title: Temsirolimus and chloroquine cooperatively exhibit a potent antitumor effect against colorectal cancer cells.
abstract: OBJECTIVE
  Temsirolimus (TEM) is a novel, water-soluble mammalian target of rapamycin (mTOR) inhibitor that has shown activity against a wide range of cancers in preclinical models, but its efficacy against colorectal cancer (CRC) has not been fully explored.
  
  
  METHODS
  We evaluated the antitumor effect of TEM in CRC cell lines (CaR-1, HT-29, Colon26) in vitro and in vivo. In vitro, cell growth inhibition was assessed using a MTS assay. Apoptosis induction and cell cycle effects were measured using flow cytometry. Modulation of mTOR signaling was measured using immunoblotting. Antitumor activity as a single agent was evaluated in a mouse subcutaneous tumor model of CRC. The effects of adding chloroquine, an autophagy inhibitor, to TEM were evaluated in vitro and in vivo.
  
  
  RESULTS
  In vitro, TEM was effective in inhibiting the growth of two CRC cell lines with highly activated AKT, possibly through the induction of G1 cell cycle arrest via a reduction in cyclin D1 expression, whereas TEM reduced HIF-1α and VEGF in all three cell lines. In a mouse subcutaneous tumor model, TEM inhibited the growth of tumors in all cell lines, not only through direct growth inhibition but also via an anti-angiogenic effect. We also explored the effects of adding chloroquine, an autophagy inhibitor, to TEM. Chloroquine significantly potentiated the antitumor activity of TEM in vitro and in vivo. Moreover, the combination therapy triggered enhanced apoptosis, which corresponded to an increased Bax/Bcl-2 ratio.
  
  
  CONCLUSIONS
  Based on these data, we propose TEM with or without chloroquine as a new treatment option for CRC.
authors.affiliation: Department of Surgical Oncology, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan, m.kaneko@fancy.ocn.ne.jp.
authors.forename: Manabu
authors.initials: M
authors.lastname: Kaneko
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nozawa
authors.forename: Masaya
authors.initials: M
authors.lastname: Hiyoshi
authors.forename: Noriko
authors.initials: N
authors.lastname: Tada
authors.forename: Koji
authors.initials: K
authors.lastname: Murono
authors.forename: Takako
authors.initials: T
authors.lastname: Nirei
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Emoto
authors.forename: Junko
authors.initials: J
authors.lastname: Kishikawa
authors.forename: Yuuki
authors.initials: Y
authors.lastname: Iida
authors.forename: Eiji
authors.initials: E
authors.lastname: Sunami
authors.forename: Nelson H
authors.initials: NH
authors.lastname: Tsuno
authors.forename: Joji
authors.initials: J
authors.lastname: Kitayama
authors.forename: Koki
authors.initials: K
authors.lastname: Takahashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000008:administration & dosage; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D019938:Cyclin D1 / Q000096:biosynthesis; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D020123:Sirolimus / Q000008:administration & dosage / Q000031:analogs & derivatives*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D023041:Xenograft Model Antitumor Assays
chemical_list: D019938:Cyclin D1; C401859:temsirolimus; D002738:Chloroquine; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus