目的：探究泛素羧基端水解酶5（ubiquitin carboxyl-terminal hydrolase L5，UCHL5）在甲状腺癌（thyroid carcinoma，TC）组织中表达的临床意义及其体外生物学效应。方法：TCGA数据库分析UCHL5 在TC组织中的表达及其与患者预后的关系，临床收集四川省人民医院血管·甲状腺外科2018 年5 月至2019 年7 月期间手术切除的TC及癌旁组织各82 例，体外培养TC细胞KTC-1 及WRO并慢病毒转染UCHL5 过表达及相应对照载体，qPCR及Western blotting 检测组织及细胞中UCHL5 及B-Raf原癌基因丝氨酸/苏氨酸蛋白激酶（B-Raf proto-oncogene serine/threonine-protein kinase，BRAF）的mRNA和蛋白表达水平，CCK-8检测细胞增殖能力，划痕修复实验及Transwell 检测细胞侵袭及迁移能力。结果：UCHL5 在TC 组织中呈低表达（P<0.01），在TNM分期高的患者肿瘤组织中表达重新上调（P<0.01），UCHL5 的表达与BRAF表达及患者TNM分期显著相关（P<0.01），而与患者年龄、性别、病理类型及BRAF突变无显著联系（P>0.05）。体外KTC-1 及WRO细胞中过表达UCHL5 可显著促进细胞BRAF的表达及细胞的增殖、转移能力（均P<0.01）。结论：UCHL5 在TC组织中低表达，但在肿瘤进展时UCHL5 表达上调，TC患者UCHL5 高表达提示预后较差；同时UCHL5 在体外可促进TC细胞的恶性行为。

Objective: To explore the clinical significance and in vitro biological effect of ubiquitin carboxyl-terminal hydrolase L5 (UCHL5)expression in thyroid carcinoma (TC) tissues. Methods: TCGA data were used to analyze the expression of UCHL5 in thyroid carcinoma tissues and its relationship with the prognosis of patients. 82 pairs of TC tissues and corresponding adjacent tissues were collected in the Department of Vascular and Thyroid Surgery, Sichuan Provincial People's Hospital from May 2018 to July 2019; TC cell lines (KTC-1 and WRO) were cultured in vitro, and transfected with UCHL5 overexpression vectors or their control vectors via lentivirus. The mRNA and protein expressions of UCHL5 and B-Raf proto-oncogene serine/threonine-protein kinase (BRAF) in tissues and cells were detected by qPCR and Western blotting, respectively. Cell proliferation was detected by CCK-8, and cell invasion and migration were detected by Transwell and Wound-healing experiments. Results: The expression of UCHL5 was low in TC tissues (P<0.01), and its expression was upregulated in tumor tissues with high TNM stage (P<0.01). The expression of UCHL5 was significantly correlated with BRAF expression and TNM stage of patients (all P<0.01), but not significantly related with patient's age, gender, pathological type and BRAF mutation (all P>0.05).In vitro overexpression of UCHL5 in KTC-1 andWRO cells could significantly promote BRAF expression, cell proliferation and metastasis (all P<0.01). Conclusion: The expression of UCHL5 is low in TC tissue, but upregulated with tumor progression. The high expression of UCHL5 in TC patients suggests poor prognosis. Meanwhile, UCHL5 can promote the malignant behaviors of TC cells in vitro.