title: Identification and validation of p50 as the cellular target of eriocalyxin B.
abstract: As an ent-kaurene diterpenoid isolated from Isodon eriocalyx var. Laxiflora, Eriocalyxin B (EriB) possesses potent bioactivity of antitumor and anti-autoimmune inflammation, which has been suggested to work through inhibition of NF-kappaB (NF-κB) signaling. However, the direct target of EriB remains elusive. In this study, we showed that EriB induced apoptosis is associated with the inhibition of NF-κB signaling in SMMC-7721 hepatocellular carcinoma cells. With activity-based probe profiling, we identified p50 protein as the direct target of EriB. We showed that cysteine 62 is the critical residue of p50 for EriB binding through the α, β-unsaturated ketones. As the result, EriB selectively blocks the binding between p50 and the response elements, whereas having no effect on the dimerization or the nuclear translocation of p50 and p65. SiRNA mediated knockdown of p50 attenuated the apoptosis induced by EriB in SMMC-7721 cells. Taken together, our studies illustrated that EriB induces cancer cell apoptosis through interfering with the binding between NF-κB and the response elements by targeting the cysteine 62 of p50, which highlights its potential for the development of p50 targeted cancer therapeutic agents.
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China. Graduate University of the Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Ling-Mei
authors.initials: LM
authors.lastname: Kong
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Zhi-Li
authors.initials: ZL
authors.lastname: Zuo
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Han-Dong
authors.initials: HD
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Qin-Shi
authors.initials: QS
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D004224:Diterpenes / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D057809:HEK293 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D058990:Molecular Targeted Therapy; D052002:NF-kappa B p50 Subunit / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020218:Response Elements; D015398:Signal Transduction; D013329:Structure-Activity Relationship
chemical_list: D004224:Diterpenes; D052002:NF-kappa B p50 Subunit; C516552:eriocalyxin B