Inducing the degradation of KRAS represents a novel strategy to combat cancers with KRAS mutation. In this study, we identify ubiquitin-specific protease 2 (USP2) as a novel deubiquitinating enzyme of KRAS in multiple myeloma (MM). Specifically, we demonstrate that gambogic acid (GA) forms a covalent bond with the cysteine 284 residue of USP2 through an allosteric pocket, inhibiting its deubiquitinating activity. Inactivation or knockdown of USP2 leads to the degradation of KRAS, resulting in the suppression of MM cell proliferation in vitro and in vivo. Conversely, overexpressing USP2 stabilizes KRAS and partially abrogates GA-induced apoptosis in MM cells. Furthermore, elevated USP2 levels may be associated with poorer prognoses in MM patients. These findings highlight the potential of the USP2/KRAS axis as a therapeutic target in MM, suggesting that strategically inducing KRAS degradation via USP2 inhibition could be a promising approach for treating cancers with KRAS mutations.

OBJECTIVE:To study the chemical constituents in antioxidant activity part of Semiaquilegia adoxoides. METH-ODS:The antioxidant activity part of S. adoxoides were isolated and purified by chromatography on silicagel and Sephadex LH-20 column,and compound structures were identified physicochemical properties and spectral data analysis. RESULTS:Nine com-pounds were isolated from the antioxidant activity part of S. adoxoides,namely magnoflorine (1),griffonilide (2),salidroside (3),ferulic acid(4),genistein(5),2,4-dihydroxybenzoic acid(6),chlorogenic acid(7),caffeic acid(8)and p-coumaric acid (9). CONCLUSIONS:The study confirms the active material basis in antioxidant activity part of S. adoxoides for the first time.