QSAR Studies on the Inhibitory Activityof Levofloxacin-thiadiazole HDACi Conjugates to Histone Deacetylases

A molecular electronegativity distance vector(M)based on 13 atomic types has been used to describe the structures of 19 conjugates(LHCc)of levofloxacin-thiadiazole HDAC inhibitor(HDACi)and related inhibitory activities(pH,i=1,2,6)of LHCc against histone deacetylases(HDACs,such as HDAC1,HDAC2 and HDAC6).The quantitative structure-activity relationships(QSAR)were established by using leaps-and-bounds regression analysis for the inhibitory activities(pH)of 19 above compounds to HDAC1,HDAC2 and HDAC6 along with M.The correlation coefficients(R~2)and the leave-one-out(LOO)cross validation Rfor the pH,pHand pHmodels were 0.976 and 0.949;0.985 and 0.977;0.976 and 0.932,respectively.The QSAR models had favorable correlations,as well as robustness and good prediction capability by R~2,F,R~2,A,Fand Vtests.Validated by using 3876 training sets,the models have good external prediction ability.The results indicate that the molecular structural units:–CH–(g=1,2),–NH,–OH,=O,–O–and–S–are the main factors which can affect the inhibitory activity of pH,pHas well as pHbioactivities of these compounds directly.Accordingly,the main interactions between HDACs inhibitor and HDACs are hydrophobic interaction,hydrogen bond,and coordination with Znto form compounds,which is consistent with the results in reports.

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.

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 inhibitor MS-275 alone or combined with bortezomib or sorafenib exhibits strong antiproliferative action in human cholangiocarcinoma cells

AIM: To investigate the antiproliferative effect of the histone deacetylase (HDAC) inhibitor MS-275 on cholangiocarcinoma cells alone and in combination with conventional cytostatic drugs (gemcitabine or doxorubicin) or the novel anticancer agents sorafenib or bortezomib. METHODS: Two human bile duct adenocarcinoma cell lines (EGI-1 and TFK-1) were studied. Crystal violet staining was used for detection of cell number changes. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase (LDH). Apoptosis was determined by measuring the enzyme activity of caspase-3. Cell cycle status reflected by the DNA content was detected by flow cytometry.RESULTS: MS-275 treatment potently inhibited the proliferation of EGI-1 and TFK-1 cholangiocarcinoma cells by inducing apoptosis and cell cycle arrest. MS-275-induced apoptosis was characterized by activation of caspase-3, up-regulation of Bax and down-regulation of Bcl-2. Cell cycle was predominantly arrested at the G1/S checkpoint, which was associated with induction of the cyclin-dependent kinase inhibitor p21Waf/CIP1. Furthermore, additive anti-neoplastic effects were observed when MS-275 treatment was combined with gemcitabine or doxorubicin, while combination with the multi-kinase inhibitor sorafenib or the proteasome inhibitor bortezomib resulted in overadditive anti-neoplastic effects.CONCLUSION: The growth of human cholangiocarcinoma cells can be potently inhibited by MS-275 alone or in combination with conventional cytostatic drugs or new, targeted anticancer agents.

Neuroprotective mechanism of TMP269, a selective class ⅡA histone deacetylase inhibitor, after cerebral ischemia/reperfusion injury

TMP269 is a selective class ⅡA histone deacetylase inhibitor that has a protective effect on the central nervous system, whose specific mechanism of action is unclear. We aimed to reveal the optimal concentration of TMP269 for protecting against cerebral ischemia/reperfusion injury and its neuroprotective mechanism. Male Sprague-Dawley rats were randomly divided into sham, ischemia/reperfusion, and 1, 4, 10 and 16 mg/kg TMP269 groups. Cerebral ischemia/reperfusion injury was induced by middle cerebral artery occlusion. TMP269 was intraperitoneally administered at different doses 0.5 hours before ischemia induction. Western blot assay and immunohistochemistry were used to detect effects of TMP269 on histone 2 acetylation. The results showed that the level of histone 2 acetylation was increased 24 hours after TMP269 injection. 2,3,5-Triphenyltetrazolium chloride staining was utilized to examine effect of TMP269 on infarct volume. The results found that different doses of TMP269 could reduce the infarct volume. Western blot assay, immunohistochemistry and Evans blue staining were employed to measure the effect of TMP269 on blood-brain barrier. The results showed that TMP269 counteracted the abnormal endothelial cell permeability changes caused by cerebral ischemia/reperfusion. Western blot assay and immunohistochemistry were used to determine the effect of TMP269 on tissue kallikrein. The results found that TMP269 up-regulated the expression of tissue kallikrein. Western blot assay further determined the optimal concentration to be 4 mg/kg. In conclusion, TMP269 plays a neuroprotective role by up-regulating the level of histone 2 acetylation, alleviating endothelial cell injury after cerebral ischemia/reperfusion, and up-regulating the expression of tissue kallikrein. The experimental protocol was approved in 2014 by the Department of Laboratory Animal Science, Fudan University, China(approval No. 20140143 C001).

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 inhibitor pre-treatment enhances the efficacy of DNA-interacting chemotherapeutic drugs in gastric cancer

BACKGROUND The prognosis of gastric cancer continues to remain poor,and epigenetic drugs like histone deacetylase inhibitors(HDACi)have been envisaged as potential therapeutic agents.Nevertheless,clinical trials are facing issues with toxicity and efficacy against solid tumors,which may be partly due to the lack of patient stratification for effective treatments.To study the need of patient stratification before HDACi treatment,and the efficacy of pre-treatment of HDACi as a chemotherapeutic drug sensitizer.METHODS The expression activity of class 1 HDACs and histone acetylation was examined in human gastric cancer cells and tissues.The potential combinatorial regime of HDACi and chemotherapy drugs was defined on the basis of observed drug binding assays,chromatin remodeling and cell death.RESULTS In the present study,the data suggest that the differential increase in HDAC activity and the expression of class 1 HDACs are associated with hypoacetylation of histone proteins in tumors compared to normal adjacent mucosa tissue samples of gastric cancer.The data highlights for the first time that pretreatment of HDACi results in an increased amount of DNA-bound drugs associated with enhanced histone acetylation,chromatin relaxation and cell cycle arrest.Fraction-affected plots and combination index-based analysis show that pre-HDACi chemo drug combinatorial regimes,including valproic acid with cisplatin or oxaliplatin and trichostatin A with epirubicin,exhibit synergism with maximum cytotoxic potential due to higher cell death at low combined doses in gastric cancer cell lines.CONCLUSION Expression or activity of class 1 HDACs among gastric cancer patients present an effective approach for patient stratification.Furthermore,HDACi therapy in pretreatment regimes is more effective with chemotherapy drugs,and may aid in predicting individual patient prognosis.

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.

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.

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.

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.

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.

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.

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.

The histone deacetylase inhibitor trichostatin A induces cell cycle arrest and rapid upregulation of gadd45β in LS174T human colon cancer cells

Histone deacetylase (HDAC) inhibitors are considered as promising therapeutic agents against several malignant diseases because they inhibit cancer cell proliferation. The stress sensor genes of the growth arrest and DNA damage-inducible protein (gadd45) family exhibit disordered expression in several types of malignant diseases and are thus a novel target for cancer therapy. However, there have been only few investigations of whether HDAC inhibitors affect the expression of gadd45 genes. We examined the effects of a HDAC inhibitor, trichostatin A (TSA), on the time-dependent expression of gadd45 genes in the human colon cancer cell line LS174T. Addition of TSA to LS174T cells induced inhibition of cell proliferation by arresting the cell cycle. We found that TSA treatment of LS174T cells induced rapid upregulation of gadd45β mRNA expression within 15 min, reaching a peak level at 3 h. Although the time-dependent expression pattern of gadd45β mRNA was similar to that of gadd45β mRNA, the peak level of gadd45β was lower than that of gadd45β. TSA treatment also upregulated the mRNA level of p21Waf1/Cip1, a prolif- eration inhibitor, after 3 h, but downregulated the mRNA levels of cyclin D1, a proliferation inducer, after 3 h, and of c-Myc after 1 h. TSA treatment induced a certain level of apoptosis, but the mRNA level of p53, a potent apoptosis inducer, was down-regulated after 3 h. These results suggest that the up-regulation of p21Waf1/Cip1 and apoptosis was independent of p53 and that the early upregulation of gadd45β gene, which precedes the upregulation of p21Waf1/Cip1 and the downregulation of cyclin D1, are important in TSA-treated LS174T cells.

Inhibitory Effect of Histone Deacetylase Inhibitor on the Proliferation of Leukemia Cells and Its Anti-Tumor Pharmacology

The aim of this study was to explore the inhibitory effect of histone deacetylase inhibitor (HDACI) on the proliferation of leukemia cells. The two kinds of leukemia cells (human promyelocytic leukemia cell (HL-60) and human acute myelogenous leukemia cell (KG-1)) were selected for in vitro research. Besides, Chidamide, a kind of benzamide HDACI, was applied to induce and culture the HL-60 and KG-1 cells, and the anti-tumor cell proliferation activity of Chidamide on HL-60 and KG-1 was detected by the methyl thiazolyl tetrazolium (MTT) assay, which was 5.6 and 6.1 in turn. The cell scratch experiment verified that Chidamide had the metastasis inhibitory effect on HL-60 and KG-1 cells. Flow cytometry was employed to measure the percentage of apoptotic cells, and it was found that the percentage of apoptotic cells was 55.6% ± 1% and 48.6% ± 1% in sequence after HL-60 and KG-1 cells were treated with Chidamide for 36 hours. The number of auto-phagosomes was determined by transmission electron microscopy showing that the number of auto-phagosomes in HL-60 and KG-1 cells was 12 ± 1 and 10 ± 1, respectively after the induction process of Chidamide. The phosphorylated histone H2AX protein (γ-H2AX) recognition antibody immunofluorescence method was adopted to determine the deoxyribonucleic acid (DNA) damage, and the positive rates of HL-60 and KG-1 cells reached 28.41% and 26.35%, respectively after Chidamide treatment. Therefore, Chidamide, as a kind of HDACI, could effectively inhibit the proliferation of leukemia cells, so that the results of this experiment had a good guiding meaning for the clinical diagnosis and treatment of leukemia.

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.

Novel histone deacetylase inhibitor exhibits antitumor activity via apoptosis induction in oral squamous cell carcinoma

Epigenetic modifications such as histone deacetylation are commonly related to tumor development and histone deacetylase (HDAC) inhibitors have been shown to be potential drugs for cancer treatment. In the present study, we investigated the effects of a novel HDAC inhibitor, Ky-2, on oral squamous carcinoma cells in vitro. Cell viability was significantly reduced by treatment with Ky-2 at 25 nM, while it also led to augmentation of the proportion of cells in the sub-G1 phase and DNA fragmentation. In addition, immunoblot analysis revealed that Ky-2 enhanced the expression of apoptosis-related proteins. Our results showed that a low concentration of Ky-2 induced apoptosis in oral squamous carcinoma cells via activation of apoptotic cascades.