The effect of SPP1 in squamous cell carcinoma of the penis (PSCC) remained unknown. We attempted to clarify the function of the SPP1 gene in PSCC. Eight paired penile cancer specimens (including penile cancer tissue, paracancerous tissue, and positive lymph node tissue) subjected to whole transcriptome sequencing were analysed to identify differentially expressed genes. We used immunohistochemistry to detect the expression of SPP1 protein and immune cell related proteins in penile cancer tissue. Then, we performed weighted gene coexpression network analysis (WGCNA) to identify the genes related to SPP1 in penile cancer tissue and positive lymph node tissue. Based on the GSE57955 dataset, the CIBERSORT and ssGSEA algorithms were carried out to investigate the immune environment of PSCC. GSVA analysis was conducted to identify the signaling pathways related to SPP1 subgroups. Enzyme-linked immunosorbent assay (ELISA) method was adopted to detect SPP1 level in the serum of 60 patients with penile cancer. Differential analysis indicated that SPP1 was the most differentially upregulated gene in both penile cancer tissues and positive lymph node tissues. Survival analysis suggested that the prognosis of the low-SPP1 group was significantly poorer than that of the high-SPP1 group. Subsequently, immune-related bioinformatics showed that SPP1 was significantly associated with B cells, CD8 + T cells, CD4 + T cells, macrophages, helper T cells, neutrophils and dendritic cells. The immunohistochemical results showed that the high-SPP1 group was characterized by relatively high expression of CD16 and relatively low expression of CD4. GSVA analysis indicated that high-SPP1 group was significantly associated with immune-related pathways such as PD-L1 expression and the PD-1 checkpoint pathway in cancer and the TNF signaling pathway. ELISA demonstrated that the serum level of SPP1 in patients with positive lymph node metastasis of penile cancer was significantly higher than that in patients with negative lymph node metastasis of penile cancer. Our study shows that the SPP1 gene might be an effective biomarker for predicting the prognosis and the efficacy of immunotherapy in PSCC patients.

中文翻译：

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SPP1与不良预后相关并预测阴茎癌免疫治疗的疗效

SPP1 在阴茎鳞状细胞癌 (PSCC) 中的作用仍不清楚。我们试图阐明 SPP1 基因在 PSCC 中的功能。对经过全转录组测序的八对阴茎癌标本（包括阴茎癌组织、癌旁组织和阳性淋巴结组织）进行分析，以鉴定差异表达基因。我们采用免疫组化方法检测阴茎癌组织中SPP1蛋白和免疫细胞相关蛋白的表达量。然后，我们进行加权基因共表达网络分析（WGCNA）来鉴定阴茎癌组织和阳性淋巴结组织中与SPP1相关的基因。基于GSE57955数据集，采用CIBERSORT和ssGSEA算法研究PSCC的免疫环境。进行 GSVA 分析以确定与 SPP1 亚组相关的信号通路。采用酶联免疫吸附试验（ELISA）法检测60例阴茎癌患者血清中SPP1的水平。差异分析表明，SPP1是阴茎癌组织和阳性淋巴结组织中差异最大的基因。生存分析提示低SPP1组的预后明显差于高SPP1组。随后，免疫相关生物信息学显示SPP1与B细胞、CD8+T细胞、CD4+T细胞、巨噬细胞、辅助性T细胞、中性粒细胞和树突状细胞显着相关。免疫组化结果显示，高SPP1组的特点是CD16表达相对较高，CD4表达相对较低。 GSVA分析表明，高SPP1组与癌症中的PD-L1表达和PD-1检查点通路以及TNF信号通路等免疫相关通路显着相关。 ELISA结果显示，阴茎癌淋巴结转移阳性患者血清SPP1水平显着高于阴茎癌淋巴结转移阴性患者。我们的研究表明，SPP1基因可能是预测PSCC患​​者预后和免疫治疗疗效的有效生物标志物。