背景：骨肉瘤（OS）是最常见的原发性骨组织恶性肿瘤，其发病隐匿，早期难以发现，且很少有具有高特异性和敏感性的早期诊断标志物。因此，本研究旨在确定能够帮助早期诊断OS并改善患者预后的潜在生物标志物。将GSE12789、GSE28424、GSE33382和GSE36001数据集进行合并和标准化，以确定差异表达基因（DEGs）。通过基因本体论（GO）、基因组百科全书（KEGG）和疾病本体论（DO）对数据进行分析。根据应用最小绝对收缩和选择运算子（LASSO）和支持向量机（SVM）两种回归方法得到的共同DEG选取中心基因。然后在GSE42572数据集中评估中心基因的诊断价值。最后，通过CIBERSORT分析免疫细胞浸润与关键基因之间的相关性。LASSO和SVM的回归分析结果是以下三个DEG：FKBP5（FK501结合蛋白51）、CCL5（C-C 单位化学因子配体5）和C1QB（补体成分1 Q亚单位B链）。我们运用受试者工作特征（ROC）分析评估了三个生物标志物（FKBP5、CCL5和C1QB）对于骨肉瘤的诊断性能。在训练组中，FKBP5、CCL5和C1QB的曲线下面积（AUC）分别为0.907、0.874和0.676。在验证组中，FKBP5、CCL5和C1QB的AUC分别为0.618、0.932和0.895。值得注意的是，这些基因在肿瘤组织中比在正常组织中的各种免疫细胞类型，如浆细胞、CD8+ T细胞、T调节细胞（Tregs）、激活的NK细胞、激活的树突状细胞和激活的肥大细胞中更高表达。这些免疫细胞类型还与我们确定的三个诊断基因的表达水平相关。我们发现CCL5可以被视为骨肉瘤的早期诊断基因，并且CCL5通过与免疫细胞的相互作用影响肿瘤的发生和发展。这些发现对于早期检测骨肉瘤和鉴定新的治疗靶点具有重要意义。Copyright© Bentham Science Publishers；若有任何疑问，请发送电子邮件至epub@benthamscience.net。

Background：Osteosarcoma (OS) is the most common primary malignant tumor of bone tissue, which has an insidious onset and is difficult to detect early, and few early diagnostic markers with high specificity and sensitivity. Therefore, this study aims to identify potential biomarkers that can help diagnose OS in its early stages and improve the prognosis of patients.The data sets of GSE12789, GSE28424, GSE33382 and GSE36001 were combined and normalized to identify differentially expressed genes (DEGs). The data were analyzed by gene ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG) and disease ontology (DO). The hub gene was selected based on the common DEG that was obtained by applying two regression methods: the least absolute shrinkage and selection operator (LASSO) and support vector machine (SVM). Then the diagnostic value of the hub gene was evaluated in the GSE42572 data set. Finally, the correlation between immunocyte infiltration and key genes was analyzed by CIBERSORT.The regression analysis results of LASSO and SVM are the following three DEGs： FK501 binding protein 51 (FKBP5), C-C motif chemokine ligand 5 (CCL5), complement component 1 Q subcomponent B chain (C1QB). We evaluated the diagnostic performance of three biomarkers (FKBP5, CCL5 and C1QB) for osteosarcoma using receiver operating characteristic (ROC) analysis. In the training group, the area under the curve (AUC) of FKBP5, CCL5 and C1QB was 0.907, 0.874 and 0.676, respectively. In the validation group, the AUC of FKBP5, CCL5 and C1QB was 0.618, 0.932 and 0.895, respectively. It is noteworthy that these genes were more expressed in tumor tissues than in normal tissues by various immune cell types, such as plasma cells, CD8+ T cells, T regulatory cells (Tregs), activated NK cells, activated dendritic cells and activated mast cells. These immune cell types are also associated with the expression levels of the three diagnostic genes that we identified.We found that CCL5 can be considered an early diagnostic gene of osteosarcoma, and CCL5 interacts with immune cells to influence tumor occurrence and development. These findings have important implications for the early detection of osteosarcoma and the identification of novel therapeutic targets.Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.