Objective: To investigate PLXNA1 expression in hepatocellular carcinoma (HCC) and explore its biological function and impacts on patients' survival outcomes and immune microenvironment.
Methods: Bioinformatic analysis of highly expressed immune-related genes in HCC were performed using TCGA database and Immport website, and 7 genes associated with the survival outcomes of the patients were identified using univariate Cox regression analysis, Gene Expression Profiling Interactive Analysis, and Kaplan Meier plotter website. The expression profile of PLXNA1 in HCC was verified using GEO database. The impact of PLXNA1 expression on survival outcomes of HCC patients was analyzed using TCGA database, Kaplan Meier, and timeROC curve analyses, and its association with immune cell infiltration was explored using TIMER website, CIBERSORT, and ssGSEA. Immunohistochemmistry was used to detect PLXNA1 expression in clinical specimens of HCC and adjacent tissues, and the correlation of PLXNA1 expression level with the patients' survival was analyzed. RT-qPCR was used to examine PLXNA1 expressions in different HCC cell lines, and the effects of PLXNA1 knockdown on proliferation and migration of SMMC-7721 cells were evaluated using CCK-8 and Transwell assays.
Results: Bioinformatic analyses suggested that PLXNA1 was highly expressed in HCC, and its high expression was associated with poor survival outcomes of the patients. PLXNA1 expression level was significantly correlated with immune cell infiltration in HCC. Immunohistochemmistry showed that compared with the adjacent tissues, HCC tissues had significantly higher PLXNA1 expressions, which were associated with a poor patient survival and served also as a diagnostic indicator for HCC (AUC= 0.9346). In cultured HCC cell lines, SMMC-7721 cells showed a higher PLXNA1 expression than HL-7702 cells, and PLXNA1 knockdown significantly suppressed proliferation and migration of SMMC-7721 cells.
Conclusion: PLXNA1 is highly expressed in HCC to promote tumor cell migration and proliferation and affect the patients' survival outcomes and immune microenvironment.
目的: 筛选在肝细胞癌（HCC）中高表达的免疫相关基因，研究PLXNA1在HCC中的表达差异及其对生物学功能、临床意义和免疫微环境产生的影响。
方法: 利用TCGA数据库和ImmPort网站分析得到在HCC中高表达的免疫相关基因集。利用单变量COX回归和GEPIA、Kaplan-Meier Plotter网站对其进行分析得到了7个与生存预后相关的基因。通过GEO数据库验证PLXNA1在HCC中的表达情况。基于TCGA数据库，采用Kaplan-Meier、timeROC曲线分析PLXNA1的表达对HCC患者生存预后的影响，通过TIMER网站、CIBERSORT、ssGSEA方法分析PLXNA1的表达与免疫细胞浸润之间的关系。通过IHC实验研究PLXNA1在HCC与癌旁中的表达情况及其对患者生存预后的影响。通过qRT-PCR实验检验其在HCC细胞中的表达情况。利用CCK-8、transwell实验检测si-NC、si-PLXNA1-1、si-PLXNA1-2组中SMMC-7721细胞的增殖、迁移能力。
结果: 在GSE64041数据集中，PLXNA1在HCC中高表达（P < 0.001）。TCGA数据库中：PLXNA1可以较为有效的评估患者的预后风险，并且其在HCC中的高表达与患者的预后不良相关（P=0.025）。PLXNA1的表达与免疫细胞的浸润程度显著相关（P < 0.05）。IHC实验结果显示：PLXNA1在HCC组织中高表达，其中PLXNA1高表达组患者的生存率较低（Log-rank P < 0.01），PLXNA1的表达对HCC具有显著的诊断价值（AUC=0.9346）。PLXNA1在SMMC-7721细胞中的表达量高于HL-7702细胞。PLXNA1敲低组的细胞增殖、迁移能力下降（P < 0.01）。
结论: 免疫相关基因PLXNA1在HCC中高表达，其促进了细胞的迁移和增殖能力，并且能够影响HCC患者的生存、预后以及免疫微环境。
Keywords: PLXNA1; biological function; hepatocellular carcinoma; immune infiltration; survival prognosis.