.831±0.044** q检验:与siRNA-PD-L1组比较**P<0.01 表 2 各组细胞PD-L1mRNA相对表达量比较(x±s)
分组 PD-L1mRNA F P MS组内 siRNA-PD-L1组 0.421±0.065 siRNA-NC组 1.243±0.201** 219.62 <0.01 0.001 空白对照组 1** q检验:与siRNA-PD-L1组比较**P<0.01 表 3 siRNA转染后不同时点各组细胞增殖率比较(x±s)
分组 n 24 h 48 h 72 h siRNA-PD-L1组 6 0.610±0.011 0.653±0.045 0.705±0.053 siRNA-NC组 6 0.628±0.029 0.710±0.029 0.901±0.034** 空白对照组 6 0.602±0.044 0.699±0.069 0.904±0.059** F — 1.10 2.16 31.44 P — >0.05 >0.05 <0.01 MS组内 — 0.001 0.003 0.003 q检验:与siRNA-PD-L1组比较**P<0.01 表 4 各组细胞侵袭能力比较(x±s)
分组 穿膜细胞数 F P MS组内 siRNA-PD-L1组 40.21±3.02 siRNA-NC组 105.31±3.03** 535.04 <0.01 17.340 空白对照组 110.62±5.78** q检验:与siRNA-PD-L1组比较**P<0.01 表 5 各组细胞迁移能力比较(x±s)
分组 细胞迁移/% F P MS组内 siRNA-PD-L1组 12.30±2.00 siRNA-NC组 63.00±2.81** 441.71 <0.01 6.220 空白对照组 66.00±3.04** q检验:与siRNA-PD-L1组比较**P<0.01 -
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