JaponiconeA Induces Apoptosis of Bortezomib-Sensitive and –Resistant Myeloma Cells In Vitro and In Vivo through Targeting IKKβ

Abstract Backgrounds: Multiple myeloma (MM) is a clonal proliferative disease of abnormal plasma cells. Relapse and drug resistance still remain to be solved, so new therapeutic drugs are needed to be adopted to further improve the prognosis of MM. JaponiconeA (JA) is a natural product isolated from Inula japonica Thunb, the anti-tumor effect and mechanism in MM has not been studied.Methods: CCK8 and flow cytometry were used to detect the proliferation, apoptosis and cell cycle of MM cell lines with JA treatment. And the in vivo effects of JA were verified in the subcutaneous xenograft mice model of MM. In addition, we analyzed the possible targets and mechanism of JA through RNA-seq and c-Map databases, and we verified the specific target of JA in MM cell lines and bortezomib-resistant MM cell line through CETSA and rescue experiments. JA and bortezomib were used separately or together to treat MM cell lines to explore the synergetic effect. Results: In vitro experiments, JA inhibited proliferation, induced apoptosis and G2/M phase arrest of MM cell lines, and JA selectively killed primary CD138+ MM cells but spared normal human mononuclear cells. In vivo experiments, JA also showed good anti-tumor effect with no observable toxicity. In addition, JA achieved good synergetic effect in combination with bortezomib, and enhanced the anti-tumor effect of bortezomib in bortezomib-resistant cells. According to RNA-seq and c-Map data, the target protein of JA might be IKKβ. CETSA experiment confirmed that JA can bind IKKβ directly in vitro, and overexpression of IKKβ could partly rescue the apoptosis induced by JA.Conclusion: JA exhibited strong anti-tumor effects in MM. It sensitized myeloma cells to bortezomib and overcame NF-κB induced drug resistance through inhibiting IKKβ, which providing a new treatment strategy for MM patients.