The E3 ubiquitin protein ligase MDM2 dictates ATRA-induced osteoblastic differentiation of osteosarcoma cells by  

出　　处：《中国药理学通报》2015年第B11期64-65,共2页Chinese Pharmacological Bulletin

摘　　要：Aim Retinoic acid receptor alpha （RARα） plays a critical role in the differentiation process of osteo- sarcoma cells induced by all-trans retinoic acid （ATRA）. However, degradation of RARoL through ubiquitin pro- teasome pathway weakens the differentiation efficiency of osteosarcoma cells. Therefore, it is necessary to explore the regulatory mechanisms involved in RARoL degradation. Methods U2OS cells were mainly used as our research models. （1） Protein levels were detected by Western blot; （2） The interactions between MDM2 and RARalpha were determined by immunofluorescence and immunoprecipitation; （3） Related proteins and genes were investiga- ted via transfection; （4） The expression levels of MDM2 and OPN in patient biopsies were detected by immunohis- tochemistry; （5） Alkaline phosphatase activity was assessed by colorimetric assays using the BCIP/NBT Alkaline Phosphatase Color Development kit. Results In this report, it demonstrated that interaction with MDM2 leaded to strong stimulation of RARoL polyubiquitination and degradation by proteasomes. MDM2 appeared to function as an ubiquitin E3 ligase in this process, since the MDM2 RING domain mutant inhibited the ubiquitination of RARoL. Furthermore, MDM2 was capable of stimulating RARoL polyubiquitination under cell-free conditions. Moreover, it also provided evidence that silencing or inhibiting MDM2 promotes the differentiation of U2OS cells as induced by ATRA. Conclusions MDM2 serves as an E3 ubiquitin ligase to regulate the degradation of RARoL and becomes a novel therapeutic target for ATRA-based differentiation therapeutic approaches in osteosarcoma.

关 键 词：OSTEOSARCOMA RARα degradation MDM2 ALL-TRANS RETINOIC acid differentiation 

分 类 号：R[医药卫生]