微小染色体维持蛋白8在食管癌组织的表达及临床意义

Clinical significance and expression of minichromosome maintenance protein 8 in esophagus carcinoma

目的分析微小染色体维持蛋白8(MCM8)在食管癌组织中的表达及其对食管癌预后、肿瘤微环境的影响。方法调取基因表达数据库(GEO)收录的食管癌、癌旁组织, 食管鳞状上皮及Barrett’s食管(BE)组织中MCM8的mRNA值, t检验分析其间差异;UALCAN分析癌症基因组图谱(TCGA)数据库中不同分期、分级食管癌中MCM8的表达;收集2022年1~3月于扬州大学附属医院住院并接受手术治疗的食管癌患者组织6例, 免疫组织化学染色(IHC)验证MCM8表达;Kaplan-Meier Plotter数据库分析MCM8与食管癌预后的关系;cBio-Portal数据库筛选MCM8的共表达基因, DAVID富集分析其可能的机制;STRING、PINA3.0数据库分析MCM8的互作网络;TISIDB数据库通过非参数检验分析MCM8与食管癌肿瘤微环境(TME)中免疫细胞浸润丰度的相关性。组间比较采用t检验。结果 GSE161533、GSE45670数据集中, MCM8在食管癌(47.36±17.59、660.30±282.00)的表达均高于癌旁组织(22.89±4.30、293.90±125.90, t=7.15、4.13, P<0.01);TCGA数据库中, MCM8在低分化癌(16.40)中的表达高于中、高分化癌(12.84、8.77, P<0.05);GSE77563中, MCM8在Barrett’s食管(BE)(5.12±1.13)中的表达高于食管正常鳞状上皮组织(3.99±0.55, t=4.26, P<0.01);IHC表明MCM8在食管鳞癌中的表达高于癌旁组织(将癌旁组织MCM8阳性的积分吸光度/总面积值标化为1, 癌组织阳性的值为2.35±0.17, t=19.74, P<0.01);MCM8高表达食管癌患者的总体生存率降低(P<0.01);富集分析提示MCM8可能参与细胞周期调控、RNA转运调节、DNA错配修复等生物学进程;互作分析表明MCM8与细胞分裂控制蛋白、复制起始位点识别复合物等家族的分子紧密相关;MCM8的表达与食管癌微环境中活化T细胞、自然杀伤细胞、树突状细胞浸润丰度呈负相关(r=-0.23、-0.22、-0.254, P<0.05)。结论 MCM8在食管癌组织中高表达, 并与食管癌的发展、预后、微环境调节密切相关, 或可作为食管癌的治疗靶标。

Objective To analyze the expression of minichromosome maintenance protein 8(MCM8)in esophagus carcinoma(ESCA)and its correlations with the prognosis and impacts on the tumor microenvironments(TME)of ESCA.Methods MRNA values of MCM8 in ESCA,adjacent tumor,esophageal squamous epithelium,Barrett’s esophageal(BE)tissues were obtained from the Gene Expression Omnibus(GEO)database,then analyzed by t tests.UALCAN was used to study the expression of MCM8 in different stages and grades of ESCA patients enrolled in the The Cancer Genome Atlas(TCGA)database.We collected 6 samples from ESCA patients hospitalized at the Affiliated Hospital of Yangzhou University and the surgical therapy was given from January to March 2022.Immunohistochemical staining(IHC)was used to verify the protein expression of MCM8.Kaplan-meier Plotter database was used to analyze the correlations between MCM8 and the prognosis of ESCA.MCM8 co-expressing genes in ESCA were obtained from cBio-portal,and the possible mechanisms were explored by DAVID enrichment analysis.MCM8 protein interaction networks were performed by STRING and PINA databases.Correlations between MCM8 and infiltrating levels of immune cells in ESCA TME were analyzed by non-parameter tests with TISIDB database.Results The MRNA expression of MCM8 from datasets GSE161533,GSE45670 in ESCA(47.36±17.59,660.30±282.00)was upregulated as compared with the adjacent tumor tissues(22.89±4.30,293.90±125.90,t=7.15,4.13,P<0.01).MRNA level of MCM8 in the low-differentiated group(16.40)was higher than the medium and high differentiated ESCA groups(12.84,8.77,P<0.05).MCM8 mRNA expression of GSE77563 in BE tissue(5.12±1.13)was upregulated compared to the esophageal squamous epithelial tissues(3.99±0.55,t=4.26,P<0.01).IHC demonstrated that MCM8 was upregulated in ESCA compared to adjacent tissues(the MCM8-positive integral optical density/area value of para-cancerous tissue was normalized to 1,then the value of positive cancer tissues was 2.35±0.17,t=19.74,P<0.01).Upregulated MCM8 was related with the short overall survival rate(P<0.01).Enrichment analysis showed that MCM8 may be involved in the regulation of cell cycle,RNA transport,DNA mismatch repair.MCM8 was closely related to the molecules from the cell division control protein and origin recognition complex families.MCM8 was negatively correlated with the infiltration of activated T cells,natural killer cells and dendritic cells in ESCA TME(r=-0.23,-0.22,-0.254,respectively,P<0.05).Conclusion We demonstrated that MCM8 was upregulated in ESCA and showed strong correlations with the progression,prognosis and immune infiltration of ESCA.MCM8 may be a potential therapeutic target for ESCA.