Anti-PD1 antibody led to a significant decrease in the number of OS lung metastases, enhanced tumor apoptosis, decreased tumor cell proliferation, and p-STAT-3/p-Erk1/2 signaling blockade in OS lung tumors.
Efficacy of the FLLL32 pharmacological inhibitor in delaying OS growth suggests that targeting JAK2/STAT3 may be a potential therapeutic strategy for patients with OS.
These results suggest that E2F1/DDR1/STAT3 pathway is critical for malignancy of osteosarcoma, which may provide a novel prognostic indicator or approach for osteosarcoma therapy.
Importantly, TBL1XR1 enhanced the tumorigenicity of osteosarcoma cells via activating STAT3 signaling and TBL1XR1 expression correlated significantly with STAT3 phosphorylation in osteosarcoma.
In our previous work, we found that several canine and human osteosarcoma (OSA) cell lines, but not normal osteoblasts, exhibit constitutive phosphorylation of STAT3.
In addition, knockdown of LIF notably suppressed the proliferation and invasion of osteosarcoma via blocking the STAT3 signal pathway; in contrast, treatment with the recombinant LIF protein significantly promoted the growth and invasion of osteosarcoma through enhancing the phosphorylation of STAT3, which can be partially neutralized by the STAT3 inhibitor, HO-3867.
We found that SC repressed cell viability and migration and induced apoptosis in vitro, while combined SC and erlotinib treatment enhanced osteosarcoma growth suppression by preventing feedback activation of STAT3.
miR-340-5p gene expression in OS tissues and U2OS cells was significantly lower than that in paracancerous tissues and hFOB1.19 cells. miR-340-5p directly interacted with the 3'-untranslated region (3'-UTR) of STAT3 gene and negatively regulated its expression.
<b>Conclusion:</b> These results demonstrated that the anti-OS effects of lycorine were at least partly due to the suppression of the Janus kinase 2/signal transducers and activators of transcription 3 (JAK2)/STAT3 pathway.