TTC9A在泛癌中的表达水平与多种癌症的预后和免疫微环境相关

A pan-cancer analysis of TTC9A expression level and its correlation with prognosis and immune microenvironment

目的确定四肽重复蛋白9A(TTC9A)在泛癌中的基因表达及其预后价值,明确其与免疫浸润的关系。方法R语言分析癌症基因组图谱及GTEx网站中TTC9A在不同肿瘤组织与正常组织中的表达及其与各种癌症的预后、DNA甲基化、肿瘤突变负荷、微卫星不稳定性的关系;应用TIMER和xCell比较TTC9A表达与免疫浸润的关系;运用免疫印迹法与RT-qPCR检测TTC9A在4种癌症中的表达情况。结果生信结果显示与正常组织相比,TTC9A在多种肿瘤中mRNA表达水平升高,少数肿瘤中下调(P<0.05)。实验结果显示在肺癌、结肠癌和肝癌中,TTC9A的蛋白和mRNA水平均较正常细胞高,与泛癌分析结果一致;而在膀胱癌细胞系中的表达下降,与泛癌分析结果相反。在头颈鳞状细胞癌、肾透明细胞癌、肾乳头状细胞癌、低级别胶质瘤、恶性间皮瘤、子宫内膜癌等肿瘤中,TTC9A的高表达与更好的总生存期、疾病特异性生存期、无进展间期密切相关(P<0.05);而在肺腺癌、胰腺癌、肾上腺癌、直肠腺癌中,高表达TTC9A与更差的总生存期、疾病特异性生存期、无进展间期密切相关(P<0.05)。在多形成性胶质细胞瘤、低级别胶质瘤、葡萄膜黑色素瘤、卵巢浆液性囊腺癌中,TTC9A高甲基化患者预后较好(P<0.05);但是,在宫颈鳞状细胞癌和宫颈内腺癌、头颈部鳞状细胞癌、肺鳞状细胞癌、肾上腺癌、子宫内膜癌中,TTC9A高甲基化患者预后较差(P<0.05)。TTC9A基因表达分别与7种和4种癌症类型的TMB和MSI显著相关(P<0.05)。在大多数癌症类型中,TTC9A与免疫细胞的浸润水平显著相关(P<0.05),尤其B细胞、CD4^(+)T细胞、CD8^(+)T细胞、巨噬细胞、中性粒细胞和树突状细胞。结论TTC9A可作为多种癌症的预后标志物,且与肿瘤突变负荷、微卫星不稳定性和免疫细胞浸润密切相关。

Objective To investigate the expression level of tetratricopeptide repeat protein 9A in tumors and its association with the patients'prognosis and immune infiltration.Methods TTC9A expression in different tumor tissues and its association with prognosis,DNA methylation,tumor mutation burden(TMB),and microsatellite instability(MSI)were analyzed based on data from TCGA and GTEx.TIMER and xCell were used to analyze the relationship between TTC9A expression and immune infiltration.Western blotting and RT-qPCR were used to detect the expression of TTC9A in 4 types of cancer cell lines.Results TTC9A expressions were significantly increased in many tumors and down-regulated in a few cancer types(P<0.05).Western blotting and RT-qPCR showed that TTC9A expressions were elevated in lung,colon and liver cancer cells but decreased in bladder cancer cells.In head and neck squamous cell carcinoma,renal clear cell carcinoma,renal papillary cell carcinoma,low-grade glioma,malignant mesothelioma,and endometrial carcinoma tumors,a high expression of TTC9A was strongly correlated with better overall survival(OS),disease-specific survival(DSS),and progression-free interval(PFI)(P<0.05),but was correlated with worse OS,DSS,and PFI in lung adenocarcinoma,pancreatic adenocarcinoma,adrenal carcinoma,and rectal adenocarcinoma(P<0.05).TTC9A hypermethylation was associated with a more favorable prognosis of glioblastoma multiforme,low-grade glioma,uveal melanoma,and ovarian plasmacytoid cystadenocarcinoma(P<0.05)but with poor prognosis of squamous cell carcinoma of the uterine cervix and intracervical adenocarcinoma,squamous cell carcinoma of head and neck,squamous cell carcinoma of the lungs,adrenal carcinoma,and endometrial carcinoma(P<0.05).In most of the cancer types,TTC9A was significantly correlated with the level of immune cell infiltration(P<0.05).Conclusion TTC9A can be used as a prognostic marker for a variety of cancers and is strongly associated with TBM,MSI and immune cell infiltration.