Current evidence for histone deacetylase inhibitors in pancreatic cancer

Pancreatic cancer is one of the most aggressive human cancers,with more than 200 000 deaths worldwide every year.Despite recent efforts,conventional treatment approaches,such as surgery and classic chemotherapy,have only slightly improved patient outcomes.More effective and well-tolerated therapies are required to reverse the current poor prognosis of this type of neoplasm.Among new agents,histone deacetylase inhibitors (HDACIs) are now being tested.HDACIs have multiple biological effects related to acetylation of histones and many non-histone proteins that are involved in regulation of gene expression,apoptosis,cell cycle progression and angiogenesis.HDACIs induce cell cycle arrest and can activate the extrinsic and intrinsic pathways of apoptosis in different cancer cell lines.In the present review,the main mechanisms by which HDACIs act in pancreatic cancer cells in vitro,as well as their antiproliferative effects in animal models are presented.HDACIs constitute a promising treatment for pancreatic cancer with encouraging anti-tumor ef-fects,at well-tolerated doses.

Drug repurposing of histone deacetylase inhibitors that alleviate neutrophilic inflammation in acute lung injury and idiopathic pulmonary fibrosis via inhibiting leukotriene a4 hydrolase and blocking LTB4 biosynthesis

OBJECTIVE Leukotriene B4(LTB4)biosynthesis and subsequently neutrophilic inflammation may provide a potential strategy for the treatment of acute lung injury(ALI)or idiopathic pulmonary fibrosis(IPF).To provide a potential strategy for the treatment of ALI or IPF,we identified potent inhibitors of Leukotriene A4 hydrolase(LTA4H),a key enzyme in the biosynthesis of LTB4.METHODS In this study,we identified two known histone deacetylase(HDAC)inhibitors,suberanilohydroxamic acid(SAHA)and its analogue 4-(dimethylamino)-N-[7-(hydroxyamino)-7-oxoheptyl]benzamide(M344),as effective inhibitors of LTA4H using enzymatic assay,thermofluor assay,and X-ray crystallographic investigation.We next tested the effect of SAHA and M344 on endogenous LTB4 biosynthesis in neutrophils by ELISA and neutrophil migration by transwell migration assay.A murine experimental model of ALI was induced by lipopolysaccharide(LPS)inhalation.Histopathological analysis of lung tissue using H&E staining revealed the serious pulmonary damage caused by LPS treatment and the effect of the SAHA.We next examined m RNA and protein levels of pro-inflammatory cytokines in lung tissue and bronchoalveolar lavage fluid using q RT-PCR and ELISA to further investigate the underlying mechanisms of anti-inflammatory activities by SAHA.We also investigated the effects of SAHA and M344 on a murine experimental model of bleomycin(BLM)-induced IPF model.RESULTS The results of enzymatic assay and X-ray crystallography showed that both SAHA and M344 bind to LTA4H,significantly decrease LTB4 levels in neutrophil,and markedly diminish early neutrophilic inflammation in mouse models of ALI and IPF under a clinical safety dose.CONCLUSION Collectively,SAHA and M344 would provide promising agents with well-known clinical safety for potential treatment in patients with ALI and IPF via pharmacologically inhibiting LAT4H and blocking LTB4 biosynthesis.

Induction of Myelogenous Leukemia Cells with Histone Deacetylase Inhibitors through Down-regulating the Daxx Protein Expression

The effects of two different histone deacetylase （HDAC） inhibitors, sodium butyrate （NAB） and trichostatin A （TSA）,on apoptosis of human leukemic cells in vitro and the molecular mechanisms were investigated. The experiments were divided up 5 groups： control group, NaB group, TSA group, NaB＋Z-VAD-FMK group and TSA＋Z-VAD-FMK group. The apoptosis rate was determined by mor- phological analysis and flow cytomytry. The expression of Daxx, Bcl-2, and Bcl-xl proteins was detected by Western blot. NaB and TSA could induce the apoptosis of HL-60 and K562 cells, and Z-VAD-FMK caused a marked decrease in apoptosis induced by HDAC inhibitors. HDAC inhibitors could down-regulate the expression of Daxx protein, but had no significant influence on the expression of Bcl-2 and Bcl-xl proteins. The results suggested that NaB and TSA induce distinct caspase-dependent apoptosis of human leukemic cells through down-regulating the expression of Daxx protein in vitro.

Determination of Fragmentation Schemes and Metabolites of Fluorinated Histone Deacetylase Inhibitors for Use as Positron Emission Tomography Imaging Agents Using HPLC-MS/MS

High performance liquid chromatography coupled with tandem mass spectrometry was developed and validated as a method for the analysis of fluorinated histone deacetylase inhibitors (F-HDACi), and then employed to study their metabolism in biosystems. Four HDACi analogs labeled with the positron emission nuclide 18F constitute a group of potential positron emission tomography imaging agents, which were developed by the Institute of Nuclear Energy Research (INER) and coded as INER-1577 #1, #2, #3, and #4 during animal studies for the diagnosis of dementia. The performance of the method was found to be suitable for the determination of analog #3, and it was employed to determine the structures and fragmentation mechanisms of all four analogs and to study the biotransformations of analogs #3 and #4. The results indicated that the method used for the determination of analog #3 was suitable for determining the abundance of the analogs in chemical and biochemical tests with high precision, accuracy, reproducibility, and recovery. Weaknesses in the chemical bonding of the analogs were found to involve the fluoro, dimethylamino, and benzamide groups in a fragmentation mechanism deduced via tandem mass spectrometry. The metabolites of analogs #3 and #4 in rat liver microsomes and rat plasma were also identified to clarify their characteristic behaviors in biosystems. The major product of analogs #3 in liver microsomes was produced by hydroxylation of the benzylic carbon atom, but in rat plasma the metabolites of analog #3 were produced by hydrolysis of the benzamide group to give a diaminobiphenyl compound with the simultaneous replacement of a fluorine atom by a hydroxyl group. The metabolites of analog #4 in liver microsomes were produced by hydroxylation of the benzylic carbon atom and hydrolysis of the benzamide bond. The results of the studies characterized the chemical and biochemical behaviors of the series F-HADCi analogs.

Experimental treatment of pancreatic cancer with two novel histone deacetylase inhibitors

AIM:To investigate in vitro and in vivo treatment with histone deacetylase inhibitors NVP-LAQ824 and NVP-LBH589 in pancreatic cancer. METHODS:Cell-growth inhibition by NVP-LAQ824 and NVP-LBH589 was studied in vitro in 8 human pancreatic cancer cell lines using the 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide(MTT) assay. In addition,the anti-tumoral effect of NVP-LBH589 was studied in a chimeric mouse model. Anti-tumoral activity of the drugs was assessed by immunoblotting for p21WAF-1,acH4,cell cycle analysis,TUNEL assay,and immunohistochemistry for MIB-1. RESULTS:In vitro treatment with both compounds significantly suppressed the growth of all cancer cell lines and was associated with hyperacetylation of nucleosomal histone H4,increased expression of p21WAF-1,cell cycle arrest at G2/M-checkpoint,and increased apoptosis. In vivo,NVP-LBH589 alone significantly reduced tumor mass and potentiated the efficacy of gemcitabine. Further analysis of the tumor specimens revealed slightly increased apoptosis and no significant reduction of cell proliferation.CONCLUSION:Our findings suggest that NVP-LBH589 and NVP-LAQ824 are active against human pancreatic cancer,although the precise mechanism of in vivo drug action is not yet completely understood. Therefore,further preclinical and clinical studies for the treatment of pancreatic cancer are recommended.

Combined inhibitors of angiogenesis and histone deacetylase:Efficacy in rat hepatoma

AIM:To evaluate the antitumoral effect of combined inhibitors of angiogenesis and histone deacetylases in an experimental rat hepatoma model.METHODS:MH7777A hepatoma cells were injected into the liver of male Buffalo rats.After 7 d treatment with the vascular endothelial growth factor receptor antagonist PTK787/ZK222584(PTK/ZK),the histone deacetylase inhibitor MS-275,tamoxifen(TAM) and/or retinoic acid was initiated(n ≥ 8 animals/group).Natural tumor development was shown in untreated control groups(control 1 with n = 12,control 2 with n = 8).The control groups were initiated at different time points to demonstrate the stability of the hepatoma model.For documentation of possible side effects,we documented any change in body weight,loss of fur and diarrhea.After 21 d treatment,the rats were euthanized.Main target parameters were tumor size and metastasis rate.Additionally,immunohistochemistry for the proliferating cell nuclear antigen(PCNA) and TdT-mediated dUTP-biotin nick end labeling(TUNEL) assay were performed.RESULTS:The control groups developed large tumor nodules with extrahepatic tumor burden in the lung and abdominal organs(control 1:6.18 cm3 ± 4.14 cm3 and control 2:8.0 cm3 ± 4.44 cm3 28 d after tumor cell injection).The tumor volume did not differ significantly in the control groups(P = 0.13).As single agents MS-275 and PTK/ZK reduced tumor volume by 58.6% ± 2.6% and 48.7% ± 3.2% vs control group 1,which was significant only for MS-275(P = 0.025).The combination of MS-275 and PTK/ZK induced a nearly complete and highly significant tumor shrinkage by 90.3% ± 1%(P = 0.005).Addition of TAM showed no further efficacy,while quadruple therapy with retinoic acid increased antitumoral efficacy(tumor reduction by 93 ± 1%) and side effects.PCNA positive cells were not significantly reduced by the single agents,while dual therapy(MS-275 and PTK/ZK) and quadruple therapy reduced the PCNA-positive cell fraction significantly by 9.1 and 20.6% vs control 1(P < 0.05).The number of TUNEL-positive cells,markers for ongoing apoptosis,was increased significantly by the single agents(control 1:6.9%,PTK/ZK:11.4%,MS-275:12.2% with P < 0.05 vs control 1).The fraction of TUNEL-positive cells was upregulated highly significantly by dual therapy(18.4%) and quadruple therapy(24.8%,P < 0.01 vs control 1).For the proliferating(PCNA positive) and apoptotic cell fraction,quadruple therapy was significantly superior to dual therapy(P = 0.01).CONCLUSION:Combined PTK/ZK and MS-275 were highly effective in this hepatoma model.Quadruple therapy enhanced the effects microscopically,but not macroscopically.These results should be investigated further.

Effects of histone deacetylase inhibitors on transcriptional regulation of the hsp70 gene in Drosophila

Histone acetyltransferases/deacetylases contribute to the activation or inactivation of transcription by modifying the structure of chromatin. Here we examined the effects ofhistone deacetylase inhibitors （HDIs）, trichostatin A, and sodium butyrate on hsp70 gene transcriptional regulation in Drosophila. The chromatin immunoprecipitation assays revealed that HDI treatments induced the hyperacetylation of histone H3 at the promoter and the transcribing regions of hsp 70 gene, increased the accessibility of heat-shock factor to target heat-shock element, and promoted the RNA polymerase Ⅱ-mediated transcription. Moreover, the quantitative real-time PCR confirmed that the HDI-induced hyperacetylation of histone H3 enhanced both the basal and the inducible expression of hsp70 mRNA level. In addition, the acetylation level ofhistone H3 at the promoter exhibited a fluctuated change upon the time of heat shock. These experimental data implicated a causal link between histone acetylation and enhanced transcription initiation of hsp 70 gene in Drosophila.

Synergy of DNA methylation and histone deacetylase inhibitors in the re-expression of RASSF1A and P16 genes silenced in QBC cells

Objective: To investigate the effects of DNA methylation and histone deacetylase inhibitors in the re-expression of P16 and RASSIF1A of QBC939. Methods: The QBC939 cells were treated with hydralazine and valproate either alone or combined, and the control group was added with RPIM-1640 culture medium. After 48 h, the expression of P16 and RASSF1A genes were evaluated by reverse transcription-PCR, Western blot, and the methylation status of the two genes were detected with MSP (methylation specific PCR). Results: Hydralazine and valproate could induce demethylation of the promoter region of the two genes, and could make them re-active. The expressions of P16 and RASSF1A of cells treated with both drugs were higher than that of the cells treated with either hydralazine or valproate (P < 0.01). There was no RASSF1A gene, and few P16 gene expressing in the control group. The demethylation effect could be found in the groups treated with hydralazine or both drugs, whereas no demethylation effect happened in the valproate group. Conclusion: The two drugs could synergistically re-express P16 and RASSF1A genes silenced in QBC939, and they exerted a great anti-tumour effect on QBC cells.

Progress in clinical trial of histone deacetylase(HDAC) inhibitors for non-small cell lung cancers

Histone deacetylase(HDAC) inhibitors, which represent a structurally diverse group of molecules, have emerged as a novel therapeutic class of molecules with significant anticancer potential. Vorinostat and romidepsin, known as the first generation of HDAC inhibitors, were approved in the United States for the treatment of T-cell lymphomas. Preliminary activity of HDAC inhibitors has also been observed in non-small cell lung cancer(NSCLC) in combination with the existing treatment regimens, of which is the focus of the current review.

Enhanced autophagic clearance of amyloid-βvia histone deacetylase 6-mediated V-ATPase assembly and lysosomal acidification protects against Alzheimer's disease in vitro and in vivo

Recent studies have suggested that abnormal acidification of lysosomes induces autophagic accumulation of amyloid-βin neurons,which is a key step in senile plaque formation.Therefore,resto ring normal lysosomal function and rebalancing lysosomal acidification in neurons in the brain may be a new treatment strategy for Alzheimer's disease.Microtubule acetylation/deacetylation plays a central role in lysosomal acidification.Here,we show that inhibiting the classic microtubule deacetylase histone deacetylase 6 with an histone deacetylase 6 shRNA or thehistone deacetylase 6 inhibitor valproic acid promoted lysosomal reacidification by modulating V-ATPase assembly in Alzheimer's disease.Fu rthermore,we found that treatment with valproic acid markedly enhanced autophagy.promoted clearance of amyloid-βaggregates,and ameliorated cognitive deficits in a mouse model of Alzheimer's disease.Our findings demonstrate a previously unknown neuroprotective mechanism in Alzheimer's disease,in which histone deacetylase 6 inhibition by valproic acid increases V-ATPase assembly and lysosomal acidification.

Deacetylase inhibitors-focus on non-histone targets and effects

Inhibitors of protein deacetylases have recently been established as a novel therapeutic principle for several human diseases,including cancer.The original notion of the mechanism of action of these compounds focused on the epigenetic control of transcriptional processes, especially of tumor suppressor genes,by interfering with the acetylation status of nuclear histone proteins,hence the name histone deacetylase inhibitors was coined.Yet,this view could not explain the high specificity for tumor cells and recent evidence now suggests that non-histone proteins represent major targets for protein deacetylase inhibitors and that the post-translational modification of the acetylome is involved in various cellular processes of differentiation,survival and cell death induction.

Histone deacetylase inhibitors and pancreatic cancer:Are there any promising clinical trials?

Pancreatic cancer,although not very frequent,has an exceptionally high mortality rate,making it one of the most common causes of cancer mortality in developed countries.Pancreatic cancer is difficult to diagnose,allowing few patients to have the necessary treatment at a relatively early stage.Despite a marginal benefit in survival,the overall response of pancreatic cancer to current systemic therapy continues to be poor,and new therapies are desperately needed.Histone deacetylase(HDAC) enzymes play an important role in the development and progression of cancer and HDAC inhibitors(HDACIs) have been shown to induce differentiation and cell cycle arrest,activate the extrinsic or intrinsic pathways of apoptosis,and inhibit invasion,migration and angiogenesis in different cancer cell lines.As a result of promising preclinical data,various HDACIs are being tested as either monotherapeutic agents or in combination regimens for both solid and hematological malignancies.Vorinostat was the first HDACI approved by the Food and Drug Administration for patients with cutaneous T-cell lymphoma.The use of HDACIs in clinical trials,in pretreated and relapsed patients suffering from advanced pancreatic cancer is discussed.Unfortunately,clinical data for HDACIs in patients with pancreatic cancer are inadequate,because only a few studies have included patients suffering from this type of neoplasm and the number of pancreatic cancer patients that entered HDACIs phase Ⅱ/Ⅲ trials,among others with advanced solid tumors,is very limited.More studies recruiting patients with pancreatic cancer remain to determine the efficiency of these therapies.

Histone deacetylase inhibitors as a novel therapeutic approach for pheochromocytomas and paragangliomas

Epigenetic mechanisms,such as DNA methylation and histone modifications(e.g.,acetylation and deacetylation),are strongly implicated in the carcinogenesis of various malignancies.During transcription,the expression and functionality of coding gene products are altered following the histone acetylation and deacetylation.These processes are regulated by histone acetyltransferases(HATs)and histone deacetylases(HDACs),respectively.HDAC inhibitors(HDACis)have been developed as promising therapeutic agents,to limit exposure to traditional and toxic chemotherapies and offer more alternatives for some specific malignant diseases with limited options.Mechanistically,these agents affect many intracellular pathways,including cell cycle arrest,apoptosis and differentiation,and their mechanism of action mainly depends on the type of cancer.Currently,five HDACis have been approved for the treatment of several hematological malignancies(e.g.,T-cell lymphoma subtypes and multiple myeloma);while,many of them are tested for further therapeutic indications in solid tumors(e.g.,colorectal,thyroid,breast,lung and pancreatic cancer).Herein,we review the literature and gather all available evidence,from in vitro and in vivo data to clinical trial results,that recognizes the antitumor activity of HDACis on pheochromocytomas and paragangliomas;and supports their clinical implementation in the treatment of these rare neuroendocrine tumors at metastatic setting.

Down-regulation of histone deacetylase 7 reduces biological activities of retinal microvascular endothelial cells under high glucose condition and related mechanism

AIM:To investigate the expression and effect of histone deacetylase 7(HDAC7)in human retinal microvascular endothelial cells(HRMECs)under high glucose condition and related mechanism,and the expression of HDAC7 in the retinal tissue in diabetic rats.METHODS:The expression of HDAC7 in HRMECs under high glucose and the retinal tissue from normal or diabetic rats were detected with immunohistochemistry and Western blot.LV-shHDAC7 HRMECs were used to study the effect of HDAC7 on cell activities.Cell count kit-8(CCK-8),5-ethynyl2’-deoxyuridine(EdU),flow cytometry,scratch test,Transwell test and tube formation assay were used to examine the ability of cell proliferation,migration,and angiogenesis.Finally,a preliminary exploration of its mechanism was performed by Western blot.RESULTS:The expression of HDAC7 was both upregulated in retinal tissues of diabetic rats and high glucosetreated HRMECs.Down-regulation of HDAC7 expression significantly reduced the ability of proliferation,migration,and tube formation,and reversed the high glucose-induced high expression of CDK1/Cyclin B1 and vascular endothelial growth factor in high glucose-treated HRMECs.CONCLUSION:High glucose can up-regulate the expression of HDAC7 in HRMECs.Down-regulation of HDAC7 can inhibit HRMECs activities.HDAC7 is proposed to be involved in pathogenesis of diabetic retinopathy and a therapeutic target.

Novel hybrids from N-hydroxyarylamide and indole ring through click chemistry as histone deacetylase inhibitors with potent antitumor activities

Novel hybrid molecules 8a-8o were designed and synthesized by connecting indole ring with N- hydroxyarylamide through alkyl substituted triazole, and their in vitro biological activities were evaluated. It was discovered that most of target compounds showed promising anticancer activities, particularly for 8n, which had a significant HDACs inhibitory and antiproliferative activities comparable to or slightly stronger than SAHA against human carcinoma cells. Furthermore, compound 8n exhibited much better selectivity for HDAC1 over HDAC6 and HDAC8 than SAHA. In addition, compound 8n also could dose-dependently induce cancer cell cycling arrest at G0/G1 phase and promote the expression of the acetylation for histone H3 and tubulin in vitro. Therefore, our novel findings may provide a new framework for the design of new selective HDAC inhibitor for the treatment of cancer.

Concept of histone deacetylases in cancer:Reflections on esophageal carcinogenesis and treatment

Esophageal cancer (EC) presents a high mortality rate, mainly due to its aggressive nature. Squamous cell carcinoma is the most common histological type world-wide, though, a continuous increase in esophageal adenocarcinomas has been noted in the past decades. Common risk factors associated with EC include smoking, alcohol consumption, gastroesophageal reflux disease, Barrett's esophagus and obesity. In an effort to overcome chemotherapy resistance in oncology, it was discovered that histone acetylation/deacetylation equilibrium is altered in carcinogenesis, leading to changes in chromatin structure and altering expression of genes important in the cell cycle, differentiation and apoptosis. Based on this knowledge, histone acetylation was addressed as a potential novel chemotherapy drug target to repress cancer cell proliferation. There are four classes of histone deacetylases (HDACs) inhibitors with a variety of different mechanisms of actions that render them possible anticancer drugs. They arrest the cell cycle, inhibit differentiation and angiogenesis and induce apoptosis. They do not necessarily act on histone proteins, since they can also exert indirect anti-cancer effects, by modifying various cellular proteins.In addition,HDACs have also been associated with increased chemotherapy resistance.Based on the literature,HDACs have been associated with EC,with surveys revealing that increased expression of certain HDACs correlates with advanced TNM stages,tumor grade,metastatic potential and decreased 5-year overall and disease-free survival.The aim of this survey is to elucidate the molecular identity and mechanism of action of HDAC inhibitors as well as verify their potential utility as anti-cancer agents in esophageal cancer.

Targeting pancreatic cancer immune evasion by inhibiting histone deacetylases

The immune system plays a vital role in maintaining the delicate balance between immune recognition and tumor development.Regardless,it is not uncommon that cancerous cells can intelligently acquire abilities to bypass the antitumor immune responses,thus allowing continuous tumor growth and development.Immune evasion has emerged as a significant factor contributing to the progression and immune resistance of pancreatic cancer.Compared with other cancers,pancreatic cancer has a tumor microenvironment that can resist most treatment modalities,including emerging immunotherapy.Sadly,the use of immunotherapy has yet to bring significant clinical breakthrough among pancreatic cancer patients,suggesting that pancreatic cancer has successfully evaded immunomodulation.In this review,we summarize the impact of genetic alteration and epigenetic modification(especially histone deacetylases,HDAC)on immune evasion in pancreatic cancer.HDAC overexpression significantly suppresses tumor suppressor genes,contributing to tumor growth and progression.We review the evidence on HDAC inhibitors in tumor eradication,improving T cells activation,restoring tumor immunogenicity,and modulating programmed death 1 interaction.We provide our perspective in targeting HDAC as a strategy to reverse immune evasion in pancreatic cancer.

Molecular mechanism revealing therapeutic opportunities of histone deacetylases inhibitors in triple-negative breast cancer

Subject Code:H31With the support by the National Natural Science Foundation of China,Ministry of Science and Technology of China and Chinese Academy of Sciences,the research team led by Prof.Geng Meiyu(耿美玉)and Ding Jian(丁健)from Shanghai Institute of Materia Medica,Chinese Academy of Sciences,demonstrated the therapeutic opportunities of histone deacetylases(HDACs)inhibitors in

Peanut testa extracts enhance anticancer effect of cisplatin against human cholangiocarcinoma cells via modulation of histone deacetylase inhibitory activity

Objective:To investigate the effect of combination treatments of cisplatin and KK4 and ICG15042 peanut testa extracts against cholangiocarcinoma cells in vitro.Methods:The growth inhibition,cell cycle arrest and apoptosis of cholangiocarcinoma cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry analysis,respectively.The levels of proteins involved in apoptosis were assessed using Western blotting assays.The caspase activity was assessed using a colorimetric caspase activity assay.Results:Cisplatin and peanut(KK4 and ICG15042)testa extracts inhibited the growth of cholangiocarcinoma cell lines(KKUM214 and KKU-100 cells)in a dose-and time-dependent manner.The combination treatments reduced cell viability and induced apoptosis of cholangiocarcinoma cells more efficiently than singledrug treatments.Cancer cell death synergistically mediated by cisplatin and peanut testa extracts was observed in KKU-M214 cells(combination index<1.0)but not in KKU-100 cells(combination index>1.0).The combination treatments also increased the subG1 population and caused KKU-M214 cell cycle arrest at S and G2/M phases,which were the combined effects of cisplatin(S phase arrest)and peanut testa extracts(G2/M phase arrest).In addition,p ERK1/2,Ac-H3,Bcl-2 and proteins related to apoptosis,including Bax and caspases 3,8,9,exhibited enhanced expression in KKUM214 cells.The combination treatments caused down-regulation of p53,whereas the expression of p21 was fairly constant when compared with cisplatin single drug treatment.Conclusions:Peanut testa extracts in combination with cisplatin synergistically reduce cell viability and induce apoptosis through stimulation of caspases 3,8 and 9 in KKU-M214 cells.

The expression of histone deacetylases and the regenerative abilities of spinal-projecting neurons after injury

Epigenetic control of regeneration after spinal cord injury： Com- plete spinal cord injury （SCI） in humans and other mammals leads to irreversible paralysis below the level of injury, due to failure of axonal regeneration in the central nervous system （CNS）. Previous work has shown that successful axon regeneration is dependent upon transcription of a large number of regeneration-associated genes （RAGs） and transcription factors （TFs） （Van Kesteren et al., 2011）. A prominent theory in the field of axon regeneration is that the large differences in regenerative potential between peripheral nervous system （PNS） neurons, which regenerate well, and CNS neurons, which do not, reflect differences in intrinsic transcriptional net- works, rather than individual genes （Van Kesteren et al., 2011）.