Aspirin Downregulates PDE4D to Inhibit Malignant Progression of Osteosarcoma through the NF-κB/p65 Pathway

Introduction: Osteosarcoma is a highly aggressive cancer with a notably low five-year survival rate. Although aspirin has demonstrated potential in inhibiting the malignant progression of osteosarcoma, the underlying mechanisms remain unclear. Methods: In this study, RNA sequencing (RNA-seq) was employed to identify the downstream targets of aspirin in osteosarcoma cells. Then, we examined the expression and clinical significance of PDE4D using osteosarcoma patient samples, tissue microarrays, and data from the TARGET and GTEx databases. The effects of PDE4D on cell growth and mobility were assessed by CCK-8, colony formation, transwell, and wound-healing assays. To explore how aspirin influenced the NF-κB/p65/PDE4D axis, we performed qRT-PCR, Western blotting, luciferase reporter assays, etc. Additionally, mouse models with subcutaneous tumors were used to confirm the roles of aspirin and PDE4D. Results: Our results showed that aspirin significantly impeded the proliferation, migration, and invasion of osteosarcoma cells by various functional assays. RNA-seq identified PDE4D as a key target modulated by aspirin treatment in osteosarcoma. Clinically, PDE4D was highly expressed in osteosarcoma cells and tissues, and higher levels of PDE4D were linked to poorer patient outcomes. Functionally, PDE4D served as an oncogene that promoted the malignant traits of osteosarcoma both in vitro and in vivo. Mechanistically, our findings revealed that NF-κB/p65 directly interacted with the core region of the PDE4D promoter, increasing its expression. Discussion: The findings of this study reveal a novel mechanism whereby aspirin exerts its anti-tumor effects by inhibiting the NF-κB/p65/PDE4D axis, providing a mechanistic basis for its therapeutic potential. Further validation in different animal models of osteosarcoma is warranted. Conclusion: Aspirin suppressed the malignant progression of osteosarcoma by targeting the NF-κB/p65/PDE4D axis, positioning PDE4D as a potential therapeutic target for aspirin- based treatment strategies.