CYP27A1对肝细胞癌预后的影响及生物学作用

The prognostic significance and biological effects of CYP27A1 in hepatocellular carcinoma

目的分析细胞色素P450家族27亚家族A成员1(CYP27A1)对肝细胞癌(HCC)预后的影响及生物学作用,并初步探讨其影响HCC生长的分子机制。方法基于癌症基因数据库(TCGA)分析CYP27A1在HCC中的表达情况及其与HCC患者预后的关系;基于CYP27A1表达量中位值,将样本分为CYP27A1高表达组(n=170)与CYP27A1低表达组(n=170),利用基因集富集分析(GSEA)分别对两组进行基因集富集分析;免疫荧光染色检测及数据库查找CYP27A1蛋白亚细胞定位;构建过表达CYP27A1质粒,转染HCC细胞MHCC-97H和HCCLM3,设置阴性对照组(转染空载质粒)与CYP27A1过表达组(转染过表达CYP27A1重组质粒)。采用CCK-8法、流式细胞仪、活性氧(ROS)荧光探针等检测过表达CYP27A1对HCC细胞活力、凋亡及ROS生成的影响;结合生物信息学分析CYP27A1与ROS生成相关基因及HCC增殖相关基因表达的相关性。结果与正常肝组织比较,HCC组织中CYP27A1 mRNA表达量明显降低(P<0.01)。CYP27A1表达与HCC患者性别、T分期、肿瘤分级和肿瘤分期有关(P<0.05)。CYP27A1低表达组总生存率明显低于高表达组(P<0.01)。GSEA富集分析结果显示,CYP27A1低表达组HCC“干性”亚类和“增殖”亚类基因集水平升高。在MHCC-97H和HCCLM3细胞中,CYP27A1主要定位于细胞核;在HepG2细胞中,CYP27A1主要定位于线粒体。与阴性对照组比较,过表达CYP27A1后,HCC细胞活力下降(P<0.01)、ROS水平降低(P<0.05),而细胞凋亡水平无明显改变(P>0.05)。CYP27A1与抑制ROS生成相关基因表达呈正相关(P<0.05),抑制ROS生成相关基因与HCC增殖相关基因表达呈负相关(P<0.05)。结论CYP27A1在HCC中呈低表达,下调CYP27A1可能通过促进ROS生成促进HCC恶性生长。

Objective To analyze the prognostic significance and biological effects of cytochrome P450 family 27 subfamily A member 1(CYP27A1)in hepatocellular carcinoma(HCC),and to preliminarily explore its molecular mechanism of regulating the malignant growth of HCC.Methods The Cance Genome Atlas(TCGA)database was used to analyze the expression level of CYP27A1 and its prognostic effect on HCC patients.The samples were divided into CYP27A1 high-expression group(n=170)and low-expression group(n=170)based on the median expression of CYP27A1 in HCC,gene set enrichment analysis(GSEA)was performed to investigate gene sets associated with CYP27A1 expression.The subcellular localization of CYP27A1 was detected by immunofluorescence staining and search database.The over-expression plasmid of CYP27A1 was constructed and then transfected into the HCC cells MHCC-97H and HCCLM3 cell lines,including two groups,namely control group(transfecting empty vector)and CYP27A1 over-expression group(transfecting CYP27A1 over-expressed vector).CCK-8,flow cytometer,and reactive oxygen species(ROS)fluorescence probe were applied to detect the effects of CYP27A1 over-expression on cell viability,apoptosis and ROS levels in HCC cells.Combining bioinformatics to analyze the correlation between CYP27A1 and the expression of ROS generation-related genes and HCC proliferation-related genes.Results Compared with the normal liver tissue,the expression level of CYP27A1 mRNA in HCC tissue was significantly reduced(P<0.01).The expression of CYP27A1 was significantly correlated with sex,T stage,tumor grade and tumor stage of HCC patients(P<0.05).Compared to the CYP27A1 high-expression group,patients in CYP27A1 low�expression group had lower survival rate(P<0.01).GSEA enrichment analysis revealed that the levels of HCC stem cell-related gene clusters and HCC proliferation gene clusters were remarkably increased in CYP27A1 low-expression group.The immunofluorescence showed that CYP27A1 was mainly located in nucleus in MHCC-97H and HCCLM3,whereas CYP27A1 was mainly located in mitochondria in HepG2.CYP27A1 over-expression attenuated cell viability(P<0.01),and reduced the ROS levels(P<0.05),whereas it had no effects on the apoptosis in HCC cells(P>0.05).The expression of CYP27A1 and the expression of inhibiting ROS generation-related genes were positively correlated(P<0.05),while the expression of inhibiting ROS generation-related genes and the expression of HCC proliferation-related genes were negatively correlated(P<0.05).Conclusions The expression of CYP27A1 was decreased in HCC,and down-regulated CYP27A1 promoted cell growth by enhancing ROS generation,although the precise mechanism requires future educidation.