Jia Meng, Guo Yaman, Lu Xiubo
Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
Department of Endocrinology, Henan Provincial People's Hospital, Zhengzhou, China.
Cell Physiol Biochem. 2018;45(5):2044-2053. doi: 10.1159/000488041. Epub 2018 Mar 7.
BACKGROUND/AIMS: To investigate the clinical significance and functional mechanisms of deubiquitinase USP33 in papillary thyroid carcinoma (PTC).
Immunohistochemistry staining was conducted to explore the expression of USP33 in PTC tissues and adjacent normal thyroid tissues. Patients' prognosis was evaluated by disease-free survival. The prognostic role of USP33 was tested by univariate and multivariate analyses. To confirm the effect of USP33 in cell proliferation and invasion, overexpression and knockdown of USP33 were performed in two PTC cell lines. Besides, cell cycle, immunoprecipitation, and apoptosis experiments were conducted to further explore the signaling pathways.
By analyzing series of 158 PTC tissues, we found that USP33 was down-regulated in tumor tissue compared with normal thyroid tissues, which was closely associated with lymph node metastasis (P<0.001). In particular, univariate and multivariate analyses indicated that USP33 was an independent prognostic biomarker for PTC, low USP33 expression indicated high recurrence risk. Cellular studies with TPC-1 and BCPAP cells demonstrated that USP33 can attenuate the cell capacities of proliferation, migration and invasion. Fluorescence-activated cell sorting experiment found no significant effect of USP33 on cell cycle, whereas the apoptotic caspase proteins were activated by USP33-overexpression. Moreover, the interaction between USP33 and Robo1 protein was identified, and knockdown of Robo1 enhancing the oncogenic effect upon USP33-knockdown, suggesting that USP33 may inhibit tumor progression through Robo1 signaling.
Our data demonstrated that USP33 downregulation in PTC tissues was correlated with poor clinical outcome, which may serve as a novel biomarker and potential therapeutic target.
背景/目的：探讨去泛素化酶USP33在甲状腺乳头状癌（PTC）中的临床意义及功能机制。
采用免疫组织化学染色法检测USP33在PTC组织及癌旁正常甲状腺组织中的表达。通过无病生存期评估患者预后。采用单因素和多因素分析检测USP33的预后作用。为证实USP33对细胞增殖和侵袭的影响，在两种PTC细胞系中进行USP33的过表达和敲低实验。此外，进行细胞周期、免疫沉淀和凋亡实验以进一步探究信号通路。
通过分析158例PTC组织系列，我们发现与正常甲状腺组织相比，USP33在肿瘤组织中表达下调，这与淋巴结转移密切相关（P<0.001）。特别是，单因素和多因素分析表明USP33是PTC的独立预后生物标志物，USP33低表达表明复发风险高。对TPC-1和BCPAP细胞的细胞研究表明，USP33可减弱细胞的增殖、迁移和侵袭能力。荧光激活细胞分选实验发现USP33对细胞周期无显著影响，而USP33过表达可激活凋亡半胱天冬酶蛋白。此外，鉴定了USP33与Robo1蛋白之间的相互作用，敲低Robo1可增强USP33敲低后的致癌作用，提示USP33可能通过Robo1信号通路抑制肿瘤进展。
我们的数据表明，PTC组织中USP33的下调与不良临床结局相关，其可能作为一种新的生物标志物和潜在的治疗靶点。
