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肝癌是最常见的恶性肿瘤之一,严重威胁着人类的健康。研究[1]表明近年来其发病率逐渐上升,在美国其每年新发病例超过42 000例,预计死亡病例约30000例,且在发展中国家保持着较高的发病率。肝癌治疗的常用手段有手术治疗和非手术治疗,其中手术切除是首选的治疗方式[2]。但很多病人在肿瘤发现时即处于终末状态, 手术已无意义, 即便能够通过外科手术去干预切除, 约2/3的病人仍然会出现复发转移[3]。近年来, 放化疗以及靶向治疗和免疫治疗等方面取得很大进展, 但由于其高侵袭性、转移、复发等因素, 肝癌病人预后仍相对较差[4]。因此进一步探究肝癌的发病机制,寻找新的潜在的治疗靶点和预后相关因素,对于提高肝癌病人的生存率,改善其生活质量至关重要。人类NOP2核仁蛋白(NOP2 nucleolar protein, NOP2)也被称为RNA甲基转移酶家族成员2(RNA methyltransferase 2, NSUN2),是SUN结构域家族成员之一,其是在mRNA和非编码RNA中通过共价键催化5-甲基胞嘧啶M5C形成的主要酶[5-7]。既往已有研究[8-9]证实NOP2可促进小鼠成纤维细胞生长和肿瘤的形成,在多种肿瘤如头颈部鳞癌、结肠癌、口腔癌、食管癌、胃癌、肝癌、胰腺癌和乳腺癌细胞及组织中高表达,发挥重要作用,但在正常组织中不表达。因此NOP2目前被证实可作为一种预测肿瘤预后的标志物。本研究旨在通过生物信息学分析,探究NOP2在肝癌发生及进展过程中的作用及其相关通路,进一步研究其对于肝癌病人预后的预测价值,为肝癌的临床治疗提供相关思路和策略。
基于生物信息学NOP2在肝癌中的预后价值研究
Prognostic value of NOP2 in liver cancer based on bioinformatics
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摘要:
目的基于生物信息学探究NOP2核仁蛋白(NOP2 nucleolar protein,NOP2)在肝癌预后中的价值。 方法采用CIBERSORT和ESTIMATE计算方法,计算497例(其中54例有癌旁组织)肝癌病人的肿瘤浸润免疫细胞(TICs)的两个主要评分。通过Cox回归分析寻找出差异表达基因(DEGs)。同时进一步收集蚌埠医学院第一附属医院行肝切除术的原发性肝癌病人10对癌组织及相邻癌旁组织进行qRT-PCR分析。 结果NOP2的表达水平与肝癌的病理特征(较晚的M分期)呈正相关,与病人的生存时间呈负相关。通过基因集富集分析(GSEA)发现NOP2高表达的基因主要富集于与免疫相关通路。进一步研究证实6种免疫细胞与NOP2表达呈正相关,包括M0巨噬细胞、静止期自然杀伤细胞、激活期CD4+记忆T细胞、CD8+T细胞、滤泡辅助性T细胞、调节性T细胞。5种免疫细胞与NOP2的表达水平呈负相关,包括记忆B细胞、嗜酸性粒细胞、M2巨噬细胞、单核细胞、休止期CD4+记忆T细胞。且qRT-PCR显示NOP2在肝癌中呈高表达,在癌旁呈低表达。 结论NOP2在肝癌中呈高表达,且与生存时间成负相关,其表达水平可有助于预测肝癌病人的预后,尤其是对于肿瘤微环境中免疫相关细胞的影响。 Abstract:ObjectiveTo explore the value of NOP2 in the prognosis of liver cancer based on bioinformatics. MethodsTwo main scores of tumor infiltrating immune cells (TICs) were calculated by CIBERSORT and ESTIMATE in 497 patients with liver cancer, 54 of whom had paracancerous tissue. The differentially expressed genes (DEGs) were found by Cox regression analysis. At the same time, qRT-PCR analysis was performed on 10 primary liver cancer patients undergoing hepatectomy in the First Affiliated Hospital of Bengbu Medical College. ResultsThe expression of NOP2 was positively correlated with the pathological features of liver cancer(late M stage) and negatively correlated with the survival time of patients. Through gene set enrichment analysis(GSEA), it was found that the genes with high NOP2 expression were mainly enriched in immune-related pathways. Further study confirmed that there was a positive correlation between the expression of NOP2 and six kinds of immune cells, which included M0 macrophages, resting natural killer cells, activated CD4+ memory T cells, CD8+ T cells, follicular helper T cells, and regulatory T cells. The expression of NOP2 was negatively correlated with the expression of five types of immune cells, including memory B cells, eosinophil granulocyte cells, M2 macrophages, monocytes, and resting CD4+ memory T cells. Moreover, qRT-PCR showed that NOP2 was highly expressed in liver cancer and low expression in adjacent tissues. ConclusionsNOP2 is highly expressed in liver cancer and negatively correlated with survival time. The expression of NOP2 may be helpful to predict the prognosis of liver cancer patients, especially to the influence of immune-related cells in tumor microenvironment. -
Key words:
- liver neoplasms /
- NOP2 /
- tumor microenvironment
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