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: Jing Wang, Tae Hyung Kim, Mee Young Ahn, Jaewon Lee, Jee H Jung, Wahn Soo Choi, Byung Mu Lee, Kyuing Sil Yoon, Sungpil Yoon, Hyung Sik Kim
• Journal: International journal of oncology (Int J Oncol) Vol. 41 Issue 3 Pg. 1101-9 (Sep 2012) ISSN: 1791-2423 [Electronic] Greece
• PMID: 22751989 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Benzamides
• Histone Deacetylase Inhibitors
• MAP1LC3A protein, human
• Microtubule-Associated Proteins
• Naphthols
• Tumor Suppressor Protein p53
• bcl-2 Homologous Antagonist-Killer Protein
• bcl-2-Associated X Protein
• sirtinol
• 3-methyladenine
• Cytochromes c
• Sirtuins
• Adenine

Topics

• Acetylation
• Adenine (analogs & derivatives, pharmacology)
• Apoptosis (drug effects)
• Autophagy (drug effects)
• Benzamides (pharmacology)
• Breast Neoplasms (drug therapy, metabolism, pathology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cytochromes c (biosynthesis, metabolism)
• Down-Regulation
• Female
• G1 Phase Cell Cycle Checkpoints (drug effects)
• Histone Deacetylase Inhibitors (pharmacology)
• Humans
• Microtubule-Associated Proteins (biosynthesis)
• Naphthols (pharmacology)
• Sirtuins (antagonists & inhibitors)
• Tumor Suppressor Protein p53 (metabolism)
• Up-Regulation
• bcl-2 Homologous Antagonist-Killer Protein (biosynthesis)
• bcl-2-Associated X Protein (biosynthesis)