Decoding SDCBP's role in tumor progression and immune cells infiltration: from databases to macrophage validation

The search for highly sensitive and specific tumor biomarkers is essential for the evaluation of prognosis and new therapeutic targets. Immune cells in the tumor microenvironment (TME) have dual roles in promoting and suppressing tumor growth, which is crucial for the development and treatment of cancer. According to previous studies, syndecan binding protein (SDCBP) participated in biological processes like epithelial-mesenchymal transformation, angiogenesis, and exosome formation and secretion during cancer metastasis, but whether SDCBP affects immune cells infiltration in the TME remains unclear. Here, we conducted a comprehensive analysis of multiple databases to explore the expression and prognosis of SDCBP in pan-cancer and focused on the effect of SDCBP on the immune cells, particularly on macrophages. The study found that SDCBP was expressed at different levels in most tumor tissues and cells. Upregulation of SDCBP was associated with malignant progression, poor patient prognosis and treatment non-response in certain tumors. Gene set enrichment analysis suggested that SDCBP was mainly involved in regulating immunity and inflammation-related pathways, which may be closely associated with the high levels of immune cells infiltration. Further experiments confirmed that SDCBP is highly expressed in macrophages, and knockdown of SDCBP in THP-1-derived macrophages reduces their chemotaxis but does not affect their polarization and phagocytic function. Our study indicated that SDCBP involves in tumor progression and macrophages infiltration, providing novel perspectives for cancer, particularly in combination with immunotherapy.