Inhibition of telomerase activity and human telomerase reverse transcriptase gene expression by histone deacetylase inhibitor in human brain cancer cells

The aim of the present study is to investigate the effect of histone deacetylase inhibitor, trichostatin A (TSA) on the cell growth, apoptosis, genomic DNA damage and the expression of telomerase and associated factors in human normal and brain cancer cells. Here, human normal un-transformed fibroblasts (MRC-5), human normal hTERT-immortalised fibroblasts (hTERT-BJ1) and human brain cancer cell lines (glioblastoma cell line, A-172 and medulloblastoma cell line, ONS-76) were treated with 0.5–3.0 μM TSA for 24 h. Exposure to TSA resulted in apoptosis in a dose-dependent manner in the brain cancer cells. Glioblastoma cell line (A-172) displayed higher sensitivity to TSA-induced cell killing effect and apoptosis than the medulloblastoma cell line (ONS-76). The brain cancer cell lines and hTERT-BJ1 cell line displayed significant inhibition in telomerase activity and hTERT mRNA level after 2 μM TSA treatment. Elevated expressions of p53 and p21 with a decrease in cyclin-D level supported the observation on cell cycle arrest following TSA treatment. Upregulation of Bax and cytochrome c correlated with the apoptotic events in TSA-treated cells. This study suggests that telomerase and hTERT might be the primary targets of TSA which may have the potential to be used as a telomerase inhibitor in cancer therapy.     

A novel histone deacetylase inhibitor Chidamide induces apoptosis of human colon cancer cells

Many studies have demonstrated that histone deacetylase (HDAC) inhibitors induce various tumor cells to undergo apoptosis, and such inhibitors have been used in different clinical trials against different human cancers. In this study, we designed and synthesized a novel HDAC inhibitor, Chidamide. We showed that Chidamide was able to increase the acetylation levels of histone H3 and to inhibit the PI3K/Akt and MAPK/Ras signaling pathways, which resulted in arresting colon cancer cells at the G1 phase of the cell cycle and promoting apoptosis. As a result, the proliferation of colon cancer cells was suppressed in vitro. Our data support the potential application of Chidamide as an anticancer agent in treating colon cancer. Future studies are needed to demonstrate its in vivo efficacy.     

PKCepsilon is essential for gelsolin expression by histone deacetylase inhibitor apicidin in human cervix cancer cells

Down-regulation of gelsolin expression is associated with cellular transformation and induction of gelsolin exerts antitumorigenic effects. In this study, we show that protein kinase C (PKC) signaling pathway is required for the induction of gelsolin by the histone deacetylase inhibitor apicidin in HeLa cells. Apicidin induces gelsolin mRNA independently of the de novo protein synthesis. Inhibitor study has revealed that the PKC signaling pathway is involved in the gelsolin expression. Furthermore, inhibition of PKCepsilon by either siRNA or dominant-negative mutant completely abrogates the expression of gelsolin by apicidin, indicating that PKCepsilon is the major isoform for this process. In parallel, apicidin induction of gelsolin is antagonized by the inhibition of Sp1 using dominant-negative Sp1 or specific Sp1 inhibitor mithramycin, and inhibition of PKC leads to suppression of Sp1 promoter activity. Our results provide mechanistic insights into molecular mechanisms of gelsolin induction by apicidin.     

Differentiation of human adipose-derived stem cells into cardiomyocyte-like cells in fibrin scaffold by a histone deacetylase inhibitor

Background

Human adipose-derived stem cells (hADSCs) are capable of differentiating into many cells such as cardiac cells. Different types of inducers are used for cardiac cell differentiation, but this question still remains to be investigated, which one is the best. The aim of this paper was to investigate the effect of combination of fibrin scaffold and trichostatin A (TSA), for differentiation of hADSCs into cardiomyocyte-like cells.

Methods

After approval of characteristics of hADSCs and fibrin scaffold, hADSCs were cultured in fibrin scaffold with 10 µM TSA for 72 h and kept in standard conditions for 4 weeks. QRT-PCR and immunostaining assay were performed for evaluating the expression pattern of special cardiac genes and proteins.

Results

In particular, our study showed that fibrin scaffold alongside TSA enhanced expression of the selected genes and proteins.

Conclusions

We concluded that the TSA alone or with fibrin scaffold can lead to the generation of cardiac like cells in a short period of time.

     

The histone deacetylase inhibitor trichostatin A alters the pattern of DNA replication origin activity in human cells

Eukaryotic chromatin structure limits the initiation of DNA replication spatially to chromosomal origin zones and temporally to the ordered firing of origins during S phase. Here, we show that the level of histone H4 acetylation correlates with the frequency of replication initiation as measured by the abundance of short nascent DNA strands within the human c-myc and lamin B2 origins, but less well with the frequency of initiation across the β-globin locus. Treatment of HeLa cells with trichostatin A (TSA) reversibly increased the acetylation level of histone H4 globally and at these initiation sites. At all three origins, TSA treatment transiently promoted a more dispersive pattern of initiations, decreasing the abundance of nascent DNA at previously preferred initiation sites while increasing the nascent strand abundance at lower frequency genomic initiation sites. When cells arrested in late G₁ were released into TSA, they completed S phase more rapidly than untreated cells, possibly due to the earlier initiation from late-firing origins, as exemplified by the β-globin origin. Thus, TSA may modulate replication origin activity through its effects on chromatin structure, by changing the selection of initiation sites, and by advancing the time at which DNA synthesis can begin at some initiation sites.     

Genome-wide histone acetylation profiling of Herpesvirus saimiri in human T cells upon induction with a histone deacetylase inhibitor

Herpesviruses establish latency in suitable host cells after primary infection and persist in their host organisms for life. Most of the viral genes are silenced during latency, also enabling the virus to escape from an immune response. This study addresses the control of viral gene silencing by epigenetic mechanisms, using Herpesvirus saimiri (HVS) as a model system. Strain C488 of this gamma-2-herpesvirus can transform human T cells to stable growth in vitro, and it persists in the nuclei of those latently infected T cells as a nonintegrating, circular, and histone-associated episome. The whole viral genome was probed for histone acetylation at high resolution by chromatin immunoprecipitation-on-chip (ChIP-on-chip) with a custom tiling microarray. Corresponding to their inactive status in human T cells, the lytic promoters consistently revealed a heterochromatic phenotype. In contrast, the left terminal region of the genome, which encodes the stably expressed oncogenes stpC and tip as well as the herpesvirus U RNAs, was associated with euchromatic histone acetylation marks representing "open" chromatin. Although HVS latency in human T lymphocytes is considered a stable and irreversible state, incubation with the histone deacetylase inhibitor trichostatin A resulted in changes reminiscent of the induction of early lytic replication. However, infectious viral particles were not produced, as the majority of cells went into apoptosis. These data show that epigenetic mechanisms are involved in both rhadinoviral latency and transition into lytic replication.     

Mechanism of histone deacetylase inhibitor Trichostatin A induced apoptosis in human osteosarcoma cells

Although histone deacetylase (HDAC) inhibitors are emerging as a promising new treatment strategy in malignancy, how they exert their effect on osteosarcoama cells is as yet unclear. This study was undertaken to investigate the underlying mechanism of a HDAC inhibitor Trichostatin A (TSA)-induced apoptosis in a osteosarcoma cell line HOS. We observed that TSA treatment decreased the viability of the cells and prominently increased acetylation of histone H3. Evidence was obtained indicating that TSA induced apoptosis of HOS cells as follows: (1) Generation of DNA fragmentation; (2) activation of procaspase-3; (3) cleavage of PARP; and (4) increase of DNA hypoploidy. The reduction of MMP and the release of cytochrome c to cytosol were also shown, indicating that TSA induces apoptosis in HOS cells in a histone acetylation- and mitochondria-dependent fashions. We also examined whether TSA can sensitize HOS cells to the action of an antitumor agent genistein. The combination therapy of TSA and genistein showed synergistic anticancer effect indicating that TSA can be considered as a novel therapeutic strategy for osteosarcoma not only from its direct apoptosis-inducing activity but also from the possibility of sensitization to other antitumor agents.     

Radioprotection by the histone deacetylase inhibitor phenylbutyrate

The histone deacetylase inhibitor (HDAC), phenylbutyrate (PB), is a novel anti-tumor agent. Studies have demonstrated that HDAC inhibitors can suppress cutaneous radiation syndrome and stimulate hematopoiesis. The objective of this study was to test the ability of PB treatment to protect against acute gamma-radiation-induced lethality in the DBA/2 mouse model. A 30-day radiation lethality study was used to assess radioprotective capability of PB. Mechanisms were evaluated using western blots, flow cytometry, and the single-cell gel electrophoresis assay. Western blot studies showed that PB treatment acetylated histones in vivo. For radiation protection studies, prophylactic administration of PB (24 h preradiation; 1–50 mg/kg) provided radioprotection against gamma radiation (8–9.5 Gy) and PB demonstrated a DRF of 1.31 (P = 0.001; 95% confidence interval: 1.27, 1.36). When PB (10 mg/kg) was administered post-radiation (4 h), it also provided significant radioprotection at 8.0 Gy radiation (P = 0.022). PB treatment before radiation was associated with significant elevations in neutrophils and platelets following radiation. Results from single-cell gel electrophoresis of peripheral blood leukocytes demonstrated that PB treatment before radiation can attenuate DNA damage and inhibit radiation-induced apoptosis. These results indicate that an HDAC inhibitor like PB has potential as a radiation protector and that mechanisms of action include attenuation of DNA damage and inhibition of apoptosis.     

Enhanced histone acetylation in somatic cells induced by a histone deacetylase inhibitor improved inter-generic cloned leopard cat blastocysts

The objective was to determine whether alterations of histone acetylation status in donor cells affected inter-generic SCNT (igSCNT)-cloned embryo development. Leopard cat cells were treated with trichostatin A (TSA; a histone deacetylase inhibitor) for 48 h, and then donor cells were transferred into enucleated oocytes from domestic cats. Compared to non-treated cells, the acetylated histone 3 at lysine 9 (AcH3K9) and histone 4 at lysine 5 (AcH4K5) in the TSA group increased for up to 48 h (P < 0.05). The AcH3K9 signal ratios of igSCNT group was higher than control group 3 h after activation (P < 0.05). Treatment with TSA significantly increased total cell number of blastocysts (109.1 ± 6.9 vs. 71.8 ± 2.9, mean ± SEM), with no significant effects on rates of cleavage or blastocyst development (71.1 ± 2.8 vs. 67.6 ± 2.9 and 12.2 ± 2.6 vs. 11.0 ± 2.6, respectively). When igSCNT cloned embryos were transferred into a domestic cat oviduct and recovered after 8 d, blastocyst development rates and total cell numbers were greater in the TSA-igSCNT group (20.7 ± 3.0% and 2847.6 ± 37.2) than in the control igSCNT group (5.7 ± 2.2% and 652.1 ± 17.6, P < 0.05). Average total cell numbers of blastocysts were approximately 4.4-fold higher in the TSA-igSCNT group (2847.6 ± 37.2, n = 10) than in the control group (652.1 ± 17.6, n = 8; P < 0.05), but were ∼2.9-fold lower than in vivo cat blastocysts produced by intrauterine insemination (8203.8 ± 29.6, n = 5; P < 0.001). Enhanced histone acetylation levels of donor cells improved in vivo developmental competence and quality of inter-generic cloned embryos; however, fewer cells in blastocysts derived from igSCNT than blastocysts produced by insemination may reduce development potential following intergeneric cloning (none of the cloned embryos were maintained to term).     

Sodium arsenite modulates histone acetylation, histone deacetylase activity and HMGN protein dynamics in human cells

Extensive epidemiological data indicate that inorganic arsenic is associated with several types of human cancer. Nevertheless, the underlying mechanisms are poorly understood. Among its mode of action are the alterations on DNA methylation, which provoke aberrant gene expression. However, beyond DNA methylation, little is known about arsenic’s effects on chromatin. In this study, we investigated the effects of sodium arsenite (NaAsO₂) on global histone modifications and nucleosome-associated proteins. Our findings revealed that NaAsO₂ exposure significantly increases global histone acetylation. This effect was related to the inhibition of histone deacetylase (HDAC) activity because NaAsO₂ was able to inhibit HDACs comparable to the well-known HDAC inhibitor trichostatin A (TSA). Furthermore, analyses of the dynamic properties of the nucleosome-associated high mobility group N proteins demonstrate that NaAsO₂ elevates their mobility. Thus, our data suggest that NaAsO₂ induces chromatin opening by histone hyperacetylation due to HDAC inhibition and increase of the mobility of nucleosome-associated proteins. As the chromatin compaction is crucial for the regulation of gene expression as well as for genome stability, we propose that chromatin opening by NaAsO₂ may play a significant role to impart its genotoxic effects. Tzutzuy Ramirez and Jan Brocher contributed equally.     

Proteasome inhibitor carfilzomib interacts synergistically with histone deacetylase inhibitor vorinostat in Jurkat T-leukemia cells

In the present study, we investigated the interactions between proteasome inhibitor carfllzomib （CFZ） and histone deacety lase inhibitor vorinostat in Jurkat Tleukemia ceils. Coexposure of cells to minimally lethal concentrations of CFZ with very low concentration of vorinostat resulted in synergistic antiproliferative effects and enhanced apoptosis in Jurkat Tleukemia cells, accompanied with the sharply increased reactive oxygen species （ROS）, the striking de crease in the mitochondrial membrane potential （MMP）, the increased release of cytochrome c, the enhanced activation of caspase9 and 3, and the cleavage of PARP. The com bined treatment of Jurkat cells pretreated with ROS sca vengers Nacetylcysteine （NAC） significantly blocked the loss of mitochondrial membrane potential, suggesting that ROS generation was a former event of the loss of mitochon drial membrane potential. Furthermore, NAC also resulted in a marked reduction in apoptotic cells, indicating a critical role for increased ROS generation by combined treatment. In addition, combined treatment arrested the cell cycle in G2M phase. These results imply that CFZ interacted syner gistically with vorinostat in Jurkat Tleukemia cells, which raised the possibility that the combination of carfflzomib with vorinostat may represent a novel strategy in treating Tcell Leukemia.     

Copper oxide nanoparticles induce anticancer activity in A549 lung cancer cells by inhibition of histone deacetylase

Objectives

Copper oxide nanoparticles (CuO NPs) promoting anticancer activity may be due to the regulation of various classes of histone deacetylases (HDACs).

Results

Green-synthesized CuO NPs significantly arrested total HDAC level and also suppressed class I, II and IV HDACs mRNA expression in A549 cells. A549 cells treated with CuO NPs downregulated oncogenes and upregulated tumor suppressor protein expression. CuO NPs positively regulated both mitochondrial and death receptor-mediated apoptosis caspase cascade pathway in A549 cells.

Conclusion

Green-synthesized CuO NPs inhibited HDAC and therefore shown apoptosis mediated anticancer activity in A549 lung cancer cell line.

     

A proteomic approach for evaluating the cell response to a novel histone deacetylase inhibitor in colon cancer cells

Epigenetic inactivation of gene expression is a general phenomenon associated with malignant transformation. Recently, we have found that a novel series of histone deacetylases (HDAC) inhibitors exhibit a broad-spectrum inhibition profile characterized by a marked effect on acetylation of histone and non-histone proteins. RC307, a representative compound of this series, caused a growth-inhibitory effect in colon carcinoma cells HCT116 associated with G2 accumulation and induction of apoptosis. The present study was designed to investigate the effect of RC307 on protein expressions in the HCT116 cells following treatment with cytotoxic drug concentrations. HCT116 cells were cultured in the absence or presence of RC307 and total cell lysates, as well as nuclear proteins, were extracted. The protein samples were then subjected to two-dimensional polyacrylamide gel electrophoresis, and the 2D gel images were compared to discover the protein changes caused by RC307 treatment. A total of 48 and 46 different spots were found to be modulated by RC307 in total lysates and nuclear proteome of HCT116 cell line. The modulated proteins were identified by tandem mass spectrometry. We found that RC307 exposure modulates proteins that are involved in proliferation, cell cycle regulation, apoptosis, gene expression, as well as chromatin and cytoskeleton organization.     

Apoptosis induced by the histone deacetylase inhibitor sodium butyrate in human leukemic lymphoblasts.

The histone deacetylase inhibitor and potential anti-cancer drug sodium butyrate is a general inducer of growth arrest, differentiation, and in certain cell types, apoptosis. In human CCRF-CEM, acute T lymphoblastic leukemia cells, butyrate, and other histone deacetylase inhibitors caused G2/M cell cycle arrest as well as apoptotic cell death. Forced G0/G1 arrest by tetracycline-regulated expression of transgenic p16/INK4A protected the cells from butyrate-induced cell death without affecting the extent of histone hyperacetylation, suggesting that the latter may be necessary, but not sufficient, for cell death induction. Nuclear apoptosis, but not G2/M arrest, was delayed but not prevented by the tripeptide broad-range caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp.fluoromethylketone (zVAD) and, to a lesser extent, by the tetrapeptide 'effector caspase' inhibitors benzyloxycarbonyl-Asp-Glu-Val-Asp.fluoromethylketone (DEVD) and benzyloxycarbonyl-Val-Glu-Ile-Asp.fluoromethyl-ketone (VEID); however, the viral protein inhibitor of 'inducer caspases', crmA, had no effect. Bcl-2 overexpression partially protected stably transfected CCRF-CEM sublines from butyrate-induced apoptosis, but showed no effect on butyrate-induced growth inhibition, further distinguishing these two butyrate effects. c-myc, constitutively expressed in CCRF-CEM cells, was down-regulated by butyrate, but this was not causative for cell death. On the contrary, tetracycline-induced transgenic c-myc sensitized stably transfected CCRF-CEM derivatives to butyrate-induced cell death.     

Identification of a potent non-hydroxamate histone deacetylase inhibitor by mechanism-based drug design

In order to find novel non-hydroxamate histone deacetylase (HDAC) inhibitors, we synthesized several suberoylanilide hydroxamic acid (SAHA)-based compounds designed on the basis of the catalytic mechanism of HDACs. Among these compounds, 5b was found to be as potent as SAHA. Kinetic enzyme assays and molecular modeling suggested that the mercaptoacetamide moiety of 5b interacts with the zinc in the active site of HDACs and removes a water molecule from the reactive site of the deacetylation.