American Association for Cancer Research
15357163mct120066-sup-f1_pdf_72k.pdf (72.79 kB)

Supplementary Figure 1 from Triggering Fbw7-Mediated Proteasomal Degradation of c-Myc by Oridonin Induces Cell Growth Inhibition and Apoptosis

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journal contribution
posted on 2023-04-03, 13:23 authored by Hui-Lin Huang, Heng-You Weng, Lu-Qin Wang, Chun-Hong Yu, Qiao-Juan Huang, Pan-Pan Zhao, Jun-Zhi Wen, Hui Zhou, Liang-Hu Qu

PDF file - 72K, Efffects of oridonin on expression of mature miRNAs and pri-miRNAs in K562 cells.



The transcription factor c-Myc is important in cell fate decisions and is frequently overexpressed in cancer cells, making it an attractive therapeutic target. Natural compounds are among the current strategies aimed at targeting c-Myc, but their modes of action still need to be characterized. To explore the mechanisms underlying the anticancer activity of a natural diterpenoid, oridonin, we conducted miRNA expression profiling and statistical analyses that strongly suggested that c-Myc was a potential molecular target of oridonin. Furthermore, experimental data showed that oridonin significantly reduced c-Myc protein levels in vitro and in vivo and that this reduction was mediated by the ubiquitin-proteasome system. Fbw7, a component of the ubiquitin-proteasome system and an E3 ubiquitin ligase of c-Myc, was upregulated rapidly in K562 cells and other leukemia and lymphoma cells, resulting in the rapid turnover of c-Myc. In cell lines harboring mutations in the WD domain of Fbw7, the degradation of c-Myc induced by oridonin was attenuated during short-term treatment. GSK-3, an Fbw7 priming kinase, was also activated by oridonin, along with an increase in T58-phosphorylated c-Myc. Furthermore, the knockdown of Fbw7 or the forced expression of stable c-Myc resulted in reduced sensitization to oridonin-induced apoptosis. Our observations help to clarify the anticancer mechanisms of oridonin and shed light on the application of this natural compound as an Fbw7-c-Myc pathway targeting agent in cancer treatment. Mol Cancer Ther; 11(5); 1155–65. ©2012 AACR.