title: Antroquinonol blocks Ras and Rho signaling via the inhibition of protein isoprenyltransferase activity in cancer cells.
abstract: Antroquinonol is the smallest anticancer molecule isolated from Antrodia camphorata thus far. The ubiquinone-like structure of Antroquinonol exhibits a broad spectrum of activity against malignancies in vivo and in vitro. However, the mechanism of action of Antroquinonol remains unclear. Here, we provide evidence that Antroquinonol plays a role in the inhibition of Ras and Ras-related small GTP-binding protein functions through the inhibition of protein isoprenyl transferase activity in cancer cells. Using cell line-based assays, we found that the inactive forms of Ras and Rho proteins were significantly elevated after treatment with Antroquinonol. We also demonstrated that Antroquinonol binds directly to farnesyltransferase and geranylgeranyltransferase-I, which are key enzymes involved in activation of Ras-related proteins, and inhibits enzymes activities in vitro. Furthermore, a molecular docking analysis illustrated that the isoprenoid moiety of Antroquinonol binds along the hydrophobic cavity of farnesyltransferase similar to its natural substrate, farnesyl pyrophosphate. In contrast, the ring structure of Antroquinonol lies adjacent to the Ras-CAAX motif-binding site on farnesyltransferase. The molecular docking study also showed a reasonable correlation with the IC50 values of Antroquinonol analogues. We also found that the levels of LC3B-II and the autophagosome-associated LC3 form were also significantly increased in H838 after Antroquinonol administration. In conclusion, Antroquinonol inhibited Ras and Ras-related GTP-binding protein activation through inhibition of protein isoprenyl transferase activity, leading to activation of autophagy and associated mode of cell death in cancer cells.
authors.affiliation: Division of Hematology/Oncology, Department of Internal Medicine, Tri-Service General Hospital, Neihu, 114, Taipei, Taiwan, ROC.
authors.forename: Ching-Liang
authors.initials: CL
authors.lastname: Ho
authors.affiliation: Agriculture Biotechnology Research Center, Academia Sinica, Nankang, 115 Taipei, Taiwan, ROC.
authors.forename: Jui-Ling
authors.initials: JL
authors.lastname: Wang
authors.affiliation: National Core Facilities for Protein Structural Analysis, Nankang, 115 Taipei, Taiwan, ROC.
authors.forename: Cheng-Chung
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Division of Biological Chemistry, Golden Biotechnology Corp., Danshui Dist., 251 New Taipei City, Taiwan, ROC.
authors.forename: Hsiu-Yi
authors.initials: HY
authors.lastname: Cheng
authors.affiliation: Division of Biological Chemistry, Golden Biotechnology Corp., Danshui Dist., 251 New Taipei City, Taiwan, ROC.
authors.forename: Wu-Che
authors.initials: WC
authors.lastname: Wen
authors.affiliation: Division of Biological Chemistry, Golden Biotechnology Corp., Danshui Dist., 251 New Taipei City, Taiwan, ROC.
authors.forename: Howard Hao-Yu
authors.initials: HH
authors.lastname: Cheng
authors.affiliation: Division of Biological Chemistry, Golden Biotechnology Corp., Danshui Dist., 251 New Taipei City, Taiwan, ROC. Electronic address: miles@goldenbiotech.com.tw.
authors.forename: Miles Chih-Ming
authors.initials: MC
authors.lastname: Chen
mesh_terms: D004122:Dimethylallyltranstransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011905:Genes, ras / Q000187:drug effects* / Q000502:physiology; D056945:Hep G2 Cells; D006801:Humans; D020014:K562 Cells; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000494:pharmacology; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D014451:Ubiquinone; C545357:antroquinonol; D004122:Dimethylallyltranstransferase; D054460:rho-Associated Kinases
keywords: Antroquinonol; Autophagy; Farnesyltransferase; Prenylation; Ras