Aberrant regulation of HDAC2 mediates proliferation of hepatocellular carcinoma cells by deregulating expression of G1/S cell cycle proteins

Novel dual-targeting inhibitors of NSD2 and HDAC2 for the treatment of liver cancer: structure-based virtual screening, molecular dynamics simulation, and in vitro and in vivo biological activity evaluations

Liver cancer exhibits a high degree of heterogeneity and involves intricate mechanisms. Recent research has revealed the significant role of histone lysine methylation and acetylation in the epigenetic regulation of liver cancer development. In this study, five inhibitors capable of targeting both histone lysine methyltransferase nuclear receptor-binding SET domain 2 (NSD2) and histone deacetylase 2 (HDAC2) were identified using a structure-based virtual screening approach. Notably, DT-NH-1 displayed a potent inhibition of NSD2 (IC50 = 0.08 ± 0.03 μM) and HDAC2 (IC50 = 5.24 ± 0.87 nM). DT-NH-1 also demonstrated a strong anti-proliferative activity against various liver cancer cell lines, particularly HepG2 cells, and exhibited a high level of biological safety. In an experimental xenograft model involving HepG2 cells, DT-NH-1 showed a significant reduction in tumour growth. Consequently, these findings indicate that DT-NH-1 will be a promising lead compound for the treatment of liver cancer with epigenetic dual-target inhibitors.

HDAC2 promotes autophagy-associated HCC malignant progression by transcriptionally activating LAPTM4B

Hepatocellular carcinoma (HCC) is a significant global health challenge. The activation of autophagy plays an essential role in promoting the proliferation and survival of cancer cells. However, the upstream regulatory network and mechanisms governing autophagy in HCC remain unclear. This study demonstrated that histone deacetylase 2 (HDAC2) regulates autophagy in HCC. Its expression was elevated in HCC tissues, and high HDAC2 expression was strongly associated with poor prognosis in individuals with HCC. Integrated in vitro and in vivo investigations confirmed that HDAC2 promotes autophagy and autophagy-related malignant progression in HCC. Mechanistically, HDAC2 bound specifically to the lysosome-associated protein transmembrane 4-β (LAPTM4B) promoter at four distinct binding sites, enhancing its transcriptional activation and driving autophagy-related malignant progression in HCC. These findings establish LAPTM4B as a direct target gene of HDAC2. Furthermore, the selective inhibitor of HDAC2 effectively alleviated the malignant development of HCC. In addition, multivariate Cox regression analysis of 105 human HCC samples revealed that HDAC2 expression is an independent predictor of HCC prognosis. This study underscores the crucial role of the HDAC2-LAPTM4B axis in regulating autophagy in the malignant evolution of HCC and highlights the potential of targeting HDAC2 to prevent and halt the malignant progression of HCC.

HDAC2 as a Target for developing Anti-cancer Drugs

Histone deacetylases (HDACs) deacetylate histones H3 and H4. An imbalance between histone acetylation and deacetylation can lead to various diseases. HDAC2 is present in the nucleus. It plays a critical role in modifying chromatin structures and regulates the expression of various genes by functioning as a transcriptional regulator. The roles of HDAC2 in tumorigenesis and anti-cancer drug resistance are discussed in this review. Several reports suggested that HDAC2 is a prognostic marker of various cancers. The roles of microRNAs (miRNAs) that directly regulate the expression of HDAC2 in tumorigenesis are also discussed in this review. This review also presents HDAC2 as a valuable target for developing anti-cancer drugs.

Structure of pre-miR-31 reveals an active role in Dicer processing

As an essential post-transcriptional regulator of gene expression, microRNA (miR) levels must be strictly maintained. The biogenesis of many, but not all, miRs is mediated by trans-acting protein partners through a variety of mechanisms, including remodeling of the RNA structure. miR-31 functions as an oncogene in numerous cancers and interestingly, its biogenesis is not known to be regulated by protein binding partners. Therefore, the intrinsic structural properties of pre-miR-31 can provide a mechanism by which its biogenesis is regulated. We determined the solution structure of the precursor element of miR-31 (pre-miR-31) to investigate the role of distinct structural elements in regulating Dicer processing. We found that the presence or absence of mismatches within the helical stem do not strongly influence Dicer processing of the pre-miR. However, both the apical loop size and structure at the Dicing site are key elements for discrimination by Dicer. Interestingly, our NMR-derived structure reveals the presence of a triplet of base pairs that link the Dicer cleavage site and the apical loop. Mutational analysis in this region suggests that the stability of the junction region strongly influence both Dicer binding and processing. Our results enrich our understanding of the active role that RNA structure plays in regulating Dicer processing which has direct implications for control of gene expression.

Recent progress on FAK inhibitors with dual targeting capabilities for cancer treatment

Focal adhesion kinase (FAK, also known as PTK2) is a tyrosine kinase that regulates integrin and growth factor signaling pathways and is involved in the migration, proliferation and survival of cancer cells. FAK is a promising target for cancer treatment. Many small molecule FAK inhibitors have been identified and proven in both preclinical and clinical studies to be effective inhibitors of tumor growth and metastasis. There are many signaling pathways, such as those involving FAK, Src, AKT, MAPK, PI3K, and EGFR/HER-2, that provide survival signals in cancer cells. Dual inhibitors that simultaneously block FAK and another factor can significantly improve efficacy and overcome some of the shortcomings of single-target inhibitors, including drug resistance. In this review, the antitumor mechanisms and research status of dual inhibitors of FAK and other targets, such as Pyk2, IGF-IR, ALK, VEGFR-3, JAK2, EGFR, S6K1, and HDAC2, are summarized, providing new ideas for the development of effective FAK dual-target preparations.

MicroRNA-455-3p functions as a tumor suppressor by targeting HDAC2 to regulate cell cycle in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers. MicroRNA has been studied more and more deeply and may become a new target for the treatment of HCC. Here, we investigated the role of miR-455-3p in HCC progression. Compared with non-tumor tissues and normal human hepatic cells, miR-455-3p expression was significantly downregulated in HCC tissues and cell lines. And overexpression of miR-455-3p inhibited cell proliferation and migration but promoted cell apoptosis in HCC cell lines HepG2 and Huh7. Mechanism studies displayed that miR-455-3p targeted HDAC2 and negatively regulated HDAC2 expression. Moreover, HDAC2 was highly expressed in HCC tissues and cell lines. Overexpression of HDAC2 reversed the inhibitory effects of miR-455-3p on cell proliferation, migration and cell cycle protein (CDK6 and cyclin D1) expression, and neutralized the promotion effects of miR-455-3p on cell apoptosis and the activation of p53 pathway. Furthermore, a p53 inhibitor Pifithrin-α (PFT-α) effectively abolished the effects of miR-455-3p on HCC cell behaviors. Additionally, the role of miR-455-3p in tumorigenesis was evaluated by using a mouse xenograft model, and the data showed that miR-455-3p suppressed tumor growth in vivo. In summary, our results suggested that miR-455-3p targeted HDAC2 to inhibit cell proliferation, migration and promote cell apoptosis via the activation of p53 pathway.

A Novel Epithelial-Mesenchymal Transition Gene Signature Correlated With Prognosis, and Immune Infiltration in Hepatocellular Carcinoma

Background: Although many genes related to epithelial-mesenchymal transition (EMT) have been explored in hepatocellular carcinoma (HCC), their prognostic significance still needs further analysis. Methods: Differentially expressed EMT-related genes were obtained through the integrated analysis of 4 Gene expression omnibus (GEO) datasets. The univariate Cox regression and Lasso Cox regression models are utilized to determine the EMT-related gene signature. Based on the results of multivariate Cox regression, a predictive nomogram is established. Time-dependent ROC curve and calibration curve are used to show the distinguishing ability and consistency of the nomogram. Finally, we explored the correlation between EMT risk score and immune immunity. Results: We identified a nine EMT-related gene signature to predict the survival outcome of HCC patients. Based on the EMT risk score's median, HCC patients in each dataset were divided into high and low-risk groups. The survival outcomes of HCC patients in the high-risk group were significantly worse than those in the low-risk group. The prediction nomogram based on the EMT risk score has better distinguishing ability and consistency. High EMT risk score was related to immune infiltration. Conclusion: The nomogram based on the EMT risk score can reliably predict the survival outcome of HCC patients, thereby providing benefits for medical decisions.

The Role of SNHG15 in the Pathogenesis of Hepatocellular Carcinoma

Long non-coding RNAs (lncRNAs) are transcripts of more than 200 nucleotides which cannot be translated into proteins. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA whose dysregulation has been found to have an important impact on carcinogenesis and affect the prognosis of cancer patients in various cancer types. Hepatocellular carcinoma (HCC) is one of the most common cancers with a poor long-term prognosis, while the best prognostic factor of the disease is its early diagnosis and surgery. Consequently, the investigation of the mechanisms of hepatocarcinogenesis, as well as the discovery of efficient molecular markers and therapeutic targets are of great significance. An extensive literature search was performed in MEDLINE in order to identify clinical studies that tried to reveal the role of SNHG15 in HCC. We used keywords such as ‘HCC’, ‘hepatocellular carcinoma’, ‘SNHG15’ and ‘clinical study’. Finally, we included four studies written in English, published during the period 2016–2021. It was revealed that SNHG15 is related to the appearance of HCC via different routes and its over-expression affects the overall survival of the patients. More assays are required in order to clarify the potential role of SNHG15 as a prognostic tool and therapeutic target in HCC.

Identification of potent HDAC 2 inhibitors using E-pharmacophore modelling, structure-based virtual screening and molecular dynamic simulation

Histone deacetylase 2 (HDAC 2) of class I HDACs plays a major role in embryonic and neural developments. However, HDAC 2 overexpression triggers cell proliferation by diverse mechanisms in cancer. Over the decades, many pan and class-specific inhibitors of HDAC were discovered. Limitations such as toxicity and differential cell localization of each isoform led researchers to hypothesize that isoform selective inhibitors may be relevant to bring about desired effects. In this study, we have employed the PHASE module to develop an e-pharmacophore model and virtually screened four focused libraries of around 300,000 compounds to identify isoform selective HDAC 2 inhibitors. The compounds with phase fitness score greater than or equal to 2.4 were subjected to structure-based virtual screening with HDAC 2. Ten molecules with docking score greater than  -12 kcal/mol were chosen for selectivity study, QikProp module (ADME prediction) and dG/bind energy identification. Compound 1A with the best dock score of  -13.3 kcal/mol and compound 1I with highest free binding energy,  -70.93 kcal/mol, were selected for molecular dynamic simulation studies (40 ns simulation). The results indicated that compound 1I may be a potent and selective HDAC 2 inhibitor. Further, in vitro and in vivo studies are necessary to validate the potency of selected lead molecule and its derivatives.

Diagnostic performance of microRNA-34a, let-7f and microRNA-31 in epithelial ovarian cancer prediction

Objective

To correlate the genome-wide methylation signature of microRNA genes with dysregulated expression of selected candidate microRNA in tissue and serum samples of epithelial ovarian cancer (EOC) and control using quantitative reverse transcription polymerase chain reaction (qRT-PCR), and evaluation of EOC predictive value of candidate microRNA at an early stage.

Methods

We performed Methylated DNA Immunoprecipitation coupled with NGS (MeDIP-NGS) sequencing of 6 EOC and 2 normal tissue samples of the ovary. Expression of selected microRNA from tissue (EOC=85, normal=30) and serum (EOC=50, normal=15) samples was evaluated using qRT-PCR. We conducted bioinformatics analysis to identify the candidate miRNA’s potential target and functional role.

Results

MeDIP-NGS sequencing revealed hypermethylation of several microRNAs gene promoters. Three candidate microRNAs were selected (microRNA-34a, let-7f, and microRNA-31) from MeDIP-NGS data analysis based on log2FC and P-value. The relative expression level of microRNA-34a, let-7f, and microRNA-31 was found to be significantly reduced in early-stage EOC tissues and serum samples (p<0.0001). The receiver operating characteristic analysis of microRNA-34a, let-7f and miR-31 showed improved diagnostic value with area under curve(AUC) of 92.0 (p<0.0001), 87.9 (p<0.0001), and 85.6 (p<0.0001) and AUC of 82.7 (p<0.0001), 82.0 (p<0.0001), and 81.0 (p<0.0001) in stage III-IV and stage I-II EOC serum samples respectively. The integrated diagnostic performance of microRNA panel (microRNA-34a+let-7f+microRNA-31) in late-stage and early-stage serum samples was 95.5 and 96.9 respectively.

Conclusion

Our data correlated hypermethylation-associated downregulation of microRNA in EOC. In addition, a combined microRNA panel from serum could predict the risk of EOC with greater AUC, sensitivity, and specificity.

miR-34a, let-7f, and miR-31 promoters were significantly methylated in EOC samples. Significant reduced level of miR-34a, miR-31 and let-7f was observed in EOC samples. Individual and combined miRNA panel have higher diagnostic value for EOC prediction. miR-34a, let-7f and miR-31 can discriminate metastatic over non-metastatic samples.

Design, synthesis and biological evaluation of novel hybrids targeting mTOR and HDACs for potential treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major contributor to global cancer incidence and mortality. Many pathways are involved in the development of HCC and various proteins including mTOR and HDACs have been identified as potential drug targets for HCC treatment. In the present study, two series of novel hybrid molecules targeting mTOR and HDACs were designed and synthesized based on parent inhibitors (MLN0128 and PP121 for mTOR, SAHA for HDACs) by using a fusion-type molecular hybridization strategy. In vitro antiproliferative assays demonstrated that these novel hybrids with suitable linker lengths exhibited broad cytotoxicity against various cancer cell lines, with significant activity against HepG2 cells. Notably, DI06, an MLN0128-based hybrid, exhibited antiproliferative activity against HepG2 cells with an IC₅₀ value of 1.61 μM, which was comparable to those of both parent drugs (MLN0128, IC₅₀ = 2.13 μM and SAHA, IC₅₀ = 2.26 μM). In vitro enzyme inhibition assays indicated that DI06, DI07 and DI17 (PP121-based hybrid) exhibited nanomolar inhibitory activity against mTOR kinase and HDACs (e.g., HDAC1, HDAC2, HDAC3, HADC6 and HADC8). Cellular studies and western blot analyses uncovered that in HepG2 cells, DI06 and DI17 induced cell apoptosis by targeting mTOR and HDACs, blocked the cell cycle at the G0/G1 phase and suppressed cell migration. The potential binding modes of the hybrids (DI06 and DI17) with mTOR and HDACs were investigated by molecular docking. DI06 displayed better stability in rat liver microsomes than DI07 and DI17. Collectively, DI06 as a novel mTOR and HDACs inhibitor presented here warrants further investigation as a potential treatment of HCC.

Histone deacetylase 2 selective inhibitors: A versatile therapeutic strategy as next generation drug target in cancer therapy

Acetylation and deacetylation of histone and several non-histone proteins are the two important processes amongst the different modes of epigenetic modulation that are involved in regulating cancer initiation and development. Abnormal expression of histone deacetylases (HDACs) is often reported in various types of cancers. Few pan HDAC inhibitors have been approved for use as therapeutic interventions for cancer treatment including vorinostat, belinostat and panobinostat. However, not all the HDAC isoforms are abnormally expressed in certain cancers, such as in the case of, ovarian cancer where overexpression of HDAC1-3, lung cancer where overexpression of HDAC 1 and 3 and gastric cancer where overexpression of HDAC2 is seen. Therefore, pan-inhibition of HDAC is not an efficient way to combat cancer via HDAC inhibition. Hence, isoform-selective HDAC inhibition can be one of the best therapeutic strategies in the treatment of cancer. In this context since aberrant expression of HDAC2 largely contributes to cancer progression by silencing pro-apoptotic protein expressions such as NOXA and APAF1 (caspase 9-activating proteins) and inactivation of tumor suppressor p53, HDAC2 specific inhibitors may help to develop not only the direct targets but also indirect targets that are crucial for tumor development. However, to develop a HDAC2 specific and potent inhibitor, extensive knowledge of its structure and specific functions is essential. The present review updates details on the structural features, physiological functions, and roles of HDAC2 in different types of cancer, emphasizing the challenges and status of the development of HDAC2 selective inhibitors against various types of cancer.

A first-in-class anticancer dual HDAC2/FAK inhibitors bearing hydroxamates/benzamides capped by pyridinyl-1,2,4-triazoles

Novel 5-pyridinyl-1,2,4-triazoles were designed as dual inhibitors of histone deacetylase 2 (HDAC2) and focal adhesion kinase (FAK). Compounds 5d, 6a, 7c, and 11c were determined as potential inhibitors of both HDAC2 (IC₅₀ = 0.09-1.40 μM) and FAK (IC₅₀ = 12.59-36.11 nM); 6a revealed the highest activity with IC₅₀ values of 0.09 μM and 12.59 nM for HDAC2 and FAK, respectively. Compound 6a was superior to reference drugs vorinostat and valproic acid in its ability to inhibit growth/proliferation of A-498 and Caki-1 renal cancer cells. Further investigation proved that 6a strongly arrests the cell cycle at the G2/M phase and triggers apoptosis in both A-498 and Caki-1 cells. Moreover, the enhanced Akt activity that is observed upon chronic application of HDAC inhibitors was effectively suppressed by the dual HDAC2/FAK inhibitor. Finally, the high potency and selectivity of 6a towards HDAC2 and FAK proteins were rationalized by molecular docking. Taken together, these findings highlight the potential of 6a as a promising dual-acting HDAC2/FAK inhibitor that could benefit from further optimization.

Histone deacetylase‑2: A potential regulator and therapeutic target in liver disease (Review)

Histone acetyltransferases are responsible for histone acetylation, while histone deacetylases (HDACs) counteract histone acetylation. An unbalanced dynamic between histone acetylation and deacetylation may lead to aberrant chromatin landscape and chromosomal function. HDAC2, a member of class I HDAC family, serves a crucial role in the modulation of cell signaling, immune response and gene expression. HDAC2 has emerged as a promising therapeutic target for liver disease by regulating gene transcription, chromatin remodeling, signal transduction and nuclear reprogramming, thus receiving attention from researchers and clinicians. The present review introduces biological information of HDAC2 and its physiological and biochemical functions. Secondly, the functional roles of HDAC2 in liver disease are discussed in terms of hepatocyte apoptosis and proliferation, liver regeneration, hepatocellular carcinoma, liver fibrosis and non-alcoholic steatohepatitis. Moreover, abnormal expression of HDAC2 may be involved in the pathogenesis of liver disease, and its expression levels and pharmacological activity may represent potential biomarkers of liver disease. Finally, research on selective HDAC2 inhibitors and non-coding RNAs relevant to HDAC2 expression in liver disease is also reviewed. The aim of the present review was to improve understanding of the multifunctional role and potential regulatory mechanism of HDAC2 in liver disease.

Histone deacetylase 2: A potential therapeutic target for cancer and neurodegenerative disorders

Histone deacetylases (HDACs) have been implicated in a number of diseases including cancer, cardiovascular disorders, diabetes mellitus, neurodegenerative disorders and inflammation. For the treatment of epigenetically altered diseases such as cancer, HDAC inhibitors have made a significant progress in terms of development of isoform selective inhibitiors. Isoform specific HDAC inhibitors have less adverse events and better safety profile. A HDAC isoform i.e., HDAC2 demonstrated significant role in the development of variety of diseases, mainly involved in the cancer and neurodegenerative disorders. Discovery and development of selective HDAC2 inhibitors have a great potential for the treatment of target diseases. In the present compilation, we have reviewed the role of HDAC2 in progression of cancer and neurodegenerative disorders, and information on the drug development opportunities for selective HDAC2 inhibition.

MiR-646 prevents proliferation and progression of human breast cancer cell lines by suppressing HDAC2 expression

BACKGROUND

Breast cancer is a type of cancer with a high incidence and mortality rate worldwide. Change in epigenetic mechanisms enhances cancer cell progression. Histon deacetylase 2 (HDAC2) was found to act as a potential oncogene in different malignancies. For better understanding the mechanisms related to breast cancer development, we investigated the role of HDAC2 in breast cancer and the inhibitory effect of miR-646 on this oncogene.

METHODS

A total of thirty cancerous tissues and 30 adjacent non-cancerous specimens and also three breast cancer cell lines were enrolled in the study. Quantitative reverse transcriptase PCR (qRT-PCR) was employed to detect the HDAC2 and miR-646 expression level in the studied samples. The biological roles of HDAC2 and miR-646 were investigated through manipulating the expression level of HDAC2 or miR-646 in breast cancer cells. Finally, we evaluated whether the HDAC2 is a direct target for miR-646.

RESULTS

In this study, we found HDAC2 is significantly upregulated in cancerous specimens and cell lines compared to non-cancerous tissues and normal cell line. On the other hand, miR-646 expression was decreased in clinical specimens and breast cancer cells compared to non-cancerous samples. Knocking out of the HDAC2 and overexpression of miR-646 inhibited breast cancer cell growth but promoted cell death, while untreated groups showed inverse results. Furthermore, we showed that in the breast cancer cells, miR-646 regulates the progression and proliferation by suppressing HDAC2.

CONCLUSION

Taken together, our study identified a miR-646/HDAC2 regulatory function in the breast cancer development and introduced a therapeutically target for breast cancer.

AR420626, a selective agonist of GPR41/FFA3, suppresses growth of hepatocellular carcinoma cells by inducing apoptosis via HDAC inhibition

Background

Hepatocellular carcinoma (HCC) is a major cause of cancer death worldwide and establishment of new chemotherapies for HCC is urgently needed. GPR41 [free fatty acid receptor 3 (FFA3)] is a G protein-coupled receptor for short chain fatty acids, including acetate, propionate, and butyrate. In our previous study, we showed that propionate enhances the cytotoxic effect of cisplatin in HCC cells and that this mechanism is dependent on inhibition of histone deacetylases (HDACs) via GPR41/FFA3. However, the antitumor action of GPR41/FFA3 has not been elucidated.

Methods

In this study, we examined AR420626 as a GPR41-selective agonist in HepG2 and HLE cells. Nude mice were used for HepG2 xenograft studies. The apoptotic effect of AR420626 was evaluated using flow cytometry analysis. Expression of apoptosis-related proteins and HDACs was evaluated by Western immunoblot. Gene silencing of HDAC 3/5/7 and GPR41 was performed using small interfering RNA. Expression of TNF-α mRNA was evaluated by TaqMan real-time polymerase chain reaction.

Results

We found that AR420626, a selective GPR41/FFA3 agonist, suppressed growth of HepG2 xenografts and inhibited proliferation of HCC cells by inducing apoptosis. AR420626 induced proteasome activation through mTOR phosphorylation, which reduced HDAC proteins, and then increased expression of TNF-α.

Conclusion

AR420626, a selective GPR41/FFA3 agonist, may be a candidate as a therapeutic agent for HCC.

Hydroxygenkwanin Inhibits Class I HDAC Expression and Synergistically Enhances the Antitumor Activity of Sorafenib in Liver Cancer Cells

Abnormal histone deacetylase (HDAC) expression is closely related to cancer development and progression. Many HDAC inhibitors have been widely used in cancer treatment; however, severe side effects often limit their clinical application. In this study, we attempted to identify natural compounds with HDAC inhibitory activity and low physiological toxicity and explored their feasibility and mechanisms of action in liver cancer treatment. A yeast screening system was used to identify natural compounds with HDAC inhibitory activity. Further, western blotting was used to verify inhibitory effects on HDAC in human liver cancer cell lines. Cell functional analysis was used to explore the effects and mechanisms and the in vitro results were verified in BALB/c nude mice. We found that hydroxygenkwanin (HGK), an extract from Daphne genkwa, inhibited class I HDAC expression, and thereby induced expression of tumor suppressor p21 and promoted acetylation and activation of p53 and p65. This resulted in the inhibition of growth, migration, and invasion of liver cancer cells and promoted cell apoptosis. Animal models revealed that HGK inhibited tumor growth in a synergistic manner with sorafenib. HGK inhibited class I HDAC expression and had low physiological toxicity. It has great potential as an adjuvant for liver cancer treatment and may be used in combination with anticancer drugs like sorafenib to improve therapeutic efficacy.

Modifications of histones in parasites as drug targets

Post-translational modifications of histones and histone modifying enzymes play important roles in gene regulations and other physiological processes in parasites. Inhibitors of such modifying enzymes could be useful as novel therapeutics against parasitic diseases or as chemical probes for investigation of epigenetics. Development of parasitic histone modulators has got rapid expansion in the last few years. A number of highly potent and selective compounds have been reported, together with extensive preclinical studies of their biological activity. Some of these compounds have been widely used in humans targeting cancer and are found non-toxic. This review summarizes the antiparasitic activities of histone and histone modifying enzymes inhibitors evaluated in last few years. As the current chemotherapy against parasites is still not satisfactory, therefore, such compounds represents good starting points for the discovery of effective antiparasitic drugs.

The Effect of 5-Aza-2'-Deoxycytidine in Combination to and in Comparison with Vorinostat on DNA Methyltransferases, Histone Deacetylase 1, Glutathione S-Transferase 1 and Suppressor of Cytokine Signaling 1 Genes Expression, Cell Growth Inhibition and Apoptotic Induction in Hepatocellular LCL-PI 11 Cell Line

Background: Aberrant methylation and histone deacetylation of tumor suppressor genes (TSGs) are the most epigenetic alterations involving in tumorigenesis. Overexpression of DNA methyltransferases (DNMTs) and histone deacetylase 1 (HDAC1) have been reported in several cancers. The reversion of hypermethylation and deacetylation by epi-drugs such as 5-aza-2'-deoxycytidine (5-AZA-CdR) and vorinostat (SAHA) can restore normal expression of TSGs. Previously, we reported that 5-AZA-CdR and valproic acid (VPA) can inhibit DNMT1 in hepatocellular carcinoma (HCC). The aim of this study was to investigate the effect of 5-AZA-CdR in combination to and in comparison with SAHA on DNMT1, DNMT3a, DNMT3b, histone deacetylase 1 (HDAC1), glutathione S-transferase 1 (GSTP1) and suppressor of cytokine signaling 1 (SOCS1) genes expression, cell growth inhibition and apoptotic induction in hepatocellular LCL-PI 11 cell line. Materials and Methods: The cells were treated with 5-AZA-CdR and SAHA and then MTT assay, cell apoptosis assay and Real-time quantitative RT-PCR (qRT-PCR) were done. Results: Both agents indicated significant inhibitory and apoptotic effect (P< 0.001). The apoptotic effect of SAHA was more than that of 5-Aza-CdR. The result of qRT-PCR indicated that 5-Aza-CdR decreased DNMT1, DNMT3a, DNMT3b and increased GSTP1and SOCS1 genes expression and SAHA decreased HDAC1 and increased GSTP1 and SOCS1 genes expression significantly. Maximal apoptosis and genes expression were seen with combined treatment. Conclusion: 5-AZA-CdR and SAHA down-regulated DNMT1, DNMT3a, DNMT3b, and HDAC1 and up-regulated GSTP1 and SOCS1 gene expression by which inhibited cell viability and induced apoptosis, suggesting that they could be used in the treatment of HCC.

Novel genetic variants in HDAC2 and PPARGC1A of the CREB-binding protein pathway predict survival of non-small-cell lung cancer

The CREB-binding protein (CBP) pathway plays an important role in transcription and activity of acetyltransferase that acetylates lysine residues of histones and nonhistone proteins. In the present study, we hypothesized that genetic variants in the CBP pathway genes played a role in survival of non-small-cell lung cancer (NSCLC). We tested this hypothesis using the genotyping data from the genome-wide association study (GWAS) dataset from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. In the single-locus analysis, we evaluated associations between 13 176 (1107 genotyped and 12 069 imputed) single-nucleotide polymorphisms (SNPs) in 72 genes and survival of 1185 patients with NSCLC. The identified 106 significant SNPs in the discovery were further validated in additional genotyping data from another GWAS dataset of 984 patients with NSCLC in the Harvard Lung Cancer Susceptibility Study. The combined results of two datasets showed that two independent, potentially functional SNPs (i.e., HDAC2 rs13213007G>A and PPARGC1A rs60571065T>A) were significantly associated with NSCLC overall survival, with a combined hazards ratio (HR) of 1.26 (95% confidence interval (CI), 1.09-1.45; P = .002) and 1.23 (1.04-1.47; P = .017), respectively. Furthermore, we performed an expression quantitative trait loci analysis and found that the survival-associated HDAC2 rs13213007A allele (GA+AA), but not PPARGC1A rs60571065A allele (TA+AA), was significantly associated with increased messenger RNA expression levels of HDAC2 in 373 lymphoblastoid cell lines. These results indicate that the HDAC2 rs13213007A allele is a potential predictor of NSCLC survival, likely by altering the HDAC2 expression.

Histone deacetylase inhibitors differentially regulate c-Myc expression in retinoblastoma cells

Retinoblastoma (RB) is the most prevalent childhood intraocular cancer type. Previous studies have demonstrated that c-myc (a proto-oncogene) is associated with tumorigenesis. However, at present, the influence of the expression profile and bioactivity of c-Myc on RB occurrence and progression is yet to be characterised. Notably, the present study demonstrated that c-myc is downregulated in the RB cell line WERI-Rb1. However, treatment with the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) was revealed to significantly upregulate the expression of c-Myc mRNA and protein in WERI-Rb1 cells. Moreover, TSA increased the activity of the c-myc promoter in WERI-Rb1 cells, and the expression of c-Myc was also regulated by other HDAC inhibitors, including vorinostat (SAHA), valproic acid sodium salt (VPA) and entinostat. Notably, although c-myc was silenced in the Y79 cell line, the HDAC inhibitor TSA did not induce upregulation of mRNA and protein in Y79 cells. By contrast, certain HDAC inhibitors (TSA, VPA and SAHA) were discovered to significantly decrease the activity of the c-myc promoter in Y79 cells. Furthermore, the current data indicated that exogenous c-myc expression has a mild inhibitory effect on WERI-Rb1 and Y79 cell viability. Therefore, the present study revealed novel insights into the expression mechanism and bioactivity of c-Myc in RB cells.

Ubiquitin specific peptidase 5 promotes ovarian cancer cell proliferation through deubiquitinating HDAC2

Globally, epithelial ovarian cancer (EOC) is the most common gynecological malignancy with poor prognosis. The expression and oncogenic roles of ubiquitin specific peptidase 5 (USP5) have been reported in several cancers except EOC. In the current study, USP5 amplification was highly prevalent in patients with EOC and associated with higher mRNA expression of USP5. USP5 amplification and overexpression was positively correlated with poor prognosis of patients of ovarian serous carcinomas. Disruption of USP5 profoundly repressed cell proliferation by inducing cell cycle G0/G1 phase arrest in ovarian cancer cells. Additionally, USP5 knockdown inhibited xenograft growth in nude mice. Knockdown of USP5 decreased histone deacetylase 2 (HDAC2) expression and increased p27 (an important cell cycle inhibitor) expression in vitro and in vivo. The promoting effects of USP5 overexpression on cell proliferation and cell cycle transition, as well as the inhibitory effects of USP5 overexpression on p27 expression were mediated by HDAC2. Moreover, USP5 interacted with HDAC2, and disruption of USP5 enhanced the ubiquitination of HDAC2. HDAC2 protein was positively correlated USP5 protein, and negatively correlated with p27 protein in ovarian serous carcinomas tissues. Collectively, our data suggest the oncogenic function of USP5 and the potential regulatory mechanisms in ovarian carcinogenesis.

Endothelial toll-like receptor 4 maintains lung integrity via epigenetic suppression of p16INK4a

We previously reported that the canonical innate immune receptor toll-like receptor 4 (TLR4) is critical in maintaining lung integrity. However, the molecular mechanisms via which TLR4 mediates its effect remained unclear. In the present study, we identified distinct contributions of lung endothelial cells (Ec) and epithelial cells TLR4 to pulmonary homeostasis using genetic-specific, lung- and cell-targeted in vivo methods. Emphysema was significantly prevented via the reconstituting of human TLR4 expression in the lung Ec of TLR4-/- mice. Lung Ec-silencing of TLR4 in wild-type mice induced emphysema, highlighting the specific and distinct role of Ec-expressed TLR4 in maintaining lung integrity. We also identified a previously unrecognized role of TLR4 in preventing expression of p16INK4a , a senescence-associated gene. Lung Ec-p16INK4a -silencing prevented TLR4-/- induced emphysema, revealing a new functional role for p16INK4a in lungs. TLR4 suppressed endogenous p16INK4a expression via HDAC2-mediated deacetylation of histone H4. These findings suggest a novel role for TLR4 in maintaining of lung homeostasis via epigenetic regulation of senescence-related gene expression.

Interferon-γ regulates cell malignant growth via the c-Abl/HDAC2 signaling pathway in mammary epithelial cells

Interferon-γ (IFN-γ) has been used to control cancers in clinical treatment. However, an increasing number of reports have suggested that in some cases effectiveness declines after a long treatment period, the reason being unclear. We have reported previously that long-term IFN-γ treatment induces malignant transformation of healthy lactating bovine mammary epithelial cells (BMECs) in vitro. In this study, we investigated the mechanisms underlying the malignant proliferation of BMECs under IFN-γ treatment. The primary BMECs used in this study were stimulated by IFN-γ (10 ng/mL) for a long term to promote malignancy. We observed that IFN-γ could promote malignant cell proliferation, increase the expression of cyclin D1/cyclin-dependent kinase 4 (CDK4), decrease the expression of p21, and upregulate the expression of cellular-abelsongene (c-Abl) and histone deacetylase 2 (HDAC2). The HDAC2 inhibitor, valproate (VPA) and the c-Abl inhibitor, imatinib, lowered the expression level of cyclin D1/CDK4, and increased the expression level of p21, leading to an inhibitory effect on IFN-γ-induced malignant cell growth. When c-Abl was downregulated, the HDAC2 level was also decreased by promoted proteasome degradation. These data suggest that IFN-γ promotes the growth of malignant BMECs through the c-Abl/HDAC2 signaling pathway. Our findings suggest that long-term application of IFN-γ may be closely associated with the promotion of cell growth and even the carcinogenesis of breast cancer.

Unmasking the pathological and therapeutic potential of histone deacetylases for liver cancer

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, currently ranking as one of the highest neoplastic-related mortalities in the world. Due to the difficulty in early diagnosis and lack of effective treatment options, the 5-year survival rate of HCC remains extremely low. Histone deacetylation is one of the most important epigenetic mechanisms, regulating cellular events such as differentiation, proliferation and cell cycle. Histone deacetylases (HDACs), the chief mediators of this epigenetic mechanism, are often aberrantly expressed in various tumours including HCC. Areas covered: This review focuses on the most up-to-date findings of HDACs and their associated molecular mechanisms in HCC onset and progression. In addition, a potential network between HDACs and non-coding RNAs including microRNAs and long noncoding RNAs underlying hepatocarcinogenesis is considered. Expert opinion: Unmasking the role of HDACs and their association with HCC pathogenesis could have implications for future personalized therapeutic and diagnostic targeting.

MicroRNA‑223 promotes osteoblast differentiation of MC3T3‑E1 cells by targeting histone deacetylase 2

MicroRNAs (miRNAs) have emerged as pivotal regulators in various physiological and pathological processes at the post‑transcriptional level, and may serve important roles in osteogenic differentiation. However, their roles and functions are not fully understood. In the present study, miR‑223‑5p was identified as a modulator of osteoblastic differentiation in MC3T3‑E1 cells. Reverse transcription‑quantitative polymerase chain reaction and western blotting demonstrated that miR‑223‑5p was significantly upregulated in MC3T3‑E1 cells following the induction of osteoblast differentiation. Overexpression of miR‑223‑5p promoted osteogenic differentiation both in vitro and vivo. Expression of histone deacetylase 2 (HDAC2), which acts as a negative regulator of osteogenesis, was regulated by miR‑223‑5p. Collectively, the results of the present study revealed a novel miR‑223‑5p/HDAC2 axis that regulates osteoblast differentiation, and may serve as a potential target for enhancing bone formation in vivo.

Histone deacetylase 2 regulates the doxorubicin (Dox) resistance of hepatocarcinoma cells and transcription of ABCB1

Histone deacetylases (HDACs) can regulate cell-cycle, differentiation, and apoptosis of hepatocarcinoma (HCC) cells, while their roles in drug sensitivity remain unclear. Our results showed that the expression of HDAC2 was significantly increased in HCC doxorubicin (Dox) resistant cells as compared with their corresponding control cells. Over expression of HDAC2 can increase the cell viability and decrease the Dox sensitivity. Kaplan-Meier Plotter assay revealed that HCC patients with higher levels of HDAC2 had significantly poor prognosis than that of the lower expression patients. Mechanistically studies revealed that HDAC2 can regulate the transcription of ABCB1 via directly binding with its promoter and increasing its expression in Dox resistant HCC cells. Knockdown of HDAC2 significantly inhibited the expression of ABCB1. Co-immunoprecipitation revealed that HDAC2 can bind with c-fos, an important transcription factor of ABCB1, in HCC/Dox cells. Knockdown of c-Fos decreased the binding between HDAC2 and promoter of ABCB1 in HCC/Dox cells. Collectively, our data revealed that HDAC2 can regulate Dox sensitivity of HCC cells and the transcription of ABCB1.

Epigenetic modification of intestinal smooth muscle cell phenotype during proliferation

Inflammation causes proliferation of intestinal smooth muscle cells (ISMC), contributing to a thickened intestinal wall and to stricture formation in Crohn’s disease. Proliferation of ISMC in vitro and in vivo caused decreased expression of marker proteins, but the underlying cause is unclear. Since epigenetic change is important in other systems, we used immunocytochemistry, immunoblotting, and quantitative PCR to examine epigenetic modification in cell lines from rat colon at low passage or after extended growth to evaluate phenotype. Exposure to the histone deacetylase (HDAC) inhibitor trichostatin A or the DNA methyltransferase inhibitor 5-azacytidine reversed the characteristic loss of phenotypic markers among high-passage cell lines of ISMC. Expression of smooth muscle actin and smooth muscle protein 22, as well as functional expression of the neurotrophin glial cell line-derived neurotrophic factor, was markedly increased. Increased expression of muscarinic receptor 3 and myosin light chain kinase was correlated with an upregulated response to cholinergic stimulation. In human ISMC (hISMC) lines from the terminal ileum, phenotype was similarly affected by extended proliferation. However, in hISMC from resected Crohn’s strictures, we observed a significantly reduced contractile phenotype compared with patient-matched intrinsic controls that was associated with increased patient-specific expression of DNA methyltransferase 1, HDAC2, and HDAC5. Therefore, protracted growth causes epigenetic alterations that account for an altered phenotype of ISMC. A similar process may promote stricture formation in Crohn’s disease, where the potential for halting progression, or even reversal, of disease through control of phenotypic modulation may become a novel treatment option.

Altered modulation of lamin A/C-HDAC2 interaction and p21 expression during oxidative stress response in HGPS

Defects in stress response are main determinants of cellular senescence and organism aging. In fibroblasts from patients affected by Hutchinson-Gilford progeria, a severe LMNA-linked syndrome associated with bone resorption, cardiovascular disorders, and premature aging, we found altered modulation of CDKN1A, encoding p21, upon oxidative stress induction, and accumulation of senescence markers during stress recovery. In this context, we unraveled a dynamic interaction of lamin A/C with HDAC2, an histone deacetylase that regulates CDKN1A expression. In control skin fibroblasts, lamin A/C is part of a protein complex including HDAC2 and its histone substrates; protein interaction is reduced at the onset of DNA damage response and recovered after completion of DNA repair. This interplay parallels modulation of p21 expression and global histone acetylation, and it is disrupted by LMNAmutations leading to progeroid phenotypes. In fact, HGPS cells show impaired lamin A/C-HDAC2 interplay and accumulation of p21 upon stress recovery. Collectively, these results link altered physical interaction between lamin A/C and HDAC2 to cellular and organism aging. The lamin A/C-HDAC2 complex may be a novel therapeutic target to slow down progression of progeria symptoms.

Functions and mechanisms of microRNA-31 in human cancers

MicroRNAs can exhibit opposite functions in different tumors. MiR-31 is a representative example as it can not only enhance tumor development and progression in pancreatic cancer, colorectal cancer and so on, but also inhibit tumorigenesis and induce apoptosis in ovarian cancer, prostate cancer and etc. The mechanism underlying its' pleiotropy remains unknown. Several recent studies that focused on the global gene expression changes caused by aberrant miR-31 provided information on the upstream and downstream events associated with deregulated miR-31. MiR-31 might interact with a number of signaling pathways including RAS/MARK, PI3K/AKT and RB/E2F to play its opposite functions. This review summarizes the target genes and pathways associated with miR-31 and examines the mechanisms underlying the function of miR-31. The resulting hypothesis is possible that the tissue-specific features of adenocarcinoma and squamous cell cancer and the positive feedback loop consists of miR-31 and its upstream and downstream may account for the diversity of miR-31 functions.

The therapeutic properties of resminostat for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer with increases in new cases being reported annually. Histopathologists have identified hepatic steatosis as a characteristic of a broad range of chronic liver diseases that are associated with the onset and development of HCC. In this context, epigenetic modifications may serve as precancerous factors predisposing normal cells to the initiation of carcinogenesis. This study demonstrated that hepatic tumorigenesis and differentiated adipocytes may modulate both global histone deacetylase (HDAC) expression and specific class I HDAC genes in the tumour microenvironment. The novel class I HDAC inhibitor Resminostat was shown to reduce the proliferation of HCC cells along with its specificity in targeting class I HDACs and oncogenes. The combined effect of Resminostat with several pharmaceutical agents such as Sorafenib, Cisplatin and Doxorubicin was also demonstrated. The inhibition of heat shock protein 90 (HSP90) has been demonstrated as a potential therapeutic option for HCC. In line with this, the specific HSP90 inhibitor 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) was selected and it was found that the combination of Resminostat and 17-AAG may provide a “smart” clinical strategy for HCC patients by targeting cellular communication within the tumour microenvironment. This study provides an insight into the use of Resminostat as an epigenetic based therapeutic for HCC along with other pharmaceutical options, in particular by targeting the cell-to-cell communication that occurs between hepatoma and adipocytes.

Synergy between histone deacetylase inhibitors and DNA-damaging agents is mediated by histone deacetylase 2 in colorectal cancer

Previous studies have associated the overexpression of histone deacetylase 2 (HDAC2) and the presence of TP53 mutations with the progression to advanced stage drug resistant colorectal cancer (CRC). However, the mechanistic link between HDAC2 expression and the TP53 mutational status has remained unexplored. Here, we investigated the function of HDAC2 in drug resistance by assessing the synergistic effects of DNA-targeted chemotherapeutic agents and HDAC inhibitors (HDACis) on two TP53-mutated colorectal adenocarcinoma CRC cell lines (SW480 and HT-29) and on the TP53-wild type carcinoma cell line (HCT116 p53+/+) and its TP53 deficient sub-line (HCT116 p53−/−). We showed that in the untreated SW480 and HT-29 cells the steady-state level of HDAC2 was low compared to a TP53-wild type carcinoma cell line (HCT116 p53+/+). Increased expression of HDAC2 correlated with drug resistance, and depletion by shRNA sensitised the multi-drug resistance cell line HT-29 to CRC chemotherapeutic drugs such as 5-fluorouracil (5-FU) and oxaliplatin (Oxa). Combined treatment with the HDACi suberoylanilide hydroxamic acid plus 5-FU or Oxa reduced the level of HDAC2 expression, modified chromatin structure and induced mitotic cell death in HT-29 cells. Non-invasive bioluminescence imaging revealed significant reductions in xenograft tumour growth with HDAC2 expression level reduced to <50% in treated animals. Elevated levels of histone acetylation on residues H3K9, H4K12 and H4K16 were also found to be associated with resistance to VPA/Dox or SAHA/Dox treatment. Our results suggest that HDAC2 expression rather than the p53 mutation status influences the outcome of combined treatment with a HDACi and DNA-damaging agents in CRC.

The prophylactic and therapeutic effects of Momordica charantia methanol extract through controlling different hallmarks of the hepatocarcinogenesis

Inspite of the wide facilities for controlling cancer growth, there are little drugs to inhibit its metastasis or prevent its angiogenesis. Discovering such natural or synthetic multi-targeted agent that might strike different targets is considered as a vital goal for tumor controlling. In a previous study, the chemoprotective effect of methanol extract of Momordicacharantia (MEMC) on albino western rats bearing hepatocarcinogenesis was evaluated. The mechanism by which MEMC exert its anticancer properties was unknown. Therefore, we aimed in this study to investigate the possible role of MEMC as anti-proliferative, anti-angiogenic and anti-metastatic agent to exert its chemoprotective effect. The study was conducted on sixty albino western rats divided into six groups, 10 rats each. Diethylnitrosamine (DENA) was injected intraperitoneally (i.p.) at a dose of 200 mg/kg body weight once, 2 weeks later rats were received carbon tetrachloride (CCl₄₎ subcutaneously (3 ml/kg/week) continued for 10 weeks. MEMC was orally produced to rats (40 mg/kg) alone, as well as before, at the same time and after DENA injection. Cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF), caspase-3,-8 (Casp-3,-8), histone deacetylase (HDAC) and matrixmetalloproteinases-2,-9 (MMP-2,-9) were evaluated. MEMC treatment significantly decreased Cox-2, VEGF, HDAC and MMP-2,-9 and increased Casp-3,-8 as compared to DENAgroup,which demonstrated that the anticancer effect of MEMC may be through the inhibition of angiogenesis, proliferation and metastasis and the activation of apoptosis. The improvement in before-treated group was more pronounced than that in after- and simultaneous-treated groups, indicating thatMEMC may act as a prophylactic agent more than being a therapeutic agent.

AR-42 induces apoptosis in human hepatocellular carcinoma cells via HDAC5 inhibition

Histone deacetylases (HDACs) play critical roles in apoptosis and contribute to the proliferation of cancer cells. AR-42 is a novel Class I and II HDAC inhibitor that shows cytotoxicity against various human cancer cell lines. The present study aims to identify the target of AR-42 in hepatocellular carcinoma (HCC) as well as evaluate its therapeutic efficacy. We found that HDAC5 was upregulated in HCC tissues compared to adjacent normal tissues, and this was correlated with reduced patient survival. CCK8 and colony-formation assays showed that HDAC5 overexpression promotes proliferation in HCC cell lines. Treatment with AR-42 decreased HCC cell growth and increased caspase-dependent apoptosis, and this was rescued by HDAC5 overexpression. We demonstrated that AR-42 can inhibit the deacetylation activity of HDAC5 and its downstream targets in vitro and in vivo. Taken together, these results demonstrate for the first time that AR-42 targets HDAC5 and induces apoptosis in human hepatocellular carcinoma cells. AR-42 therefore shows potential as a new drug candidate for HCC therapy.

CRISPR-mediated HDAC2 disruption identifies two distinct classes of target genes in human cells

The transcriptional functions of the class I histone deacetylases (HDACs) HDAC1 and HDAC2 are mainly viewed as both repressive and redundant based on murine knockout studies, but they may have additional independent roles and their physiological functions in human cells are not as clearly defined. To address the individual epigenomic functions of HDAC2, here we utilized CRISPR-Cas9 to disrupt HDAC2 in human cells. We find that while HDAC2 null cells exhibited signs of cross-regulation between HDAC1 and HDAC2, specific epigenomic phenotypes were still apparent using RNA-seq and ChIP assays. We identified specific targets of HDAC2 repression, and defined a novel class of genes that are actively expressed in a partially HDAC2-dependent manner. While HDAC2 was required for the recruitment of HDAC1 to repressed HDAC2-gene targets, HDAC2 was dispensable for HDAC1 binding to HDAC2-activated targets, supporting the notion of distinct classes of targets. Both active and repressed classes of gene targets demonstrated enhanced histone acetylation and methylation in HDAC2-null cells. Binding of the HDAC1/2-associated SIN3A corepressor was altered at most HDAC2-targets, but without a clear pattern. Overall, our study defines two classes of HDAC2 targets in human cells, with a dependence of HDAC1 on HDAC2 at one class of targets, and distinguishes unique functions for HDAC2.

The pentapeptide Gly-Thr-Gly-Lys-Thr confers sensitivity to anti-cancer drugs by inhibition of CAGE binding to GSK3β and decreasing the expression of cyclinD1

We previously reported the role of cancer/testis antigen CAGE in the response to anti-cancer drugs. CAGE increased the expression of cyclinD1, and pGSK3βSer9, an inactive GSK3β, while decreasing the expression of phospho-cyclinD1Thr286. CAGE showed binding to GSK3β and the domain of CAGE (amino acids 231-300) necessary for binding to GSK3β and for the expression regulation of cyclinD1 was determined. 269GTGKT273 peptide, corresponding to the DEAD box helicase domain of CAGE, decreased the expression of cyclinD1 and pGSK3βSer9 while increasing the expression of phospho-cyclinD1Thr286. GTGKT peptide showed the binding to CAGE and prevented CAGE from binding to GSK3β. GTGKT peptide changed the localization of CAGE and inhibited the binding of CAGE to the promoter sequences of cyclin D1. GTGKT peptide enhanced the apoptotic effects of anti-cancer drugs and decreased the migration, invasion, angiogenic, tumorigenic and metastatic potential of anti-cancer drug-resistant cancer cells. We found that Lys272 of GTGKT peptide was necessary for conferring anti-cancer activity. Peptides corresponding to the DEAD box helicase domain of CAGE, such as AQTGTGKT, QTGTGKT and TGTGKT, also showed anti-cancer activity by preventing CAGE from binding to GSK3β. GTGKT peptide showed ex vivo tumor homing potential. Thus, peptides corresponding to the DEAD box helicase domain of CAGE can be developed as anti-cancer drugs in cancer patients expressing CAGE.

A validated, transitional and translational porcine model of hepatocellular carcinoma

Difficult questions are confronting clinicians attempting to improve hepatocellular carcinoma (HCC) outcomes. A large animal model with genetic, anatomical, and physiological similarities to humans is required to transition from mouse models to human clinical trials to address unmet clinical needs. To validate our previously reported inducible porcine cancer model (Oncopig) as a transitional HCC model, Oncopig hepatocyte cultures were transformed using Cre recombinase. The resulting porcine HCC cells (pHCC) expressed oncogenic TP53R167H and KRASG12D, and displayed nuclear pleomorphisms with pale to granular cytoplasm arranged in expanded plates similar to human HCC histopathology. Human HCC transcriptional hallmarks were detected in pHCC cells using RNA-seq, including TERT reactivation, apoptosis evasion, angiogenesis activation, and Wnt signaling activation. Master regulators of gene expression were conserved across Oncopig and 18 human HCC cell lines. pHCC injection into SCID mice resulted in tumors recapitulating human HCC characteristics, including thick trabeculae formation, pseudoacini patterning, and sheets of well-vascularized stroma. Finally, autologous injection of pHCC cells subcutaneously yielded a tumor histologically characterized as Edmondson Steiner (HCC nuclear grade assessment system) grade 2 HCC with trabecular patterning and T-lymphocyte infiltration. These data demonstrate the Oncopig HCC model's utility for improving detection, treatment, and biomarker discovery relevant to human HCC.

Inhibitory effects of 1,25(OH)2D3 on the proliferation of hepatocellular carcinoma cells through the downregulation of HDAC2

The inhibitory effects of 1,25(OH)2D3 on the proliferation of a variety of cancer cell lines have been extensively reported. However, the underlying mechanisms remain largely unknown. In the present study, the effects of 1,25(OH)2D3 on the in vitro proliferation of human hepatocellular carcinoma HepG2 cells and the mechanism involved were investigated. Flow cytometry and MTT assay revealed that 1,25(OH)2D3 inhibited cell proliferation in vitro. Western blotting and real-time PCR indicated that 1,25(OH)2D3 upregulated the expression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and attenuated that of histone deacetylase 2 (HDAC2). Knockdown of HDAC2 completely mimicked the effects of 1,25(OH)2D3 on PTEN gene expression. The influence of 1,25(OH)2D3 on PTEN expression was reversed in the cells treated with a recombinant pEGFP-LV2-HDAC2 plasmid. Akt phosphorylation, which was downregulated by 1,25(OH)2D3 treatment, was promoted by HDAC2 overexpression. These findings revealed that 1,25(OH)2D3 inhibited cell growth possibly by HDAC2-mediated PTEN upregulation, Akt deactivation, and inhibition of the PI3K/Akt signaling pathway.

Teng-Long-Bu-Zhong-Tang induces p21-dependent cell senescence in colorectal carcinoma LS174T cells via histone acetylation

Teng-Long-Bu-Zhong-Tang (TLBZT) is a Chinese herbal formula for colorectal carcinoma treatment. TLBZT effectively induces cell senescence in colorectal carcinoma, accompanied by p21 upregulation. In this study, we further explored the role of p21 in TLBZT-induced cell senescence, as well as the mechanism by which TLBZT upregulates p21. Specific knockdown of p21 expression by small interfering RNA significantly attenuated TLBZT-induced cell senescence in human colorectal carcinoma LS174T cells. Silencing of p53 by small interfering RNA did not affect TLBZT-induced p21 upregulation. Meanwhile, TLBZT inhibited histone deacetylase activity. Furthermore, TLBZT increased acetylation levels of histone H3 and H4, enhancing their binding to the p21 promoter. These data suggested that TLBZT induces cell senescence in LS174T cells through a mechanism involving p21 upregulation via histone H3 and H4 acetylation. This study provides new insights into the application of TLBZT for colorectal carcinoma treatment.

Prognostic Biomarker Identification Through Integrating the Gene Signatures of Hepatocellular Carcinoma Properties

Many molecular classification and prognostic gene signatures for hepatocellular carcinoma (HCC) patients have been established based on genome-wide gene expression profiling; however, their generalizability is unclear. Herein, we systematically assessed the prognostic effects of these gene signatures and identified valuable prognostic biomarkers by integrating these gene signatures. With two independent HCC datasets (GSE14520, N = 242 and GSE54236, N = 78), 30 published gene signatures were evaluated, and 11 were significantly associated with the overall survival (OS) of postoperative HCC patients in both datasets. The random survival forest models suggested that the gene signatures were superior to clinical characteristics for predicting the prognosis of the patients. Based on the 11 gene signatures, a functional protein-protein interaction (PPI) network with 1406 nodes and 10,135 edges was established. With tissue microarrays of HCC patients (N = 60), we determined the prognostic values of the core genes in the network and found that RAD21, CDK1, and HDAC2 expression levels were negatively associated with OS for HCC patients. The multivariate Cox regression analyses suggested that CDK1 was an independent prognostic factor, which was validated in an independent case cohort (N = 78). In cellular models, inhibition of CDK1 by siRNA or a specific inhibitor, RO-3306, reduced cellular proliferation and viability for HCC cells. These results suggest that the prognostic predictive capacities of these gene signatures are reproducible and that CDK1 is a potential prognostic biomarker or therapeutic target for HCC patients.

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Eleven gene signatures have promising values for the OS prediction of HCC patients who undergo the surgical treatments.

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Prediction results for the 11 gene signatures were in moderate concordance, and genes included were functionally linked.

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CDK1 is an independent prognostic biomarker and a potential therapeutic target for HCC patients.

Various gene signatures for hepatocellular carcinoma (HCC) patients have been reported; however, their generalizability is unclear. Using two HCC patient datasets, we assessed the prognostic values of these gene signatures and identified 11 gene signatures that were associated with overall survival for postoperative HCC patients in both cohorts. Genes derived from these signatures formed a functional protein-protein interaction network with 1,406 nodes and 10,135 edges, and the expression levels of three core genes, RAD21, CDK1, and HDAC2, in the network were negatively associated with the overall survival of HCC patients. Further studies suggested that CDK1 is an independent prognostic factor and that it is a potential therapeutic target for HCC patients.

Silencing of histone deacetylase 2 suppresses malignancy for proliferation, migration, and invasion of glioblastoma cells and enhances temozolomide sensitivity

Histone deacetylases (HDACs) can regulate the progression of various cancers, while their roles in glioblastoma multiforme (GBM) are not well known. Our present study investigated the expression of class I HDACs (HDAC1, 2, 3, 8) in GBM U87, A172, U251, and LN229 cells and compared their levels with that in primary normal human astrocytes (NHA) cells. It showed that HDAC2 expression is significantly up-regulated in GBM cells. Silencing of HDAC2 via its specific siRNAs can suppress the in vitro proliferation, migration, and invasion of GBM U87 and A172 cells. Furthermore, silencing of HDAC2 can increase the sensitivity of GBM cells to temozolomide (TMZ), a standard-of-care during clinical GBM treatment. This might be due to that si-HDAC can significantly down-regulate the mRNA and protein expression of MRP1, while has no effect on ABCB1 and ABCG2. Schisandrin B (Sch B), a specific inhibitor of MRP1, can further increase the TMZ sensitivity in HDAC2-knocked down GBM cells. Collectively, our data revealed that targeted HDAC2 can suppress the malignancy of GBM cells and increase their sensitivity of TMZ via down-regulation of MRP1. It suggested that HDAC2 might be a potential target for GBM therapy and improvement in TMZ therapy efficiency.

MicroRNA-31 functions as a tumor suppressor by regulating cell cycle and epithelial-mesenchymal transition regulatory proteins in liver cancer

MicroRNA-31 (miR-31) is among the most frequently altered microRNAs in human cancers and altered expression of miR-31 has been detected in a large variety of tumor types, but the functional role of miR-31 still hold both tumor suppressive and oncogenic roles in different tumor types. MiR-31 expression was down-regulated in a large cohort of hepatocellular carcinoma (HCC) patients, and low expression of miR-31 was significantly associated with poor prognosis of HCC patients. Ectopic expression of miR-31 mimics suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins. Additional study evidenced miR-31 directly to suppress HDAC2 and CDK2 expression by inhibiting mRNA translation in HCC cells. We also found that ectopic expression of miR-31 mimics reduced metastatic potential of HCC cells by selectively regulating epithelial-mesenchymal transition (EMT) regulatory proteins such as N-cadherin, E-cadherin, vimentin and fibronectin. HCC tissues derived from chemical-induced rat liver cancer models validated that miR-31 expression is significantly down-regulated, and that those cell cycle- and EMT-regulatory proteins are deregulated in rat liver cancer. Overall, we suggest that miR-31 functions as a tumor suppressor by selectively regulating cell cycle and EMT regulatory proteins in human hepatocarcinogenesis providing a novel target for the molecular treatment of liver malignancies.

By recruiting HDAC1, MORC2 suppresses p21 Waf1/Cip1 in gastric cancer

Microrchidia (MORC) family CW-type zinc-finger 2 (MORC2) regulates chromatin remodeling during the DNA-damage response, represses gene transcription, promotes lipogenesis. Here, we found that MORC2 down-regulated p21 by recruiting HDAC1 to the p21 promoter, in a p53-independent manner. MORC2-mediated down-regulation of p21 in turn promoted cell cycle progression in gastric cancer cells. Furthermore, MORC2 expression correlated negatively with p21 expression in gastric tumors in patients. We suggest that MORC2 may be a potential therapeutic target in cancer.

Epigenetic regulation of cell signaling pathways in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous cancer that is characterized by rapid and uncontrolled proliferation of immature B- or T-lymphoid precursors. Although ALL has been regarded as a genetic disease for many years, the crucial importance of epigenetic alterations in leukemogenesis has become increasingly evident. Epigenetic mechanisms, which include DNA methylation and histone modifications, are critical for gene regulation during many key biological processes. Here, we review the cell signaling pathways that are regulated by DNA methylation or histone modifications in ALL. Recent studies have highlighted the fundamental role of these modifications in ALL development, and suggested that future investigation into the specific genes and pathways that are altered by epigenetic mechanisms can contribute to the development of novel drug-based therapies for ALL.

Droxinostat, a Histone Deacetylase Inhibitor, Induces Apoptosis in Hepatocellular Carcinoma Cell Lines via Activation of the Mitochondrial Pathway and Downregulation of FLIP

BACKGROUND

The current chemotherapeutic outcomes for hepatocellular carcinoma (HCC) are not encouraging, and long-term survival of this patient group remains poor. Recent studies have demonstrated the utility of histone deacetylase inhibitors that can disrupt cell proliferation and survival in HCC management. However, the effects of droxinostat, a type of histone deacetylase inhibitor, on HCC remain to be established.

METHODS

The effects of droxinostat on HCC cell lines SMMC-7721 and HepG2 were investigated. Histone acetylation and apoptosis-modulating proteins were assessed via Western blot. Proliferation was examined with 3-(4, 5 dimetyl-2-thiazolyl)-2, 5-diphenyl 2H-tetrazolium bromide, cell proliferation, and real-time cell viability assays, and apoptosis with flow cytometry.

RESULTS

Droxinostat inhibited proliferation and colony formation of the HCC cell lines examined. Hepatoma cell death was induced through activation of the mitochondrial apoptotic pathway and downregulation of FLIP expression. Droxinostat suppressed histone deacetylase (HDAC) 3 expression and promoted acetylation of histones H3 and H4. Knockdown of HDAC3 induced hepatoma cell apoptosis and histone H3 and H4 acetylation.

CONCLUSIONS

Droxinostat suppresses HDAC3 expression and induces histone acetylation and HCC cell death through activation of the mitochondrial apoptotic pathway and downregulation of FLIP, supporting its potential application in the treatment of HCC.

4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to inhibit hepatocellular carcinoma cells

The aim of the present study is to investigate the potential anti-hepatocellular carcinoma (HCC) cell activity by 4SC-202, a novel class I HDAC inhibitor (HDACi). The associated signaling mechanisms were also analyzed. We showed that 4SC-202 treatment induced potent cytotoxic and proliferation-inhibitory activities against established HCC cell lines (HepG2, HepB3, SMMC-7721) and patient-derived primary HCC cells. Further, adding 4SC-202 in HCC cells activated mitochondrial apoptosis pathway, which was evidenced by mitochondrial permeability transition pore (mPTP) opening, cytochrome C cytosol release and caspase-3/-9 activation. Inhibition of this apoptosis pathway, by caspase-3/-9 inhibitors, mPTP blockers, or by shRNA-mediated knockdown of cyclophilin-D (Cyp-D, a key component of mPTP), significantly attenuated 4SC-202-induced HCC cell death and apoptosis. Reversely, over-expression of Cyp-D enhanced 4SC-202's sensitivity in HCC cells. Further studies showed that 4SC-202 induced apoptosis signal-regulating kinase 1 (ASK1) activation, causing it translocation to mitochondria and physical association with Cyp-D. This mitochondrial ASK1-Cyp-D complexation appeared required for mediating 4SC-202-induced apoptosis activation. ASK1 stable knockdown by targeted-shRNAs largely inhibited 4SC-202-induced mPTP opening, cytochrome C release, and following HCC cell apoptotic death. Together, we suggest that 4SC-202 activates ASK1-dependent mitochondrial apoptosis pathway to potently inhibit human HCC cells.

1,25(OH)2D3 inhibits the progression of hepatocellular carcinoma via downregulating HDAC2 and upregulating P21(WAFI/CIP1)

Vitamin D, termed 1,25(OH)2D3 in it's active form, activity is associated with a reduced risk of hepatocellular carcinoma (HCC) and is an important immune regulator. However, the detail molecular mechanisms underlying the effects of 1,25(OH)2D3 on the progression of HCC are widely unknown. Histone deacetwylase 2 (HDAC2) is usually expressed at high levels in tumors, and its downregulation leads to high expression levels of cell cycle components, including p21(WAF1/Cip1), a well-characterized modulator, which is critical in cell senescence and apoptosis. The present study investigated whether vitamin D inhibits HCC via the regulation of HDAC2 and p21(WAF1/Cip1). Firstly, the toxic concentrations of 1,25(OH)2D3 were determined, according to trypan blue and [(3)H]thymidine incorporation assays. Secondly, HCC cells lines were treated with different concentrations of 1,25(OH)2D3. The expression of HDAC2 was either silenced via short hairpin (sh)RNA or induced by transfection of plasmids expressing the HDAC2 gene in certain HCC cells. Finally the mRNA and protein levels of HDAC2 and p21(WAF1/Cip1) were measured using reverse transcription-quantitative polymerase chain reaction and western blot analyses. The results revealed that 1,25(OH)2D3 treatment reduced the expression of HDAC2 and increased the expression of p21(WAF1/Cip1), in a dose-dependent manner, resulting in the reduction of HCC growth. Elevated levels of HDAC2 reduced the expression of p21(WAF1/Cip1), resulting in an increase in HCC growth. HDAC2 shRNA increased the expression of p21(WAF1/Cip1), resulting in reduction in HCC growth. Thus, 1,25(OH)2D3 exerted antitumorigenic effects through decreasing the expression levels of HDAC2 and increasing the expression of p21(WAF1/Cip1), which inhibited the development of HCC and may indicate the possible underlying mechanism. These results suggest that vitamin D3 may be developed as a potential drug for effective therapy in the treatment of HCC.

MicroRNA-129-1 acts as tumour suppressor and induces cell cycle arrest of GBM cancer cells through targeting IGF2BP3 and MAPK1

BACKGROUND

MicroRNA-129-1 (miR-129-1) seems to behave as a tumour suppressor since its decreased expression is associated with different tumours such as glioblastoma multiforme (GBM). GBM is the most common form of brain tumours originating from glial cells. The impact of miR-129-1 downregulation on GBM pathogenesis has yet to be elucidated.

METHODS

MiR-129-1 was overexpressed in GBM cells, and its effect on proliferation was investigated by cell cycle assay. MiR-129-1 predicted targets (CDK6, IGF1, HDAC2, IGF2BP3 and MAPK1) were also evaluated by western blot and luciferase assay.

RESULTS

Restoration of miR-129-1 reduced cell proliferation and induced G1 accumulation, significantly. Several functional assays confirmed IGF2BP3, MAPK1 and CDK6 as targets of miR-129-1. Despite the fact that IGF1 expression can be suppressed by miR-129-1, through 3'-untranslated region complementary sequence, we could not find any association between IGF1 expression and GBM. MiR-129-1 expression inversely correlates with CDK6, IGF2BP3 and MAPK1 in primary clinical samples.

CONCLUSION

This is the first study to propose miR129-1 as a negative regulator of IGF2BP3 and MAPK1 and also a cell cycle arrest inducer in GBM cells. Our data suggests miR-129-1 as a potential tumour suppressor and presents a rationale for the use of miR-129-1 as a novel strategy to improve treatment response in GBM.