title: Clarithromycin attenuates autophagy in myeloma cells.
abstract: It has been reported that clarithromycin (CAM) augments the anti-tumor activity of thalidomide against multiple myeloma (MM) cells, while the mechanism remains unclear. A myeloma cell line or primary myeloma cells were treated with CAM. Autophagy was analyzed by morphological changes, LC3 expression and lysotracker staining. CAM induced vacuoles in the cytoplasm of MM cells which resembled autolysosomes. The manifestation of the CAM-induced vacuoles was blocked by treatment with PI3-kinase inhibitor. CAM induced an accumulation of LC3-II without affecting the mTOR or AKT pathways, eventually leading to cell death. CAM may halt the autophagy process after fusion of autophagosomes with lysosomes. This phenomenon may explain how CAM, combined with thalidomide, augments the cytotoxic effects of the latter on MM cells and suggests that modification of autophagy might represent a new approach for therapy of MM.
authors.affiliation: Department of Hematology, Kumamoto University Hospital, Kumamoto 860-8556, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Nakamura
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kikukawa
authors.forename: Motohiro
authors.initials: M
authors.lastname: Takeya
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsuya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hata
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001343:Autophagy / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D017291:Clarithromycin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D017291:Clarithromycin; D008869:Microtubule-Associated Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C477012:MAP1LC3A protein, human; C546842:MTOR protein, human