Regulation of apoptosis-associated genes by histone deacetylase inhibitors: implications in cancer therapy

The mechanism of sodium butyrate on the growth of mouse B16 melanoma cells by inhibiting the differentiation of M2-type macrophages and down-regulating the expressions of VEGF and TGF-β

Melanoma is a highly malignant cancer with a high differentiation potential and metastatic capacity. Sodium butyrate, known for its anti-cancer activity, is used in various types of solid tumors. This study aimed to investigate the effects of sodium butyrate on B16 melanoma cells using in vitro and in vivo mouse models. The study utilized MTT assay, flow cytometry, and immunoblot analysis. Mice were treated with normal saline (control) or 1 mM, 2 mM, 3 mM, or 5 mM sodium butyrate. Results showed that cell viabilities were significantly reduced in 2 mM, 3 mM, and 5 mM sodium butyrate groups after 24 to 48 hours (p < 0.01 for all). Moreover, sodium butyrate exhibited a tumor suppression effect that was time-dependent and lasted for 30 days (p < 0.01 for all). A significant tumor suppression effect was observed in the case of 5 mM sodium butyrate after 30 days (p < 0.001 for all). As compared to control (no sodium butyrate), tumor-associated macrophages were decreased in 2 mM, 3 mM, and 5 mM sodium butyrate groups (<0.01 for all). The maximum reduction was observed in 5 mM sodium butyrate groups. Sodium borate decreased the release of interleukin-10, vascular endothelial growth factor, transforming growth factor beta, and β-actin (<0.01 for all). A significant reduction was observed in the case of 5 mM concentration. Overall, these findings suggest that sodium butyrate is effective in the treatment of melanoma and may offer a promising new avenue for melanoma therapy.

Menin signaling and therapeutic targeting in breast cancer

To date, mounting evidence have shown that patients with multiple endocrine neoplasia type 1 (MEN1) may face an increased risk for breast carcinogenesis. The product of the MEN1 gene, menin, was also indicated to be an important regulator in breast cancer signaling network. Menin directly interacts with MLL, EZH2, JunD, NF-κB, PPARγ, VDR, Smad3, β-catenin and ERα to modulate gene transcriptions leading to cell proliferation inhibition. Moreover, interaction of menin-FANCD2 contributes to the enhancement of BRCA1-mediated DNA repair mechanism. Ectopic expression of menin causes Bax-, Bak- and Caspase-8-dependent apoptosis. However, despite numbers of menin inhibitors were exploited in other cancers, data on the usage of menin inhibitors in breast cancer treatment remain limited. In this review, we focused on the menin associated signaling pathways and gene transcription regulations, with the aim of elucidating its molecular mechanisms and of guiding the development of novel menin targeted drugs in breast cancer therapy.

Histone deacetylase inhibitor butyrate inhibits the cellular immunity and increases the serum immunity of pearl oyster Pinctada fucata martensii

Histone acetylation is a dynamic epigenetic modification and sensitive to the changes in extracellular environment. Butyrate, a histone deacetylase inhibitor, can inhibit the deacetylation process of histones. In this study, we found that the acetylation level of H3 was enhanced at 12 h after lipopolysaccharide (LPS) stimulation and increased at 6 h after combining treatment with LPS and butyrate in pearl oyster Pinctada fucata martensii. Transcriptome analysis indicated that butyrate counter-regulated 29.95%-36.35% of the genes repressed by LPS, and these genes were mainly enriched in the "cell proliferation" and "Notch signaling pathway". Meanwhile, butyrate inhibited the up-regulation of 31.54%-54.96% of the genes induced by LPS, and these genes were mainly enriched in "Notch signaling pathway", "cell proliferation", "NF-kappa B signaling pathway", "TNF signaling pathway", "apoptosis", "NOD-like receptor signaling pathway", "RIG-I-like receptor signaling pathway" and "cytosolic DNA-sensing pathway". Gene expression analysis showed that butyrate downregulated most of cell proliferation, immune-related genes effected by LPS. The activities of LAP, LYS, ACP, ALP, and GSH-Px were up-regulated at 6 h after combining treatment with LPS and butyrate, suggesting that butyrate could activate serum immune-related enzymes in pearl oyster. These results can improve our understanding of the function of histone deacetylase in the immune response of pearl oyster and provide references for an in-depth study of the functions of histone deacetylase in mollusks.

Epigenetic drugs induce the potency of classic chemotherapy, suppress post-treatment re-growth of breast cancer, but preserve the wound healing ability of stem cells

Epigenetic therapy augments neoadjuvant chemotherapy (NACT) in breast cancer and may aid post-surgical wound healing affected by NACT. Our study investigates: (1) The cytotoxicity of classic paclitaxel chemotherapy on triple negative breast cancer (TNBC) independently and in combination with epigenetic drugs. (2) The sustainable inhibition of breast cancer regrowth following paclitaxel and epigenetic therapies. (3) The effects of paclitaxel with and without epigenetic therapy on the post-treatment viability and wound healing potential of adipose stem cells (ASCs). Cytotoxicity assays were performed on TNBC and ASCs. Cells were treated and recovered in drug-free medium. Cell viability was measured via cell counts and MTT assays. W -ound healing was tested with scratch assays. The combination of epigenetic drugs shows increased toxicity against TNBC cells compared to standard chemotherapy alone. Moreover, the combination of paclitaxel with epigenetic treatments causes cancer toxicity that is sustainable to TNBC cells after the drugs' removal with minimal effect on ASCs wound healing ability. The use of epigenetic drugs in addition to standard chemotherapy is cytotoxic to TNBC cells and prevents post-treatment recovery of TNBC while maintaining ASC wound healing ability. This strategy may be useful in maximizing post-surgical wound healing following NACT in TNBC.

Crosstalk Between ROS and Autophagy in Tumorigenesis: Understanding the Multifaceted Paradox

Cancer formation is a highly regulated and complex process, largely dependent on its microenvironment. This complexity highlights the need for developing novel target-based therapies depending on cancer phenotype and genotype. Autophagy, a catabolic process, removes damaged and defective cellular materials through lysosomes. It is activated in response to stress conditions such as nutrient deprivation, hypoxia, and oxidative stress. Oxidative stress is induced by excess reactive oxygen species (ROS) that are multifaceted molecules that drive several pathophysiological conditions, including cancer. Moreover, autophagy also plays a dual role, initially inhibiting tumor formation but promoting tumor progression during advanced stages. Mounting evidence has suggested an intricate crosstalk between autophagy and ROS where they can either suppress cancer formation or promote disease etiology. This review highlights the regulatory roles of autophagy and ROS from tumor induction to metastasis. We also discuss the therapeutic strategies that have been devised so far to combat cancer. Based on the review, we finally present some gap areas that could be targeted and may provide a basis for cancer suppression.

Evaluation of the antioxidative and genotoxic effects of sodium butyrate on breast cancer cells

Oncogenic stimulation shows a rise in reactive oxygen species (ROS), and ROS can eventually induce carcinogenesis by causing DNA damage. In this context, this study aims to evaluate some biochemical and genotoxic changes in the control of cell death caused by NaBu (Sodium butyrate). treatment in breast cancer cells. NaBu’s impact on cell proliferation was determined via WST-1 assay. The lipid peroxidation (MDA), reduced glutathione (GSH), Nitric Oxide (NO), hydrogen peroxide (H₂O₂), and superoxide dismutase (SOD) enzyme levels were determined biochemically. NaBu-induced genotoxic damage was estimated via single-cell gel electrophoresis (SCGE). NaBu reduced cell viability and potentially induced GSH, but decreased SOD enzyme activity and the level of MDA and NO decreased also H₂O₂ decreased at different times and NaBu concentrations. Higher NaBu concentrations amplified DNA damage in MCF-7 cells compared to the control group. NaBu shows anticancer and genotoxic effects, especially through antioxidant enzymes, one of the oxidative stress parameters in breast cancer. However, the anticancer and genotoxic effects of NaBu is changed in the oxidative stress parameters with time and treatment concentration of NaBu in MCF-7 cells. Furthermore, his oxidative stress-dependent effect changes need to be clarified by further evaluation with molecular and more biochemical parameters.

Oxidative Stress in Cancer Cell Metabolism

Reactive oxygen species (ROS) are important in regulating normal cellular processes whereas deregulated ROS leads to the development of a diseased state in humans including cancers. Several studies have been found to be marked with increased ROS production which activates pro-tumorigenic signaling, enhances cell survival and proliferation and drives DNA damage and genetic instability. However, higher ROS levels have been found to promote anti-tumorigenic signaling by initiating oxidative stress-induced tumor cell death. Tumor cells develop a mechanism where they adjust to the high ROS by expressing elevated levels of antioxidant proteins to detoxify them while maintaining pro-tumorigenic signaling and resistance to apoptosis. Therefore, ROS manipulation can be a potential target for cancer therapies as cancer cells present an altered redox balance in comparison to their normal counterparts. In this review, we aim to provide an overview of the generation and sources of ROS within tumor cells, ROS-associated signaling pathways, their regulation by antioxidant defense systems, as well as the effect of elevated ROS production in tumor progression. It will provide an insight into how pro- and anti-tumorigenic ROS signaling pathways could be manipulated during the treatment of cancer.

Overcoming key challenges in cancer immunotherapy with engineered T cells

PURPOSE OF REVIEW

A number of clinical trials are currently testing chimeric antigen receptor (CAR) and T cell receptor (TCR) engineered T cells for the treatment of haematologic malignancies and selected solid tumours, and CD19-CAR-T cells have produced impressive clinical responses in B-cell malignancies. Here, we summarize the current state of the field, highlighting the key aspects required for the optimal application of CAR and TCR-engineered T cells for cancer immunotherapy.

RECENT FINDINGS

Toxicities, treatment failure and disease recurrence have been observed at different rates and kinetics. Several strategies have been designed to overcome these hurdles: the identification and combination of known and new antigens, together with the combination of immunotherapeutic and classical approaches may overcome cancer immune evasion. New protocols for genetic modification and T cell culture may improve the overall fitness of cellular products and their resistance to hostile tumour immunomodulatory signals. Finally, the schedules of T cell administration and toxicity management have been adapted to improve the safety of this transformative therapeutic approach.

SUMMARY

In order to develop effective adoptive T cell treatments for cancer, therapeutic optimization of engineered CAR and TCR T cells is crucial, by simultaneously focusing on intrinsic and extrinsic factors. This review focuses on the innovative approaches designed and tested to overcome the hurdles encountered so far in the clinical practice, with new excitement on novel laboratory insights and ongoing clinical investigations.

The Therapeutic Strategy of HDAC6 Inhibitors in Lymphoproliferative Disease

Histone deacetylases (HDACs) are master regulators of chromatin remodeling, acting as epigenetic regulators of gene expression. In the last decade, inhibition of HDACs has become a target for specific epigenetic modifications related to cancer development. Overexpression of HDAC has been observed in several hematologic malignancies. Therefore, the observation that HDACs might play a role in various hematologic malignancies has brought to the development of HDAC inhibitors as potential antitumor agents. Recently, the class IIb, HDAC6, has emerged as one potential selective HDACi. This isoenzyme represents an important pharmacological target for selective inhibition. Its selectivity may reduce the toxicity related to the off-target effects of pan-HDAC inhibitors. HDAC6 has also been studied in cancer especially for its ability to coordinate a variety of cellular processes that are important for cancer pathogenesis. HDAC6 has been reported to be overexpressed in lymphoid cells and its inhibition has demonstrated activity in preclinical and clinical study of lymphoproliferative disease. Various studies of HDAC6 inhibitors alone and in combination with other agents provide strong scientific rationale for the evaluation of these new agents in the clinical setting of hematological malignancies. In this review, we describe the HDACs, their inhibitors, and the recent advances of HDAC6 inhibitors, their mechanisms of action and role in lymphoproliferative disorders.

Histone Deacetylases as New Therapeutic Targets in Triple-negative Breast Cancer: Progress and Promises

Triple-negative breast cancer (TNBC) lacks expression of estrogen receptor (ER), progesterone receptor (PR) and HER2 gene. It comprises approximately 15-20% of breast cancers (BCs). Unfortunately, TNBC's treatment continues to be a clinical problem because of its relatively poor prognosis, its aggressiveness and the lack of targeted therapies, leaving chemotherapy as the mainstay of treatment. It is essential to find new therapies against TNBC, in order to surpass the resistance and the invasiveness of already existing therapies. Given the fact that epigenetic processes control both the initiation and progression of TNBC, there is an increasing interest in the mechanisms, molecules and signaling pathways that participate at the epigenetic modulation of genes expressed in carcinogenesis. The acetylation of histone proteins provokes the transcription of genes involved in cell growth, and the expression of histone deacetylases (HDACs) is frequently up-regulated in many malignancies. Unfortunately, in the field of BC, HDAC inhibitors have shown limited effect as single agents. Nevertheless, their use in combination with kinase inhibitors, autophagy inhibitors, ionizing radiation, or two HDAC inhibitors together is currently being evaluated. HDAC inhibitors such as suberoylanilidehydroxamic acid (SAHA), sodium butyrate, mocetinostat, panobinostat, entinostat, YCW1 and N-(2-hydroxyphenyl)-2-propylpentanamide have shown promising therapeutic outcomes against TNBC, especially when they are used in combination with other anticancer agents. More studies concerning HDAC inhibitors in breast carcinomas along with a more accurate understanding of the TNBC's pathobiology are required for the possible identification of new therapeutic strategies.

Antitumor effects of histone deacetylase inhibitor suberoylanilide hydroxamic acid in epidermal growth factor receptor-mutant non-small-cell lung cancer lines in vitro and in vivo

Histone acetylation is one of the most abundant post-translational modifications in eukaryotic cells; aberrant histone acetylation is related to a range of cancer types because of the dysregulation of histone deacetylases (HDACs). Inhibition of HDACs leads to suppression of tumor growth in multiple cancers, whereas the inhibitory effects of HDAC inhibitors remain incompletely understood in epidermal growth factor receptor (EGFR)-mutant lung cancers. In this study, the antitumor effects of HDACs inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) were examined in EGFR-mutant lung cancer cell lines. The results of the present work showed that SAHA markedly inhibited cell viability and proliferation, induced cell apoptosis by arresting the cell cycle in the G2/M phase, and significantly reduced tumor growth in a xenograft model. Further study confirmed that the suppression function of SAHA might be mediated by regulating the ERK-dependent and/or the AKT-dependent pathway; meanwhile, angiogenesis abrogation induced by SAHA exerted effects on tumor regression in vivo. Taken together, our results identify the antitumor effects of HDACs inhibitor SAHA as an alternative therapeutic application for the epigenetic treatment of EGFR-mutant non-small-cell lung cancer.

Selective Histone Deacetylase 6 Inhibitor 23BB Alleviated Rhabdomyolysis-Induced Acute Kidney Injury by Regulating Endoplasmic Reticulum Stress and Apoptosis

Histone deacetylase 6 (HDAC6) contributed to the pathogenesis of rhabdomyolysis-induced acute kidney injury (AKI) and selective inhibition of HDAC6 activity may be a promising strategy for the treatment of AKI. Compound 23BB as a highly selective HDAC6 inhibitor was designed, synthesized by our lab and exhibited therapeutic potential in various cancer models with good safety. However, it remained unknown whether 23BB as a drug candidate could offer renal protective effect against rhabdomyolysis-induced AKI. In the present study, we investigated the effect of 23BB in a murine model of glycerol (GL) injection-induced rhabdomyolysis. Following GL injection, the mice developed severe AKI as indicated by acute renal dysfunction and histologic changes, accompanied by increased HDAC6 expression in the cytoplasm of tubular epithelial cells. Pharmacological inhibition of HDAC6 by 23BB pretreatment significantly reduced serum creatinine and serum blood urea nitrogen (BUN) levels as well as attenuated renal tubular damage in GL-injured kidneys. HDAC6 inhibition also resulted in reduced TdT-mediated dUTP nick-end labeling (TUNEL)-positive tubular cells, suppressed BAX, BAK, cleaved caspase-3 levels, and preserved Bcl-2 expression, indicating that 23BB exerted potent renoprotective effects by the regulation of tubular cell apoptosis. Moreover, GL-induced kidney injury triggered multiple signal mediators of endoplasmic reticulum (ER) stress including GRP78, CHOP, IRE1α, p-eIF2α, ATF4, XBP1, p-JNK, and caspase-12. Oral administration of 23BB improved above-mentioned responses in injured kidney tissues and suggested that 23BB modulated tubular cell apoptosis via the inactivation of ER stress. Overall, these data highlighted that renal protection of novel HDAC6 inhibitor 23BB is substantiated by the reduction of ER stress-mediated apoptosis in tubular epithelial cells of rhabdomyolysis-induced AKI.

Histone deacetylase inhibitor trichostatin A and autophagy inhibitor chloroquine synergistically exert anti-tumor activity in H-ras transformed breast epithelial cells

Histone deacetylase inhibitors (HDACIs) cause oncogene‑transformed mammalian cell death. Our previous study indicated that HDACIs activate forkhead box O1 (FOXO1) and induce autophagy in liver and colon cancer cells. However, whether FOXO1 is involved in HDACI‑mediated oncogene‑transformed mammalian cell death remains unclear. In the present study, H‑ras transformed MCF10A cells were used to investigate the role of FOXO1 in this pathway. Results showed that trichostatin A (TSA), a HDACI, activated apoptosis in MCF10A‑ras cells, but not in MCF10A cells. Furthermore, TSA activated FOXO1 via P21 upregulation, whereas the knockdown of FOXO1 reduced TSA‑induced cell death. In addition, TSA induced autophagy in MCF10A and MCF10A‑ras cells by blocking the mammailian target of rapamycin signaling pathway. Furthermore, autophagy inhibition lead to higher MCF10A‑ras cell death by TSA, thus indicating that autophagy is essential in cell survival. Taken together, the present study demonstrated that TSA causes oncogene‑transformed cell apoptosis via activation of FOXO1 and HDACI‑mediated autophagy induction, which served as important cell survival mechanisms. Notably, the present findings imply that a combination of HDACIs and autophagy inhibitors produce a synergistic anticancer effect.

Ricolinostat, a selective HDAC6 inhibitor, shows anti-lymphoma cell activity alone and in combination with bendamustine

Histone deacetylase inhibitors (HDACis) have emerged as a new class of anticancer agents, targeting the biological process including cell cycle and apoptosis. We investigated and explained the anticancer effects of an HDAC6 inhibitor, ricolinostat alone and in combination with bendamustine in lymphoma cell lines. Cell viability was measured by MTT assay. Apoptosis, reactive oxygen species (ROS) generation, Bcl-2 protein expression, cell cycle progression and tubuline expression were determined by flow cytometry. The effects of ricolinostat alone and in combination on the caspases, PI3K/Akt, Bcl-2 pathways, ER stress and UPR were assessed by immunoblotting. Ricolinostat shows anti lymphoma activity when used as single agent and its capability to induce apoptosis is synergistically potentiated by the bendamustine in lymphoma cell lines. Drug combination reduced the proportion of cells in the G0/G1 and S phases and caused an increase of "sub-G0/G1" peak. The synergistic effect accompanied with the increased ROS, activation of caspase-8, -9, and -3, the cleavage of PARP and modulated by Bcl-2 proteins family. In addition, the exposure of ricolinostat induced the acetylation level of α-tubulin, the extend of which was not further modified by bendamustine. Finally, the apoptosis effect of ricolinostat/bendamustine may be mediated by a corresponding effect on microtubule stabilization. Our data suggest that ricolinostat in combination with bendamustine may be a novel combination with potential for use as an antitumor agent in lymphoma.

Overexpression of Histone Deacetylase and Amyloid Precursor Protein in Hepatocellular Carcinoma

Epigenetic modifications are involved in the pathogenesis of cancer, and histone deacetylase inhibitors are considered potential therapeutic agents. Histone tails undergo acetylation at lysine residues, which is associated with transcriptional activation. However, previous studies indicated that as histone deacetylase inhibitors, both (-)-epigallocatechin-3-gallate and valproic acid presented the effects of downregulation of amyloid precursor protein expression, which resulted in the induction of apoptosis. The downregulation of amyloid precursor protein, instead of conventionally activating gene expression as histone deacetylase inhibitor, was attractive. However, there was no relevant report on the correlation of the expression of amyloid precursor protein and histone deacetylase 1 in cancer. In the present study, we detected the expression of amyloid precursor protein and histone deacetylase 1 in hepatocellular carcinoma and adjacent tissues, as well as the correlations among histone deacetylase 1, amyloid precursor protein, and tumor stage. The results showed that the expressions of amyloid precursor protein and histone deacetylase 1 were significantly higher in hepatocellular carcinoma tissues than that in adjacent tissues ( P < .05), however, there was no statistical difference between amyloid precursor protein and histone deacetylase 1 with tumor stages. The present findings provided more foundation for the study on amyloid precursor protein metabolism in cancer, especially on the regulation of amyloid precursor protein by histone deacetylases.

Sodium butyrate-induced apoptosis and ultrastructural changes in MCF-7 breast cancer cells

This study investigated the effects of sodium butyrate (NaB) on Michigan Cancer Foundation-7 (MCF-7) breast cancer cells and analyzed the relevant mechanism. Here, we demonstrated that a certain concentration of NaB effectively induced MCF-7 cell apoptosis. Cell counting kit-8 (CCK-8) assay was used to detect cell viability and the apoptosis rate. Western blotting was used to detect changes in the Bcl-2 expression level. We observed cell shape changes with microscopy. Immunofluorescence revealed some apoptotic nuclei. Electron microscopy revealed thick nucleoli, chromatin margination, reduced mitochondria, and dramatic vacuoles. Collectively, our findings elucidated the morphological mechanism by which NaB changed the ultrastructure of MCF-7 cells.

Receptor-Independent Ectopic Activity of Prolactin Predicts Aggressive Lung Tumors and Indicates HDACi-Based Therapeutic Strategies

AIMS

Ectopic activation of tissue-specific genes accompanies malignant transformation in many cancers. Prolactin (PRL) aberrant activation in lung cancer was investigated here to highlight its value as a biomarker.

RESULTS

PRL is ectopically activated in a subset of very aggressive lung tumors, associated with a rapid fatal outcome, in our cohort of 293 lung tumor patients and in an external independent series of patients. Surprisingly PRL receptor expression was not detected in the vast majority of PRL-expressing lung tumors. Additionally, the analysis of the PRL transcripts in lung tumors and cell lines revealed systematic truncations of their 5' regions, including the signal peptide-encoding portions. PRL expression was found to sustain cancer-specific gene expression circuits encompassing genes that are normally responsive to hypoxia. Interestingly, this analysis also indicated that histone deacetylase (HDAC) inhibitors could counteract the PRL-associated transcriptional activity.

INNOVATION AND CONCLUSION

Altogether, this work not only unravels a yet unknown oncogenic mechanism but also indicates that the specific category of PRL-expressing aggressive lung cancers could be particularly responsive to an HDAC inhibitor-based treatment.

Novel and emerging targeted-based cancer therapy agents and methods

After several decades of uncovering the cancer features and following the improvement of therapeutic agents, however cancer remains as one of the major reasons of mortality. Chemotherapy is one of the main treatment options and has significantly improved the overall survival of cancer patients, but chemotherapeutic agents are highly toxic for normal cells. Therefore, there is a great unmet medical need to develop new therapeutic principles and agents. Targeted-based cancer therapy (TBCT) agents and methods have revolutionized the cancer treatment efficacy. Monoclonal antibodies (mAbs) and small molecule inhibitors (SMIs) are among the most effective agents of TBCT. These drugs have improved the prognosis and survival of cancer patients; however, the therapeutic resistance has subdued the effects. Several mechanisms lead to drug resistance such as mutations in the drug targets, activation of compensatory pathways, and intrinsic or acquired resistance of cancer stem cells. Therefore, new modalities, improving current generation of inhibitors and mAbs, and optimizing the combinational therapy regimens are necessary to decrease the current obstacles in front of TBCT. Moreover, the success of new TBCT agents such as mAbs, SMIs, and immunomodulatory agents has sparked further therapeutic modalities with novel targets to inhibit. Due to the lack of cumulative information describing different agents and methods of TBCT, this review focuses on the most important agents and methods of TBCT that are currently under investigation.

(-)-Epigallocatechin-3-gallate induces cancer cell apoptosis via acetylation of amyloid precursor protein

Epigenetic modifications are involved in cancer pathogenesis, and HDACis are considered potential therapeutic agents. We and others have shown the inhibitory activity of EGCG on HDAC1. But little is known about the effect of EGCG as on epigenetic regulation in cancer. Here, we try to demonstrate that EGCG acts as an HDACi downregulated APP expression, which was pathophysiologically upregulated in cancers and exerts a key role in cancer cell growth. We used PC-12 cells, SK-N-SH cells and primary tumor tissues for our analysis. Male 4-week-old athymic nude mice were used for heterotopic tumor growth assay. We employed Western blotting analysis to detect Bcl-2, Bax, APP, caspase-3, caspase-7, HDAC1 and H4Ac. We used AnnexinV-FITC and TUNEL staining for apoptosis detection. Tumor tissues were examined by immunohistochemical staining. We demonstrated that EGCG suppresses the growth of xenografted adrenal pheochromocytoma. Flow cytometry analysis and TUNEL staining showed that EGCG induced the apoptosis. Treatment with EGCG resulted in decrease in Bcl-2 but increase in Bax and activated caspase-3 and caspase-7. HDAC inhibitor EGCG leaded to hyperacetylated histone H4 by immunofluorescence. EGCG decreased APP levels by immunofluorescence staining and Western blot analysis. Silencing specific to HDAC1 leaded to caspase-3 and caspase-7 activation and cleavage. Our results are the first to demonstrate a functional interaction between EGCG and APP in suppression tumor growth, and provide a new epigenetic effects of EGCG on antitumor.

Histone deacetylase inhibitor sensitizes apoptosis-resistant melanomas to cytotoxic human T lymphocytes through regulation of TRAIL/DR5 pathway

Modern immune therapies (PD-1/PD-L1 and CTLA-4 checkpoints blockade and adoptive cell transfer) have remarkably improved the response rates of metastatic melanoma. These modalities rely on the killing potential of CTL as proximal mediator of antimelanoma responses. Mechanisms of tumor resistance to and the predominant cytotoxic pathway(s) used by melanoma-reactive CTL are important outcome determinants. We hypothesized that downmodulation of death receptors (DRs) in addition to aberrant apoptotic signaling might confer resistance to death signals delivered by CTL. To test these two hypotheses, we used an in vitro model of MART CTL-resistant melanoma sublines. TCR-transgenic and patient-derived CTLs used the TRAIL cytotoxic pathway through DR5. Furthermore, recombinant human TRAIL and drozitumab (anti-DR5 agonistic mAb) were used to explicitly verify the contribution of the DR5/TRAIL pathway in killing melanomas. CTL resistance was due to DR5 downregulation and an inverted ratio of pro- to antiapoptotic molecules, both of which were reversed by the histone deacetylase inhibitor suberoylanilide hydroxanic acid. Apoptosis negative (c-IAP-2 and Bcl-xL) and positive (DR5) regulators were potential incriminators partly regulating CTL sensitivity. These preclinical findings suggest that exposure to this chromatin remodeling drug of immune-resistant melanomas can skew toward an intracellular proapoptotic milieu, increase DR expression, and overcome acquired immune resistance.

The chemopreventive activity of the histone deacetylase inhibitor tributyrin in colon carcinogenesis involves the induction of apoptosis and reduction of DNA damage

The chemopreventive activity of the histone deacetylase inhibitor (HDACi) tributyrin (TB), a prodrug of butyric acid (BA), was evaluated in a rat model of colon carcinogenesis. The animals were treated with TB (TB group: 200mg/100g of body weight, b.w.) or maltodextrin (MD isocaloric control group: 300 mg/100g b.w.) daily for 9 consecutive weeks. In the 3rd and 4th weeks of treatment, the rats in the TB and MD groups were given DMH (40 mg/kg b.w.) twice a week. After 9 weeks, the animals were euthanized, and the distal colon was examined. Compared with the control group (MD group), TB treatment reduced the total number of aberrant crypt foci (ACF; p<0.05) as well as the ACF with ≥4 crypts (p<0.05), which are considered more aggressive, but not inhibited the formation of DMH-induced O6-methyldeoxyguanosine DNA adducts. The TB group also showed a higher apoptotic index (p<0.05) and reduced DNA damage (p<0.05) compared with MD group. TB acted as a HDACi, as rats treated with the prodrug of BA had higher levels of histone H3K9 acetylation compared with the MD group (p<0.05). TB administration resulted in increased colonic tissue concentrations of BA (p<0.05) compared with the control animals. These results suggest that TB can be considered a promising chemopreventive agent for colon carcinogenesis because it reduced the number of ACF, including those that were more aggressive. Induction of apoptosis and reduction of DNA damage are cellular mechanisms that appear to be involved in the chemopreventive activity of TB.

Extending in silico mechanism-of-action analysis by annotating targets with pathways: application to cellular cytotoxicity readouts

BACKGROUND

An in silico mechanism-of-action analysis protocol was developed, comprising molecule bioactivity profiling, annotation of predicted targets with pathways and calculation of enrichment factors to highlight targets and pathways more likely to be implicated in the studied phenotype.

RESULTS

The method was applied to a cytotoxicity phenotypic endpoint, with enriched targets/pathways found to be statistically significant when compared with 100 random datasets. Application on a smaller apoptotic set (10 molecules) did not allowed to obtain statistically relevant results, suggesting that the protocol requires modification such as analysis of the most frequently predicted targets/annotated pathways.

CONCLUSION

Pathway annotations improved the mechanism-of-action information gained by target prediction alone, allowing a better interpretation of the predictions and providing better mapping of targets onto pathways.

Expression of histone deacetylases in diffuse large B-cell lymphoma and its clinical significance

BACKGROUND

Histone deacetylase inhibitors are a new class of drugs used in treatment of malignant tumors. Diffuse large B-cell lymphoma (DLBCL) is the most common type of B-cell lymphoma, and it accounts for more than 40% of all B-cell lymphomas. In this study, we aimed to determine the expression patterns of histone deacetylases (HDACs) in DLBCL, to examine whether HDAC expression patterns differ among cases, and to assess whether these findings have clinical significance.

MATERIALS AND METHODS

We selected 91 cases of DLBCL diagnosed at St. Vincent Hospital, The Catholic University of Korea, from 2001-2012. We performed a pathology slide review and collected clinical data including age, sex, tumor site, survival time, and mortality. Immunohistochemical analysis was performed using primary antibodies for HDACs, including HDAC1 and 2 of class I, HDAC4 and 5 of class IIa, and HDAC6 of class IIb. Expression site was determined to be nuclear, cytoplasmic, or both. Staining intensities were graded as low and high. We assessed correlations between HDAC expression levels and clinical data and survival analysis.

RESULTS

Of the 91 cases examined, 46 (50.5%) were men and 45 (49.5%) were women. Most of the patients were elderly, and 74 (81.3%) cases were older than 46 y. Forty-six (50.5%) cases showed lymph node involvement, and 45 (49.5%) cases showed lymphoma at extranodal sites. In nodal lymphoma, staining was strongly positive for HDAC2, whereas staining was weak or negative for HDAC4; however, there was no significant correlation with survival. But nodal lymphoma cases with high nuclear expression of HDAC2 and nodal lymphoma cases with high nuclear expression of HDAC2 and low nuclear expression of HDAC4 showed significantly shorter survival times compared with other cases.

CONCLUSIONS

High nuclear expression of HDAC2 may play an important role in survival of DLBCL patients, especially in those with nodal lymphoma, which is associated with a shorter survival time. Our results may have important implications for treatment of DLBCL by epigenetic regulation.

SAHA, an HDAC inhibitor, attenuates antibody-mediated allograft rejection

BACKGROUND

Antibody-mediated rejection (AMR) is gaining increasing recognition as a critical causative factor contributing to graft loss in organ transplantation. However, current therapeutic options for prevention and treatment of AMR are very limited and ineffective. The impact of epigenetic modification in B-cell function and its involvement in AMR is still yet to be explored.

METHODS

The impacts of suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor, on isolated murine B-cell viability, proliferation, apoptosis, expression of surface marker, and secretion of immunoglobulin and interleukin-10 were investigated. In vivo, a murine cardiac transplant model was used to evaluate the effect of SAHA on splenic B-cell subsets and on AMR in Rag1(-/-) recipient mice after reconstitution of allostimulated B cells.

RESULTS

SAHA possesses capability to repress B-cell function. Specifically, SAHA is potent to decrease the viability of isolated B cells by inducing apoptosis. SAHA was also found capable of suppressing the expression of B-cell costimulatory molecules and, as a result, addition of SAHA into the cultures attenuated B-cell proliferation and immunoglobulin secretion. In line with these results, administration of SAHA significantly suppressed AMR in Rag1(-/-) recipient mice after reconstitution of allostimulated B cells along with enhanced cardiac allograft survival time. Mechanistic studies revealed that SAHA promotes B-cell secretion of interleukin-10.

CONCLUSIONS

Our data support that SAHA could be a promising immunosuppressive agent with potential beneficial effect on prevention and treatment of AMR.

Preclinical data and early clinical experience supporting the use of histone deacetylase inhibitors in multiple myeloma

Histone deacetylases (HDACs) mediate protein acetylation states, which in turn regulate normal cellular processes often dysregulated in cancer. These observations led to the development of HDAC inhibitors that target tumors through multiple effects on protein acetylation. Clinical evidence demonstrates that treatment with HDAC inhibitors (such as vorinostat, panobinostat, and romidepsin) in combination with other antimyeloma agents (such as proteasome inhibitors and immunomodulatory drugs) has promising antitumor activity in relapsed/refractory multiple myeloma patients. This mini-review highlights the role of protein acetylation in the development of cancers and the rationale for the use of HDAC inhibitors in this patient population.

Immunologic targeting of FOXP3 in inflammatory breast cancer cells

The forkhead transcription factor FOXP3 is necessary for induction of regulatory T lymphocytes (Tregs) and their immunosuppressive function. We have previously demonstrated that targeting Tregs by vaccination of mice with murine FOXP3 mRNA-transfected dendritic cells (DCs) elicits FOXP3-specific T cell responses and enhances tumor immunity. It is clear that FOXP3 expression is not restricted to T-cell lineage and herein, using RT-PCR, flow cytometry, and western immunoblot we demonstrate for the first time that FOXP3 is expressed in inflammatory breast cancer (IBC) cells, SUM149 (triple negative, ErbB1-activated) and SUM190 (ErbB2-overexpressing). Importantly, FOXP3-specific T cells generated in vitro using human FOXP3 RNA-transfected DCs as stimulators efficiently lyse SUM149 cells. Interestingly, an isogenic model (rSUM149) derived from SUM149 with an enhanced anti-apoptotic phenotype was resistant to FOXP3-specific T cell mediated lysis. The MHC class I cellular processing mechanism was intact in both cell lines at the protein and transcription levels suggesting that the resistance to cytolysis by rSUM149 cells was not related to MHC class I expression or to the MHC class I antigen processing machinery in these cells. Our data suggest that FOXP3 may be an effective tumor target in IBC cells however increased anti-apoptotic signaling can lead to immune evasion.

Inhibition of class I histone deacetylases in non-small cell lung cancer by honokiol leads to suppression of cancer cell growth and induction of cell death in vitro and in vivo

Non-small-cell lung cancer (NSCLC) represents approximately 80% of all types of lung cancer. Here, we report the chemotherapeutic effect of honokiol, a phytochemical from Magnolia grandiflora, on NSCLC cells and the molecular mechanisms underlying these effects using in vitro and in vivo models. Treatment of NSCLC cells (A549, H1299, H460 and H226) with honokiol (20, 40 and 60 µM) inhibited histone deacetylase (HDAC) activity, reduced the levels of class I HDAC proteins and enhanced histone acetyltransferase activity in a dose-dependent manner. These effects of honokiol were associated with a significant reduction in the viability of NSCLC cells. Concomitant treatment of cells with a proteasome inhibitor, MG132, prevented honokiol-induced degradation of class I HDACs, suggesting that honokiol reduced the levels of HDACs in NSCLC cells through proteasomal degradation. Valproic acid, an inhibitor of HDACs, exhibited a similar pattern of reduced viability and induction of death of NSCLC cells. Treatment of A549 and H1299 cells with honokiol resulted in an increase in G 1 phase arrest, and a decrease in the levels of cyclin D1, D2 and cyclin dependent kinases. Further, administration of honokiol by oral gavage significantly inhibited the growth of subcutaneous A549 and H1299 tumor xenografts in athymic nude mice, which was associated with the induction of apoptotic cell death and marked inhibition of class I HDACs proteins and HDAC activity in the tumor xenograft tissues. Together, our study provides new insights into the role of class I HDACs in the chemotherapeutic effects of honokiol on lung cancer cells.

Role of apoptosis in disease

Since the initial description of apoptosis, a number of different forms of cell death have been described. In this review we will focus on classic caspase-dependent apoptosis and its variations that contribute to diseases. Over fifty years of research have clarified molecular mechanisms involved in apoptotic signaling as well and shown that alterations of these pathways lead to human diseases. Indeed both reduced and increased apoptosis can result in pathology. More recently these findings have led to the development of therapeutic approaches based on regulation of apoptosis, some of which are in clinical trials or have entered medical practice.

Reactive oxygen species regulation of autophagy in cancer: implications for cancer treatment

Reactive oxygen species (ROS) are important in regulating normal cellular processes, but deregulated ROS contribute to the development of various human diseases including cancers. Autophagy is one of the first lines of defense against oxidative stress damage. The autophagy pathway can be induced and upregulated in response to intracellular ROS or extracellular oxidative stress. This leads to selective lysosomal self-digestion of intracellular components to maintain cellular homeostasis. Hence, autophagy is the survival pathway, conferring stress adaptation and promoting viability under oxidative stress. However, increasing evidence has demonstrated that autophagy can also lead to cell death under oxidative stress conditions. In addition, altered autophagic signaling pathways that lead to decreased autophagy are frequently found in many human cancers. This review discusses the advances in understanding of the mechanisms of ROS-induced autophagy and how this process relates to tumorigenesis and cancer therapy.

Anticancer activity of MPT0E028, a novel potent histone deacetylase inhibitor, in human colorectal cancer HCT116 cells in vitro and in vivo

Recently, histone deacetylase (HDAC) inhibitors have emerged as a promising class of drugs for treatment of cancers, especially subcutaneous T-cell lymphoma. In this study, we demonstrated that MPT0E028, a novel N-hydroxyacrylamide-derived HDAC inhibitor, inhibited human colorectal cancer HCT116 cell growth in vitro and in vivo. The results of NCI-60 screening showed that MPT0E028 inhibited proliferation in both solid and hematological tumor cell lines at micromolar concentrations, and was especially potent in HCT116 cells. MPT0E028 had a stronger apoptotic activity and inhibited HDACs activity more potently than SAHA, the first therapeutic HDAC inhibitor proved by FDA. In vivo murine model, the growth of HCT116 tumor xenograft was delayed and inhibited after treatment with MPT0E028 in a dose-dependent manner. Based on in vivo study, MPT0E028 showed stronger anti-cancer efficacy than SAHA. No significant body weight difference or other adverse effects were observed in both MPT0E028-and SAHA-treated groups. Taken together, our results demonstrate that MPT0E028 has several properties and is potential as a promising anti-cancer therapeutic drug.

Oxidative stress in apoptosis and cancer: an update

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

REST is up-regulated by epidermal growth factor in HeLa cells and inhibits apoptosis by influencing histone H3 acetylation

REST (repressor element 1-silencing transcription factor) is a transcription factor that recruits histone deacetylases to silence gene transcription. REST appears to play a paradoxical role in cancer cells: it exhibits tumor suppressor activity or promotes tumorigenesis, depending upon the setting. The extracellular signaling molecules that control REST gene expression in cancer cells remain poorly understood. In this study, we report that REST expression in HeLa cells is elevated in cells exposed to epidermal growth factor or serum, whereas the rate of cell apoptosis is low. Apoptosis induced by serum withdrawal is significantly increased in HeLa cells treated with an antisense phosphorothioate oligodeoxynucleotide (AS ODN) capable of down-regulating REST expression, whereas in HeLa cells transfected with a REST expressing plasmid, REST overexpression reduces the marked apoptosis caused, in absence of serum, by exposure to an anti-Fas receptor antibody imitating the Fas ligand activity plus PD 98059, a blocker of extracellular signal-regulated kinase 1/2 activation. REST knockdown also reduces mRNA levels of the antiapoptotic protein Bcl-X(L) whereas in HeLa cells overexpressing REST, the reduction of Bcl-X(L) mRNA caused by the anti-Fas receptor antibody plus PD 98059 is significantly decreased. Finally, we report that acetylation of histone H3 is increased in HeLa cells exposed to AS ODN or anti-Fas receptor antibody, whereas it is reduced in cells transfected with the REST expressing plasmid. Our findings indicate that REST is a novel gene regulated by EGF in HeLa cells that potentially contributes to the modulation of apoptosis via epigenetic mechanisms.

Histone deacetylase inhibitor potentiates chemotherapy-induced apoptosis through Bim upregulation in Burkitt's lymphoma cells

PURPOSE

Although polychemotherapy regiments have improved clinical outcome for Burkitt's lymphoma (BL) patients, salvage treatment of patients with refractory disease remains very poor. Combined therapies protocols have been emerging to improve treatment strategies to circumvent responseless BL patients. We evaluate the cell death effect of histone deacetylase inhibitor (HDACI) combined with etoposide (VP-16) and cisplatin (CDDP) on BL cell lines.

METHODS

3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay was performed to assess drug toxicity. To establish the concentrations and time of incubation for the combined treatment, a kinetic analysis was performed for each drug on BL41 and Raji BL cell lines for 24, 48 and 72 h. Apoptosis was assessed by flow cytometry using Annexin V/propidium iodide (PI) and cleaved caspase 3 labeling assays. Caspase 9 activation and levels of Bcl-2 family proteins were analyzed by Western blot.

RESULTS

The doses of NaB (1.0 mM), CDDP (1.0 and 2.5 μM), and VP-16 (0.1 and 0.3 μM) after 24 h of incubation were chosen for the evaluation of combined therapy. The apoptotic effects on BL cell lines of NaB/VP-16 and NaB/CDDP were followed by upregulation of Bim protein (P < 0.05), activation of caspase-3 and caspase-9, followed by Mcl-1 downregulation (P < 0.05). However, Bim overexpression was not correlated with Bcl-2 inhibition (P > 0.05) and was accompanied by increase in Bax expression (P < 0.05). The combination effects of NaB/VP-16 and NaB/CDDP were found to be synergistic and additive, respectively, in both the cell lines.

CONCLUSIONS

The study provides strong evidence for the synergistic effects of the association with HDCI and chemotherapy in BL cells.

New therapeutic targets in melanoma

Research into molecular targets for drug development in melanoma is starting to bear fruit. Of the drugs tested to date in patients with metastatic melanoma, those that have yielded the best results are V600E BRAF inhibitors in melanomas carrying the V600E mutation; c-kit tyrosine kinase activity inhibitors in melanomas carrying c-kit mutations; and anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies, which block the mechanisms involved in immune tolerance. Many problems have yet to be resolved in these areas, however, such as the rapid development of resistance to BRAF and c-kit inhibitors and the lack of biomarkers to predict treatment response in the case of CTLA-4 blockers. We review the results of targeted therapy with these and other drugs in metastatic melanoma and discuss what the future holds for this field.

Curcumin sensitizes chemotherapeutic drugs via modulation of PKC, telomerase, NF-κB and HDAC in breast cancer

Background: Several tumor markers are overexpressed in breast cancer. Chemotherapy in breast cancer fails due to resistance to chemotherapeutic drugs. A phytochemical such as curcumin can be used in a therapeutic modality as it elicits anti-tumor effects. Methods: Action of curcumin on the expression of several tumor markers, such as protein kinase C, telomerase, NF-κB and histone deacetylase in MCF-7 (ER positive), MDA-MB-231 (ER negative), MCF-12F (control) and also in mice mammary tumors were investigated. Results: Curcumin downregulated the expression of tumor markers both in vitro and in vivo and sensitized tumor cells to the chemotherapeutic drugs cyclophosphamide and paclitaxel. Discussion: Curcumin may be of considerable value in synergistic therapy of cancer such that the drug dose level could be minimized reducing the associated toxicity.