title: Bisleuconothine A Induces Autophagosome Formation by Interfering with AKT-mTOR Signaling Pathway.
abstract: We have previously reported that bisleuconothine A (Bis-A), a novel bisindole alkaloid isolated from Leuconotis griffithii, showed cytostatic activity in several cell lines. In this report, the mechanism of Bis-A-induced cytostatic activity was investigated in detail using A549 cells. Bis-A did not cause apoptosis, as indicated by analysis of annexin V and propidium iodide staining. Expression of all tested apoptosis-related proteins was also unaffected by Bis-A treatment. Bis-A was found to increase LC3 lipidation in MCF7 cells as well as A549 cells, suggesting that Bis-A cytostatic activity may be due to induction of autophagy. Subsequent investigation via Western blotting and immunofluorescence staining indicated that Bis-A induced formation but prevented degradation of autophagosomes. Mechanistic studies showed that Bis-A down-regulated phosphorylation of protein kinase B (AKT) and its downstream kinase, PRAS40, which is an mTOR repressor. Moreover, phosphorylation of p70S6K, an mTOR-dependent kinase, was also down-regulated. Down-regulation of these kinases suggests that the increase in LC3 lipidation may be due to mTOR deactivation. Thus, the cytostatic activity shown by Bis-A may be attributed to its induction of autophagosome formation. The Bis-A-induced autophagosome formation was suggested to be caused by its interference with the AKT-mTOR signaling pathway.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Chin Piow
authors.initials: CP
authors.lastname: Wong
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Ari
authors.initials: A
authors.lastname: Seki
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Horiguchi
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Shoji
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Arai
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Alfarius Eko
authors.initials: AE
authors.lastname: Nugroho
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hirasawa
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Sato
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Kaneda
authors.affiliation: Faculty of Pharmaceutical Sciences, Hoshi University, Ebara 2-4-41 Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morita
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001343:Autophagy; D045744:Cell Line, Tumor; D054697:Cytostatic Agents / Q000737:chemistry / Q000494:pharmacology; D015536:Down-Regulation; D005260:Female; D006801:Humans; D026121:Indole Alkaloids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D008296:Malaysia; D015394:Molecular Structure; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000187:drug effects; D014747:Vinblastine / Q000494:pharmacology
chemical_list: D017304:Annexin A5; D051017:Apoptosis Regulatory Proteins; D054697:Cytostatic Agents; D026121:Indole Alkaloids; C550713:bisleuconothine A; D014747:Vinblastine; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases