title: Sirtinol, a class III HDAC inhibitor, induces apoptotic and autophagic             cell death in MCF-7 human breast cancer cells.
abstract: Sirtuins (SIRTs), NAD+-dependent class III histone deacetylases (HDACs), play an important role in the regulation of cell division, survival and senescence. Although a number of effective SIRT inhibitors have been developed, little is known about the specific mechanisms of their anticancer activity. In this study, we investigated the anticancer effects of sirtinol, a SIRT inhibitor, on MCF-7 human breast cancer cells. Apoptotic and autophagic cell death were measured. Sirtinol significantly inhibited the proliferation of MCF-7 cells in a concentration-dependent manner. The IC50 values of sirtinol were 48.6 µM (24 h) and 43.5 µM (48 h) in MCF-7 cells. As expected, sirtinol significantly increased the acetylation of p53, which has been reported to be a target of SIRT1/2. Flow cyto-metry analysis revealed that sirtinol significantly increased the G1 phase of the cell cycle. The upregulation of Bax, downregulation of Bcl-2 and cytochrome c release into the cytoplasm, which are considered as mechanisms of apoptotic cell death, were observed in the MCF-7 cells treated with sirtinol. The annexin V-FITC assay was used to confirm sirtinol-induced apoptotic cell death. Furthermore, the expression of LC3-II, an autophagy-related molecule, was significantly increased in MCF-7 cells after sirtinol treatment. Autophagic cell death was confirmed by acridine orange and monodansylcadaverine (MDC) staining. Of note, pre-treatment with 3-methyladenine (3-MA) increased the sirtinol-induced MCF-7 cell cytotoxicity, which is associated with blocking autophagic cell death and increasing apoptotic cell death. Based on our results, the downregulation of SIRT1/2 expression may play an important role in the regulation of breast cancer cell death; thus, SIRT1/2 may be a novel molecular target for cancer therapy and these findings may provide a molecular basis for targeting SIRT1/2 in future cancer therapy.
authors: College of Pharmacy, Pusan National University, Busan 609-735,                     Republic of Korea.
authors: Jing
authors: J
authors: Wang
authors: Tae Hyung
authors: TH
authors: Kim
authors: Mee Young
authors: MY
authors: Ahn
authors: Jaewon
authors: J
authors: Lee
authors: Jee H
authors: JH
authors: Jung
authors: Wahn Soo
authors: WS
authors: Choi
authors: Byung Mu
authors: BM
authors: Lee
authors: Kyuing Sil
authors: KS
authors: Yoon
authors: Sungpil
authors: S
authors: Yoon
authors: Hyung Sik
authors: HS
authors: Kim
mesh_terms: D000107:Acetylation; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D045304:Cytochromes c / Q000096:biosynthesis / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology*; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis; D009284:Naphthols / Q000494:pharmacology*; D037761:Sirtuins / Q000037:antagonists & inhibitors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D015854:Up-Regulation; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000096:biosynthesis; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
chemical_list: D001549:Benzamides; D056572:Histone Deacetylase Inhibitors; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D009284:Naphthols; D016159:Tumor Suppressor Protein p53; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; C439060:sirtinol; C025946:3-methyladenine; D045304:Cytochromes c; D037761:Sirtuins; D000225:Adenine