骨肉瘤（OSA）是人和狗中最常见的原发性骨恶性肿瘤。我们之前对犬 OSA 与健康骨骼进行的分子比较导致鉴定出差异表达的蛋白质表达基因（叉头盒蛋白 O4 (FOXO4)、干扰素调节因子 8 (IRF8) 和淋巴增强子结合因子 1 (LEF1)）。免疫组织化学 (IHC) 和 H 评分提供了核染色和细胞质染色的半定量评估以及定性数据以进行染色背景分析（n = 26 名患者）。 FOXO4 主要在细胞质中表达，核 H 分数显着较低。在整个队列中，细胞核和细胞质中的 IRF8 H 分数范围为 0 到 3。 LEF1 在所有患者中表达，与细胞核相比，细胞质染色明显较低。没有观察到性别或解剖位置差异。虽然 FOXO4 水平降低可能表明恶性肿瘤，但蛋白质表达较弱或缺失限制了其作为诊断肿瘤标志物的主要用途。 IRF8 和 LEF1 在预后和诊断用途方面具有更大的潜力，并有助于进一步了解它们在各自分子途径中的作用，包括 Wnt/β-连环蛋白/LEF1 信号传导和肿瘤抑制基因的差异调节。更深入地了解 OSA 所涉及的机制对于人类和兽医领域新型诊断、预后和治疗方案的开发做出了重要贡献。

Osteosarcoma (OSA) is the most common type of primary bone malignancy in people and dogs. Our previous molecular comparisons of canine OSA against healthy bone resulted in the identification of differentially expressed protein-expressing genes (forkhead box protein O4 (FOXO4), interferon regulatory factor 8 (IRF8), and lymphoid enhancer binding factor 1 (LEF1)). Immunohistochemistry (IHC) and H-scoring provided semi-quantitative assessment of nuclear and cytoplasmic staining alongside qualitative data to contextualise staining (n = 26 patients). FOXO4 was expressed predominantly in the cytoplasm with significantly lower nuclear H-scores. IRF8 H-scores ranged from 0 to 3 throughout the cohort in the nucleus and cytoplasm. LEF1 was expressed in all patients with significantly lower cytoplasmic staining compared to nuclear. No sex or anatomical location differences were observed. While reduced levels of FOXO4 might indicate malignancy, the weak or absent protein expression limits its primary use as diagnostic tumour marker. IRF8 and LEF1 have more potential for prognostic and diagnostic uses and facilitate further understanding of their roles within their respective molecular pathways, including Wnt/beta-catenin/LEF1 signalling and differential regulation of tumour suppressor genes. Deeper understanding of the mechanisms involved in OSA are essential contributions towards the development of novel diagnostic, prognostic, and treatment options in human and veterinary medicine contexts.