Timosaponin A1 exerts antitumor effect against osteosarcoma by targeting JAK2/STAT3 signaling pathway.

Novel therapeutic agents are urgently needed since osteosarcoma is a highly aggressive bone tumor primarily affecting children and adolescents that remains poorly responsive to conventional chemotherapy. Persistent aberrant activation of STAT3, particularly via the IL-6/JAK2/STAT3 signaling axis, is frequently observed across multiple malignancies and correlates with poor prognosis, making STAT3 inhibition a compelling therapeutic strategy for osteosarcoma. In this study, we provide the first evidence that Timosaponin A1 (TA1), a naturally occurring saponin isolated from Anemarrhena asphodeloides Bge., suppresses JAK2/STAT3 signaling in osteosarcoma. By inducing cell-cycle arrest and apoptosis, while inhibiting migration and invasion, TA1 markedly reduced the malignant phenotype of osteosarcoma cells. Mechanistically, TA1 directly bound to JAK2, thereby inhibiting STAT3 transcriptional activity and reducing the phosphorylation levels of JAK2 and STAT3. Furthermore, TA1 effectively inhibited IL-6-induced STAT3 phosphorylation and nuclear translocation. Genetic knockdown of STAT3 significantly impaired osteosarcoma cell proliferation and attenuated the inhibitory effects of TA1, supporting a STAT3-dependent mechanism. Finally, an orthotopic tibial osteosarcoma xenograft model in nude mice was used to evaluate the therapeutic potential of TA1 in vivo. Together, our findings demonstrate that TA1 exerts potent antitumor effects by suppressing aberrant STAT3 activation, highlighting its potential as a promising therapeutic candidate for osteosarcoma.