title: Curcumin targets Akt cell survival signaling pathway in HTLV-I-infected T-cell lines.
abstract: The Akt signaling pathway is important for survival and growth of cancer cells. In the present paper we show that the Akt signaling pathway is constitutively activated in human T-cell leukemia virus type I (HTLV-I)-infected T-cell lines and in primary adult T-cell leukemia (ATL) cells. Curcumin, a natural compound present in turmeric, has been studied vigorously as a potent chemopreventive agent for cancer therapy because of its inhibitory effect on proliferation and induction of apoptosis in several tumor cell lines. We investigated the effect of curcumin on Akt activity in HTLV-I-infected T-cell lines and primary ATL cells. Phosphorylated PDK1 is an activator of Akt by phosphorylating Akt. Curcumin reduced phosphorylation of PDK1 and inhibited constitutive activation of Akt. Curcumin activated glycogen synthase kinase (GSK)-3beta, a downstream target of Akt kinase, by inhibiting phosphorylation of this protein. Curcumin reduced the expression of cell cycle regulators, cyclin D1 and c-Myc proteins, which are both degraded by activated GSK-3beta. Our results suggest that activation of the Akt signaling pathway plays an important role in ATL cell survival, and that curcumin may have anti-ATL properties mediated, at least in part, by inhibiting Akt activity. We propose that Akt-targeting agents could be useful for the treatment of ATL. In this regard, curcumin is a potentially promising compound for the treatment of ATL.
authors.affiliation: Division of Molecular Virology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Tomita
authors.forename: Takehiro
authors.initials: T
authors.lastname: Matsuda
authors.forename: Hirochika
authors.initials: H
authors.lastname: Kawakami
authors.forename: Jun-Nosuke
authors.initials: JN
authors.lastname: Uchihara
authors.forename: Taeko
authors.initials: T
authors.lastname: Okudaira
authors.forename: Masato
authors.initials: M
authors.lastname: Masuda
authors.forename: Kazuiku
authors.initials: K
authors.lastname: Ohshiro
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects*; D003474:Curcumin / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D015368:Human T-lymphotropic virus 1 / Q000187:drug effects*; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000821:virology*; D014407:Tumor Cells, Cultured / Q000821:virology
chemical_list: D000970:Antineoplastic Agents; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D003474:Curcumin