Tenuigenin inhibits osteosarcoma growth via CIP2A/PP2A/NF-κB axis

BackgroundPolygala tenuifolia and its active components have been revealed to possess anti-tumor activities. However, the role of Tenuigenin (TEN), a bioactive ingredient from Polygala tenuifolia, in tumors such as osteosarcoma (OS) remains unclear. The present research intended to explore the efficacy and underlying mechanism of TEN on OS.MethodsOS cells were administrated with different concentrations of TEN. Cell viability, proliferation, invasion, and migration were assessed with CCK-8 assay, colony formation assay, transwell assay, and wound healing assay, respectively. Protein and mRNA levels were determined with western blot and qRT-PCR, while protein phosphatase 2A (PP2A) activity was tested with PP2A phosphatase assay kit. The interaction between PP2A and cancerous inhibitor of protein phosphatase 2A (CIP2A) or nuclear factor kappaB (NF-kappa B) signaling was detected using co-immunoprecipitation. p-p65 expression in the nucleus was determined with immunofluorescence. The efficacy of TEN in vivo was also explored in a xenograft tumor model. Immunohistochemistry was performed to detect CIP2A and Ki67 in mice.ResultsTEN treatment or CIP2A depletion repressed cell viability, proliferation, invasion, and migration in OS cells. Additionally, TEN reduced CIP2A, increased PP2A activity, and inactivated NF-kappa B signaling. PP2A directly interacted with CIP2A or NF-kappa B signaling, and PP2A inhibition reversed CIP2A knockdown-induced repression of NF-kappa B signaling. CIP2A overexpression overturned the efficacy of TEN, which was reversed by NF-kappa B inhibition. TEN decreased CIP2A, elevated PP2A activity, inactivated NF-kappa B signaling, and inhibited tumor growth in vivo, which was antagonized by CIP2A overexpression.ConclusionTEN suppressed OS growth via CIP2A/PP2A/NF-kappa B axis, indicating that it would be a novel drug for treating OS.