The prognosis is very poor for patients DAPT who have unresectable tumors, with a median survival of approximately 6 months.2 At present, even the most effective forms of systemic therapy, such as doxorubicin1, 3 or sorafenib,2, 4 only minimally extend the lifespan of these patients. Therefore, a thorough

understanding of the underlying mechanisms regarding tumor growth and metastasis is vital for the development of efficacious therapeutics. Sirtuins are mammalian homologs of the yeast silent information regulator 2 (SIR2), which are histone deacetylases that utilizes nicotinamide adenine dinucleotide as a cofactor for their functions.5 The yeast, SIR2, regulates aging by maintaining transcriptional silencing of the mating-type loci, the ribosomal DNA locus, and the telomeres.6 In mammals, there are seven homologs of SIR2 (SIRT1-7), of which SIRT1 is considered to be the human ortholog of SIR2.7 SIRT1 is mainly localized to the nucleus and plays a key role in energy metabolism, telomeric maintenance,

and genomic stability by targeting a variety of nonhistone proteins.8-11 The role of SIRT1 in cancer is controversial because it may act as a tumor promoter or suppressor, depending on the tumor type.12 SIRT2 acts on certain substrates of SIRT1, such as H4K16, p53, FOXO3, and p65.13-16 Nevertheless, the predominant cytoplasmic localization of SIRT2 and its role in the regulation 上海皓元医药股份有限公司 of tubulin dynamics and neuronal motility suggested that it might have Dabrafenib nmr functional roles distinctive from SIRT1.17, 18 Indeed, recent findings suggested that SIRT2 is associated

with mitotic apparatus during the cell cycle19, 20 and is essential for maintaining genomic stability by deacetylating CDH1 and CDC20 of the anaphase-promoting complex/cyclosome.21 Emerging evidence has also suggested that SIRT2 is involved in tumorigenesis.21 SIRT2 deficiency results in aneuploidy and mitotic cell death, and SIRT2-deficient mice have a higher propensity for developing tumors.21 Moreover, SIRT2 expression is down-regulated in some cancers,21, 22 suggestive of a tumor-suppressor function. SIRT1 expression is up-regulated in HCC, and SIRT1 may play a role in HCC tumorigenesis through telomere maintenance.23 In this study, we showed that SIRT2 is also up-regulated in HCC. Overexpression of SIRT2 in primary HCC tumors is positively correlated with microscopic vascular invasion and adverse patient prognosis. Using HCC cell models, we uncovered a key role of SIRT2 as a tumor promoter in HCC by promoting epithelial-mesenchymal transition (EMT) and motility of HCC cells by targeting the protein kinase B/glycogen synthase kinase (Akt/GSK)3-β/β-catenin-signaling pathway. Our findings provide a rationale for the clinical exploration of the use of sirtuin inhibitors in HCC therapy.