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SIRT1

epithelial-mesenchymal transition (EMT) is supposed to be an inflammation induced response which may take a central role in tumorigenesis. Since recent evidence indicates that microRNAs may be involved in EMT, the present study set out to reveal the miRNA which might regulate the EMT in CP (chronic pancreatitis) and PC (pancreatic cancer) and its potential mechanism. Firstly, we provided evidence that both CP and PC tissues demonstrated active EMT profile. Consistently, miR-217 was obviously down-regulated in CP, PC and TGF-beta1 treated PC cells, while negatively correlated to its direct target SIRT1. Moreover, either ectopic expression of miR-217 or inhibition of SIRT1 remarkably induced mesenchymal to epithelial transition (MET) in TGF-beta1 treated PC cells. On the contrary, miR-217 inhibitor promoted EMT in PC cells but not in SIRT-knockdown PC cells. Clinical information from a cohort of 54 PC patients demonstrated that down-regulated miR-217 was positively correlated with late tumor stage, lymphatic invasion, vascular infiltration and distant metastasis. These results suggest that the overexpressed TGF-beta1 in inflammation triggers the deregulation of the miR-217-SIRT1 pathway and then promotes the EMT process, which might be involved in the tumorigenesis of PC. Additionally, miR-217 may function as a novel target and predictor for PC prevention and therapy.CI - Copyright (c) 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Pancreatic cancer is the most aggressive cancer worldwide with poor response to current therapeutics. Alisertib (ALS), a potent and selective Aurora kinase A inhibitor, exhibits potent anticancer effects in preclinical and clinical studies; however, the effect and underlying mechanism of ALS in the pancreatic cancer treatment remain elusive. This study aimed to examine the effects of ALS on cell growth, autophagy, and epithelial-to-mesenchymal transition (EMT) and to delineate the possible molecular mechanisms in human pancreatic cancer PANC-1 and BxPC-3 cells. The results showed that ALS exerted potent cell growth inhibitory, pro-autophagic, and EMT-suppressing effects in PANC-1 and BxPC-3 cells. ALS remarkably arrested PANC-1 and BxPC-3 cells in G2/M phase via regulating the expression of cyclin-dependent kinases 1 and 2, cyclin B1, cyclin D1, p21 Waf1/Cip1, p27 Kip1, and p53. ALS concentration-dependently induced autophagy in PANC-1 and BxPC-3 cells, which may be attributed to the inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), p38 mitogen-activated protein kinase (p38 MAPK), and extracellular signal-regulated kinases 1 and 2 (Erk1/2) but activation of 5'-AMP-dependent kinase signaling pathways. ALS significantly inhibited EMT in PANC-1 and BxPC-3 cells with an increase in the expression of E-cadherin and a decrease in N-cadherin. In addition, ALS suppressed the expression of sirtuin 1 (Sirt1) and pre-B cell colony-enhancing factor/visfatin in both cell lines with a rise in the level of acetylated p53. These findings show that ALS induces cell cycle arrest and promotes autophagic cell death but inhibits EMT in pancreatic cancer cells with the involvement of PI3K/Akt/mTOR, p38 MAPK, Erk1/2, and Sirt1-mediated signaling pathways. Taken together, ALS may represent a promising anticancer drug for pancreatic cancer treatment. More studies are warranted to investigate other molecular targets and mechanisms and verify the efficacy and safety of ALS in the treatment of pancreatic cancer.

As a critical developmental process, epithelial-mesenchymal transition (EMT) involves complex transcriptional reprogramming and has been closely linked to malignant progression. Although various epigenetic modifications, such as histone deacetylation and H3K9 methylation, have been implicated in this process, how they are coordinated remains elusive. We recently revealed that MPP8 couples H3K9 methylation and DNA methylation for E-cadherin gene silencing and promotes tumor cell migration, invasion, and EMT. Here, we show that MPP8 cooperates with the class III HDAC SIRT1 in this process through their physical interaction. SIRT1 antagonizes PCAF-catalyzed MPP8-K439 acetylation to protect MPP8 from ubiquitin-proteasome-mediated proteolysis. Conversely, MPP8 recruits SIRT1 for H4K16 deacetylation after binding to methyl-H3K9 on target promoters. Consequently, disabling either MPP8 methyl-H3K9 binding or SIRT1 interaction de-represses E-cadherin and reduces EMT phenotypes, as does knockdown of MPP8 or SIRT1 in prostate cancer cells. These results illustrate how SIRT1 and MPP8 reciprocally promote each other's function and coordinate epithelial gene silencing and EMT.CI - (c) 2015 The Authors.

MicroRNAs (miRs) play crucial roles in tumorigenesis by directly suppressing the protein expression levels of their target genes. miR-204 has been suggested to act as a tumor suppressor in several types of human cancer. However, the exact role of miR-204 in osteosarcoma (OS) remains undetermined. In the present study, we aimed to investigate the effects of miR-204 on OS cell proliferation, migration and invasion, as well as the underlying molecular mechanisms. We found that the expression of miR-204 was frequently downregulated in four OS cell lines compared to the level in normal human osteoblast cells. Moreover, overexpression of miR-204 significantly inhibited the proliferation, migration and invasion of OS cells. Based on bioinformatics prediction and a luciferase reporter assay, we identified Sirtuin 1 (Sirt1) as a direct target gene of miR-204 in OS Saso-2 cells. Moreover, the protein expression of Sirt1 was negatively mediated by miR-204 in the OS cells. siRNA-mediated knockdown of Sirt1 also inhibited the proliferation, migration and invasion of the OS cells. Moreover, overexpression of Sirt1 reversed the inhibitory effect of miR-204 overexpression on the proliferation, migration and invasion of the OS cells. In addition, after miR-204 overexpression or Sirt1 knockdown in OS cells, the expression of E-cadherin was increased, while the N-cadherin protein level was reduced. Based on these findings, we suggest that miR-204 inhibits the proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) of OS cells by directly targeting Sirt1.

Silent mating type information regulation 1 (SIRT1) is implicated in tumorigenesis through its effect on autophagy. In gastric cancer (GC), SIRT1 is a marker for prognosis and is involved in cell invasion, proliferation, epithelial-mesenchymal transition (EMT) and drug resistance. Autophagy can function as a cell-survival mechanism or lead to cell death during the genesis and treatment of GC. This functionality is determined by factors including the stage of the tumor, cellular context and stress levels. Interestingly, SIRT1 can regulate autophagy through the deacetylation of autophagy-related genes (ATGs) and mediators of autophagy. Taken together, these findings support the need for continued research efforts to understand the mechanisms mediating the development of gastric cancer and unveil new strategies to eradicate this disease.CI - Copyright (c) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

BACKGROUND: Nasal polyps (NPs) imply a refractory clinical course in patients with chronic rhinosinusitis (CRS). Previously, we showed that hypoxia-inducible factor (HIF) 1 could mediate nasal polypogenesis through epithelial-to-mesenchymal transition (EMT). Sirtuin 1 (SIRT1), a histone deacetylase, reportedly suppresses the transcriptional activity of HIF-1. Thus we hypothesized that SIRT1 attenuates nasal polyposis by inhibiting HIF-1-induced EMT. OBJECTIVE: We sought to determine the role of SIRT1 in patients with nasal polyposis. METHODS: The effects of SIRT1 on nasal polypogenesis were investigated in previously developed murine models. Immunohistochemistry, immunoblotting, and immunoprecipitation were done to evaluate SIRT1, EMT, and hypoxic markers in human nasal epithelial cells or sinonasal tissues from the mice and the patients with CRS with or without NPs. RESULTS: SIRT1 transgenic mice had significantly fewer mucosal lesions with epithelial disruption and fewer NPs than wild-type (WT) mice. In addition, resveratrol (a SIRT1 activator) treatment suppressed nasal polypogenesis in WT mice; however, sirtinol (a SIRT1 inhibitor) administration increased the polyp burden in SIRT1 transgenic mice. In sinonasal specimens from patients with CRS, SIRT1 was downregulated in the mucosa from patients with polyps compared with levels seen in patients without polyps. SIRT1 overexpression or activation reversed hypoxia-induced EMT in human nasal epithelial cells. The intranasal transfection of a small hairpin SIRT1 lentiviral vector induced more nasal polypoid lesions in SIRT1 transgenic mice. Finally, mucosal extracts from patients with CRS without NPs increased SIRT1 expression in nasal epithelial cells, whereas those from patients with CRS with NPs did not. CONCLUSION: SIRT1 suppressed NP formation, possibly because of inhibition of HIF-1-induced EMT. Thus nasal epithelium SIRT1 might be a therapeutic target for NPs.CI - Copyright (c) 2015 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Absence of therapeutic targets poses a critical hurdle in improving prognosis for patients with triple negative breast cancer (TNBC). We evaluated interaction between SIRT1 and epithelial mesenchymal transition (EMT)-associated proteins as well as the role of combined protein expression as a predictor of lymph node metastasis and clinical outcome in TNBC through in vivo and vitro studies. Three hundred nineteen patients diagnosed with TNBC were chosen, immunohistochemical staining for SIRT1 and EMT-related markers' expression was performed on tissue microarrays, and in vitro experiments with each of the three human TNBC cell lines were carried out. The cohort was reclassified according to the use of adjuvant chemotherapy, tumor size, and AJCC stage to analyze the prognostic role of SIRT1 and EMT-related proteins' expression considering different therapeutic modalities and AJCC stages. Combination of four proteins including SIRT1 and three EMT-related proteins was revealed to be a statistically significant independent predictor of lymph node metastasis in the tumor size cohort as well as in the total patient population. Upon Cox regression analysis, increased expression level of the combined proteins correlated with decreased disease-free survival in the total patients as well as those who received adjuvant chemotherapy and those who had early stage breast cancer. In additional in vitro experiments, inhibition of SIRT1 expression with small interfering RNA (siRNA) suppressed tumor invasion in three different TNBC cell lines, and altered expression levels of EMT-related proteins following SIRT1 gene inhibition were identified on western blotting and fluorescence activated cell sorting (FACS) analysis; on the other hand, no change in expression levels of the cell cycle-related factors was observed. Our analysis showed the potential role of SIRT1 in association with EMT-related factors on tumor invasion, metastasis, and disease-free survival in TNBC, SIRT1, and associated EMT-related markers may offer a new prognostic indicator as well as a novel therapeutic candidate.

BACKGROUND The epithelial-mesenchymal transition (EMT) has been shown to be involved in the process of invasion and metastasis of prostate cancer. SIRT1 is the mammalian homologue of the silent information regulator 2 (Sir2) gene, and is abnormally expressed in prostate cancer cells. Therefore, it is hypothesized that SIRT1 mediates the invasion/metastatic ability of prostate cancer via EMT regulation. This study thus investigated the effect of SIRT1 gene on the invasion and migration of prostate cancer cell line PC-3 via the small interference RNA (siRNA) against SIRT1. MATERIAL AND METHODS SiRNA construct was transfected into PC-3 cells, which were tested for the cell migration and invasion ability by scratch assay and Transwell migration assay, respectively. expression levels of vimentin, E-cadherin, and N-cadherin were further quantified by Western blotting and RT-PCR. RESULTS Both mRNA and protein levels of SIRT1 were depressed after siRNA transfection, along with weakened migration and invasion ability of PC-3 cells. Elevated E-cadherin and suppressed N-cadherin and vimentin were observed in those transfected cells. CONCLUSIONS The silencing of SIRT1 gene in PC-3 cells can suppress the movement, migration, and invasion functions of prostate cancer cells, possibly via the down-regulation of mesenchymal markers vimentin and N-cadherin accompanied with up-regulation of epithelial marker N-cadherin, thus reversing the EMT process.

The non-steroidal anti-inflammatory drugs (NSAIDs) celecoxib and sulindac have been reported to suppress lung cancer migration and invasion. The class III deacetylase sirtuin 1 (SIRT1) possesses both pro- and anticarcinogenic properties. However, its role in inhibition of lung cancer cell epithelial-mesenchymal transition (EMT) by NSAIDs is not clearly known. We attempted to investigate the potential use of NSAIDs as inhibitors of TGF-beta1-induced EMT in A549 cells, and the underlying mechanisms of suppression of lung cancer migration and invasion by celecoxib and sulindac. We demonstrated that celecoxib and sulindac were effective in preventing TGF-beta1-induced EMT, as indicated by upregulation of the epithelial marker, E-cadherin, and downregulation of mesenchymal markers and transcription factors. Moreover, celecoxib and sulindac could inhibit TGF-beta1-enhanced migration and invasion of A549 cells. SIRT1 downregulation enhanced the reversal of TGF-beta1-induced EMT by celecoxib or sulindac. In contrast, SIRT1 upregulation promoted TGF-beta1-induced EMT. Taken together, these results indicate that celecoxib and sulindac can inhibit TGF-beta1-induced EMT and suppress lung cancer cell migration and invasion via downregulation of SIRT1. Our findings implicate overexpressed SIRT1 as a potential therapeutic target to reverse TGF-beta1-induced EMT and to prevent lung cancer cell migration and invasion.

SIRT1 belongs to the mammalian sirtuin family and plays an important role in deacetylating histone and nonhistone proteins. It is reported that SIRT1 is associated with tumor metastasis in several kinds of tumors. However, the effect of SIRT1 on the metastasis of chondrosarcoma cells is still unknown. In this study, we demonstrated that up and down-regulation of SIRT1 expression could significantly change the invasive and metastatic potential in chondrosarcoma cell line. Besides that, the result from the nude mice confirmed the effect of SIRT1 on metastasis of chondrosarcoma cells. Furthermore, we also found that SIRT1 effectively enhanced the metastasis by inducing epithelial-mesenchymal transition (EMT) in chondrosarcoma cells. Inhibition the expression of SIRT1 could block the incidence of metastasis and EMT in chondrosarcoma cells. In addition, we also observed that SIRT1 could enhance the expression of Twist which is a key transcriptional factor of EMT. A clinicopathological analysis showed that SIRT1 expression was significantly correlated with the poor prognosis of pelvis chondrosarcoma. Kaplan-Meier survival curves revealed that positive SIRT1 expression was associated with poor prognosis in patients with pelvis chondrosarcoma. Taken together, these results indicate that SIRT1 may promote the metastasis of chondrosarcoma by inducing EMT and can be a potential molecular target for chondrosarcoma therapy.

We have previously reported that perfluorooctanesulfonate (PFOS) causes cell apoptosis in renal tubular epithelial cells (RTCs). Here, we extend our findings and provide evidence of epithelial-mesenchymal transition (EMT)-associated renal fibrosis caused by PFOS and the protection by l-carnitine. Our results demonstrate that PFOS increased the expression of EMT and renal injury biomarkers (eg, N-cadherin, vimentin, Snail, Kim1, and Lcn2). In addition, PFOS caused EMT induction through Sirt1-mediated PPARgamma deacetylation and inactivation. l-carnitine reversed the EMT induction caused by PFOS and alleviated PFOS-mediated increases in cell migration by reactivating PPARgamma through the inhibition of Sirt1 activity. The critical role of Sirt1 in this process was validated by using Sirt1 overexpression, resveratrol (a pharmacologic activator of Sirt1), nicotinamide (a Sirt1 inhibitor) and siSirt1. Nicotinamide and siSirt1, but not Sirt1 overexpression and resveratrol, alleviated PFOS-mediated EMT induction, suggesting that increased Sirt1 activity contributed to the alterations. Furthermore, through PPARgamma overexpression and pharmacologic interventions, we validated the crucial role of increased PPARgamma deacetylation caused by aberrant increased Sirt1 activity in RTC transformation. Similar to PPARgamma overexpression, rosiglitazone (a PPARgamma agonist) alleviated the effects of PFOS on the EMT-related features, whereas GW9662 (a PPARgamma antagonist) mimicked the effects. The protective effect of l-carnitine was also verified in a mouse model of chronic PFOS exposure, in which decreased EMT biomarker levels and renal fibrosis by l-carnitine were observed in Western blot and histological analyses. Accordingly, l-carnitine alleviated EMT-associated renal fibrosis caused by PFOS through a Sirt1- and PPARgamma-dependent mechanism.CI - (c) The Author 2017. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Sirtuin1 (SIRT1) belongs to the mammalian sirtuin family and plays an important role in deacetylating histones and non-histones. SIRT1 is associated with tumor metastasis in several tumors. However, the effect of SIRT1 on the mechanism of metastasis in resistant esophageal cancer remains unclear. In this study, we demonstrated that increased migration and invasion in drug-resistant esophageal cancer cells (EC109/PTX, TE-1/PTX). Our experiments revealed that the selective SIRT1 inhibitor (EX527) significantly suppressed cells migrate and inhibited the occurrence of the epithelial-mesenchymal transition (EMT), thereby altering the invasiveness and metastatic potential of the esophageal cancer cell lines. In addition, we observed that the inhibition of SIRT1 could alter the expression of snail. In conclusion, these results indicate that SIRT1 may promote the transformation of tumor cells by inducing the EMT and may serve as a potential molecular target for the treatment of resistant esophageal cancer.CI - Copyright (c) 2018 Elsevier Masson SAS. All rights reserved.