Suberoylanilide Hydroxamic Acid Treatment Research Articles

Anticancer effects of suberoylanilide hydroxamic acid in esophageal squamous cancer cellsin vitroandin vivo

The effects of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, have not been studied in esophageal squamous cell cancer (ESCC). Cell viability assay; flow cytometry for cell cycle and annexin V apoptosis assays; assays for cell migration, invasion, and adhesion to extracellular matrix (ECM); and immunoblotting and immunofluorescence staining were performed in three ESCC cell lines. Tumor xenograft with semiquantitative immunohistochemistry was used to study the effects of SAHA in vivo. SAHA effectively inhibited growth of ESCC cells with half-inhibitory concentrations (IC50 ) ranging from 2.6 to 6.5 μmol/L. SAHA restored acetylation of histone 3 lysine 9 (H3K9Ac) and histone 4 lysine 12 (H4K12Ac) with an induction of G1 or G2 cell cycle arrest and apoptosis. Expression of cell cycle checkpoint regulatory proteins including cyclin-dependent kinases (CDKs) and cyclins was decreased, whereas expression of cell cycle suppressors, p21, p27, and Rb was increased in ESCC cells after SAHA treatment. SAHA inhibited migration, invasion, and ECM adhesion in ESCC cells with an induction of E-cadherin expression. SAHA significantly inhibited growth of ESCC tumors with increased expression of p21, p27, Rb, and E-cadherin while decreasing expression of CDK4 and cyclin D1 within the murine tumors. In conclusion, SAHA had antigrowth activity against ESCC cells in vitro and in vivo while inhibiting cell migration, cell invasion, and ECM adhesion, suggesting its potential as an epigenetic therapeutic agent for ESCC.

SAHA Treatment Reveals the Link between Histone Lysine Acetylation and Proteome in Nonsmall Cell Lung Cancer A549 Cells

Suberoylanilide hydroxamic acid (SAHA) is a well-known pan HDAC inhibitor, and its clinical application (Vorinostat) has been demonstrated to treat nonsmall cell lung cancer (NSCLS). Nevertheless, the impact of SAHA treatment on histone lysine acetylation and proteome in NSCLS cells still need further elucidate. In NSCLS A549 cells, by using stable isotope labeling for cell culture (SILAC)-based quantitative proteomics, biochemistry assay, and bioinformatic analysis, here we for the first time comprehensively identified and quantified histone lysine acetylation in A549 cells toward SAHA treatment. Despite the fact that SAHA treatment significantly increased histone lysine acetylation in specific sites, unexpectedly, some important "histone markers" showed markedly decreased acetylation level. Further quantitative proteome studies showed that among totally quantifiable 2818 nonredundant proteins, 1355 proteins were with increased level and 1463 with decreased level in response to SAHA treatment. Bioinformatic analysis further revealed that those quantifiable proteins were mainly involved in multiple biological functions and metabolic and enzyme-regulated pathways as well as protein complexes. By establishing the link between histone modification and whole proteome in response to SAHA treatment in NSCLS cells, this study therefore may deepen our understanding of HDAC inhibitor-mediated cancer therapeutics.

Abstract 354: Acetylation Regulates miR-133a Expression In Cardiac Hypertrophy

Background: The expression level of several microRNAs (miRNAs) is affected by pressure overload hypertrophy and has an impact on cardiac function. Histone deacetylases (HDACs) regulate the transcription of many genes whose expression is altered in hypertrophy. Therefore, we hypothesize that acetylation regulates the expression of some miRs during cardiac hypertrophy . Methods: Transverse aortic constriction (TAC) was performed to initiate cardiac hypertrophy induced by pressure overload. Mice were treated with the Class I and IIb HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) in the drinking water post-TAC for 2 and 4 weeks. miRNAs expression normalized to RNU6B was determined by qRT-PCR. Echocardiography was performed at baseline and post-TAC endpoints to assess physiological parameters. Chromatin immunoprecipitation (ChIP) was used to identify HDACs and transcription factors associated with miR-133a promoter. Results: Based on previous studies, we selected 8 miRNAs that play major roles in hypertrophy and assessed the effect of SAHA treatment on their expression level. The expression of one of the miRNAs, miR-133a was significantly (P < 0.05) downregulated at both 2 weeks (1887 ±105, n=8) and 4 weeks post-TAC (1651 ±103, n=9) compared to control group (2972 ±334, n=11). SAHA treatment significantly de-repressed miR-133a expression 2 weeks post-TAC (3317 ±560, n=12) and to a lesser extent after 4 weeks post-TAC (2391 ±455, n=10). As expected, left atrium (LA) diameter, a marker of diastolic pressure, increased 2 weeks post-TAC, while SAHA treatment significantly reduced LA diameter. miR-133a targets connective tissue growth factor (CTGF) and collagen 1a1. Consistent with SAHA-mediated miR-133a de-repression, CTGF expression and collagen volume fraction were decreased compared to TAC alone. Importantly, ChIP analysis revealed that HDAC2 was present on the miR-133a promoter. Conclusion: We show that HDAC2, a Class I HDAC, plays a role in the regulation of miR-133a expression in cardiac hypertrophy. HDACs and miRNAs are key regulators of the events mediating cardiac pathology. Our work demonstrates that HDAC inhibition may be an attractive therapeutic strategy for the regulation of some miRNAs in heart disease.

SAHA Enhances Synaptic Function and Plasticity In Vitro but Has Limited Brain Availability In Vivo and Does Not Impact Cognition

Suberoylanilide hydroxamic acid (SAHA) is an inhibitor of histone deacetylases (HDACs) used for the treatment of cutaneous T cell lymphoma (CTCL) and under consideration for other indications. In vivo studies suggest reducing HDAC function can enhance synaptic function and memory, raising the possibility that SAHA treatment could have neurological benefits. We first examined the impacts of SAHA on synaptic function in vitro using rat organotypic hippocampal brain slices. Following several days of SAHA treatment, basal excitatory but not inhibitory synaptic function was enhanced. Presynaptic release probability and intrinsic neuronal excitability were unaffected suggesting SAHA treatment selectively enhanced postsynaptic excitatory function. In addition, long-term potentiation (LTP) of excitatory synapses was augmented, while long-term depression (LTD) was impaired in SAHA treated slices. Despite the in vitro synaptic enhancements, in vivo SAHA treatment did not rescue memory deficits in the Tg2576 mouse model of Alzheimer’s disease (AD). Along with the lack of behavioral impact, pharmacokinetic analysis indicated poor brain availability of SAHA. Broader assessment of in vivo SAHA treatment using high-content phenotypic characterization of C57Bl6 mice failed to demonstrate significant behavioral effects of up to 150 mg/kg SAHA following either acute or chronic injections. Potentially explaining the low brain exposure and lack of behavioral impacts, SAHA was found to be a substrate of the blood brain barrier (BBB) efflux transporters Pgp and Bcrp1. Thus while our in vitro data show that HDAC inhibition can enhance excitatory synaptic strength and potentiation, our in vivo data suggests limited brain availability may contribute to the lack of behavioral impact of SAHA following peripheral delivery. These results do not predict CNS effects of SAHA during clinical use and also emphasize the importance of analyzing brain drug levels when interpreting preclinical behavioral pharmacology.

Novel pharmacologic treatment attenuates septic shock and improves long-term survival

We have demonstrated previously that suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improves survival in a lipopolysaccharide-induced lethal model of endotoxemia. The goal of this study was to investigate the impact of SAHA on survival in a more clinically relevant model of cecal ligation and puncture (CLP)-induced septic shock and to elucidate changes in cytokine responses and organ injury. C57BL/6J mice were subjected to CLP, and 1 hour later were given intraperitoneally either SAHA dissolved in dimethyl sulfoxide or dimethyl sulfoxide only. Survival was monitored for 10 days. In a second study, livers were harvested for evaluation of acute liver injury, and peritoneal fluid and blood samples were collected for cytokine assays. In addition, RAW264.7 and bone marrow-derived macrophages were used to assess effects of SAHA on cytokine responses. SAHA-treated animals displayed a substantial improvement in survival. In addition, SAHA also attenuated cytokine levels in blood and peritoneal fluid compared with vehicle animals, as well as in culture supernatant of macrophages stimulated with bacterial components (lipopolysaccharide or Pam3CSK4). Moreover, SAHA-treated animals showed a substantial decrease in acute liver injury. SAHA treatment improves survival, decreases "cytokine storm," and prevents distant organ damage in a lethal septic model.

Suppressive effect of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) on hepatitis C virus replication

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has a clinical promise for treatment of cancer including hepatocellular carcinoma (HCC). To investigate effect of SAHA on hepatitis C virus (HCV) replication, we treated the HCV replicon cell OR6 with SAHA. HCV replication was significantly inhibited by SAHA at concentrations below 1 μM with no cellular toxicity. Another HDAC inhibitor, tricostatin A, also showed reduction of HCV replication. The microarray analysis and quantitative RT-PCR demonstrated up-regulation of osteopontin (OPN) and down-regulation of apolipoprotein-A1 (Apo-A1) after SAHA treatment. Direct gene induction of OPN and knockdown of Apo-A1 also showed reduction of HCV replication. The liver specific microRNA-122, which is involved in HCV replication, was not affected by SAHA treatment. These results suggest that SAHA has suppressive effect on HCV replication through alterations of gene expression such as OPN and Apo-A1 in host cells. Epigenetic treatment with HDAC inhibitors may be a novel therapeutic approach for diseases associated with HCV infection such as chronic hepatitis, liver cirrhosis, and HCC.

Prenatal exposure to suberoylanilide hydroxamic acid perturbs corticogenesis

Suberoylanilide hydroxamic acid (SAHA) is one of the epidrugs developed for cancer treatment that works epigenetically by inhibiting histone deacetylases (HDACs). SAHA has been reported to diffuse across the placenta and found in fetal plasma in preclinical study, implying that it can influence fetus if taken by pregnant cancer patients. However, report regarding this aspect and the study of in utero HDAC inhibition by SAHA especially on fate specification of neural stem/progenitor cells within the developing mammalian cortex, is yet unavailable. Here we show that transient exposure of SAHA to mouse embryos during prominent neurogenic period resulted in an enhancement of cortical neurogenesis, which is accompanied by an increased expression of proneuronal transcription factor Neurog1. Neurogenesis was enhanced due to the increase number of proliferating Tbr2+ intermediate progenitor cells following SAHA exposure. In this relation, we observed that SAHA perturbed neonatal cortical lamination because of the increased production of Cux1+ and Satb2+ upper-layer neurons, and decreased that of Ctip2+ deep-layer neurons. Furthermore, an upper-layer neuronal lineage determinant Satb2 was also up-regulated, whereas those of deep-layer ones Fezf2 and Ctip2 were down-regulated by SAHA treatment. Taken together, our study suggests that proper regulation of HDACs is important for precise embryonic corticogenesis.

Combined treatment with SAHA, bortezomib, and clarithromycin for concomitant targeting of aggresome formation and intracellular proteolytic pathways enhances ER stress-mediated cell death in breast cancer cells

The ubiquitin–proteasome pathway and the autophagy–lysosome pathway are two major intracellular protein degradation systems. We previously reported that clarithromycin (CAM) blocks autophagy flux, and that combined treatment with CAM and proteasome inhibitor bortezomib (BZ) enhances ER-stress-mediated apoptosis in breast cancer cells, whereas treatment with CAM alone results in almost no cytotoxicity. Since HDAC6 is involved in aggresome formation, which is recognized as a cytoprotective response serving to sequester misfolded proteins and facilitate their clearance by autophagy, we further investigated the combined effect of vorinostat (suberoylanilide hydroxamic acid (SAHA)), which has a potent inhibitory effect for HDAC6, with CAM and BZ in breast cancer cell lines. SAHA exhibited some cytotoxicity along with an increased acetylation level of α-tubulin, a substrate of HDAC6. Combined treatment of SAHA, CAM, and BZ potently enhanced the apoptosis-inducing effect compared with treatment using each reagent alone or a combination of two of the three. Expression levels of ER-stress-related genes, including the pro-apoptotic transcription factor CHOP (GADD153), were maximally induced by the simultaneous combination of three reagents. Like breast cancer cell lines, a wild-type murine embryonic fibroblast (MEF) cell line exhibited enhanced cytotoxicity and maximally up-regulated Chop after combined treatment with SAHA, CAM, and BZ; however, a Chop knockout MEF cell line almost completely canceled this enhanced effect. The specific HDAC6 inhibitor tubacin also exhibited a pronounced cytocidal effect with a combination of CAM plus BZ. These data suggest that simultaneous targeting of intracellular proteolytic pathways and HDAC6 enhances ER-stress-mediated apoptosis in breast cancer cells.

Inhibition of proliferation, sprouting, tube formation and Tie2 signaling of lymphatic endothelial cells by the histone deacetylase inhibitor SAHA

Histone deacetylase (HDAC) inhibitors exert potent inhibitory effects on various types of human cancer. The pioneer drug suberoylanilide hydroxamic acid (SAHA) is currently used in the clinic for cancer treatment. However, the effect of SAHA on tumor lymphangiogenesis is unclear. We recently showed that SAHA suppresses the expression and production of pro-lymphagenic factor vascular endothelial growth factor‑C (VEGF-C) in breast cancer cells. In the present study, the effect of SAHA on lymphatic endothelial cells (LECs) was examined. We generated a lymphatic-like endothelial cell line (named FP01) by overexpressing the master LEC transcription factor PROX1 in EA.hy926 endothelial cells. This cell line exhibited a gene expression pattern and phenotype similar to primarily cultured LECs. SAHA inhibited cell cycle progression and proliferation of FP01 cells. In addition, SAHA suppressed sprouting and tube formation in these cells. Moreover, SAHA attenuated the angiopoietin (Ang)/Tie signaling pathway which plays important roles in the regulation of LEC function. FP01 cells expressed Ang1, Ang2, Tie1 and Tie2, and SAHA dose-dependently reduced the expression of Tie2 in these cells. Tie2 promoter activity was attenuated by SAHA indicating a transcriptional repression. Importantly, Tie2 protein was significantly reduced by SAHA at the concentration in which no alteration of Tie2 mRNA was detected. We found that SAHA enhanced Tie2 protein degradation via the ubiquitin-proteasome pathway, and the expression of c-Cbl, the E3 ligase for Tie2 ubiquitination, rapidly increased after SAHA treatment. Knockdown of c-Cbl reversed SAHA‑induced Tie2 protein degradation. Taken together, our results demonstrate that SAHA impairs the proliferation, sprouting and tube formation of LECs and attenuates Ang/Tie signaling in LECs by downregulating Tie-2 via transcriptional and post-transcriptional mechanisms.

Constitutive Somatostatin Receptor Subtype 2 Activity Attenuates GH Synthesis

Somatostatin signals predominantly through somatostatin receptor (SSTR) subtype 2 to attenuate GH release. However, the independent role of the receptor in regulating GH synthesis is unclear. Because we had previously demonstrated constitutive SSTR2 activity in mouse corticotrophs, we now analyzed GH regulation in rat pituitary somatotroph (GC) tumor cells, which express SSTR2 exclusively and are devoid of endogenous somatostatin ligand. We demonstrate that moderately stable SSTR2 overexpression (GpSSTR2(WT) cells) was associated with decreased GH promoter activity, GH mRNA, and hormone levels compared with those of control transfectants (GpCon cells). In contrast, levels of GH mRNA and peptide and GH promoter activity were unchanged in GpSSTR2(DRY) stable transfectants moderately expressing DRY motif mutated SSTR2 (R140A). GpSSTR(2DRY) did not exhibit an enhanced octreotide response as did GpSSTR2(WT) cells; however, both SSTR2(WT)-enhanced yellow fluorescent protein (eYFP) and SSTR2(DRY)-eYFP internalized on octreotide treatment. Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, increased GH synthesis in wild-type GC cells and primary pituitary cultures. GpSSTR2(WT) cells induced GH synthesis more strongly on SAHA treatment, evident by both higher GH peptide and mRNA levels compared with the moderate but similar GH increase observed in GpCon and GpSSTR2(DRY) cells. In vivo SAHA also increased GH release from GpSSTR2(WT) but not from control xenografts. Endogenous rat GH promoter chromatin immunoprecipitation showed decreased baseline acetylation of the GH promoter with exacerbated acetylation after SAHA treatment in GpSSTR2(WT) compared with that of either GpSSTR(2DRY) or control cells, the latter 2 transfectants exhibiting similar GH promoter acetylation levels. In conclusion, modestly increased SSTR2 expression constitutively decreases GH synthesis, an effect partially mediated by GH promoter histone deacetylation.

Abstract 4889: Alteration of cancer stem cell-like phenotype by histone deacetylase inhibitors in squamous cell carcinoma of the head and neck.

Abstract Recent progression in the understanding of stem cell biology has greatly facilitated the identification and characterization of cancer stem cells (CSCs) from various tumors. In squamous cell carcinoma of the head and neck (SCCHN), various cell surface markers, including CD44, CD133 and ALDH1, have been identified as the potential markers to isolate CSCs. Evidence has accumulated indicating that conventional cancer treatments are potentially ineffective against CSCs. Histone deacetylase inhibitors (HDACi) have multiple biologic effects consequent to alteration in patterns of acetylation of histones and are promising new group of anticancer agents. In this study, we investigate the effects of two HDACi, suberoylanilide hydroxamic acid (SAHA) and trichostatin A (TSA) on two CD44+ cancer stem-like cell lines from SCCHN cultured in serum-free medium containing epidermal growth factor and basic fibroblast growth factor. SAHA and TSA inhibited the growth of SCCHN cell lines in a dose dependent manner as measured by MTS assays. Moreover, SAHA and TSA induced G2/M cell cycle arrest and apoptosis in these SCCHN cell lines. Interestingly, the expression of cancer stem cell markers, CD44 and ABCG2 on SCCHN cell lines were decreased by SAHA or TSA treatment. HDACi also decreased the mRNA expression levels of stemness-related genes (Notch and Nanog) and TGF-β. As expected, HDACi markedly increased the expression of E-cadherin. In addition, the combination of HDACi and chemotherapeutic agents, including cisplatin and docetaxel had a synergistic effect on SCCHN cell lines. Taken together, our data indicate that HDACi not only inhibit the growth of SCCHN cell lines by inducing apoptosis and cell cycle arrest, but also alter stem-like properties of the SCCHN cells, raising the possibility that HDACi may have therapeutic potentials for cancer stem cells of SCCHN. Citation Format: Koichi Sakakura, Takaaki Murata, Kazuaki Chikamatsu. Alteration of cancer stem cell-like phenotype by histone deacetylase inhibitors in squamous cell carcinoma of the head and neck. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4889. doi:10.1158/1538-7445.AM2013-4889

Abstract 1725: HDAC inhibition induces Bim expression and apoptosis in breast cancer cells undergoing paclitaxel or antiestrogen treatment.

Abstract Paclitaxel functions by preventing microtubule degradation, leading to mitotic arrest and apoptotic death. Of particular interest, paclitaxel-induced death in breast cancer cells is dependent, in part, on the levels of BimEL, a pro-apoptotic member of the Bcl-2 family of proteins. In addition, our recent studies demonstrated that BimEL is required for 4-hydroxytamoxifen-induced apoptosis of estrogen receptor positive (ER+) MCF-7 breast cancer cells [Breast Cancer Res. 2012 Mar 19;14(2):R52]. In contrast, we demonstrated low-level BimEL expression in ER+ T47D breast cancer cells that do not undergo antiestrogen-induced apoptosis. Thus, low-level BimEL expression in ER+ breast cancer may predict a poor apoptotic threshold which ultimately would facilitate the development of acqured resistance to paclitaxel, as well as antiestrogen therapy. Based on the ability of HDAC inhibitors to increase the transcription of pro-apoptotic genes, we hypothesized that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) would increase BimEL expression in T47D breast cancer cells and induce a robust apoptotic response to paclitaxel chemotherapy and antiestrogen treatment. In this study, we now demonstrate that SAHA does significantly up-regulate BimEL expression in T47D cells, as well as in MCF-7 cells. Concomitant with BimEL upregulation, SAHA sensitizes T47D and MCF-7 cells to paclitaxel-induced apoptosis. Similarly, SAHA sensitizes T-47D cells to antiestrogen-induced apoptosis, while augmenting the level of antiestrogen-induced apoptosis in MCF-7 cells. These studies indicate that the pro-apoptotic protein BimEL is required for SAHA-induced sensitization of breast cancer cells to paclitaxel and/or antiestrogen-induced apoptosis. Currently, siRNA studies are being conducted to determine if BimEL is a key death effector in response to SAHA treatment and if the increased death from SAHA and paclitaxel or SAHA and antiestrogens is synergistic or additive. Our results provide strong support for the use of HDAC inhibitors when designing novel combination therapies to reduce the emergence of acquired resistance in breast cancer cells undergoing chemo- or antihormonal therapy. Acknowledgement: this work was supported by teh MCG foundation and NIHRO1 CA121438 to P.V.S. Citation Format: Aric Berning, Alexander Eason, Nathan Gilley, Suchreet Takhar, Sally ElShafey, Muthusamy Thangaraju, Patricia V. Schoenlein. HDAC inhibition induces Bim expression and apoptosis in breast cancer cells undergoing paclitaxel or antiestrogen treatment. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1725. doi:10.1158/1538-7445.AM2013-1725

Suberoylanilide hydroxamic acid induces limited changes in the transcriptome of primary CD4+ T cells

To assess the off-target effects of the histone deacetylase inhibitor (HDACi) suberoylanilide hydroxamic acid (SAHA) in human primary CD4 T cells. A pharmacologically relevant concentration (340 nmol/l) of SAHA was shown to significantly increase histone hyperacetylation by 24 h and this length of treatment was selected to determine its impact on gene expression in primary CD4 T cells. Illumina Beadchips for microarray gene expression analysis were used to analyze differential gene expression between cells treated or not with SAHA with a paired analysis using multivariate permutation tests. Gene ontology, biological pathway and protein interaction network analyses were used to identify the higher order biological processes affected by SAHA treatment. Modest modulation by SAHA was observed for 1847 genes with 80% confidence level of no more than 10% false positives. A thousand genes were upregulated by SAHA and 847 downregulated. Pathways and gene ontologies overrepresented in the list of differentially expressed genes included Glycolysis/Gluconeogenesis, tRNA Modification, and the Histone Acetyltransferase Complex. Protein interaction network analysis revealed that transcription factor c-Myc, which was downregulated by SAHA treatment at the mRNA level, interacts with a number of SAHA-responsive genes. The effects on transcription by SAHA were sufficiently modest to support trials to activate HIV replication as part of an eradication strategy. SAHA did not appear to modulate proliferative or apoptotic processes to a great extent, which might impact the ability of patients to eradicate the virus reservoir following activation by HDACi treatment.

Epigenetic Regulation of Opioid-Induced Hyperalgesia, Dependence, and Tolerance in Mice

Repeated administration of opioids such as morphine induces persistent behavioral changes including opioid-induced hyperalgesia (OIH), tolerance, and physical dependence. In the current work we explored how the balance of histone acetyltransferase (HAT) versus histone deacetylase (HDAC) might regulate these morphine-induced changes. Nociceptive thresholds, analgesia, and physical dependence were assessed during and for a period of several weeks after morphine exposure. To probe the roles of histone acetylation, the HAT inhibitor curcumin or a selective HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) was administered daily to groups of animals. Histone acetylation in spinal cord was assessed by Western blot and immunohistochemistry. Concurrent administration of curcumin with morphine for 4 days significantly reduced development of opioid-induced mechanical allodynia, thermal hyperalgesia, tolerance, and physical dependence. Conversely, the HDAC inhibitor SAHA enhanced these responses. Interestingly, SAHA treatment after the termination of opioid administration sustained these behavioral changes for at least 4 weeks. Histone H3 acetylation in the dorsal horn of the spinal cord was increased after chronic morphine treatment, but H4 acetylation was unchanged. Moreover, we observed a decrease in HDAC activity in the spinal cords of morphine-treated mice while overall HAT activity was unchanged, suggesting a shift toward a state of enhanced histone acetylation. PerspectiveThe current study indicates that epigenetic mechanisms play a crucial role in opioid-induced long-lasting neuroplasticity. These results provide new sight into understanding the mechanisms of opioid-induced neuroplasticity and suggest new strategies to limit opioid abuse potential and increase the value of these drugs as analgesics.

Proteins implicated in the increase of adhesivity induced by suberoylanilide hydroxamic acid in leukemic cells

We have previously shown that suberoylanilide hydroxamic acid (SAHA) treatment increases the adhesivity of leukemic cells to fibronectin at clinically relevant concentrations. Now, we present the results of the proteomic analysis of SAHA effects on leukemic cell lines using 2-DE and ProteomLab PF2D system. Histone acetylation at all studied acetylation sites reached the maximal level after 5 to 10 h of SAHA treatment. No difference in histone acetylation between subtoxic and toxic SAHA doses was observed. SAHA treatment induced cofilin phosphorylation at Ser3, an increase in vimentin and paxillin expression and a decrease in stathmin expression as confirmed by western-blotting and immunofluorescence microscopy. The interaction of cofilin with 14-3-3 epsilon was documented using both Duolink system and coimmunoprecipitation. However, this interaction was independent of cofilin Ser3 phosphorylation and the amount of 14-3-3-ε-bound cofilin did not rise following SAHA treatment. SAHA-induced increase in the cell adhesivity was associated with an increase in PAK phosphorylation in CML-T1 cells and was abrogated by simultaneous treatment with IPA-3, a PAK inhibitor. The effects of SAHA on JURL-MK1 cells were similar to those of other histone deacetylase inhibitors, tubastatin A and sodium butyrate. The proteome analysis also revealed several potential non-histone targets of histone deacetylases.

Suberoylanilide hydroxamic acid (SAHA) as an agent to attenuate Toll-like receptor 4–induced septic shock

Severe sepsis and septic shock are still associated with high mortality despite the advancement of antibiotics and critical care. Macrophages detect bacterial lipopolysaccharide (LPS) by a mechanism mediated by Toll-like receptor 4 (TLR4). This receptor causes activation of proinflammatory cascade and production of proteins and cytokines, such as myeloid differentiation primary response gene 88 (MyD88), interleukin (IL)-1 (including IL-1 receptor-associated kinase [IRAK]-1), tumor necrosis factor receptor-associated factor 6, and nuclear factor-κB (NF-κB), which can lead to robust and potentially exaggerated immune response of the body. In a paper recently published in the Journal of Surgical Research, Chong et al. show that suberoylanilide hydroxamic acid (SAHA) can improve survival of LPS-induced septic shock in mice, but the mechanism of this has largely been unknown [ [1] Chong W. Li Y. Liu B. et al. Histone deacetylase inhibitor suberoylanilide hydroxamic acid attenuates Toll-like receptor 4 signaling in lipopolysaccharide-stimulated mouse macrophages.. J Surg Res. 2012; 178: 851 Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar ]. In this in vitro study, they demonstrated that treatment of SAHA significantly reduced the MyD88 and IRAK-1 production as well as the nuclear translocation of NF-κB and, eventually, production of tumor necrosis factor (TNF)-α and IL-6, thus attenuating the LPS/TLR4 signaling cascade by inhibiting the upstream proteins. It was also demonstrated that SAHA acetylated heat shock protein (HSP) 90, which is another component of the proinflammatory pathway. Acetylation of HSP90 inhibits its interaction with IRAK1, which in turn leads to degradation of IRAK-1, thus potentially causing impairment of TLR4-activated inflammatory pathway [ [1] Chong W. Li Y. Liu B. et al. Histone deacetylase inhibitor suberoylanilide hydroxamic acid attenuates Toll-like receptor 4 signaling in lipopolysaccharide-stimulated mouse macrophages.. J Surg Res. 2012; 178: 851 Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar ]. Histone deacetylase inhibitor suberoylanilide hydroxamic acid attenuates Toll-like receptor 4 signaling in lipopolysaccharide-stimulated mouse macrophagesJournal of Surgical ResearchVol. 178Issue 2PreviewWe have previously demonstrated that pretreatment and posttreatment of animals with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, can improve survival in a mouse model of lipopolysaccharide (LPS)-induced severe shock. This study was designed to assess whether SAHA affects LPS/Toll-like receptor 4 signaling through acetylation of heat shock protein 90 (HSP90) and degradation of its client protein interleukin-1 receptor–associated kinase 1 (IRAK1). Full-Text PDF

Creating a “pro-survival” phenotype through epigenetic modulation

We demonstrated recently that treatment with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, improved survival in a rodent model of lipopolysaccharide (LPS)-induced endotoxic shock. The precise mechanisms, however, have not been well-defined. The aim of this study was to investigate the impact of SAHA treatment on gene expression profiles at an early stage of shock. Male C57BL/6J mice were treated with or without SAHA (50 mg/kg, IP), followed by a lethal dose of LPS (20 mg/kg, IP) and a second dose of SAHA. Lungs of the animals (LPS and SAHA+LPS groups; n= 3 per group) were harvested 3 hours post-LPS insult. Sham mice (no LPS and no SAHA) served as controls. RNA was isolated from the tissues and gene expression was analyzed using Affymatrix microarray (23,000 genes). A lower confidence bound of fold change was determined for comparison of LPS versus SAHA + LPS, and genes with a lower confidence bound of >2 were considered to be differentially expressed. Reverse transcriptase polymerase chain reaction, Western blotting, and tissue staining were performed to verify the key changes. Network graphs were used to determine gene interaction and biologic relevance. The expression of many genes known to be involved in septic pathophysiology changed after the LPS insult. Interestingly, a number of genes not implicated previously in the septic response were also altered. SAHA treatment attenuated expression of several key genes involved in inflammation. It also decreased neutrophil infiltration in lungs and histologic evidence of acute lung injury. Further analysis confirmed genes engaged in the cellular and humoral arms of the innate immune system were specifically inhibited by SAHA. Gene network analysis identified numerous molecules for the potential development of targeted therapies. Administration of SAHA in a rodent model of LPS shock rapidly modulates gene transcription, with an attenuation of inflammatory mediators derived from both arms (cellular and humoral) of the innate immune system. This may be a novel mechanism responsible for the survival advantage seen with SAHA treatment.

Abstract 158: Regulation of miR-21 Expression by Acetylation in Myocardial Infarction

Cardiovascular diseases are one of the leading causes of morbidity and mortality in the world, underlining the need for innovative therapies and diagnosis. Recent reports have identified microRNAs (miRNAs) as central players in regulating gene expression and showed that several miRNAs are aberrantly expressed in cardiac arrhythmia, hypertrophy, fibrosis, ischemia, vascular atherosclerosis and heart failure. Gene expression is also regulated at the transcriptional level by histone deacetylases (HDACs) under basal and pathological conditions. We previously demonstrated that 1) class I and class II HDACs play an important role in the basal expression and upregulation of the sodium-calcium exchanger (Ncx1) gene in adult cardiomyocytes and pressure-overloaded ventricle and 2) treatment with class I/IIb HDAC inhibitors trichostatin (TSA) or suberoylanilide hydroxamic acid (SAHA) improved ventricular function by suppressing matrix metalloproteinases (MMPs) gene expression in myocardial infarction (MI).Therefore it is possible that protein acetylation regulates the expression of some miRNAs and we hypothesize that HDAC inhibition would attenuate the shift in expression of certain miRNAs that are aberrantly expressed post-MI. In a pilot study, ligation of the left anterior descending (LAD) coronary artery was performed to induce MI with and without SAHA treatment. Because of its misregulation and relevance in cardiac hypertrophy and MI, we examined the expression level of miR-21. qRT-PCR confirmed that miR-21 is increased by 8 fold 7 days post-MI. Interestingly, SAHA treatment significantly attenuated the abnormal expression of miR-21. To our knowledge, it is the first report of the regulation of a miRNA by HDACs in the heart. We anticipate that not only miR-21 but other miRNAs will fall under the same mechanistic control via acetylation. The miR-21 promoter contains binding sites for several transcription factors that get acetylated and we speculate that one or more HDAC mediate the expression of miR-21 by controlling the acetylation state of transcription factors interacting with the miR-21 promoter.

REST is a novel prognostic factor and therapeutic target for medulloblastoma.

Medulloblastoma is a malignant pediatric brain tumor. Current treatment following patient stratification into standard and high-risk groups using clinical features has improved survival. However, a subset of patients with standard risk features have unanticipated aggressive disease, underscoring the need for a better understanding of tumor biology and the development of novel treatments. Poor differentiation, a hallmark of medulloblastomas is associated with elevated expression levels of the repressor of neuronal differentiation called repressor element 1-silencing transcription factor (REST). Here, we assessed whether elevated REST expression levels had prognostic significance and whether its pharmacologic manipulation would promote neurogenesis and block tumor cell growth. REST levels in patient tumors were measured by immunohistochemistry and stratified into negative, low/moderate- (+/++/+++), and high-REST (+++++) groups. Kaplan-Meier curves revealed that patients with high-REST tumors had worse overall and event-free survival compared with patients with REST-negative or REST-low tumors. Because histone deacetylases (HDAC) are required for REST-dependent repression of neurogenesis, we evaluated a panel of HDAC inhibitors (HDACI) for their effects on growth and differentiation of established and primary REST-positive cell lines. MS-275, trichostatin-A (TSA), valproic acid (VPA), and suberoylanilide hydroxamic acid (SAHA) upregulated expression of the REST-target neuronal differentiation gene, Syn1, suggesting a potential effect of these HDACIs on REST function. Interestingly, VPA and TSA substantially increased histone acetylation at the REST promoter and activated its transcription, whereas SAHA unexpectedly promoted its proteasomal degradation. A REST-dependent decrease in cell growth was also observed following SAHA treatment. Thus, our studies suggest that HDACIs may have therapeutic potential for patients with REST-positive tumors. This warrants further investigation.

Histone deacetylase inhibitor suberoylanilide hydroxamic acid attenuates Toll-like receptor 4 signaling in lipopolysaccharide-stimulated mouse macrophages

ObjectiveWe have previously demonstrated that pretreatment and posttreatment of animals with suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, can improve survival in a mouse model of lipopolysaccharide (LPS)-induced severe shock. This study was designed to assess whether SAHA affects LPS/Toll-like receptor 4 signaling through acetylation of heat shock protein 90 (HSP90) and degradation of its client protein interleukin-1 receptor–associated kinase 1 (IRAK1). MethodsRAW264.7 cells were exposed to LPS (1 μg/mL) for 2 h, followed by treatment with SAHA (10 μM) or geldanamycin (3 μM), an inhibitor of HSP90. Sham (no SAHA, no LPS) macrophages served as a control. The cells were harvested at different time points, and time zero served as the reference point. ResultsLPS dramatically increased protein expression of myeloid differentiation factor 88 and IRAK1, and stimulated nuclear translocation of nuclear factor κB, leading to an increases of gene expression and protein production of tumor necrosis factor α and interleukin-6. Treatment with SAHA significantly attenuated these LPS-stimulated alterations. LPS or SAHA did not change the levels of HSP90 protein, but immunoprecipitation studies demonstrated that SAHA treatment enhanced acetylation of HSP90, and increased the dissociation of IRAK1, compared to the LPS control. ConclusionsSAHA suppresses LPS/Toll-like receptor 4 signaling in LPS-stimulated macrophages through multiple potential mechanisms. It inhibits the function of HSP90 through hyperacetylation of the chaperone protein, which results in dissociation and degradation of the client protein IRAK1 and, at least in part, leads to a decrease in nuclear translocation of nuclear factor κB and attenuation of key proinflammatory cytokine expression.