Trichostatin A targets the mitochondrial respiratory chain, increasing mitochondrial reactive oxygen species production to trigger apoptosis in human breast cancer cells

Acute chromatin decompaction stiffens the nucleus as revealed by nanopillar-induced nuclear deformation in cells

Chromatin architecture is critical in determining nuclear mechanics. Most studies focus on the mechanical rigidity conferred by chromatin condensation from densely packed heterochromatin, but less is known on how transient chromatin decompaction impinge on nucleus stiffness. Here, we used an array of vertically aligned nanopillars to study nuclear deformability in situ after chromatin decompaction in cells. The nucleus significantly stiffened within 4 h of chromatin decompaction but softened at longer timescales. This acute stiffening of the nucleus was underpinned predominantly by an increase in nucleus volume and nuclear import, and partially by enhanced lamin protein recruitment to the periphery. The coupling between nucleus stiffening and acute chromatin decompaction was observed in low malignancy cancer cell lines (e.g. MCF7, PEO1, A549) but weakened in highly malignant counterparts (e.g. MDA-MB-231, HEYA8, HT1080) due to the capacity to efficiently compact heterochromatin into foci that sustains nucleus deformability required for confined migration. Our work signals how rapid chromatin remodeling is a physiologically relevant pathway to modulate nucleus mechanics and cell migration behavior.

Bioinspired hydrogel microspheres enhance nucleus pulposus regeneration through N-cadherin interaction with extracellular matrix mimicry

Intervertebral disc degeneration (IVDD) is a common cause of debilitating spinal conditions, necessitating regenerative therapies to restore tissue function. This study explores the potential of enhancing nucleus pulposus cell (NPC) viability and extracellular matrix (ECM) synthesis through surface modification of GelMA microspheres with His-Ala-Val (HAV) peptides. The HAV peptides, mimicking N-cadherin's adhesive properties, aim to promote cell-cell interactions akin to NPCs' native environment. In vitro studies demonstrated enhanced ECM secretion by NPCs cultured on HAV-functionalized GelMA microspheres, suggesting a potential for improved regenerative capacity. The microspheres promoted NP tissue regeneration when implanted in rat tail IVDs post-discectomy, indicating their therapeutic efficacy in vivo. This research provides insights into novel strategies for enhancing cell-material interactions in tissue engineering applications to mitigate IVDD.

SMC2 and Condensin II Subunits Are Essential for the Development of Hematopoietic Stem and Progenitor Cells in Zebrafish

Hematopoietic stem and progenitor cells (HSPCs) play a pivotal role in blood cell production, maintaining the health and homeostasis of individuals. Dysregulation of HSPC function can lead to blood-related diseases, including cancer. Despite its importance, our understanding of the genes and pathways underlying HSPC development and the associated pathological mechanisms remains limited. To elucidate these unknown mechanisms, we analyzed databases of patients with blood disorders and performed functional gene studies using zebrafish. We employed bioinformatics tools to explore three public databases focusing on patients with myelodysplastic syndrome (MDS) and related model studies. This analysis identified significant alterations in several genes, especially SMC2 and other condensin-related genes, in patients with MDS. To further investigate the role of Smc2 in hematopoiesis, we generated smc2 loss-of-function zebrafish mutants using CRISPR mutagenesis. Further analyses of the mutants revealed that smc2 depletion induced G2/M cell cycle arrest in HSPCs, leading to their maintenance and expansion failure. Notably, although the condensin II subunits (ncaph2, ncapg2, and ncapd3) were essential for HSPC maintenance, the condensin I subunits did not affect HSPC development. These findings emphasize the crucial role of condensin II in ensuring healthy hematopoiesis via promoting HSPC proliferation.

Super-resolution microscopy reveals the nanoscale cluster architecture of the DEK protein cancer biomarker

DEK protein, a key chromatin regulator, is strongly overexpressed in various forms of cancer. While conventional microscopy revealed DEK as uniformly distributed within the cell nucleus, advanced super-resolution techniques uncovered cluster-like structures. However, a comprehensive understanding of DEK's cellular distribution and its implications in cancer and cell growth remained elusive. To bridge this gap, we employed single-molecule localization microscopy (SMLM) to dissect DEK's nanoscale organization in both normal-like and aggressive breast cancer cell lines. Our investigation included characteristics such as localizations per cluster, cluster areas, and intra-cluster localization densities (ICLDs). We elucidated how cluster features align with different breast cell types and how chromatin decompaction influences DEK clusters in these contexts. Our results indicate that DEK's intra-cluster localization density and nano-organization remain preserved and not significantly influenced by protein overexpression or chromatin compaction changes. This study advances the understanding of DEK's role in cancer and underscores its stable nanoscale behavior.

Pharmacological Properties of Trichostatin A, Focusing on the Anticancer Potential: A Comprehensive Review

Trichostatin A (TSA), a natural derivative of dienohydroxamic acid derived from a fungal metabolite, exhibits various biological activities. It exerts antidiabetic activity and reverses high glucose levels caused by the downregulation of brain-derived neurotrophic factor (BDNF) expression in Schwann cells, anti-inflammatory activity by suppressing the expression of various cytokines, and significant antioxidant activity by suppressing oxidative stress through multiple mechanisms. Most importantly, TSA exhibits potent inhibitory activity against different types of cancer through different pathways. The anticancer activity of TSA appeared in many in vitro and in vivo investigations that involved various cell lines and animal models. Indeed, TSA exhibits anticancer properties alone or in combination with other drugs used in chemotherapy. It induces sensitivity of some human cancers toward chemotherapeutical drugs. TSA also exhibits its action on epigenetic modulators involved in cell transformation, and therefore it is considered an epidrug candidate for cancer therapy. Accordingly, this work presents a comprehensive review of the most recent developments in utilizing this natural compound for the prevention, management, and treatment of various diseases, including cancer, along with the multiple mechanisms of action. In addition, this review summarizes the most recent and relevant literature that deals with the use of TSA as a therapeutic agent against various diseases, emphasizing its anticancer potential and the anticancer molecular mechanisms. Moreover, TSA has not been involved in toxicological effects on normal cells. Furthermore, this work highlights the potential utilization of TSA as a complementary or alternative medicine for preventing and treating cancer, alone or in combination with other anticancer drugs.

A Histone Deacetylase Inhibitor Induces Acetyl-CoA Depletion Leading to Lethal Metabolic Stress in RAS-Pathway Activated Cells

BACKGROUND

The mechanism of action of romidepsin and other histone deacetylase inhibitors is still not fully explained. Our goal was to gain a mechanistic understanding of the RAS-linked phenotype associated with romidepsin sensitivity.

METHODS

The NCI60 dataset was screened for molecular clues to romidepsin sensitivity. Histone acetylation, DNA damage, ROS production, metabolic state (real-time measurement and metabolomics), and gene expression alterations (transcriptomics) were determined in KRAS-WT versus KRAS-mutant cell groups. The search for biomarkers in response to HDACi was implemented by supervised machine learning analysis on a 608-cell transcriptomic dataset and validated in a clinical dataset.

RESULTS

Romidepsin treatment induced depletion in acetyl-CoA in all tested cell lines, which led to oxidative stress, metabolic stress, and increased death-particularly in KRAS-mutant cell lines. Romidepsin-induced stresses and death were rescued by acetyl-CoA replenishment. Two acetyl-CoA gene expression signatures associated with HDACi sensitivity were derived from machine learning analysis in the CCLE (Cancer Cell Line Encyclopedia) cell panel. Signatures were then validated in the training cohort for seven HDACi, and in an independent 13-patient cohort treated with belinostat.

CONCLUSIONS

Our study reveals the importance of acetyl-CoA metabolism in HDAC sensitivity, and it highlights acetyl-CoA generation pathways as potential targets to combine with HDACi.

5-Azacitidine and Trichostatin A induce DNA damage and apoptotic responses in tongue squamous cell carcinoma: An in vitro study

OBJECTIVE

The present in vitro study aims to investigate the potential use of epigenetic inhibitors as treatment modalities in tongue squamous cell carcinoma.

DESIGN

The human tongue squamous cell carcinoma cell line (CAL-27) was cultured and exposed to varying concentrations of 5-Azacitidine (5-Aza) or Trichostatin A (TSA) in the culture medium. The cell apoptosis was evaluated using Annexin V/PI by flow cytometry. To evaluate DNA damage response, γH2AX foci analysis was performed using immunofluorescence. Single cell gel electrophoresis (SCGE) was applied to measure DNA strand breaks. Gene expression was assessed by quantitative real-time PCR.

RESULTS

The results showed that 5-Aza and TSA had apoptotic effects on the SCC cell line at concentrations of 50-200 µM and 0.5-5 µM, respectively. Immunofluorescence analysis showed increased expression of γH2AX, the marker of DNA damage response after treatment of 5-Aza and TSA that was associated with increased DNA strand breaks. The expressions of urokinase plasminogen activator, its receptor and matrix metalloproteinase-2, were significantly reduced in TSA- and 5-Aza-treated cells.

CONCLUSIONS

Our results showed that 5-Aza and TSA increase apoptotic and DNA damage response in squamous cell carcinoma cell line while reducing the expression of tumor invasion genes that further indicating the potential therapeutic value of two epigenetic modifiers in squamous cell carcinoma.

Low Dose of Trichostatin A Improves Radiation Resistance by Activating Akt/Nrf2-Dependent Antioxidation Pathway in Cancer Cells

Numerous studies have shown that histone deacetylase inhibitors (HDACis) improve cellular acetylation while also enhancing the radiation sensitivity. In this work, however, we confirmed that low-dose trichostatin A (TSA) as a typical HDACi could reduce rather than increase the radiosensitivity of cancer cells, while the cellular acetylation was also increased with TSA-induced epigenetic modification. The surviving fraction of HeLa/HepG2 cells pretreated with 25 nM TSA for 24 h was higher at 1 Gy/2 Gy of γ-ray radiation than that of the cells with the same radiation dose but without TSA pretreatment. To understand the underlying mechanism, we investigated the effect of low-dose TSA on HO-1, SOD and CAT induction and activating Akt together with its downstream Nrf2 signaling pathway. Our results indicated that TSA activated HO-1, SOD and CAT expression by increasing the phosphorylation level of Nrf2 in an Akt-dependent manner. In addition, we also observed that the 25-nM-TSA-pretreated group showed a significant increase in the antioxidant capacity in terms of SOD and CAT activities. Therefore, our results suggest that low-dose TSA can activate the Akt/Nrf2 pathway and upregulate expression of HO-1, SOD and CAT to stimulate the cellular defense mechanism. This work demonstrates that low-dose TSA treatment may activate the adaptation mechanism against the oxidative stress induced by ionizing radiation, and application of HDACi treatment should be undertaken with caution to avoid its possible radioresistance in radiotherapy.

Ability of plasma-activated acetated Ringer's solution to induce A549 cell injury is enhanced by a pre-treatment with histone deacetylase inhibitors

Non-thermal plasma (NTP) is applicable to living cells and has emerged as a novel technology for cancer therapy. NTP affect cells not only by direct irradiation, but also by an indirect treatment with previously prepared plasma-activated liquid. Histone deacetylase (HDAC) inhibitors have the potential to enhance susceptibility to anticancer drugs and radiation because these reagents decondense the compact chromatin structure by neutralizing the positive charge of the histone tail. The aim of the present study was to demonstrate the advantage of the combined application of plasma-activated acetated Ringer’s solution (PAA) and HDAC inhibitors on A549 cancer cells. PAA maintained its ability for at least 1 week stored at any temperature tested. Cell death was enhanced more by combined regimens of PAA and HDAC inhibitors, such as trichostatin A (TSA) and valproic acid (VPA), than by a single PAA treatment and was accompanied by ROS production, DNA breaks, and mitochondria dysfunction through a caspase-independent pathway. These phenomena induced the depletion of ATP and elevations in intracellular calcium concentrations. The sensitivities of HaCaT cells as normal cells to PAA were less than that of A549 cells. These results suggest that HDAC inhibitors synergistically induce the sensitivity of cancer cells to PAA.

Proteasome inhibitors trigger mutations via activation of caspases and CAD, but mutagenesis provoked by the HDAC inhibitors vorinostat and romidepsin is caspase/CAD-independent

Genotoxic anti-cancer therapies such as chemotherapy and radiotherapy can contribute to an increase in second malignancies in cancer survivors due to their oncogenic effects on non-cancerous cells. Inhibition of histone deacetylase (HDAC) proteins or the proteasome differ from chemotherapy in that they eliminate cancer cells by regulating gene expression or cellular protein equilibrium, respectively. As members of these drug classes have been approved for clinical use in recent times, we investigated whether these two drug classes exhibit similar mutagenic capabilities as chemotherapy. The HDAC inhibitors vorinostat/SAHA and romidepsin/FK288 were found to induce DNA damage, and mis-repair of this damage manifested into mutations in clonogenically viable surviving cells. DNA damage and mutations were also detected in cells treated with the proteasome inhibitor bortezomib. Exposure to both drug classes stimulated caspase activation consistent with apoptotic cell death. Inhibition of caspases protected cells from bortezomib-induced acute (but not clonogenic) death and mutagenesis, implying caspases were required for the mutagenic action of bortezomib. This was also observed for second generation proteasome inhibitors. Cells deficient in caspase-activated DNase (CAD) also failed to acquire DNA damage or mutations following treatment with bortezomib. Surprisingly, vorinostat and romidepsin maintained an equivalent level of killing and mutagenic ability regardless of caspase or CAD activity. Our findings indicate that both drug classes harbour mutagenic potential in vitro. If recapitulated in vivo, the mutagenicity of these agents may influence the treatment of cancer patients who are more susceptible to oncogenic mutations due to dysfunctional DNA repair pathways.

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.

Peroxiredoxin-mediated disulfide bond formation is required for nucleocytoplasmic translocation and secretion of HMGB1 in response to inflammatory stimuli

The nuclear protein HMGB1 (high mobility group box 1) is secreted by monocytes-macrophages in response to inflammatory stimuli and serves as a danger-associated molecular pattern. Acetylation and phosphorylation of HMGB1 are implicated in the regulation of its nucleocytoplasmic translocation for secretion, although inflammatory stimuli are known to induce H₂O₂ production. Here we show that H₂O₂-induced oxidation of HMGB1, which results in the formation of an intramolecular disulfide bond between Cys²³ and Cys⁴⁵, is necessary and sufficient for its nucleocytoplasmic translocation and secretion. The oxidation is catalyzed by peroxiredoxin I (PrxI) and PrxII, which are first oxidized by H₂O₂ and then transfer their disulfide oxidation state to HMGB1. The disulfide form of HMGB1 showed higher affinity for nuclear exportin CRM1 compared with the reduced form. Lipopolysaccharide (LPS)–induced HMGB1 secretion was greatly attenuated in macrophages derived from PrxI or PrxII knockout mice, as was the LPS-induced increase in serum HMGB1 levels.

Ubiquinol-cytochrome C reductase core protein II promotes tumorigenesis by facilitating p53 degradation

Background

Ubiquinol-cytochrome C reductase core protein II (QCR2) is essential for mitochondrial functions, yet, its role in cancer development has remained elusive.

Methods

The expression of QCR2 in cancer patients was assessed by immunohistochemistry. The proliferation of cancer cells was assessed by CCK-8 assay, EdU staining and Flow cytometry analysis. The biological function of QCR2 and PHB were determined using western blotting, RT-qPCR, microarray analysis and xenografts. The interactions between proteins and the ubiquitination of p53 were assessed by immunoprecipitation, mass spectrometry analysis and GST pull down. The subcellular location of PHB and QCR2 was assessed by immunoblotting and immunofluorescence.

Finding

The expression of QCR2 is upregulated in multiple human tumors. Suppression of QCR2 inhibits cancer cell growth by activating p53 signaling and inducing p21-dependent cell cycle arrest and senescence. QCR2 directly interacts with PHB in the mitochondria. Overexpression of QCR2 inhibits PHB binding to p53 in the nucleus, and facilitates p53 ubiquitination and degradation, consequently leading to tumorigenesis. Also, increased QCR2 and decreased PHB protein levels are well correlated with decreased expression of p21 in cervical cancer tissues.

Interpretation

These results identify a novel role for QCR2, together with PHB, in negative regulation of p53 stability and activity, thus promote cervical carcinogenesis.

Fund

“973” Program of China, the National Science-technology Supporting Plan Projects, the National Natural Science Foundation of China, National Science and Technology Major Sub-Project and Technical Innovation Special Project of Hubei Province.

Trichostatin A Shows Transient Protection from Chronic Alcohol-Induced Reactive Oxygen Species (ROS) Production in Human Monocyte-Derived Dendritic Cells

OBJECTIVE

The objective of this study was to understand whether histone deacetylase (HDACs) inhibitor Trichostatin A or TSA can block and/or reverse chronic alcohol exposure-induced ROS in human monocyte-derived dendritic cells (MDDCs). Additionally, since nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a known regulator of antioxidant responses, we studied the effects of alcohol and TSA on ROS production and modulation of Nrf2 by MDDCs.

METHODS

Intra-cellular, extra-cellular, and total ROS levels were measured in MDDCs treated chronically with alcohol (0.1 and 0.2 % EtOH) using 2',7'-dichlorofluorescin diacetate (DCF-DA) followed by detection of ROS in microplate reader and imaging flow cytometer. Nrf2 expression was analyzed by qRT- PCR and western blot. In addition, NFE2L2 (Nrf2), class I HDAC genes HDAC1, HDAC2, and histone acetyltransferase genes KAT5 were analyzed in silico using the GeneMania prediction server.

RESULTS

Our results confirmed alcohol's ability to increase intracellular ROS levels in MDDCs within minutes of treatment. Our findings have also demonstrated, for the first time, that TSA has a transient protective effect on MDDCs treated chronically with alcohol since the ability of TSA to reduce intracellular ROS levels is only detected up to 15 minutes post-chronic alcohol treatment with no significant protective effects by 10 hours. In addition, chronic alcohol treatment was able to increase the expression of the antioxidant regulator Nrf2 in a dose dependent manner, and the effect of the higher amount of alcohol (0.2%) on Nrf2 gene expression was significantly enhanced by TSA.

CONCLUSION

This study demonstrates that TSA has a transient protective effect against ROS induced by chronic alcohol exposure of human MDDCs and chronic long-term exposure of MDDCs with alcohol and TSA induces cellular toxicity. It also highlights imaging flow cytometry as a novel tool to detect intracellular ROS levels. Overall, the effect of TSA might be mediated through Nrf2; however, further studies are needed to fully understand the molecular mechanisms.

Quercetin enhances the antitumor effect of trichostatin A and suppresses muscle wasting in tumor-bearing mice

Quercetin, a flavonol, displays anti-inflammatory and anti-cancer properties. This study aimed to investigate whether a diet containing 0.1% or 1% quercetin (LQ and HQ, respectively) enhances the anti-tumor effects of trichostatin A (TSA) and prevents muscle wasting induced by TSA. The positive control group received quercetin intraperitoneally (IQ). Three weeks after injecting A549 cells, nude mice were given TSA alone or in combination with quercetin administered orally or intraperitoneally for 16 weeks. Tumor volumes as well as body, muscle and epididymal fat weights were determined during or after the experiment. Quercetin given as a diet supplement dose-dependently enhanced the anti-tumor potency of TSA (p < 0.05). The enhancing effect of HQ was similar to that of IQ. HQ also significantly increased the expression of p53, a tumor suppressor, in tumor tissues compared with the TSA alone group. In addition, TSA-induced loss of gastrocnemius muscle weight was inhibited by oral quercetin in a dose dependent manner; the efficiencies of LQ and HQ were similar to or better than IQ. Moreover, both LQ and HQ decreased TSA-induced activation of Forkhead box O1 (FOXO1), a crucial transcription factor that regulates muscle wasting associated genes. Consistently, LQ and HQ suppressed muscle wasting associated proteins atrophy gene-1 and muscle ring-finger protein-1 expression as well as increased the myosin heavy chain level in the gastrocnemius muscles. Besides, quercetin attenuated TSA-increased oxidative damage and proinflammatory cytokines (p < 0.05). These findings demonstrate that a diet containing 0.1% or 1% quercetin enhances the antitumor effect of TSA and prevents TSA-induced muscle wasting.

Droxinostat sensitizes human colon cancer cells to apoptotic cell death via induction of oxidative stress

Upregulation of histone acetylation plays a critical role in the dysregulation of transcription. It alters the structure of chromatin, which leads to the onset of cancer. Histone deacetylase inhibitors may therefore be a promising way to limit cancer progression. In this study, we examined the effects of droxinostat on the growth of HT-29 colon cancer cells. Our results show that droxinostat effectively inhibited cell growth and colony-forming ability by inducing cellular apoptosis and ROS production in HT-29 cells. Notably, the apoptotic inhibitor Z-VAD-FMK significantly decreased the levels of cellular apoptosis and the antioxidant γ-tocotrienol (GT3) significantly decreased ROS production induced by droxinostat treatment. Z-VAD-FMK and GT3 also partially reversed the negative growth effects of droxinstat on HT-29 cells. GT3 treatment decreased cellular apoptosis and increased colony-forming ability upon droxinostat administration. Z-VAD-FMK treatment also partially decreased droxinostat-induced ROS production. Our findings suggest that the effects of droxinostat on colon cancer cells are mediated by the induction of oxidative stress and apoptotic cell death.

The histone deacetylase inhibitor SAHA induces HSP60 nitration and its extracellular release by exosomal vesicles in human lung-derived carcinoma cells

HSP60 undergoes changes in quantity and distribution in some types of tumors suggesting a participation of the chaperonin in the mechanism of transformation and cancer progression. Suberoylanilide hydroxamic acid (SAHA), a member of a family of histone deacetylase inhibitors (HDACi), has anti-cancer potential but its interaction, if any, with HSP60 has not been elucidated. We investigated the effects of SAHA in a human lung-derived carcinoma cell line (H292). We analysed cell viability and cycle; oxidative stress markers; mitochondrial integrity; HSP60 protein and mRNA levels; and HSP60 post-translational modifications, and its secretion. We found that SAHA is cytotoxic for H292 cells, interrupting the cycle at the G2/M phase, which is followed by death; cytotoxicity is associated with oxidative stress, mitochondrial damage, and diminution of intracellular levels of HSP60; HSP60 undergoes a post-translational modification and becomes nitrated; and nitrated HSP60 is exported via exosomes. We propose that SAHA causes ROS overproduction and mitochondrial dysfunction, which leads to HSP60 nitration and release into the intercellular space and circulation to interact with the immune system. These successive steps might constitute the mechanism of the anti-tumor action of SAHA and provide a basis to design supplementary therapeutic strategies targeting HSP60, which would be more efficacious than the compound alone.

Novel biomolecule lycopene-reduced graphene oxide-silver nanoparticle enhances apoptotic potential of trichostatin A in human ovarian cancer cells (SKOV3)

Background

Recently, there has been much interest in the field of nanomedicine to improve prevention, diagnosis, and treatment. Combination therapy seems to be most effective when two different molecules that work by different mechanisms are combined at low dose, thereby decreasing the possibility of drug resistance and occurrence of unbearable side effects. Based on this consideration, the study was designed to investigate the combination effect of reduced graphene oxide-silver nanoparticles (rGO-AgNPs) and trichostatin A (TSA) in human ovarian cancer cells (SKOV3).

Methods

The rGO-AgNPs were synthesized using a biomolecule called lycopene, and the resultant product was characterized by various analytical techniques. The combination effect of rGO-Ag and TSA was investigated in SKOV3 cells using various cellular assays such as cell viability, cytotoxicity, and immunofluorescence analysis.

Results

AgNPs were uniformly distributed on the surface of graphene sheet with an average size between 10 and 50 nm. rGO-Ag and TSA were found to inhibit cell viability in a dose-dependent manner. The combination of rGO-Ag and TSA at low concentration showed a significant effect on cell viability, and increased cytotoxicity by increasing the level of malondialdehyde and decreasing the level of glutathione, and also causing mitochondrial dysfunction. Furthermore, the combination of rGO-Ag and TSA had a more pronounced effect on DNA fragmentation and double-strand breaks, and eventually induced apoptosis.

Conclusion

This study is the first to report that the combination of rGO-Ag and TSA can cause potential cytotoxicity and also induce significantly greater cell death compared to either rGO-Ag alone or TSA alone in SKOV3 cells by various mechanisms including reactive oxygen species generation, mitochondrial dysfunction, and DNA damage. Therefore, this combination chemotherapy could be possibly used in advanced cancers that are not suitable for radiation therapy or surgical treatment and facilitate overcoming tumor resistance and disease progression.

Plant Responses to Abiotic Stress Regulated by Histone Deacetylases

In eukaryotic cells, histone acetylation and deacetylation play an important role in the regulation of gene expression. Histone acetylation levels are modulated by histone acetyltransferases and histone deacetylases (HDACs). Recent studies indicate that HDACs play essential roles in the regulation of gene expression in plant response to environmental stress. In this review, we discussed the recent advance regarding the plant HDACs and their functions in the regulation of abiotic stress responses. The role of HDACs in autophagy was also discussed.

Fighting Cancer with Corroles

Corroles are exceptionally promising platforms for the development of agents for simultaneous cancer-targeting imaging and therapy. Depending on the element chelated by the corrole, these theranostic agents may be tuned primarily for diagnostic or therapeutic function. Versatile synthetic methodologies allow for the preparation of amphipolar derivatives, which form stable noncovalent conjugates with targeting biomolecules. These conjugates can be engineered for imaging and targeting as well as therapeutic function within one theranostic assembly. In this review, we begin with a brief outline of corrole chemistry that has been uniquely useful in designing corrole-based anticancer agents. Then we turn attention to the early literature regarding corrole anticancer activity, which commenced one year after the first scalable synthesis was reported (1999-2000). In 2001, a major advance was made with the introduction of negatively charged corroles, as these molecules, being amphipolar, form stable conjugates with many proteins. More recently, both cellular uptake and intracellular trafficking of metallocorroles have been documented in experimental investigations employing advanced optical spectroscopic as well as magnetic resonance imaging techniques. Key results from work on both cellular and animal models are reviewed, with emphasis on those that have shed new light on the mechanisms associated with anticancer activity. In closing, we predict a very bright future for corrole anticancer research, as it is experiencing exponential growth, taking full advantage of recently developed imaging and therapeutic modalities.

PU.1-Bim axis is involved in Trichostatin A-induced apoptosis in murine pro-B lymphoma FL5.12 cells

Trichostatin A (TSA) is a well-known histone deacetylases (HDACs) inhibitor that has been reported to show potent anti-tumor capabilities in some types of cancer cell lines. However, detailed mechanism of TSA action on lymphoma remains to be described. In the present study, anti-proliferative effects of TSA were investigated using a murine pro-B lymphoma cell line FL5.12. MTT assay revealed that TSA potently inhibited the proliferation of FL5.12 cells in a time- and dose-dependent manner. Bright-field microscopy of FL5.12 cells showed apoptotic morphology at 24 h after TSA treatment. Consistently, TSA treatment led to DNA fragmentation and increased the protein levels of cleaved caspase 3 and PARP as revealed by western blot analysis. To explore the underlying mechanism of TSA-induced apoptosis of FL5.12 cells, we further analyzed the hematopoietic transcription factor Purine Rich Box-1 (PU.1) by western blot analysis. TSA treatment resulted in the inhibition of PU.1 in FL5.12 cells. In contrast, apoptotic protein Bim was induced by TSA, which was inversely correlated with the survival of FL5.12 cells. These results suggest the possible mechanism of TSA-induced apoptosis in murine pro-B lymphoma FL5.12 cells via the PU.1-Bim axis.

Extracellularly secreted APE1/Ref-1 triggers apoptosis in triple-negative breast cancer cells via RAGE binding, which is mediated through acetylation

The present study evaluated the mechanism of apoptosis caused by post-translational modification, hyperacetylation in triple-negative breast cancer (TNBC) cells. We previously showed that trichostatin A (TSA) induced secretion of acetylated apurinic apyrimidinic endonuclease 1/redox factor-1 (Ac-APE1/Ref-1). This is the first report showing that Ac-APE1/Ref-1 initiates apoptosis in TNBC cells by binding to the receptor for advanced glycation end products (RAGE). The functional significance of secreted Ac-APE1/Ref-1 was studied by induction of intracellular hyperacetylation through co-treatment with acetylsalicylic acid and TSA in MDA-MB-231 cells. In response to hyperacetylation, secretion of Ac-APE1/Ref-1 in vesicles was observed, resulting in significantly decreased cell viability and induction of apoptosis with increased expression of RAGE. The hyperacetylation-induced apoptosis was similar in two other TNBC cell lines: BT-459 and MDA-MB-468. Therefore, hyperacetylation may be a therapeutic target for treatment of TNBCs. This study introduces a novel paradigm whereby post-translational modification induces apoptotic cell death in breast cancer cells resistant to standard chemotherapeutic agents through secretion of auto- or paracrine molecules such as Ac-APE1/Ref-1.

A gene-signature progression approach to identifying candidate small-molecule cancer therapeutics with connectivity mapping

Background

Gene expression connectivity mapping has gained much popularity recently with a number of successful applications in biomedical research testifying its utility and promise. Previously methodological research in connectivity mapping mainly focused on two of the key components in the framework, namely, the reference gene expression profiles and the connectivity mapping algorithms. The other key component in this framework, the query gene signature, has been left to users to construct without much consensus on how this should be done, albeit it has been an issue most relevant to end users. As a key input to the connectivity mapping process, gene signature is crucially important in returning biologically meaningful and relevant results. This paper intends to formulate a standardized procedure for constructing high quality gene signatures from a user’s perspective.

Results

We describe a two-stage process for making quality gene signatures using gene expression data as initial inputs. First, a differential gene expression analysis comparing two distinct biological states; only the genes that have passed stringent statistical criteria are considered in the second stage of the process, which involves ranking genes based on statistical as well as biological significance. We introduce a “gene signature progression” method as a standard procedure in connectivity mapping. Starting from the highest ranked gene, we progressively determine the minimum length of the gene signature that allows connections to the reference profiles (drugs) being established with a preset target false discovery rate. We use a lung cancer dataset and a breast cancer dataset as two case studies to demonstrate how this standardized procedure works, and we show that highly relevant and interesting biological connections are returned. Of particular note is gefitinib, identified as among the candidate therapeutics in our lung cancer case study. Our gene signature was based on gene expression data from Taiwan female non-smoker lung cancer patients, while there is evidence from independent studies that gefitinib is highly effective in treating women, non-smoker or former light smoker, advanced non-small cell lung cancer patients of Asian origin.

Conclusions

In summary, we introduced a gene signature progression method into connectivity mapping, which enables a standardized procedure for constructing high quality gene signatures. This progression method is particularly useful when the number of differentially expressed genes identified is large, and when there is a need to prioritize them to be included in the query signature. The results from two case studies demonstrate that the approach we have developed is capable of obtaining pertinent candidate drugs with high precision.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1066-x) contains supplementary material, which is available to authorized users.

Trichostatin A potentiates TRAIL-induced antitumor effects via inhibition of ERK/FOXM1 pathway in gastric cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an ideal apoptosis inducer and believed to have promise in cancer therapy, yet part of cancer cells exhibit resistance to TRAIL-mediated apoptosis. This necessitates the exploration of agents that resensitizes cancer cells to TRAIL. In our study, we found that Trichostatin A (TSA), an histone deacetylase (HDAC) inhibitor, augmented TRAIL-induced apoptosis in gastric cancer cells in a caspase-dependent manner. Besides, upregulation of DR5 and downregulation of anti-apoptotic proteins including XIAP, Mcl-1, Bcl-2 and Survivin also contributed to this synergism. Noticeably, TSA treatment inhibited Forkhead boxM1 (FOXM1), which expression level showed negative correlation with TRAIL sensitivity. Similarly, silencing of FOXM1 by small interfering RNA (siRNA) resensitized cancer cells to TRAIL and strengthened the TRAIL-augmenting effect of TSA. In addition, we demonstrated the depletion of FOXM1 was a consequence of the inactivation of ERK mediated by TSA. Collectively, it was first shown that TSA potentiated TRAIL sensitivity via ERK/FOXM1 pathway in gastric cancer cells. FOXM1 might serve as a biomarker for predicting sensitivity to TRAIL.

Histone deacetylases in monocyte/macrophage development, activation and metabolism: refining HDAC targets for inflammatory and infectious diseases

Macrophages have central roles in danger detection, inflammation and host defense, and consequently, these cells are intimately linked to most disease processes. Major advances in our understanding of the development and function of macrophages have recently come to light. For example, it is now clear that tissue-resident macrophages can be derived from either blood monocytes or through local proliferation of phagocytes that are originally seeded during embryonic development. Metabolic state has also emerged as a major control point for macrophage activation phenotypes. Herein, we review recent literature linking the histone deacetylase (HDAC) family of enzymes to macrophage development and activation, particularly in relation to these recent developments. There has been considerable interest in potential therapeutic applications for small molecule inhibitors of HDACs (HDACi), not only for cancer, but also for inflammatory and infectious diseases. However, the enormous range of molecular and cellular processes that are controlled by different HDAC enzymes presents a potential stumbling block to clinical development. We therefore present examples of how classical HDACs control macrophage functions, roles of specific HDACs in these processes and approaches for selective targeting of drugs, such as HDACi, to macrophages. Development of selective inhibitors of macrophage-expressed HDACs and/or selective delivery of pan HDACi to macrophages may provide avenues for enhancing efficacy of HDACi in therapeutic applications, while limiting unwanted side effects.

The effects of anticancer drugs TSA and GSK on spermatogenesis in male mice

OBJECTIVE

The effect of anticancer drugs Trichostation A (TSA) and GSK2126458 (GSK) on genetic recombination of sperm meiosis in mice was investigated, and their clinical feasibility of fertility preservation in cancer patients was also assessed.

METHODS

Eighteen Kunming mice were randomly given TSA or GSK at the concentrations of 0, 0.1 and 0.2 umol/L for three months. Immunofluorescence was used to evaluate the genetic recombination of homologous chromosomes and fidelity of chromosome synapsis. Sperm density, motility and viability were also examined to investigate the spermatogenic function.

RESULTS

The average number of MLH1 foci in each spermatocyte was greatly higher in TSA (0.1) group than that in control (P<0.05), but no difference with the TSA (0.2) group (P>0.05). The frequency of SC with no MLH1 foci was lower while the frequency of SC with one MLH1 foci was higher in spermatocyte of mice with different doses of TSA compared with controls (P<0.05). The weight of left testis in TSA (0.1) group was significant decreased compared with that in control (P<0.05). However, no significant differences were observed in average number of MLH1, frequency of SC with 0-3 MLH1 foci, spermatocyte percentage of XY chromosomes containing MLH1 foci and percentages of cells containing gaps and splits among groups with or without the treatment of GSK. Furthermore, there were no statistical differences in body weight, testicular weight, sperm density, sperm motility and sperm viability among the three groups.

CONCLUSION

TSA increased genetic recombination frequency of spermatocyte meiosis. GSK had no significant effect on genetic recombination frequency of spermatocyte meiosis and spermatogenic function.

Subcellular Localization of Class I Histone Deacetylases in the Developing Xenopus tectum

Histone deacetylases (HDACs) are thought to localize in the nucleus to regulate gene transcription and play pivotal roles in neurogenesis, apoptosis, and plasticity. However, the subcellular distribution of class I HDACs in the developing brain remains unclear. Here, we show that HDAC1 and HDAC2 are located in both the mitochondria and the nucleus in the Xenopus laevis stage 34 tectum and are mainly restricted to the nucleus following further brain development. HDAC3 is widely present in the mitochondria, nucleus, and cytoplasm during early tectal development and is mainly distributed in the nucleus in stage 45 tectum. In contrast, HDAC8 is broadly located in the mitochondria, nucleus, and cytoplasm during tectal development. These data demonstrate that HDAC1, HDAC2, and HDAC3 are transiently localized in the mitochondria and that the subcellular distribution of class I HDACs in the Xenopus tectum is heterogeneous. Furthermore, we observed that spherical mitochondria accumulate in the cytoplasm at earlier stages, whereas elongated mitochondria are evenly distributed in the tectum at later stages. The activity of histone acetylation (H4K12) remains low in mitochondria during tectal development. Pharmacological blockades of HDACs using a broad spectrum HDAC inhibitor of Trichostatin A (TSA) or specific class I HDAC inhibitors of MS-275 and MGCD0103 decrease the number of mitochondria in the tectum at stage 34. These findings highlight a link between the subcellular distribution of class I HDACs and mitochondrial dynamics in the developing optic tectum of Xenopus laevis.

A Histone Deacetylase Inhibitor Suppresses Epithelial-Mesenchymal Transition and Attenuates Chemoresistance in Biliary Tract Cancer

Epithelial-mesenchymal transition (EMT) is involved in the characteristics of malignancy, such as invasion, metastasis, and chemoresistance. In biliary tract cancer (BTC), EMT is induced by transforming growth factor-beta 1 (TGF-β1). The EMT is reversible; therefore, it is conceivable that it could be related to some epigenetic changes. We focused on histone deacetylase (HDAC) inhibitors as regulators of TGF-β1 signaling, and investigated their effect on EMT and chemoresistance. We employed four BTC cell lines (MzChA-1, gemcitabine-resistant MzChA-1, TFK-1, and gemcitabine-resistant TFK-1) and used vorinostat as the HDAC inhibitor. The relative mRNA expression of an epithelial marker (CDH1) and mesenchymal markers (CDH2, vimentin, SNAI1) were measured by qRT-PCR to evaluate factors associated with EMT. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed to evaluate the chemoresistance of each cell line. In addition, NOD/SCID mice were used to evaluate the effect of vorinostat in vivo. In the parent MzChA-1 and TFK-1 cell lines, TGF-β1 induced EMT and chemoresistance; while vorinostat inhibited the EMT and chemoresistance induced by TGF-β1. In gemcitabine-resistant cell lines that highly expressed TGF-β1, vorinostat inhibited EMT and attenuated chemoresistance. We showed that vorinostat inhibits nuclear translocation of SMAD4 which is a signaling factor of TGF-β1, and this is one of the mechanisms by which vorinostat regulates EMT. We also showed that vorinostat attenuates the binding affinity of SMAD4 to the CDH1-related transcription factors SNAI1, SNAI2, ZEB1, ZEB2, and TWIST. Furthermore, combination therapy with vorinostat and gemcitabine improved survival time in the mice xenografted with gemcitabine resistant MzChA-1 cells. In conclusion, vorinostat regulated TGF-β1-induced EMT and chemoresistance through inhibition of SMAD4 nuclear translocation.

Histone Deacetylase Inhibitors Promote Mitochondrial Reactive Oxygen Species Production and Bacterial Clearance by Human Macrophages

Broad-spectrum histone deacetylase inhibitors (HDACi) are used clinically as anticancer agents, and more isoform-selective HDACi have been sought to modulate other conditions, including chronic inflammatory diseases. Mouse studies suggest that HDACi downregulate immune responses and may compromise host defense. However, their effects on human macrophage antimicrobial responses are largely unknown. Here, we show that overnight pretreatment of human macrophages with HDACi prior to challenge with Salmonella enterica serovar Typhimurium or Escherichia coli results in significantly reduced intramacrophage bacterial loads, which likely reflect the fact that this treatment regime impairs phagocytosis. In contrast, cotreatment of human macrophages with HDACi at the time of bacterial challenge did not impair phagocytosis; instead, HDACi cotreatment actually promoted clearance of intracellular S. Typhimurium and E. coli. Mechanistically, treatment of human macrophages with HDACi at the time of bacterial infection enhanced mitochondrial reactive oxygen species generation by these cells. The capacity of HDACi to promote the clearance of intracellular bacteria from human macrophages was abrogated when cells were pretreated with MitoTracker Red CMXRos, which perturbs mitochondrial function. The HDAC6-selective inhibitor tubastatin A promoted bacterial clearance from human macrophages, whereas the class I HDAC inhibitor MS-275, which inhibits HDAC1 to -3, had no effect on intracellular bacterial loads. These data are consistent with HDAC6 and/or related HDACs constraining mitochondrial reactive oxygen species production from human macrophages during bacterial challenge. Our findings suggest that, whereas long-term HDACi treatment regimes may potentially compromise host defense, selective HDAC inhibitors may have applications in treating acute bacterial infections.

Berberine Regulated Lipid Metabolism in the Presence of C75, Compound C, and TOFA in Breast Cancer Cell Line MCF-7

Berberine interfering with cancer reprogramming metabolism was confirmed in our previous study. Lipid metabolism and mitochondrial function were also the core parts in reprogramming metabolism. In the presence of some energy-related inhibitors, including C75, compound C, and TOFA, the discrete roles of berberine in lipid metabolism and mitochondrial function were elucidated. An altered lipid metabolism induced by berberine was observed under the inhibition of FASN, AMPK, and ACC in breast cancer cell MCF-7. And the reversion of berberine-induced lipid suppression indicated that ACC inhibition might be involved in that process instead of FASN inhibition. A robust apoptosis induced by berberine even under the inhibition of AMPK and lipid synthesis was also indicated. Finally, mitochondrial function regulation under the inhibition of AMPK and ACC might be in an ACL-independent manner. Undoubtedly, the detailed mechanisms of berberine interfering with lipid metabolism and mitochondrial function combined with energy-related inhibitors need further investigation, including the potential compensatory mechanisms for ATP production and the upregulation of ACL.

New targeted therapies for breast cancer: A focus on tumor microenvironmental signals and chemoresistant breast cancers

Breast cancer is the most frequent female malignancy worldwide. Current strategies in breast cancer therapy, including classical chemotherapy, hormone therapy, and targeted therapies, are usually associated with chemoresistance and serious adverse effects. Advances in our understanding of changes affecting the interactome in advanced and chemoresistant breast tumors have provided novel therapeutic targets, including, cyclin dependent kinases, mammalian target of rapamycin, Notch, Wnt and Shh. Inhibitors of these molecules recently entered clinical trials in mono- and combination therapy in metastatic and chemo-resistant breast cancers. Anticancer epigenetic drugs, mainly histone deacetylase inhibitors and DNA methyltransferase inhibitors, also entered clinical trials. Because of the complexity and heterogeneity of breast cancer, the future in therapy lies in the application of individualized tailored regimens. Emerging therapeutic targets and the implications for personalized-based therapy development in breast cancer are herein discussed.