Computational discovery of novel colony‑stimulating factor‑1 receptor as a potential therapeutic biomarker in osteosarcoma and a novel inhibitor from herbal sources

Osteoclast differentiation and activation pathways drive abnormally enhanced bone resorption in osteosarcoma, and have thus emerged as potential therapeutic targets for this malignancy. However, the diagnostic value of osteoclast differentiation-related genes (ODRGs) in osteosarcoma remains largely uncharacterized. The present study first analyzed the expression profiles of ODRGs in osteosarcoma using multiple Gene Expression Omnibus datasets. Analysis of single cell RNA-sequencing data from osteosarcoma tissues demonstrated that colony-stimulating factor-1 receptor (CSF1R), a key ODRG, was widely expressed in osteoblasts and monocyte/macrophage lineages within the osteosarcoma microenvironment. Subgroup analysis further revealed that patients with osteosarcoma in the low-CSF1R expression group exhibited significantly increased sensitivity to immune checkpoint inhibitors compared with those in the high-CSF1R expression group. Furthermore, pan-cancer analysis across The Cancer Genome Atlas datasets demonstrated that CSF1R expression was aberrantly regulated in multiple tumor types and strongly correlated with the expression levels of immune checkpoint markers and the infiltration levels of immune cells. Functional validation experiments confirmed that treatment with CSF1R-specific inhibitors significantly reduced the viability of the MG63 and Saos-2 cell lines. To identify novel, natural-product-derived CSF1R inhibitors, structure-based virtual screening was combined with in vitro experimental assays (CCK-8 and western blotting). Among the validated candidates, sarsasapogenin, a compound identified from the screen, effectively suppressed CSF1R protein expression and inhibited the proliferation of both MG63 and Saos-2 cells in a dose-dependent manner. Collectively, the present findings highlight CSF1R as a clinically promising diagnostic biomarker and therapeutic target for osteosarcoma.