title: Sinodielide A exerts thermosensitizing effects and induces apoptosis and G2/M cell cycle arrest in DU145 human prostate cancer cells via the Ras/Raf/MAPK and PI3K/Akt signaling pathways.
abstract: Sinodielide A (SA) is a naturally occurring guaianolide, which is isolated from the root of Sinodielsia yunnanensis. This root, commonly found in Yunnan province, is used in traditional Chinese medicine as an antipyretic, analgesic and diaphoretic agent. A number of studies have reported that agents isolated from a species of Umbelliferae (Apiaceae) have antitumor activities. We previously reported, using combined treatments with this medicinal herb and hyperthermia at various temperatures, an enhanced cytotoxicity in the human prostate cancer androgen‑independent cell lines, PC3 and DU145, and analyzed the related mechanisms. In the present study, we investigated the effects of treatment with SA prior to hyperthermia on the thermosensitivity of DU145 cells, and the mechanisms related to the induction of apoptosis and G(2)/M cell cycle arrest via the activation of extracellular-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathways, as well as the phosphoinositide 3-kinase (PI3K)/Akt signaling pathways. Cells were exposed to hyperthermia alone (40-44˚C) or hyperthermia in combination with SA. Lethal damage to cells treated with mild hyperthermia (40 or 42˚C) for up to 6 h was slight; however, hyperthermia in combination with SA synergistically enhanced thermosensivity. Lethal damage to cells treated with acute hyperthermia (43 or 44˚C) was more severe, but these effects were also enhanced and were more significant by the combined treatment with SA. The kinetics of apoptosis induction and cell cycle distribution were analyzed by flow cytometry. In addition, the levels of ERK1/2, JNK and Akt were determined by western blot analysis. The incidence of apoptotic cells after treatment with SA (20.0 µM) at 37˚C for 4 h, hyperthermia (44˚C) alone for 30 min, and the combination in sequence were examined. The sub-G1 division (%) in the diagram obtained by flow cytometry was applied to that assay. The percentage of apoptotic cells (10.53±5.02%) was higher at 48 h as compared to 0, 12 and 24 h after treatment. The distribution of DU145 cells in the G2/M cell cycle phase was markedly increased after 24 h of heating at 44˚C and after the combined treatment with heating and SA. The phosphorylation of ERK1/2 was reduced following treatment with heating and SA, while the levels of phosphorylated JNK (p-JNK) were markedly increased immediately after heating at 44˚C and when heating was combined with SA. By contrast, the levels of phosphorylated Akt (p-Akt) were immediately increased only after heating at 44˚C. Thus, we concluded that SA exerts its thermosensitizing effects on DU145 cells by inhibiting the activation of the MAPK/ERK1/2 and PI3K/Akt signaling pathways.
authors.affiliation: Research and Development Department, The Wakasa Wan Energy Research Center, Tsuruga, Fukui 914-0192, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Hatashita
authors.affiliation: Department of Pharmacognosy, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Pharmacognosy, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka 569-1094, Japan.
authors.forename: Kimiye
authors.initials: K
authors.lastname: Baba
authors.affiliation: The Center for Urology and Nephrology, Saitama Ken-oh Hospital, Okegawa, Saitama 363-0008, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Koshiba
authors.affiliation: Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa 252-0374, Japan.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Sato
authors.affiliation: The Center for Urology and Nephrology, Saitama Ken-oh Hospital, Okegawa, Saitama 363-0008, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Jujo
authors.affiliation: The Center for Urology and Nephrology, Saitama Ken-oh Hospital, Okegawa, Saitama 363-0008, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Suzuki
authors.affiliation: Department of Experimental Radiology and Health Physics, Faculty of Medical Science, University of Fukui, Matsuokashimoaizuki, Fukui 910-1193, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Hayashi
mesh_terms: D019661:Apiaceae / Q000737:chemistry; D017209:Apoptosis / Q000187:drug effects*; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D016195:G2 Phase / Q000502:physiology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D015398:Signal Transduction; D013696:Temperature
chemical_list: D010936:Plant Extracts; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D016283:Proto-Oncogene Proteins p21(ras)