SAHA induces apoptosis in hepatoma cells and synergistically interacts with the proteasome inhibitor Bortezomib

PaDef (Persea americana var. drymifolia), a Plant Antimicrobial Peptide, Triggers Apoptosis, and Induces Global Epigenetic Modifications on Histone 3 in an Acute Lymphoid Leukemia Cell Line

In recent years, it has been recognized that epigenetic alterations play an important role in the development and maintenance of cancer, including leukemias. Furthermore, it is known that these alterations are involved in the emergence of resistance to conventional chemotherapeutics. Consequently, molecules with an anticancer activity whose activity is ruled by epigenetic modifications are attractive to search for new therapies against cancer. The plant antimicrobial peptides have been widely evaluated as molecules with anticancer activity; however, the analysis of the epigenetic regulation induced by these molecules associated with this activity is scarce and still is an unexplored field. In this work, we show that the PaDef defensin, a plant antimicrobial peptide from Mexican avocado fruit (Persea americana var. drymifolia) is cytotoxic for Jurkat cell line from acute lymphoid leukemia cells, through an apoptotic process. PaDef inhibited cell viability in a concentration-dependent manner, with an IC₅₀ = 47.3 μM. Treatment of Jurkat cells with PaDef (IC₅₀) induced cell death by apoptosis dependent on caspases 8 and 9; besides, it was related to an increase in the production of reactive oxygen species and the loss of mitochondrial membrane potential. Interestingly, the inhibition of caspase activation by inhibitors of caspases 8 and 9 does not revert the reduction in viability, suggesting that other mechanisms, in addition to caspase activity, could be participating in the PaDef cytotoxic effect. Also, the modifications in the histone 3 tails induced by PaDef in Jurkat cells were evaluated, specifically acetylation and methylation. PaDef increased global histone 3 acetylation and lysine 9 specific marks (2-fold and up to 4-fold, respectively). These effects correlated with the reduction of the Histone Deacetylase activity (HDAC, ∼50%). Based on methylation marks, PaDef treatment increased lysine 9 di- and tri-methylation tags (2-fold in both cases). The epigenetic modulation induced by PaDef on Jurkat cells could be related to the chromatin compaction-decompaction promoting gene expression or repression; however, further studies are necessary to correlate these marks with the transcription of specific genes. Therefore, the study of new molecules that may have anticancer activity through epigenetic modulation is interesting.

Pharmacological inhibition of HDAC1/3-interacting proteins induced morphological changes, and hindered the cell proliferation and migration of hepatocellular carcinoma cells

Liver diseases are particularly severe health problems, but the options available for preventing and treating them remain limited. Accumulating evidence has shown that there is altered expression of individual histone deacetylase (HDAC) family members in hepatocellular carcinoma cells. In a previous study, we have identified a set of proteins which interact with histone deacetylase 1 and 3 (HDAC1/3) in hepatocellular carcinoma cell lines HepG2 by proteomic approach. This study was designed to investigate the therapeutic potential and expression of HDAC1/3-interacting genes in a human hepatocellular carcinoma cell line (HepG2). Pharmacological and transcriptional inhibition of HDAC1/3 resulted in the suppression of cancer cell proliferation, change of cell morphology, and downregulation of HDAC1/3 genes in HepG2 cells. The pharmacological inhibition also resulted in inhibition of liver cancer cell migration by wound scratch assay. Taken together, the results from this study show that the upregulation of HDAC1/3 in hepatocellular carcinoma resulted in the overexpression of CNOT1, PFDN2/6, and HMG20B, and that these genes could serve as novel molecular targets in liver cancer.

Trichostatin A inhibits proliferation of PC3 prostate cancer cells by disrupting the EGFR pathway

Prostate cancer (PC) is the most common type of malignancy to exist in men within developed countries. Androgen deprivation therapy is performed for metastatic and advanced PC. However, the majority of cases of prostate cancer become refractory during therapy, leading to castration-resistant PC (CRPC). Histone deacetylases (HDACs) are key factors in regulating gene transcription and have been associated with cancer development. In the present study the small molecule inhibitor trichostatin A (TSA), which targets HDACs, was demonstrated to inhibit the proliferation of CRPC PC3 cells by disrupting the epidermal growth factor receptor (EGFR)-STAT3 pathway. The expression of EGFR and STAT3 was downregulated following TSA treatment, and cell cycle arrest was induced by downregulating the expression of cyclin D1 and CDK6, and via retinoblastoma protein phosphorylation. Furthermore, the transcription of cyclin D1 and CDK6 was suppressed by TSA. Apoptosis of PC3 cells treated with TSA was also investigated, and it was revealed that TSA induced apoptosis by upregulating BAX and downregulating BCL-2. The combination of TSA with doxorubicin exerted a synergistic inhibitory effect on PC3 cell proliferation through the induction of apoptosis. The results of the present study revealed a promising epigenetic-based therapeutic strategy that could be implemented in cases of CRPC.

The in vitro and in vivo anti-melanoma effects of hydroxyapatite nanoparticles: influences of material factors

Background

Treatment for melanoma is a challenging clinical problem, and some new strategies are worth exploring.

Purpose

The objective of this study was to investigate the in vitro and in vivo anti-melanoma effects of hydroxyapatite nanoparticles (HANPs) and discuss the involved material factors.

Materials and methods

Five types of HANPs, ie, HA-A, HA-B, HA-C, HA-D, and HA-E, were prepared by wet chemical method combining with polymer template and appropriate post-treatments. The in vitro effects of the as-prepared five HANPs on inhibiting the viability of A375 melanoma cells and inducing the apoptosis of the cells were evaluated by Cell Counting Kit-8 analysis, cell nucleus morphology observation, flow cytometer, and PCR analysis. The in vivo anti-melanoma effects of HANPs were studied in the tumor model of nude mice.

Results

The five HANPs had different physicochemical properties, including morphology, size, specific surface area (SSA), crystallinity, and so on. By the in vitro cell study, it was found that the material factors played important roles in the anti-melanoma effect of HANPs. Among the as-prepared five HANPs, HA-A with granular shape, smaller size, higher SSA, and lower crystallinity exhibited best effect on inhibiting the viability of A375 cells. At the concentration of 200 μg/mL, HA-A resulted in the lowest cell viability (34.90%) at day 3. All the HANPs could induce the apoptosis of A375 cells, and the relatively higher apoptosis rates of the cells were found in HA-A (20.10%) and HA-B (19.41%) at day 3. However, all the HANPs showed no inhibitory effect on the viability of the normal human epidermal fibroblasts. The preliminary in vivo evaluation showed that both HA-A and HA-C could delay the formation and growth speed of melanoma tissue significantly. Likely, HA-A exhibited better effect on inhibiting the growth of melanoma tissue than HA-C. The inhibition rate of HA-A for tumor tissue growth reached 49.1% at day 23.

Conclusion

The current study confirmed the anti-melanoma effect of HANPs and provided a new idea for the clinical treatment of melanoma.

Spotlight on Bortezomib: potential in the treatment of hepatocellular carcinoma

INTRODUCTION

This study reviews the evidence for the use of Bortezomib (BZB), a first-in-class proteasome inhibitor in advanced Hepatocellular carcinoma (HCC). This review aims to delineate the role of BZB within the management of non-surgical and metastatic HCC, either as an alternative or as an adjunct to the current treatment paradigm.

AREAS COVERED

In addition to BZB pharmacology and mechanism of action, safety and tolerance profiles of the drug obtained from clinical trials are explored. The utility of BZB as a therapeutic agent either alone or in combination with other therapies against HCC, including its application in both preclinical and clinical settings has been reviewed. In particular, we highlight the importance of preclinical evaluation of BZB as a combinatorial agent in synergism with other therapies for the use in the management of HCC.

EXPERT OPINION

There has been much interest surrounding the use of BZB, a first-in-class proteasome inhibitor for HCC therapy. The discernment of outcomes of BZB clinical trials for HCC need to take into consideration the disease-specific factors that can affect survival outcomes including patient selection and aetiological differences. Further preclinical testing of BZB in combination with other therapeutic modalities can be important for eliciting enhanced anti-HCC effects.

New insights into diagnosis and therapeutic options for proliferative hepatoblastoma

Surgery and cisplatin-based treatment of hepatoblastoma (HB) currently guarantee the survival of 70%-80% of patients. However, some important challenges remain in diagnosing high-risk tumors and identifying relevant targetable pathways offering new therapeutic avenues. Previously, two molecular subclasses of HB tumors have been described, C1 and C2, with C2 being the subgroup with the poorest prognosis, a more advanced tumor stage, and the worst overall survival rate. An associated 16-gene signature to discriminate the two tumoral subgroups was proposed, but it has not been transferred into clinical routine. To address these issues, we performed RNA sequencing of 25 tumors and matched normal liver samples from patients. The transcript profiling separated HB into three distinct subgroups named C1, C2A, and C2B, identifiable by a concise four-gene signature: hydroxysteroid 17-beta dehydrogenase 6, integrin alpha 6, topoisomerase 2-alpha, and vimentin, with topoisomerase 2-alpha being characteristic for the proliferative C2A tumors. Differential expression of these genes was confirmed by quantitative RT-PCR on an expanded cohort and by immunohistochemistry. We also revealed significant overexpression of genes involved in the Fanconi anemia (FA) pathway in the C2A subgroup. We then investigated the ability of several described FA inhibitors to block growth of HB cells in vitro and in vivo. We demonstrated that bortezomib, a Food and Drug Administration-approved proteasome inhibitor, strongly impairs the proliferation and survival of HB cell lines in vitro, blocks FA pathway-associated double-strand DNA repair, and significantly impedes HB growth in vivo.

CONCLUSION

The highly proliferating C2A subtype is characterized by topoisomerase 2-alpha gene up-regulation and FA pathway activation, and the HB therapeutic arsenal could include bortezomib for the treatment of patients with the most aggressive tumors. (Hepatology 2018;68:89-102).

Therapeutic potential and functional interaction of carfilzomib and vorinostat in T-cell leukemia/lymphoma

We previously showed that the proteasome inhibitor carfilzomib and the histone deacetylase inhibitor (HDACI) vorinostat cooperated to induce cell apoptosis in one T-cell leukemia cell line in vitro, implying the possibility of the combination treatment of carfilzomib and vorinostat as a potential therapeutic strategy in human T-cell leukemia/lymphoma. Here we report that combination treatment of carfilzomib and vorinostat enhanced cell apoptosis and induced a marked increase in G2-M arrest, reactive oxygen species (ROS) generation, and activated the members of mitogen-activated protein kinases (MAPK) family, including the stress-activated kinases JNK, p38MAPK, and ERK1/2. Carfilzomib/vorinostat-mediated apoptosis was blocked by the ROS scavenger N-acetylcysteine (NAC). The JNK inhibitor SP600125 and the p38MAPK inhibitor SB203580 but not the MEK1/2 inhibitor U0126 significantly attenuated carfilzomib/vorinostat-induced apoptosis, suggesting that p38MAPK and JNK activation contribute to carfilzomib and vorinostat-induced apoptosis. This was further confirmed via short hairpin (shRNA) RNA knockdown of p38MAPK and JNK. Interestingly, the ROS scavenger NAC attenuated carfilzomib/vorinostat-mediated activation of p38MAPK and JNK. However, p38MAPK shRNA but not JNK shRNA diminished carfilzomib/vorinostat-mediated ROS generation. In contrast, overexpression of p38MAPK significantly increased carfilzomib/vorinostat-mediated ROS generation, suggesting that an amplification loop exists between ROS and p38MAPK pathway. Combination treatment of carfilzomib and vorinostat enhanced their individual antitumor activity in both a human xenograft model as well as human primary T-cell leukemia/lymphoma cells. These data suggest the potential clinical benefit and underlying molecular mechanism of combining carfilzomib with vorinostat in the treatment of human T-cell leukemia/lymphoma.

Modification of Epigenetic Histone Acetylation in Hepatocellular Carcinoma

Cells respond to various environmental factors such as nutrients, food intake, and drugs or toxins by undergoing dynamic epigenetic changes. An imbalance in dynamic epigenetic changes is one of the major causes of disease, oncogenic activities, and immunosuppressive effects. The aryl hydrocarbon receptor (AHR) is a unique cellular chemical sensor present in most organs, and its dysregulation has been demonstrated in multiple stages of tumor progression in humans and experimental models; however, the effects of the pathogenic mechanisms of AHR on epigenetic regulation remain unclear. Apart from proto-oncogene activation, epigenetic repressions of tumor suppressor genes are involved in tumor initiation, procession, and metastasis. Reverse epigenetic repression of the tumor suppressor genes by epigenetic enzyme activity inhibition and epigenetic enzyme level manipulation is a potential path for tumor therapy. Current evidence and our recent work on deacetylation of histones on tumor-suppressive genes suggest that histone deacetylase (HDAC) is involved in tumor formation and progression, and treating hepatocellular carcinoma with HDAC inhibitors can, at least partially, repress tumor proliferation and transformation by recusing the expression of tumor-suppressive genes such as TP53 and RB1.

Therapeutic Strategies against Epstein-Barr Virus-Associated Cancers Using Proteasome Inhibitors

Epstein-Barr virus (EBV) is closely associated with several lymphomas (endemic Burkitt lymphoma, Hodgkin lymphoma and nasal NK/T-cell lymphoma) and epithelial cancers (nasopharyngeal carcinoma and gastric carcinoma). To maintain its persistence in the host cells, the virus manipulates the ubiquitin-proteasome system to regulate viral lytic reactivation, modify cell cycle checkpoints, prevent apoptosis and evade immune surveillance. In this review, we aim to provide an overview of the mechanisms by which the virus manipulates the ubiquitin-proteasome system in EBV-associated lymphoid and epithelial malignancies, to evaluate the efficacy of proteasome inhibitors on the treatment of these cancers and discuss potential novel viral-targeted treatment strategies against the EBV-associated cancers.

Vorinostat suppresses hypoxia signaling by modulating nuclear translocation of hypoxia inducible factor 1 alpha

Histone deacetylase inhibitors (HDACis) are a potent class of tumor-suppressive agents traditionally believed to exert their effects through loosening tightly-wound chromatin resulting in de-inhibition of various tumor suppressive genes. Recent literature however has shown altered intratumoral hypoxia signaling with HDACi administration not attributable to changes in chromatin structure. We sought to determine the precise mechanism of HDACi-mediated hypoxia signaling attenuation using vorinostat (SAHA), an FDA-approved class I/IIb/IV HDACi. Through an in-vitro and in-vivo approach utilizing cell lines for hepatocellular carcinoma (HCC), osteosarcoma (OS), and glioblastoma (GBM), we demonstrate that SAHA potently inhibits HIF-a nuclear translocation via direct acetylation of its associated chaperone, heat shock protein 90 (Hsp90). In the presence of SAHA we found elevated levels of acetyl-Hsp90, decreased interaction between acetyl-Hsp90 and HIF-a, decreased nuclear/cytoplasmic HIF-α expression, absent HIF-α association with its nuclear karyopharyin Importin, and markedly decreased HIF-a transcriptional activity. These changes were associated with downregulation of downstream hypoxia molecules such as endothelin 1, erythropoietin, glucose transporter 1, and vascular endothelial growth factor. Findings were replicated in an in-vivo Hep3B HRE-Luc expressing xenograft, and were associated with significant decreases in xenograft tumor size. Altogether, this study highlights a novel mechanism of action of an important class of chemotherapeutic.

Induction of MAPK- and ROS-dependent autophagy and apoptosis in gastric carcinoma by combination of romidepsin and bortezomib

Proteasome inhibitors and histone deacetylase (HDAC) inhibitors can synergistically induce apoptotic cell death in certain cancer cell types but their combinatorial effect on the induction of autophagy remains unknown. Here, we investigated the combinatorial effects of a proteasome inhibitor, bortezomib, and an HDAC inhibitor, romidepsin, on the induction of apoptotic and autophagic cell death in gastric carcinoma (GC) cells. Isobologram analysis showed that low nanomolar concentrations of bortezomib/romidepsin could synergistically induce killing of GC cells. The synergistic killing was due to the summative effect of caspase-dependent intrinsic apoptosis and caspase-independent autophagy. The autophagic cell death was dependent on the activation of MAPK family members (ERK1/2 and JNK), and generation of reactive oxygen species (ROS), but was independent of Epstein-Barr virus infection. In vivo, bortezomib/romidepsin also significantly induced apoptosis and autophagy in GC xenografts in nude mice. This is the first report demonstrating the potent effect of combination of HDAC and proteasome inhibitors on the induction of MAPK- and ROS-dependent autophagy in addition to caspase-dependent apoptosis in a cancer type.

Juglone loaded poloxamer 188/phospholipid mixed micelles evaluated in vitro and in vivo in breast cancer

AIM

Investigating the effects of juglone loaded P188/phospholipid mixed micelles (J-MM) in breast cancer.

MATERIALS & METHODS

In vitro cytotoxicity, apoptotic effects, in vivo therapeutic efficacy and toxicity were used to assess its antitumour effect. Uptake and imaging were used to evaluate the effect on the uptake and passive targeting.

RESULTS

Mixed micelle carrier enhanced the targeting and uptake by MB-231 cells. The tumour inhibition rates in tumour xenograft models for paclitaxel, juglone, J-MM (10mg/kg) and J-MM (40mg/kg) were 46%, 27%, 39% and 53%, respectively. J-MM (10mg/kg) exhibited lower toxicity compared with that by free juglone or high dose J-MM.

CONCLUSION

J-MM exhibited low toxicity, improved cellular uptake, passive targeting and anti-cancer effects in breast cancer model.

dbPHCC: a database of prognostic biomarkers for hepatocellular carcinoma that provides online prognostic modeling

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers with a poor prognosis. For decades, more and more biomarkers were found to effect on HCC prognosis, but these studies were scattered and there were no unified identifiers. Therefore, we built the database of prognostic biomarkers and models for hepatocellular carcinoma (dbPHCC).

METHODS

dbPHCC focuses on biomarkers which were related to HCC prognosis by traditional experiments rather than high-throughput technology. All of the prognostic biomarkers came from literatures issued during 2002 to 2014 in PubMed and were manually selected. dbPHCC collects comprehensive information of candidate biomarkers and HCC prognosis.

RESULTS

dbPHCC mainly contains 567 biomarkers: 323 proteins, 154 genes, and 90 microRNAs. For each biomarker, the reference information, experimental conditions, and prognostic information are shown. Based on two available patient cohort data sets, an exemplified prognostic model was constructed using 15 phosphotransferases in dbPHCC. The web interface does not only provide a full range of browsing and searching, but also provides online analysis tools. dbPHCC is available at http://lifecenter.sgst.cn/dbphcc/

CONCLUSIONS

dbPHCC provides a comprehensive and convenient search and analysis platform for HCC prognosis research.

GENERAL SIGNIFICANCE

dbPHCC is the first database to focus on experimentally verified individual biomarkers, which are related to HCC prognosis. Prognostic markers in dbPHCC have the potential to be therapeutic drug targets and may help in designing new treatments to improve survival of HCC patients. This article is part of a Special Issue entitled "System Genetics" Guest Editor: Dr. Yudong Cai and Dr. Tao Huang.

A correlation analysis between HDAC1 over-expression and clinical features of laryngeal squamous cell carcinoma

CONCLUSION

HDAC1 may be a prognostic biomarker for LSCC malignant potency and a potent factor resulting in decreased sensitivity of LSCC in radiotherapy.

OBJECTIVE

The aim of this study was to evaluate the correlation between histone deacetylase 1 (HDAC1) over-expression and clinical features in laryngeal squamous cell carcinoma (LSCC).

METHODS

This study assessed the HDAC1 expressions in 90 formalin-fixed paraffin-embedded LSCC samples, 30 adjacent non-neoplastic tissues, and 30 laryngeal polyp tissues by immunohistochemistry (IHC). In addition, another 40 LSCC samples were collected that were divided into two groups after 3-month radiotherapy: the high radio-sensitive group (HRS) and low radio-sensitive group (LRS). Overall survival curves of all the LSCC patients were constructed by Kaplan-Meier method and long-rank test.

RESULTS

All ninety samples were positively immunostained for HDAC1. The expression of HDAC1 was up-regulated and significantly associated with T classification, lymph node metastases, tumor location and clinical stage. HDAC1 was mainly labeled in the epithelial cells of laryngeal polyp tissues and adjacent non-neoplastic tissues. In addition, the expression of HDAC1 was significantly higher in LRS than that in HRS. The positive rates for stage III-IV tumor were significantly higher than those for stage II. LSCC patients with HDAC1 over-expression and LRS presented a shorter 5-year overall survival rate.

The synergistic effect of SAHA and parthenolide in MDA-MB231 breast cancer cells

The sesquiterpene lactone Parthenolide (PN) exerted a cytotoxic effect on MDA-MB231 cells, a triple-negative breast cancer (TNBC) cell line, but its effectiveness was scarce when employed at low doses. This represents an obstacle for a therapeutic utilization of PN. In order to overcome this difficulty we associated to PN the suberoylanilide hydroxamic acid (SAHA), an histone deacetylase inhibitor. Our results show that SAHA synergistically sensitized MDA-MB231 cells to the cytotoxic effect of PN. It is noteworthy that treatment with PN alone stimulated the survival pathway Akt/mTOR and the consequent nuclear translocation of Nrf2, while treatment with SAHA alone induced autophagic activity. However, when the cells were treated with SAHA/PN combination, SAHA suppressed PN effect on Akt/mTOR/Nrf2 pathway, while PN reduced the prosurvival autophagic activity of SAHA. In addition SAHA/PN combination induced GSH depletion, fall in Δψm, release of cytochrome c, activation of caspase 3 and apoptosis. Finally we demonstrated that combined treatment maintained both hyperacetylation of histones H3 and H4 induced by SAHA and down-regulation of DNMT1 expression induced by PN. Inhibition of the DNA-binding activity of NF-kB, which is determined by PN, was also observed after combined treatment. In conclusion, combination of PN to SAHA inhibits the cytoprotective responses induced by the single compounds, but does not alter the mechanisms leading to the cytotoxic effects. Taken together our results suggest that this combination could be a candidate for TNBC therapy.

The potential of histone deacetylase inhibitors in breast cancer therapy

SUMMARY 

Breast cancer is the second leading cause of cancer-related mortality in women. Despite improvements in prevention, detection and treatment, breast cancer will be responsible for nearly 40,000 deaths in 2014. The function of histone deacetylases (HDACs) and their potential as therapeutic targets has become an area of intense investigation and small molecule inhibitors of HDACs (HDACi) are now being investigated as potential chemotherapeutics for breast cancer. In addition to altering chromatin structure through stabilization of histone acetylation, HDACi treatment induces the accumulation of acetylated isoforms of many nonhistone proteins, altering their structure and function. These structural changes influence protein–protein interactions and cellular processes including cell cycle arrest, apoptosis, autophagy, induction of reactive oxygen species and mitotic catastrophe. While the usefulness of these compounds as single agents for treatment of breast cancer is still under investigation, cotreatment with other therapies is being evaluated in a number of clinical trials.

Intracellular redox potential-responsive micelles based on polyethylenimine-cystamine-poly(ε-caprolactone) block copolymer for enhanced miR-34a delivery

A novel polymer polyethylenimine-cystamine-poly(ε-caprolactone) with intracellular redox potential-responsive cleavable ability was synthesized and fabricated the micelles as smart gene vectors.

TPGS-g-PLGA/Pluronic F68 mixed micelles for tanshinone IIA delivery in cancer therapy

Tanshinone IIA (TAN) has few clinical applications for anti-cancer therapy mainly due to its high lipophicity, low cellular uptake, and poor bioavailability. To improve the anti-cancer effect and bioavailability of TAN, we developed a mixed micelle system constituted with D-α-tocopheryl polyethylene glycol succinate-graft-poly(D,L-lactide-co-glycolide) (TPGS-g-PLGA) copolymer and Pluronic F68. TAN was encapsulated in the TPGS-g-PLGA/Pluronic F68 mixed micelles by using the thin film hydration technology optimized by the central composite design/response surface method (CCD/RSM). TAN-loaded mixed micelles were highly stable in the presence or absence of bovine serum albumin (BSA) and achieved sustained drug release in vitro. Compared with free TAN, TAN mixed micelles had higher cytotoxicity and pro-apoptotic effects against human hepatocellular carcinoma HepG2 cells. The significant enhancement on pro-apoptosis by TAN micelles was evidenced by increased chromosome condensation, mitochondria membrane potential loss, cell apoptosis, and cleavages of caspase-3 and PARP. Furthermore, pharmacokinetic studies revealed that TAN mixed micelles significantly prolonged the circulation time and improved bioavailability of TAN in rats. These results demonstrated that TAN-loaded TPGS-g-PLGA/F68 mixed micelles are an effective strategy to deliver TAN for cancer therapy.

Epigenetic therapy as a novel approach in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver malignancy and one with high fatality. Its 5-year survival rate remains low and thus, there is a need for improvement of current treatment strategies as well as development of novel targeted methodologies in order to optimize existing therapeutic protocols. To this end, only recently, it was discovered that its pathophysiology also involves epigenetic alterations in DNA methylation, histone modifications and/or non-coding microRNA patterns. Unlike genetic events, epigenetic alterations are reversible and thus potentially considered to be an alternative option in cancer treatment protocols. In this review, we describe the general characteristics and resulted major alterations of the epigenetic machinery as well as current state of progress of epigenetic therapy (via different single or combinatorial experimental approaches) in HCC.

Combination of SAHA and bortezomib up-regulates CDKN2A and CDKN1A and induces apoptosis of Epstein-Barr virus-positive Wp-restricted Burkitt lymphoma and lymphoblastoid cell lines

Epstein-Barr virus (EBV) latent proteins exert anti-apoptotic effects on EBV-transformed lymphoid cells by down-regulating BCL2L11 (BIM), CDKN2A (p16(INK4A) ) and CDKN1A (p21(WAF1) ). However, the potential therapeutic effects of targeting these anti-apoptotic mechanisms remain unexplored. Here, we tested both in vitro and in vivo effects of the combination of histone deacetylase (HDAC) and proteasome inhibitors on the apoptosis of six endemic Burkitt lymphoma (BL) lines of different latency patterns (types I and III and Wp-restricted) and three lymphoblastoid cell lines (LCLs). We found that the combination of HDAC and proteasome inhibitors (e.g. SAHA/bortezomib) synergistically induced the killing of Wp-restricted and latency III BL and LCLs but not latency I BL cells. The synergistic killing was due to apoptosis, as evidenced by the high percentage of annexin V positivity and strong cleavage of PARP1 (PARP) and CASP3 (caspase-3). Concomitantly, SAHA/bortezomib up-regulated the expression of CDKN2A and CDKN1A but did not affect the level of BCL2L11 or BHRF1 (viral homologue of BCL2). The apoptotic effects were dependent on reactive oxygen species generation. Furthermore, SAHA/bortezomib suppressed the growth of Wp-restricted BL xenografts in nude mice. This study provides the rationale to test the novel application of SAHA/bortezomib on the treatment of EBV-associated Wp-restricted BL and post-transplant lymphoproliferative disorder.

Valproic acid, an anti-epileptic drug and a histone deacetylase inhibitor, in combination with proteasome inhibitors exerts antiproliferative, pro-apoptotic and chemosensitizing effects in human colorectal cancer cells: underlying molecular mechanisms

Although the therapeutic efficacy of valproic acid (VPA) has been observed in patients with solid tumors, the very high concentration required to induce antitumor activity limits its clinical utility. The present study focused on the development of combined molecular targeted therapies using VPA and proteasome inhibitors (PIs: MG132, PI-1 and PR-39) to determine whether this combination of treatments has synergistic anticancer and chemosensitizing effects against colorectal cancer. Furthermore, the potential molecular mechanisms of action of the VPA/PI combinations were evaluated. The effects of VPA in combination with PIs on the growth of colorectal cancer cells were assessed with regard to proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) generation and the expression of genes that control the cell cycle, apoptosis and pro-survival/stress-related pathways. Treatment with combinations of VPA and PIs resulted in an additive/synergistic decrease in colorectal cancer cell proliferation compared to treatment with VPA or PIs alone. The combination treatment was associated with a synergistic increase in apoptosis and in the number of cells arrested in the S phase of the cell cycle. These events were associated with increased ROS generation, pro-apoptotic gene expression and stress-related gene expression. These events were also associated with the decreased expression of anti-apoptotic genes and pro-survival genes. The combination of VPA with MG132 or PI-1 enhanced the chemosensitivity of the SW1116 (29-185‑fold) and SW837 (50-620-fold) colorectal cancer cells. By contrast, the combination of VPA/PR-39 induced a pronounced increase in the chemosensitivity of the SW837 (16-54-fold) colorectal cancer cells. These data provide a rational basis for the clinical use of this combination therapy for the treatment of colorectal cancer.

The histone deacetylase inhibitor vorinostat prevents TNFα-induced necroptosis by regulating multiple signaling pathways

Histone deacetylase (HDAC) inhibitors are novel anticancer reagents that have recently been reported to have anti-inflammatory and neuroprotective effects; however, the mechanisms underlying their activities are largely undefined. The data from this study show that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) can protect L929 cells from TNFα-induced necroptosis. This effect involves multiple mechanisms, including the upregulation of cFLIPL expression, the enhanced activation of NFκB and p38 MAPK, and the inactivation of JNK. In addition, SAHA could initiate cell autophagy by inhibiting Akt and mTOR, which also play important roles in protecting cells from necroptosis. Because cell necroptosis is important for inflammation-related deterioration and neurodegenerative disease, our results indicate that preventing cell necrosis may be an important mechanism through which HDAC inhibitor compounds exert their anti-inflammatory or neuroprotective effects.

Combination of proteasome and class I HDAC inhibitors induces apoptosis of NPC cells through an HDAC6-independent ER stress-induced mechanism

The current paradigm stipulates that inhibition of histone deacetylase (HDAC) 6 is essential for the combinatorial effect of proteasome and HDAC inhibitors for the treatment of cancers. Our study aims to investigate the effect of combining different class I HDAC inhibitors (without HDAC6 action) with a proteasome inhibitor on apoptosis of nasopharyngeal carcinoma (NPC). We found that combination of a proteasome inhibitor, bortezomib, and several class I HDAC inhibitors, including MS-275, apicidin and romidepsin, potently induced killing of NPC cells both in vitro and in vivo. Among the drug pairs, combination of bortezomib and romidepsin (bort/romidepsin) was the most potent and could induce apoptosis at low nanomolar concentrations. The apoptosis of NPC cells was reactive oxygen species (ROS)- and caspase-dependent but was independent of HDAC6 inhibition. Of note, bort/romidepsin might directly suppress the formation of aggresome through the downregulation of c-myc. In addition, two markers of endoplasmic reticulum (ER) stress-induced apoptosis, ATF-4 and CHOP/GADD153, were upregulated, whereas a specific inhibitor of caspase-4 (an initiator of ER stress-induced apoptosis) could suppress the apoptosis. When ROS level in the NPC cells was reduced to the untreated level, ER stress-induced caspase activation was abrogated. Collectively, our data demonstrate a model of synergism between proteasome and class I HDAC inhibitors in the induction of ROS-dependent ER stress-induced apoptosis of NPC cells, independent of HDAC6 inhibition, and provide the rationale to combine the more specific and potent class I HDAC inhibitors with proteasome inhibitors for the treatment of cancers.

Gemcitabine sensitizes lung cancer cells to Fas/FasL system-mediated killing

Gemcitabine is a chemotherapy agent commonly used in the treatment of non-small cell lung cancer (NSCLC) that has been demonstrated to induce apoptosis in NSCLC cells by increasing functionally active Fas expression. The aim of this study was to evaluate the Fas/Fas ligand (FasL) system involvement in gemcitabine-induced lung cancer cell killing. NSCLC H292 cells were cultured in the presence or absence of gemcitabine. FasL mRNA and protein were evaluated by real-time PCR, and by Western blot and flow cytometry, respectively. Apoptosis of FasL-expressing cells was evaluated by flow cytometry, and caspase-8 and caspase-3 activation by Western blot and a colorimetric assay. Cytotoxicity of lymphokine-activated killer (LAK) cells and malignant pleural fluid lymphocytes against H292 cells was analysed in the presence or absence of the neutralizing anti-Fas ZB4 antibody, by flow cytometry. Gemcitabine increased FasL mRNA and total protein expression, the percentage of H292 cells bearing membrane-bound FasL (mFasL) and of mFasL-positive apoptotic H292 cells, as well as caspase-8 and caspase-3 cleavage. Moreover, gemcitabine increased CH11-induced caspase-8 and caspase-3 cleavage and proteolytic activity. Cytotoxicity of LAK cells and pleural fluid lymphocytes was increased against gemcitabine-treated H292 cells and was partially inhibited by ZB4 antibody. These results demonstrate that gemcitabine: (i) induces up-regulation of FasL in lung cancer cells triggering cell apoptosis via an autocrine/paracrine loop; (ii) induces a Fas-dependent apoptosis mediated by caspase-8 and caspase-3 activation; (iii) enhances the sensitivity of lung cancer cells to cytotoxic activity of LAK cells and malignant pleural fluid lymphocytes, partially via Fas/FasL pathway. Our data strongly suggest an active involvement of the Fas/FasL system in gemcitabine-induced lung cancer cell killing.

Differential cytotoxicity and particle action of hydroxyapatite nanoparticles in human cancer cells

Aim: While hydroxyapatite nanoparticles (HAPNs) have been reported to exhibit anticancer effects on several types of human cancer cells, no investigation has been performed to compare their cytotoxicity with different types of cancer cells. The objective of the present study is to investigate the cytotoxic action of HAPNs in different types of human cancer cell and to explore the possible mechanisms involved. Materials & methods: Rod-shaped HAPNs were prepared by the aqueous precipitation method and then labeled with ?uorescein isothiocyanate to visualize the cellular uptake and distribution. Their cytotoxicity to three human carcinoma cell lines (gastric cancer cells [MGC80-3], cervical adenocarcinoma epithelial cells [HeLa] and hepatoma cells [HepG2], as well as to normal human hepatocyte cells [L-02]) was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis was characterized by the changes in nuclear morphology with 4’,6-diamidino-2-phenylindole staining and by ?ow cytometric analysis with Annexin V-?uorescein isothiocyanate/propidium iodide double staining. Furthermore, the activity of apoptotic proteins (caspase-3, -8 and -9), intracellular reactive oxygen species and glutathione levels were analyzed in HAPN-treated cells. The cellular uptake of HAPNs was studied using flow cytometry analysis, and changes in intracellular calcium levels were investigated using the Ca2+-sensitive fluorescent dye, fluo-3 AM. Results: HAPNs significantly inhibited cell proliferation and induced apoptosis of cancer cells with an order of MGC80-3 > HepG2 > HeLa, but had no impact on normal hepatic cells (L-02). The increase in apoptosis was accompanied by the activation of caspase-3 and -9, but not activation of caspase-8. Moreover, HAPN treatment led to reactive oxygen species generation and decreased intracellular glutathione in cancer cells, with the most remarkable reactive oxygen species burst in HeLa cells. The degree of cytotoxicity did not correlate with the cellular uptake efficiency of HAPNs. However, more HAPNs were found inside the nucleus of MGC80-3 cells, and an increase in the intracellular calcium level was observed in all cancer cells, with the highest level also detected in MGC80-3. Conclusion: Varying cytotoxicity of HAPNs was observed in different cancer cell types. Our results suggest that possible mechanisms of cytotoxicity in various types of cancer cells could be different. The elevated calcium concentration and nuclear localization of the particles might be the main mechanism of growth inhibition by HAPNs in cancer cells.

Original submitted 18 April 2012; Revised submitted 14 September 2012; Published online 24 April 2013

A microenvironment-mediated c-Myc/miR-548m/HDAC6 amplification loop in non-Hodgkin B cell lymphomas

A dynamic interaction occurs between the lymphoma cell and its microenvironment, with each profoundly influencing the behavior of the other. Here, using a clonogenic coculture growth system and a xenograft mouse model, we demonstrated that adhesion of mantle cell lymphoma (MCL) and other non-Hodgkin lymphoma cells to lymphoma stromal cells confers drug resistance, clonogenicity, and induction of histone deacetylase 6 (HDAC6). Furthermore, stroma triggered a c-Myc/miR-548m feed-forward loop, linking sustained c-Myc activation, miR-548m downregulation, and subsequent HDAC6 upregulation and stroma-mediated cell survival and lymphoma progression in lymphoma cell lines, primary MCL and other B cell lymphoma cell lines. Treatment with an HDAC6-selective inhibitor alone or in synergy with a c-Myc inhibitor enhanced cell death, abolished cell adhesion–mediated drug resistance, and suppressed clonogenicity and lymphoma growth ex vivo and in vivo. Together, these data suggest that the lymphoma-stroma interaction in the lymphoma microenvironment directly impacts the biology of lymphoma through genetic and epigenetic regulation, with HDAC6 and c-Myc as potential therapeutic targets.

The anti-tumor effects and molecular mechanisms of suberoylanilide hydroxamic acid (SAHA) on the aggressive phenotypes of ovarian carcinoma cells

Histone deacetylase inhibitors (HDACi), such as suberoylanilide hydroxamic acid (SAHA), have been shown to act selectively on gene expression, and are potent inducers of growth arrest, differentiation and apoptosis in various types of cancers in vitro and in vivo. This study aimed to elucidate the anti-tumor effects and molecular mechanisms of SAHA on the aggressive phenotypes of ovarian carcinoma. Two pairs of cell lines (SKOV3 and SKOV3/DDP; HO8910 and HO8910-PM) were exposed to SAHA treatment, and the effects on acetyl-Histone H3 and H4 expression levels were analyzed and compared against the aggressive behaviors of ovarian carcinoma. Our results showed that SAHA suppressed proliferation in both a concentration- and time-dependent manner in all four cell lines; induced S/G₂ arrest in SKOV3 and SKOV3/DDP cells; and conversely, induced G₁ arrest in HO8910 and HO8910-PM cells. SAHA treatment induced apoptosis and reduced migration, invasion and lamellipodia formation in the ovarian carcinoma cells; furthermore, SAHA decreased expression of Cyclin B1 and CDC2P34 mRNA, and downregulated CDC2P34, Erk1/2, CyclinB1 and MMP-9 proteins. In contrast, SAHA increased expression of Caspase-3, p21 and p53 mRNA, and upregulated acetyl-Histones H3 and H4, Caspase-8, and p53 proteins. Basal acetylation of histone H3 and H4 was higher in ovarian carcinoma compared to normal ovarian tissues and benign ovarian tumors, and in borderline tumor than in normal ovarian tissues, and was positively correlated with differentiation and expression of the proliferative marker, Ki-67 (P < 0.05). We suggest that SAHA may suppress growth, migration and invasion in ovarian carcinoma cells, including cisplatin-resistant or highly-invasive ovarian cells, by promoting histone acetylation and modulating their phenotype-related molecules. As such, aberrant acetylation of histone H3 and H4 may play an important role in the carcinogenesis and differentiation of ovarian carcinoma.

A phase I study of vorinostat in combination with bortezomib in patients with advanced malignancies

BACKGROUND

A phase I study to assess the maximum-tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacokinetics (PK) and antitumor activity of vorinostat in combination with bortezomib in patients with advanced solid tumors.

METHODS

Patients received vorinostat orally once daily on days 1-14 and bortezomib intravenously on days 1, 4, 8 and 11 of a 21-day cycle. Starting dose (level 1) was vorinostat (400 mg) and bortezomib (0.7 mg/m(2)). Bortezomib dosing was increased using a standard phase I dose-escalation schema. PKs were evaluated during cycle 1.

RESULTS

Twenty-three patients received 57 cycles of treatment on four dose levels ranging from bortezomib 0.7 mg/m(2) to 1.5 mg/m(2). The MTD was established at vorinostat 400 mg daily and bortezomib 1.3 mg/m(2). DLTs consisted of grade 3 fatigue in three patients (1 mg/m(2),1.3 mg/m(2) and 1.5 mg/m(2)) and grade 3 hyponatremia in one patient (1.5 mg/m(2)). The most common grade 1/2 toxicities included nausea (60.9%), fatigue (34.8%), diaphoresis (34.8%), anorexia (30.4%) and constipation (26.1%). Objective partial responses were observed in one patient with NSCLC and in one patient with treatment-refractory soft tissue sarcoma. Bortezomib did not affect the PKs of vorinostat; however, the Cmax and AUC of the acid metabolite were significantly increased on day 2 compared with day 1.

CONCLUSIONS

This combination was generally well-tolerated at doses that achieved clinical benefit. The MTD was established at vorinostat 400 mg daily × 14 days and bortezomib 1.3 mg/m(2) on days 1, 4, 8 and 11 of a 21-day cycle.

Combining histone deacetylase inhibitors with MDA-7/IL-24 enhances killing of renal carcinoma cells

In the present study we show that histone deacetylase inhibitors (HDACIs) enhance the anti-tumor effects of melanoma differentiation associated gene-7/interleukin 24 (mda-7/IL-24) in human renal carcinoma cells. Similar data were obtained in other GU tumor cells. Combination of these two agents resulted in increased autophagy that was dependent on expression of ceramide synthase 6, with HDACIs enhancing MDA-7/IL-24 toxicity by increasing generation of ROS and Ca²⁺. Knock down of CD95 protected cells from HDACI and MDA-7/IL-24 lethality. Sorafenib treatment further enhanced (HDACI + MDA-7/IL-24) lethality. Anoikis resistant renal carcinoma cells were more sensitive to MDA-7/IL-24 that correlated with elevated SRC activity and tyrosine phosphorylation of CD95. We employed a recently constructed serotype 5/3 adenovirus, which is more effective than a serotype 5 virus in delivering mda-7/IL-24 to renal carcinoma cells and which conditionally replicates (CR) in tumor cells expressing MDA-7/IL-24 by virtue of placing the adenoviral E1A gene under the control of the cancer-specific promoter progression elevated gene-3 (Ad.5/3-PEG-E1A-mda-7; CRAd.5/3-mda-7, Ad.5/3-CTV), to define efficacy in renal carcinoma cells. Ad.5/3-CTV decreased the growth of renal carcinoma tumors to a significantly greater extent than did a non-replicative virus Ad.5/3-mda-7. In contralateral uninfected renal carcinoma tumors Ad.5/3-CTV also decreased the growth of tumors to a greater extent than did Ad.5/3-mda-7. In summation, our data demonstrates that HDACIs enhance MDA-7/IL-24-mediated toxicity and tumor specific adenoviral delivery and viral replication of mda-7/IL-24 is an effective pre-clinical renal carcinoma therapeutic.

Histone deacetylase inhibitors interact with melanoma differentiation associated-7/interleukin-24 to kill primary human glioblastoma cells

We presently demonstrate that histone deacetylase inhibitors (HDACIs) enhance toxicity of melanoma differentiation-associated gene-7/interleukin 24 (mda-7/IL-24) in invasive primary human glioblastoma multiforme (GBM) cells. Additionally, a method is described to augment the efficacy of adenoviral delivery of mda-7/IL-24 in these cells. HDACIs synergized with melanoma differentiation-associated (MDA)-7/IL-24 killing GBM cells. Enhanced lethality correlated with increased autophagy that was dependent on the expression of ceramide synthase 6. HDACIs interacted with MDA-7/IL-24 prolonging generation of reactive oxygen species and Ca(2+). Quenching of reactive oxygen species and Ca(2+) blocked HDACI and MDA-7/IL-24 killing. In vivo MDA-7/IL-24 prolonged the survival of animals carrying orthotopic tumors, and HDACIs enhanced survival further. A serotype 5/3 adenovirus more effectively delivers mda-7/IL-24 to GBM tumors than a serotype 5 virus. Hence, we constructed a serotype 5/3 adenovirus that conditionally replicates in tumor cells expressing MDA-7/IL-24, in which the adenoviral early region 1A (E1A) gene was driven by the cancer-specific promoter progression elevated gene-3 [Ad.5/3 (INGN 241)-PEG-E1A-mda-7; also called Ad.5/3-CTV (cancer terminator virus)]. Ad.5/3-CTV increased the survival of mice carrying GBM tumors to a significantly greater extent than did a nonreplicative virus Ad.5/3-mda-7. Ad.5/3-CTV exhibited no toxicity in the brains of Syrian hamsters. Collectively our data demonstrate that HDACIs enhance MDA-7/IL-24 lethality, and adenoviral delivery of mda-7/IL-24 combined with tumor-specific viral replication is an effective preclinical GBM therapeutic.

Intrinsic and extrinsic apoptotic pathway signaling as determinants of histone deacetylase inhibitor antitumor activity

Histone deacetylase inhibitors (HDACi) can elicit a range of biological responses that impede the growth and/or survival of tumor cells. Depending on the physiological context, HDACi can induce apoptosis via two well-defined apoptotic pathways; the intrinsic/mitochondrial pathway and the death receptor (DR)/extrinsic pathway. A number of groups have demonstrated that overexpression of prosurvival Bcl-2 family members significantly reduces HDACi-mediated tumor cell death and therapeutic efficacy in preclinical models. In many cases, HDACi activate the intrinsic pathway via upregulation of a number of proapoptotic BH3-only Bcl-2 family genes including Bim, Bid, and Bmf. Additionally, HDACi can engage the extrinsic pathway through upregulation of DR expression, reductions in c-FLIP, and upregulation of ligands such as TRAIL. Overall, it appears that activation of the intrinsic apoptotic pathway is the predominant mechanism of HDACi-induced tumor cell death; however, the DR pathway may also be engaged, either to amplify the apoptotic signal through the intrinsic pathway or to directly induce cell death.

A novel submicron emulsion system loaded with vincristine-oleic acid ion-pair complex with improved anticancer effect: in vitro and in vivo studies

Background

Vincristine (VCR), which is a widely used antineoplastic drug, was integrated with a submicron-emulsion drug-delivery system to enhance the anticancer effect.

Methods

After the formation of a VCR-oleic acid ion-pair complex (VCR-OA), the VCR-OA-loaded submicron emulsion (VCR-OA-SME), prepared by classical high-pressure homogenization, was characterized and its in vitro anticancer effects were evaluated.

Results

The submicron-emulsion formulation exhibited a homogeneous round shape. The mean particle size, zeta potential, and encapsulation efficiency were 157.6 ± 12.6 nm, −26.5 ± 5.0 mV and 78.64% ± 3.44%, respectively. An in vitro release study of the VCR-OA-SME revealed that 12.4% of the VCR was released within the first 2 hours (initial burst-release phase) and the rest of the drug was detected in the subsequent sustained-release phase. Compared with VCR solution, the pharmacokinetic study of VCR-OA-SME showed relatively longer mean residence time (mean residence time [0–∞] increased from 187.19 to 227.56 minutes), higher maximum concentration (from 252.13 ng/mL to 533.34 ng/mL), and greater area under the curve (area under the curve [0–∞] from 11,417.77 μg/L/minute to 17,164.34 μg/L/minute. Moreover, the VCR-OA-SME exhibited higher cytotoxicity (P < 0.05) on tumor cells by inducing cell arrest in the G2/M phase or even apoptosis (P < 0.05).

Conclusion

The VCR-OA-SME formulation in our study displayed great potential for an anticancer effect for VCR.

Bortezomib and SAHA synergistically induce ROS-driven caspase-dependent apoptosis of nasopharyngeal carcinoma and block replication of Epstein-Barr virus

A novel drug combination of a proteasome inhibitor, bortezomib, and a histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), was tested in nasopharyngeal carcinoma (NPC), both in vitro and in vivo. Dose-response of different concentrations of bortezomib and SAHA on inhibition of cell proliferation of NPC was determined. Mechanisms of apoptosis and effects on lytic cycle activation of Epstein-Barr virus (EBV) were investigated. Combination of bortezomib and SAHA (bortezomib/SAHA) synergistically induced killing of a panel of NPC cell lines. Pronounced increase in sub-G1, Annexin V-positive, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cell populations were detected after treatment with bortezomib/SAHA when compared with either drug alone. Concomitantly, markedly augmented proteolytic cleavage of PARP, caspase-3, -7, -8, and -9, reactive oxygen species (ROS) generation, and caspase-8-dependent histone acetylation were observed. ROS scavenger, N-acetyl cysteine, diminished the apoptotic effects of bortezomib/SAHA, whereas caspase inhibitor Z-VAD-FMK significantly suppressed the apoptosis without decreasing the generation of ROS. Bortezomib inhibited SAHA's induction of EBV replication and abrogated production of infectious viral particles in NPC cells. Furthermore, bortezomib/SAHA potently induced apoptosis and suppressed the growth of NPC xenografts in nude mice. In conclusion, the novel drug combination of bortezomib and SAHA is highly synergistic in the killing of NPC cells in vitro and in vivo. The major mechanism of cell death is ROS-driven caspase-dependent apoptosis. Bortezomib antagonizes SAHA's activation of EBV lytic cycle in NPC cells. This study provides a strong basis for clinical testing of the combination drug regimen in patients with NPC.

A phase I trial of vorinostat and bortezomib in children with refractory or recurrent solid tumors: a Children's Oncology Group phase I consortium study (ADVL0916)

BACKGROUND

A pediatric Phase I trial was performed to determine the maximum-tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of vorinostat and bortezomib, in patients with solid tumors.

PROCEDURE

Oral vorinostat was administered on days 1-5 and 8-12 of a 21-day cycle (starting dose 180 mg/m(2) /day with dose escalations to 230 and 300 mg/m(2) /day). Bortezomib (1.3 mg/m(2) i.v.) was administered on days 1, 4, 8, and 11 of the same cycle. PK and correlative biology studies were performed during Cycle 1.

RESULTS

Twenty-three eligible patients [17 male, median age 12 years (range: 1-20)] were enrolled of whom 17 were fully evaluable for toxicity. Cycle 1 DLTs that occurred in 2/6 patients at dose level 3 (vorinostat 300 mg/m(2) /day) were Grade 2 sensory neuropathy that progressed to Grade 4 (n = 1) and Grade 3 nausea and anorexia (n = 1). No objective responses were observed. There was wide interpatient variability in vorinostat PK parameters. Bortezomib disposition was best described by a three-compartment model that demonstrated rapid distribution followed by prolonged elimination. We did not observe a decrease in nuclear factor-κB activity or Grp78 induction after bortezomib treatment in peripheral blood mononuclear cells from solid tumor patients.

CONCLUSION

The recommended Phase 2 dose and schedule is vorinostat (230 mg/m(2) /day PO on days 1-5 and 8-12) in combination with bortezomib (1.3 mg/m(2) /day i.v. on days 1, 4, 8, and 11 of a 21-day cycle) in children with recurrent or refractory solid tumors.

Combination of a novel HDAC inhibitor OBP-801/YM753 and a PI3K inhibitor LY294002 synergistically induces apoptosis in human endometrial carcinoma cells due to increase of Bim with accumulation of ROS

OBJECTIVE

In most endometrial carcinoma, it has been observed that the PI3K/Akt pathway is abnormally accelerated in association with mutations in PIK3CA and PTEN. The present study aimed to examine the combined effect of a novel histone deacetylase (HDAC) inhibitor OBP-801/YM753 and a PI3K inhibitor LY294002 against human endometrial carcinoma cells.

METHODS

The effects of OBP-801/YM753 and LY294002 on the growth of human endometrial carcinoma HEC-1A cells were examined using WST-8 and colony formation assays. The distribution of the cell cycle or apoptosis was analyzed by flow cytometry. The accumulation of intracellular reactive oxygen species (ROS) was measured with a 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA) dye. The expression of apoptosis-related proteins was investigated by Western blotting. Mice engrafted with 1×10(8) HEC-1A cells were treated with OBP-801/YM753, LY294002 or the combination, and tumor volumes were measured.

RESULTS

The combination of OBP-801/YM753 and LY294002 significantly inhibited the cell growth on comparison with each agent alone and synergistically increased apoptosis with the induction of Bim, a well-known apoptosis inducer. Additionally, the apoptosis induced by the combination was shown to be dependent on intracellular ROS accumulation and Bim induction. Moreover, the apoptosis-inducing effect of OBP-801/YM753 with LY294002 was more potent than that of SAHA with LY294002. Combined treatment with OBP-801/YM753 and LY294002 significantly suppressed tumor growth compared to the control in vivo.

CONCLUSIONS

The combination of OBP-801/YM753 and LY294002 is effective on the inhibition of the growth of HEC-1A cells, and we suggest that this combination is promising a novel therapeutic strategy for endometrial carcinoma.

Epigenetic therapy using belinostat for patients with unresectable hepatocellular carcinoma: a multicenter phase I/II study with biomarker and pharmacokinetic analysis of tumors from patients in the Mayo Phase II Consortium and the Cancer Therapeutics Research Group

PURPOSE

Epigenetic aberrations have been reported in hepatocellular carcinoma (HCC). In this study of patients with unresectable HCC and chronic liver disease, epigenetic therapy with the histone deacetylase inhibitor belinostat was assessed. The objectives were to determine dose-limiting toxicity and maximum-tolerated dose (MTD), to assess pharmacokinetics in phase I, and to assess activity of and explore potential biomarkers for response in phase II.

PATIENTS AND METHODS

Major eligibility criteria included histologically confirmed unresectable HCC, European Cooperative Oncology Group performance score ≤ 2, and adequate organ function. Phase I consisted of 18 patients; belinostat was given intravenously once per day on days 1 to 5 every 3 weeks; dose levels were 600 mg/m(2) per day (level 1), 900 mg/m(2) per day (level 2), 1,200 mg/m(2) per day (level 3), and 1,400 mg/m(2) per day (level 4). Phase II consisted of 42 patients. The primary end point was progression-free survival (PFS), and the main secondary end points were response according to Response Evaluation Criteria in Solid Tumors (RECIST) and overall survival (OS). Exploratory analysis was conducted on pretreatment tumor tissues to determine whether HR23B expression is a potential biomarker for response.

RESULTS

Belinostat pharmacokinetics were linear from 600 to 1,400 mg/m(2) without significant accumulation. The MTD was not reached at the maximum dose administered. Dose level 4 was used in phase II. The median number of cycles was two (range, one to 12). The partial response (PR) and stable disease (SD) rates were 2.4% and 45.2%, respectively. The median PFS and OS were 2.64 and 6.60 months, respectively. Exploratory analysis revealed that disease stabilization rate (complete response plus PR plus SD) in tumors having high and low HR23B histoscores were 58% and 14%, respectively (P = .036).

CONCLUSION

Epigenetic therapy with belinostat demonstrates tumor stabilization and is generally well-tolerated. HR23B expression was associated with disease stabilization.

Preclinical cancer chemoprevention studies using animal model of inflammation-associated colorectal carcinogenesis

Inflammation is involved in all stages of carcinogenesis. Inflammatory bowel disease, such as ulcerative colitis and Crohn’s disease is a longstanding inflammatory disease of intestine with increased risk for colorectal cancer (CRC). Several molecular events involved in chronic inflammatory process are reported to contribute to multi-step carcinogenesis of CRC in the inflamed colon. They include over-production of free radicals, reactive oxygen and nitrogen species, up-regulation of inflammatory enzymes in arachidonic acid biosynthesis pathway, up-regulation of certain cytokines, and intestinal immune system dysfunction. In this article, firstly I briefly introduce our experimental animal models where colorectal neoplasms rapidly develop in the inflamed colorectum. Secondary, data on preclinical cancer chemoprevention studies of inflammation-associated colon carcinogenesis by morin, bezafibrate, and valproic acid, using this novel inflammation-related colorectal carcinogenesis model is described.

Vorinostat approved in Japan for treatment of cutaneous T-cell lymphomas: status and prospects

Histone acetylation and deacetylation play important roles in the regulation of gene transcription and in the modulation of chromatin structure. The levels of histone acetylation are determined by the activities of histone acetyltransferases and histone deacetylases (HDACs). HDACs are associated with a number of oncogenes and tumor suppressor genes and can be aberrantly expressed and/or inappropriately activated in cancer cells. HDAC inhibitors have therefore recently emerged as a novel treatment modality against malignancies. They regulate gene expression by enhancing the acetylation of not only histones but also nonhistone proteins, including transcription factors, transcription regulators, signal transduction mediators, and DNA repair enzymes, and they inhibit cancer growth. Vorinostat (suberoylanilide hydroxamic acid) is one of the most potent HDAC inhibitors, and was approved in Japan in 2011 for the treatment of cutaneous T-cell lymphoma. Numerous clinical trials have shown it to be effective against cutaneous T-cell lymphoma but less so against other types of cancer. Because vorinostat can overcome resistance to or enhance the efficacy of other anticancer agents, such as 5-fluorouracil, carboplatin, paclitaxel, bortezomib, and tamoxifen, combination therapies using vorinostat and these agents have been investigated. This review introduces the background and mechanism of action of vorinostat and describes the results of clinical trials using vorinostat, both as a single agent and in combination with other anticancer agents, against cutaneous T-cell lymphoma and other malignancies.

CS055 (Chidamide/HBI-8000), a novel histone deacetylase inhibitor, induces G1 arrest, ROS-dependent apoptosis and differentiation in human leukaemia cells

CS055 (Chidamide/HBI-8000) is a novel benzamide-type HDACi (histone deacetylase inhibitor), which has entered Phase I clinical trials in the U.S. and Phase II/III in China. In the present study, we investigated the effects of CS055 on proliferation, differentiation and apoptosis in human leukaemia cell lines and primary myeloid leukaemia cells. The results showed that at low concentrations (<1 μM), CS055 induced G1 arrest. At moderate concentrations (0.5 μM–2 μM), CS055 induced differentiation, as determined by the increased expression of the myeloid differentiation marker CD11b. At relatively high concentrations (2 μM–4 μM), CS055 potently induced caspase-dependent apoptosis. Co-treatment with the ROS (reactive oxygen species) scavengers N-acetyl-L-cysteine or Tiron blocked CS055-induced cell differentiation and apoptosis, suggesting an essential role for ROS in these effects. Cytochrome c release and ROS-mediated mitochondrial dysfunction are involved in CS055-induced apoptosis of leukaemia. In addition to cell lines, CS055 also exhibits therapeutic effects in human primary leukaemia cells. Moreover, daily oral CS055 treatment of nude mice bearing HL60 cell xenografts suppressed tumour growth, induced tumour cell apoptosis and prolonged the survival of tumour-bearing mice. In conclusion, our findings demonstrate that CS055 is a novel HDACi with potential chemotherapeutic value in several haematological malignancies, especially leukaemia.

Targeting the Fas/FasL signaling pathway in cancer therapy

INTRODUCTION

The Fas/FasL system plays a significant role in tumorigenesis. Research has shown that its impairment in cancer cells may lead to apoptosis resistance and contribute to tumor progression. Thus, the development of effective therapies targeting the Fas/FasL system may play an important role in the fight against cancer.

AREAS COVERED

In this review the recent literature on targeting the Fas/FasL system for therapeutic exploitation at different levels is reviewed. Promising pre-clinical approaches and various exceptions are highlighted. The potential of combined therapies is also explored, whereby tumor sensitivity to Fas-mediated apoptosis is restored, before an effective targeted therapy is employed.

EXPERT OPINION

The success of the Fas/FasL system targeting for therapeutics will require a better understanding of the alterations conferring resistance, in order to use the most appropriate sensitizing chemotherapeutic or radiotherapeutic agents in combination with effective targeted therapies.

Dual targeting of mTORC1/C2 complexes enhances histone deacetylase inhibitor-mediated anti-tumor efficacy in primary HCC cancer in vitro and in vivo

BACKGROUND & AIMS

The mammalian target of rapamycin (mTOR) plays a pivotal role in hepatocellular carcinoma (HCC). Previous studies indicated that inhibition of mTORC1 enhanced histone deacetylase inhibitors (HDACis)-mediated anti-tumor activity, accompanied with feedback activation of AKT. Therefore, dual targeting of mTORC1/C2 should be more efficient in suppressing AKT activity and in enhancing the anti-tumor activity of HDACi in HCC.

METHODS

The interactions between mTOR kinase inhibitors (mTORKis) (i.e., Pp242, AZD8055, OSI027) and HDACis (i.e., SAHA, LBH589) were examined in vitro using HCC cell lines and in vivo using patient-derived primary HCC xenografts on SCID mice.

RESULTS

mTORKis significantly enhanced HDACi-induced apoptosis in HCC cells. The inhibition of both mTORC1/2 not only efficiently blocked mTORC1 signaling, but also abrogated AKT-feedback activation caused by selective mTORC1 inhibition. The co-treatment of mTORKi and HDACi further inhibited AKT signaling and upregulated Bim. Dysfunction of mTORC2 by shRNA significantly lowered the threshold of HDACi-induced cytotoxicity by abrogating AKT activation. Knockdown of AKT1 sensitized Pp242/HDACi-induced apoptosis and ectopic expression of constitutively active AKT1 abrogated the combination-induced cytotoxicity, indicating AKT plays a vital role in the combination-induced effects. Knockdown of Bim prevented Pp242/HDACis-induced cytotoxicity in HCC. Lastly, in vivo studies indicated that the combination of AZD8055 and SAHA almost completely inhibited tumor-growth, without obvious adverse effects, by abrogating AKT and upregulating Bim; while either agent alone shows only 30% inhibition in primary HCC xenografts.

CONCLUSIONS

Our findings suggest that a combining-regimen of mTORKi and HDACi may be an effective therapeutic strategy for HCC.

Phase II trial of vorinostat in combination with bortezomib in recurrent glioblastoma: a north central cancer treatment group study

Vorinostat, a histone deacetylase (HDAC) inhibitor, has shown evidence of single-agent activity in glioblastoma (GBM), and in preclinical studies, we have demonstrated significant synergistic cytotoxicity between HDAC inhibitors and proteasome inhibitors in GBM cell lines. We therefore conducted a phase II trial to evaluate the efficacy of vorinostat in combination with the proteasome inhibitor bortezomib in patients with recurrent GBM. Vorinostat was administered at a dose of 400 mg daily for 14 days of a 21-day cycle, and bortezomib was administered at a dose of 1.3 mg/m(2) intravenously on days 1, 4, 8, and 11 of the cycle. A total of 37 patients were treated, and treatment was well tolerated: grade 3, 4 nonhematologic toxicity occurred in 30% of patients and consisted mainly of fatigue (14%) and neuropathy (5%); grade 3, 4 hematologic toxicity occurred in 37% of patients and consisted of thrombocytopenia (30%), lymphopenia (4%), and neutropenia (4%). The trial was closed at the predetermined interim analysis, with 0 of 34 patients being progression-free at 6 months. One patient achieved a partial response according to the Macdonald criteria. The median time to progression for all patients was 1.5 months (range, 0.5-5.6 months), and median overall survival (OS) was 3.2 months. Patients who had received prior bevacizumab therapy had a shorter time to progression and OS, compared with those who had not. On the basis of the results of this phase II study, further evaluation of the vorinostat-bortezomib combination in GBM patients in this dose and schedule is not recommended.

Suberoylanilide hydroxamic acid (SAHA) combined with bortezomib inhibits renal cancer growth by enhancing histone acetylation and protein ubiquitination synergistically

OBJECTIVE

To investigate the combined effect of two clinically feasible drugs, the proteasome inhibitor bortezomib and the histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA), on human renal cancer cells in vitro and in vivo.

MATERIALS AND METHODS

The effectiveness of the combination of bortezomib (10-20 nm) and SAHA (1-5 µm) on renal cancer cells (Caki-1, ACHN, A-498, 786-O, 769-P) was assessed by MTS assay, colony formation assay, cell cycle analysis, and apoptosis assay. In vivo efficacy was evaluated using murine subcutaneous (s.c.) tumour models. Protein ubiquitination, unfolded protein response, histone acetylation, and changes in the expression of HDAC were evaluated by western blotting.

RESULTS

The combination of SAHA and bortezomib induced apoptosis and inhibited cancer cell proliferation synergistically (combination indices <1) and colony formation significantly (P < 0.05). In s.c. tumour models a 10-day treatment with a combination of SAHA (50 mg/kg) and bortezomib (60 µg/kg) inhibited tumour growth significantly (P < 0.05). Mechanistically, SAHA combined with bortezomib enhanced protein ubiquitination synergistically and enhanced histone acetylation by inhibiting the expression of HDACs.

CONCLUSION

SAHA combined with bortezomib inhibits the proliferation of renal cancer cells in vitro and in vivo, and the effectiveness of the combination is due to its synergistic enhancement of histone acetylation and protein ubiquitination.

SAHA/TRAIL combination induces detachment and anoikis of MDA-MB231 and MCF-7 breast cancer cells

SAHA, an inhibitor of histone deacetylase activity, has been shown to sensitize tumor cells to apoptosis induced by TRAIL, a member of TNF-family. In this paper we investigated the effect of SAHA/TRAIL combination in two breast cancer cell lines, the ERα-positive MCF-7 and the ERα-negative MDA-MB231. Treatment of MDA-MB231 and MCF-7 cells with SAHA in combination with TRAIL caused detachment of cells followed by anoikis, a form of apoptosis which occurs after cell detachment, while treatment with SAHA or TRAIL alone did not produce these effects. The effects were more evident in MDA-MB231 cells, which were chosen for ascertaining the mechanism of SAHA/TRAIL action. Our results show that SAHA decreased the level of c-FLIP, thus favouring the interaction of TRAIL with the specific death receptors DR4 and DR5 and the consequent activation of caspase-8. These effects increased when the cells were treated with SAHA/TRAIL combination. Because z-IEDT-fmk, an inhibitor of caspase-8, prevented both the cleavage of the focal adhesion-kinase FAK and cell detachment, we suggest that activation of caspase-8 can be responsible for both the decrement of FAK and the consequent cell detachment. In addition, treatment with SAHA/TRAIL combination caused dissipation of ΔΨ(m), activation of caspase-3 and decrement of both phospho-EGFR and phospho-ERK1/2, a kinase which is involved in the phosphorylation of BimEL. Therefore, co-treatment also induced decrement of phospho-BimEL and a concomitant increase in the dephosphorylated form of BimEL, which plays an important role in the induction of anoikis. Our findings suggest the potential application of SAHA in combination with TRAIL in clinical trials for breast cancer.

Design, synthesis, docking, and biological evaluation of novel diazide-containing isoxazole- and pyrazole-based histone deacetylase probes

The design, synthesis, docking, and biological evaluation of novel potent HDAC3 and HDAC8 isoxazole- and pyrazole-based diazide probes suitable for binding ensemble profiling with photoaffinity labeling (BEProFL) experiments in cells is described. Both the isoxazole- and pyrazole-based probes exhibit low nanomolar inhibitory activity against HDAC3 and HDAC8, respectively. The pyrazole-based probe 3f appears to be one of the most active HDAC8 inhibitors reported in the literature with an IC(50) of 17 nM. Our docking studies suggest that unlike the isoxazole-based ligands the pyrazole-based ligands are flexible enough to occupy the second binding site of HDAC8. Probes/inhibitors 2b, 3a, 3c, and 3f exerted the antiproliferative and neuroprotective activities at micromolar concentrations through inhibition of nuclear HDACs, indicating that they are cell permeable and the presence of an azide or a diazide group does not interfere with the neuroprotection properties, or enhance cellular cytotoxicity, or affect cell permeability.