title: DAPK1 mediates the G1 phase arrest in human nasopharyngeal carcinoma cells induced by grifolin, a potential antitumor natural product.
abstract: Grifolin, a secondary metabolite isolated from the fresh fruiting bodies of the mushroom Albatrellus confluens, has been shown to induce G1 phase cell-cycle arrest in tumor cells in previous studies of our group. However, the mechanisms of action are not completely understood. Our group further demonstrated that grifolin upregulates death-associated protein kinase 1 (DAPK1) in nasopharyngeal carcinoma cells (NPCs). Here, we found that grifolin induced dephosphorylation of DAPK1 (Ser308) to activate DAPK1 and subsequent phosphorylation of its potential downstream effector p21 (Thr145) in nasopharyngeal carcinoma cell CNE1. Inhibition of DAPK1 by introducing siRNA targeting DAPK1 reversed the grifolin- induced phosphorylation of p21. Furthermore, we confirmed that grifolin increased the half-life of p21 and promoted its stability. Flow cytometry analysis demonstrated that DAPK1 was involved in grifolin-induced G1 phase arrest in CNE1 cells. The similar effects induced by grifolin and mechanism beneath were identified in another nasopharyngeal carcinoma cell HONE1. In addition, we observed that grifolin promoted the protein-protein interaction of DAPK1 and ERK1/2 to prevent ERK1/2 nucleolus translocation. Our findings indicate that DAPK1 plays a crucial role in the induction of cell-cycle arrest at G1 phase by grifolin. Grifolin might represent a promising candidate in the prevention and intervention of cancer by targeting DAPK1 signaling to induce cell cycle G1 phase arrest.
authors.affiliation: Cancer Research Institute, Xiangya School of Medicine, Central South University, Changsha, Hunan 410078, PR China.
authors.forename: Xiang-jian
authors.initials: XJ
authors.lastname: Luo
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Li-fang
authors.initials: LF
authors.lastname: Yang
authors.forename: Xin-fang
authors.initials: XF
authors.lastname: Yu
authors.forename: Lan-bo
authors.initials: LB
authors.lastname: Xiao
authors.forename: Min
authors.initials: M
authors.lastname: Tang
authors.forename: Xin
authors.initials: X
authors.lastname: Dong
authors.forename: Qi-pan
authors.initials: QP
authors.lastname: Deng
authors.forename: Ann M
authors.initials: AM
authors.lastname: Bode
authors.forename: Ji-kai
authors.initials: JK
authors.lastname: Liu
authors.forename: Ya
authors.initials: Y
authors.lastname: Cao
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D001688:Biological Products / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000187:drug effects / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000737:chemistry / Q000378:metabolism; D064550:Death-Associated Protein Kinases; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D013729:Terpenes / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; D001688:Biological Products; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D013729:Terpenes; C058858:grifolin; C579096:DAPK1 protein, human; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3