Department of Hepatopancreatobiliary Surgery, Hangzhou First People's Hospital, The Affiliated Hospital of Medical School of Zhejiang University. Hangzhou 310006, Zhejiang Province, China.
World J Gastroenterol. 2020 Feb 28;26(8):804-817. doi: 10.3748/wjg.v26.i8.804.
Liver cancer has a high mortality and morbidity rate throughout the world. In clinical practice, the prognosis of liver cancer patients is poor, and the complex reasons contribute to treatment failures, including fibrosis, hepatitis viral infection, drug resistance and metastasis. Thus, screening novel prognostic biomarkers is of great importance for guiding liver cancer therapy. Orosomucoid genes () encode acute phase plasma proteins, including orosomucoid 1 (ORM1) and ORM2. Previous studies showed their upregulation upon inflammation, but the specific function of ORMs has not yet been determined, especially in the development of liver cancer.
To determine the expression of ORMs and their potential function in liver cancer.
Analysis of the expression of ORMs in different human tissues was performed on data from the HPA RNA-seq normal tissues project. The expression ratio of ORMs was determined using the HCCDB database, including the ratio between liver cancer and other cancers, normal liver and other normal tissues, liver cancer and adjacent normal liver tissues. Analysis of ORM expression in different cancer types was performed using The Cancer Genome Atlas and TIMER database. The expression of ORMs in liver tumor tissues and adjacent normal tissues were further confirmed using Gene Expression Omnibus data, including GSE36376 and GSE14520. The 10-year overall survival (OS), progression-free survival (PFS) and relapse-free survival (RFS) rates between high and low ORM expression groups in liver cancer patients were determined using the Kaplan-Meier plotter tool. Gene Set Enrichment Analysis (GSEA) was employed to explore the ORM2-associated signaling network. Correlations between ORM2 expression and tumor purity or the infiltration level of macrophages in liver tumor tissues were determined using the TIMER database. The correlation between ORM2 gene levels, tumor-associated macrophage (TAM) markers (including CD68 and TGFβ1) and T cell immunosuppression (including CTLA4 and PD-1) in liver tumor tissues and liver GTEx was determined using the GEPIA database.
ORM1 and ORM2 were highly expressed in normal liver and liver tumor tissues. ORM1 and ORM2 expression was significantly decreased in liver tumor tissues compared with adjacent normal tissues, and similar results were also noted in cholangiocarcinoma, esophageal carcinoma, and lung squamous cell carcinoma. Further analysis of the Gene Expression Omnibus Database also confirmed the downregulation of ORM1 and ORM2 in liver tumors. Survival analysis showed that the high ORM2 group had better survival rates in OS, PFS and RFS. ORM1 only represented better performance in PFS, but not in OS or RFS. GSEA analysis of ORM2 from The Cancer Genome Atlas liver cancer data identified that ORM2 positively associated with the G2/M checkpoint, E2F target signaling, as well as Wnt/β-catenin and Hedgehog signaling. Moreover, apoptosis, IFN-α responses, IFN-γ responses and humoral immune responses were upregulated in the ORM2 high group. ORM2 expression was negatively correlated with the macrophage infiltration level, CD68, TGFβ1, CTLA4 and PD-1 levels.
The results showed that ORM1 and ORM2 were highly expressed specifically in liver tissues, whereas ORM1 and ORM2 were downregulated in liver tumor tissues. ORM2 is a better prognostic factor for liver cancer. Furthermore, ORM2 is closely associated with cancer-promoting pathways.
肝癌在全球范围内具有较高的死亡率和发病率。在临床实践中，肝癌患者的预后较差，导致治疗失败的复杂原因包括纤维化、肝炎病毒感染、耐药性和转移。因此，筛选新的预后生物标志物对于指导肝癌治疗具有重要意义。乳白蛋白基因（ORMs）编码急性相血浆蛋白，包括乳白蛋白 1（ORM1）和乳白蛋白 2（ORM2）。先前的研究表明，它们在炎症时上调，但 ORMs 的具体功能尚未确定，特别是在肝癌的发展过程中。
确定 ORMs 的表达及其在肝癌中的潜在功能。
使用 HPA RNA-seq 正常组织项目的数据，分析不同人组织中 ORMs 的表达。使用 HCCDB 数据库确定 ORMs 的表达比率，包括肝癌与其他癌症、正常肝与其他正常组织、肝癌与相邻正常肝组织之间的比率。使用 The Cancer Genome Atlas 和 TIMER 数据库分析不同癌症类型中 ORM 的表达。使用基因表达综合数据库（GEO）数据，包括 GSE36376 和 GSE14520，进一步证实 ORMs 在肝肿瘤组织和相邻正常组织中的表达。使用 Kaplan-Meier 绘图器工具确定肝癌患者中高和低 ORM 表达组的 10 年总生存率（OS）、无进展生存率（PFS）和无复发生存率（RFS）。采用基因集富集分析（GSEA）方法探索 ORM2 相关信号网络。使用 TIMER 数据库确定 ORM2 表达与肝肿瘤组织中肿瘤纯度或巨噬细胞浸润水平之间的相关性。使用基因表达综合数据库（GEO）确定 ORM2 基因水平与肝肿瘤组织中肿瘤相关巨噬细胞（TAM）标志物（包括 CD68 和 TGFβ1）和 T 细胞免疫抑制（包括 CTLA4 和 PD-1）之间的相关性。
ORM1 和 ORM2 在正常肝组织和肝肿瘤组织中高表达。与相邻正常组织相比，肝肿瘤组织中 ORM1 和 ORM2 的表达明显降低，胆管癌、食管癌和肺鳞癌也有类似的结果。对基因表达综合数据库的进一步分析也证实了 ORM1 和 ORM2 在肝肿瘤中的下调。生存分析表明，高 ORM2 组在 OS、PFS 和 RFS 中的生存率更高。ORM1 仅在 PFS 中表现更好，而在 OS 或 RFS 中则不然。从癌症基因组图谱肝癌数据中对 ORM2 进行 GSEA 分析发现，ORM2 与 G2/M 检查点、E2F 靶信号以及 Wnt/β-catenin 和 Hedgehog 信号呈正相关。此外，在 ORM2 高组中，细胞凋亡、IFN-α 反应、IFN-γ 反应和体液免疫反应上调。ORM2 表达与巨噬细胞浸润水平、CD68、TGFβ1、CTLA4 和 PD-1 水平呈负相关。
结果表明，ORM1 和 ORM2 特异性地在肝组织中高表达，而 ORM1 和 ORM2 在肝肿瘤组织中下调。ORM2 是肝癌较好的预后标志物。此外，ORM2 与促进癌症的途径密切相关。
