Supplementary Material for: High expression of cancer-derived sialylated immunoglobulin G: a novel biomarker for poor prognosis in laryngeal squamous cell carcinoma

Introduction: Laryngeal squamous cell carcinoma (LSCC) is the most common type of laryngeal cancer, with around 60% of patients being diagnosed at an advanced stage. Recently, cancer-derived sialylated immunoglobulin G (SIA-IgG) has been suggested to play a role in the progression of various epithelial tumors, but its significance in LSCC remains unknown. This study aims to investigate the clinical significance of SIA-IgG as a novel biomarker in relation to the initiation, progression, and prognostication of LSCC.
Methods: Immunohistochemistry (IHC) were utilized to assess SIA-IgG expression in tumor samples from 75 LSCC patients, aiming to investigate its correlation with clinical prognosis. Vitro functional experiments were conducted to explore the impact of SIA-IgG expression on the proliferative and migratory abilities of laryngocarcinoma cells.
Results: High expression of SIA-IgG was associated with pT stage, pN stage, TNM stage, and recurrence during follow-up, and was correlated with poor disease-free survival (DFS) and overall survival (OS). Multivariate Cox analysis demonstrated that SIA-IgG served as an independent risk factor for OS and DFS. Knocking down SIA-IgG significantly weakened laryngocarcinoma cells' proliferation, clonogenesis, and migration abilities.
Conclusions: The frequent expression of SIA-IgG in LSCC is significantly associated with poor prognosis. High levels of SIA-IgG can enhance proliferation and migration in laryngocarcinoma cells. These findings suggest that SIA-IgG has potential as a novel biomarker for LSCC.

引言：喉鳞状细胞癌（Laryngeal squamous cell carcinoma, LSCC）是最常见的喉癌类型，约60%的患者在确诊时已处于晚期阶段。近年来，有研究表明肿瘤源性唾液酸化免疫球蛋白G（cancer-derived sialylated immunoglobulin G, SIA-IgG）在多种上皮性肿瘤的进展中发挥作用，但其在LSCC中的临床意义仍未明确。本研究旨在探讨SIA-IgG作为新型生物标志物，与LSCC发生、进展及预后相关的临床意义。
方法：采用免疫组织化学（Immunohistochemistry, IHC）检测75例LSCC患者的肿瘤样本中SIA-IgG的表达水平，以探究其与临床预后的相关性；同时开展体外功能实验，探讨SIA-IgG表达对喉癌细胞增殖与迁移能力的影响。
结果：SIA-IgG高表达与pT分期、pN分期、TNM分期及随访期间的肿瘤复发显著相关，且与较差的无病生存期（disease-free survival, DFS）和总生存期（overall survival, OS）密切相关。多因素Cox回归分析显示，SIA-IgG可作为OS和DFS的独立危险因素。敲低SIA-IgG可显著削弱喉癌细胞的增殖、克隆形成及迁移能力。
结论：SIA-IgG在LSCC中的高频表达与不良预后显著相关；高表达的SIA-IgG可增强喉癌细胞的增殖与迁移能力。上述研究结果表明，SIA-IgG有望成为LSCC的新型生物标志物。