Antitumor activity of histone deacetylase inhibitor trichostatin A in osteosarcoma cells

Screening for the presence of aberrantly expressed ACTR2 in osteosarcoma and analyzing its mechanism of action through an online database

Osteosarcoma (OS) represents the most prevalent malignant bone tumor clinically, significantly impacting the health and safety of patients. The exploration of molecular pathogenic mechanisms is deemed a breakthrough for OS diagnosis and treatment. Within the GSE16088 dataset, a total of 1,948 differentially expressed genes (DEGs) were identified, comprising 1,697 down-regulated and 251 up-regulated genes. Notably, only two DEGs were associated with the response to trichostatin A: ARP2 actin-related protein 2 homolog (ACTR2) and MEF2C; ACTR2 garnered particular interest. Subsequently, 57 OS patients (research group) and 50 healthy controls from the same period (control group) were selected for analysis. The expression of ACTR2 in peripheral blood in both groups, as well as its levels in cancerous tissues and adjacent counterparts of OS patients, were evaluated, ascertaining the correlation between ACTR2 and OS. OS cases exhibited lower levels of ACTR2 compared to controls (P<0.05), with ACTR2 expression demonstrating a robust diagnostic capability for OS. Similarly, ACTR2 expression was diminished in cancer tissues (P<0.05). A three-year prognostic follow-up was conducted to assess the prognostic value of ACTR2 in OS patients. The follow-up findings revealed a significantly lower survival rate among patients with low ACTR2 expression in contrast to those with high expression (P<0.05). In vitro studies involved the construction of abnormal expression vectors for ACTR2 and miR-374a-5p, which were transfected into human OS cells (U2OS, SAOS). The outcomes indicated that elevating ACTR2 or suppressing miR-374a-5p attenuated the proliferative, invasive, and migratory capacities as well as the epithelial-mesenchymal transition (EMT) of OS cells while enhancing their apoptosis. Conversely, upregulation of miR-374a-5p yielded opposing effects (P<0.05). The dual-luciferase reporter (DLR) assay demonstrated that the fluorescence activity of ACTR2-WT was significantly inhibited by the miR-374a-5p mimic sequence (P<0.05), confirming the presence of a targeted regulatory relationship between ACTR2 and miR-374a-5p. These findings offer novel insights for future research directions in the diagnosis and treatment of OS.

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.

Selective Targeting of Class I Histone Deacetylases in a Model of Human Osteosarcoma

Dysregulation of histone deacetylases (HDACs) is associated with the pathogenesis of human osteosarcoma, which may present an epigenetic vulnerability as well as a therapeutic target. Domatinostat (4SC-202) is a next-generation class I HDAC inhibitor that is currently being used in clinical research for certain cancers, but its impact on human osteosarcoma has yet to be explored. In this study, we report that 4SC-202 inhibits osteosarcoma cell growth in vitro and in vivo. By analyzing cell function in vitro, we show that the anti-tumor effect of 4SC-202 involves the combined induction of cell-cycle arrest at the G2/M phase and apoptotic program, as well as a reduction in cell invasion and migration capabilities. We also found that 4SC-202 has little capacity to promote osteogenic differentiation. Remarkably, 4SC-202 revised the global transcriptome and induced distinct signatures of gene expression in vitro. Moreover, 4SC-202 decreased tumor growth of established human tumor xenografts in immunodeficient mice in vivo. We further reveal key targets regulated by 4SC-202 that contribute to tumor cell growth and survival, and canonical signaling pathways associated with progression and metastasis of osteosarcoma. Our study suggests that 4SC-202 may be exploited as a valuable drug to promote more effective treatment of patients with osteosarcoma and provide molecular insights into the mechanism of action of class I HDAC inhibitors.

Targeting the Cancer Epigenome with Histone Deacetylase Inhibitors in Osteosarcoma

Epigenetic deregulation is an emerging hallmark of cancer that enables tumor cells to escape surveillance by tumor suppressors and ultimately progress. The structure of the epigenome consists of covalent modifications of chromatin components, including acetylation by histone acetyltransferases (HATs) and deacetylation by histone deacetylases (HDACs). Targeting these enzymes with inhibitors to restore epigenetic homeostasis has been explored for many cancers. Osteosarcoma, an aggressive bone malignancy that primarily affects children and young adults, is notable for widespread genetic and epigenetic instability. This may explain why therapy directed at unique molecular pathways has failed to substantially improve outcomes in osteosarcoma over the past four decades. In this review, we discuss the potential of targeting the cancer epigenome, with a focus on histone deacetylase inhibitors (HDACi) for osteosarcoma. We additionally highlight the safety and tolerance of HDACi, combination chemotherapy with HDACi, and the ongoing challenges in the development of these agents.

Trichostatin A Sensitizes Hepatocellular Carcinoma Cells to Enhanced NK Cell-mediated Killing by Regulating Immune-related Genes

BACKGROUND/AIM

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. The ability of HCC to avoid immune detection is considered one of the main factors making it difficult to cure. Abnormal histone deacetylation is thought to be one of the mechanisms for HCC immune escape, making histone deacetylases (HDACs) attractive targets for HCC treatment. Here, we investigated the effect of trichostatin A (TSA), a highly potent HDAC inhibitor, on HCC (HepG2) gene expression and function.

MATERIALS AND METHODS

A genome wide-transcriptional microarray was used to identify genes regulated by TSA in HepG2 cells. Gene Ontology was used to identify pathways regulated by TSA, and these changes were confirmed by qPCR. The effect of TSA on natural killer (NK) cell-mediated killing of HCC cell lines were analyzed by both flow cytometry and LDH cytotoxicity assay. A study was also conducted in a Balb/c nude mice xenograft model to assess the anti-tumor activity of TSA.

RESULTS

TSA regulated the transcription of numerous innate immunity & tumor antigen recognition-associated genes, such as ULBP1 and RAET1G, in HCC cells. In vivo, TSA reduced tumor cell growth in an NK cell-dependent manner. In vitro, TSA treatment of HepG2 cells rendered them more susceptible to NK cell-mediated killing while increasing the expression of NKGD2 ligands, including ULBP1/2/3 and MICA/B. TSA also induced direct killing of HCC cells by stimulating apoptosis.

CONCLUSION

TSA likely increases killing of HCC cells indirectly by increasing NK cell-directed killing and directly by increasing apoptosis.

Therapeutic applications of histone deacetylase inhibitors in sarcoma

Sarcomas are a rare group of malignant tumors originating from mesenchymal stem cells. Surgery, radiation and chemotherapy are currently the only standard treatments for sarcoma. However, their response rates to chemotherapy are quite low. Toxic side effects and multi-drug chemoresistance make treatment even more challenging. Therefore, better drugs to treat sarcomas are needed. Histone deacetylase inhibitors (HDAC inhibitors, HDACi, HDIs) are epigenetic modifying agents that can inhibit sarcoma growth in vitro and in vivo through a variety of pathways, including inducing tumor cell apoptosis, causing cell cycle arrest, impairing tumor invasion and preventing metastasis. Importantly, preclinical studies have revealed that HDIs can not only sensitize sarcomas to chemotherapy and radiotherapy, but also increase treatment responses when combined with other chemotherapeutic drugs. Several phase I and II clinical trials have been conducted to assess the efficacy of HDIs either as monotherapy or in combination with standard chemotherapeutic agents or targeted therapeutic drugs for sarcomas. Combination regimen for sarcomas appear to be more promising than monotherapy when using HDIs. This review summarizes our current understanding and therapeutic applications of HDIs in sarcomas.

Histone Deacetylase Inhibitor Trichostatin a Promotes the Apoptosis of Osteosarcoma Cells through p53 Signaling Pathway Activation

Purpose: The purpose of this study was to investigate the profile of histone deacetylase (HDAC) activity and expression in osteosarcoma cells and tissues from osteosarcoma patients and to examine the mechanism by which a histone deacetylase (HDAC) inhibitor, Trichostatin A (TSA), promotes the apoptosis of osteosarcoma cells. Methods: HDAC activity and histone acetyltransferase (HAT) activity were determined in nuclear extracts of MG63 cells, hFOB 1.19 cells and tissues from 6 patients with primary osteosarcoma. The protein expression of Class I HDACs (1, 2, 3 and 8) and the activation of the p53 signaling pathway were examined by Western blot. Cell growth and apoptosis were determined by 3-(4, 5-dimethyl-2-thiazolyl)-2H-tetrazolium bromide (MTT) assay and flow cytometry, respectively. Results: Nuclear HDAC activity and class I HDAC expression were significantly higher in MG63 cells than in hFOB 1.19 cells, and a similar trend was observed in the human osteosarcoma tissues compared with the paired adjacent non-cancerous tissues. TSA significantly inhibited the growth of MG63 cells and promoted apoptosis in a dose-dependent manner through p53 signaling pathway activation. Conclusion: Class I HDACs play a central role in the pathogenesis of osteosarcoma, and HDAC inhibitors may thus have promise as new therapeutic agents against osteosarcoma.

MiR-542-5p is a negative prognostic factor and promotes osteosarcoma tumorigenesis by targeting HUWE1

Recent evidence has demonstrated that microRNAs (miRNAs) are involved in the proliferation and metastasis of osteosarcoma. Using miRNA microarray and functional screening methods to compare miRNA expression profiles in osteosarcoma cell lines treated with Trichostatin A (TSA), overexpression of miR-542-5p was determined to be involved in the proliferation of osteosarcoma. We used isobaric tags for relative and absolute quantitation (iTRAQ) and nanoscale liquid chromatography-mass spectrometry (NanoLC−MS/MS) to identify differentially expressed proteins in MNNG/HOS and U2OS osteosarcoma cell lines transfected with miR-542-5p; in both cell lines, seven proteins were downregulated, and nine were upregulated. HUWE1 was found to be a direct target of miR-542-5p in both osteosarcoma cell lines, and was negatively correlated with miR-542-5p levels in human osteosarcoma tissues. Moreover, the expression of miR-542-5p was upregulated in human osteosarcoma tissue compared with non-tumor adjacent tissue. Kaplan-Meier analysis revealed that overexpression of miR-542-5p predicted poor prognosis for osteosarcoma patients. Taken together, our results indicated that miR-542-5p plays a critical role in the proliferation of osteosarcoma and targets HUWE1.

Histone deacetylase inhibitors induce invasion of human melanoma cells in vitro via differential regulation of N-cadherin expression and RhoA activity

Background

Histone deacetylase inhibitors (HDACi) exert multiple cytotoxic actions on cancer cells. Currently, different synthetic HDACi are in clinical use or clinical trials; nevertheless, since both pro-invasive and anti-invasive activities have been described, there is some controversy about the effect of HDACi on melanoma cells.

Methods

Matrigel and Collagen invasion assays were performed to evaluate the effect of several HDACi (Butyrate, Trichostatin A, Valproic acid and Vorinostat) on two human melanoma cell line invasion (A375 and HT-144). The expression of N- and E-Cadherin and the activity of the RhoA GTPase were analyzed to elucidate the mechanisms involved in the HDACi activity.

Results

HDACi showed a pro-invasive effect on melanoma cells in vitro. This effect was accompanied by an up-regulation of N-cadherin expression and an inhibition of RhoA activity. Moreover, the down-regulation of N-cadherin through blocking antibodies or siRNA abrogated the pro-invasive effect of the HDACi and, additionally, the inhibition of the Rho/ROCK pathway led to an increase of melanoma cell invasion similar to that observed with the HDACi treatments.

Conclusion

These results suggest a role of N-cadherin and RhoA in HDACi induced invasion and call into question the suitability of some HDACi as antitumor agents for melanoma patients.

TRPM2 mediates histone deacetylase inhibition-induced apoptosis in bladder cancer cells

PURPOSE

Inhibition of histone deacetylase (HDAC) activity results in growth arrest and apoptosis in multiple types of cancer cells. It has been well established that p21 is responsible for HDAC inhibitor (HDACi)-induced growth inhibition, while the mechanism underlying HDACi-elicited apoptosis in bladder cancer cells remains largely unknown.

METHODS

In this study, the apoptotic response to HDACi (trichostatin A and sodium butyrate) with different concentrations was determined by flow cytometry analysis and real-time polymerase chain reaction was conducted to examine the TRPM2 (Transient receptor potential cation channel, subfamily M, member 2) expression change on HDACi treatment. TRPM2 knockdown and overexpression were performed to investigate the role of TRPM2 in HDACi-induced apoptosis. The mechanism of HDACi-elicited upregulation of TRPM2 was studied by chromatin-immunoprecipitation.

RESULTS

HDACi efficiently induced cell apoptosis and TRPM2 upregulation in a time- and dose-dependent manner in T24 bladder cancer cells. Functional analysis revealed that TRPM2 overexpression promotes apoptosis of T24 cells. Conversely, TRPM2 depletion remarkably antagonized HDACi-induced apoptosis. Furthermore, HDAC inhibition-elicited TRPM2 upregulation is caused by the increase of acetylated H3K9 (H3K9Ac) enrichment in TRPM2 promoter.

CONCLUSIONS

These data suggest that the HDACi-elicited upregulation of TRPM2 expression is required for HDACi-induced apoptosis in bladder cancer cells and that HDACi activated the enrichment of H3K9Ac-represented permissive chromatin in TRPM2 promoter.

Effects of histone deacetylase inhibitor trichostatin A combined with cisplatin on apoptosis of A549 cell line

BACKGROUND

Histone deacetylase (HDAC) inhibitors combined with other drugs for the treatment of malignant tumors are used more and more widely. In this study, we investigated the effect of trichostatin A (TSA), a HDAC inhibitor, in combination with cisplatin, a cytotoxic chemotherapy agent, on the apoptosis of lung cancer A549 cells.

METHODS

A549 cells were treated with TSA alone, cisplatin alone or the two drugs combined. Cell viability and apoptosis were evaluated using a light microscope, methyl thiazolyl tetrazolium (MTT) (3-[4, 5-dimethylthiazol-2-yl] -2, 5-diphenyltetrazolium bromide) assay and Hochst33258 staining. Moreover, Western blot analysis was employed to examine the alterations of apoptosis protein: cellular Fas-associated death domain-like interleukin-1 β converting enzyme inhibitory protein (cFLIP) and caspase-8 in A549 cells in response to the different exogenous stimuli.

RESULTS

Compared with single-agent treatment, the co-treatment of A549 cells with TSA and cisplatin synergistically inhibited cell proliferation, induced apoptosis, and increased the inhibition rate. Treatment with TSA and cisplatin led to a significant decrease of cFLIP expression. Furthermore, the treatment of A549 cells with TSA and cisplatin resulted in a significant decrease of pro-caspase-8 and a significant increase of caspase-8.

CONCLUSIONS

Synergistic anti-tumor effects are observed between cisplatin and TSA in lung cancer cells. The combination of TSA with cisplatin may be a more effective method in human lung cancer treatment.

A new cell counting method to evaluate anti-tumor compound activity

Determining cell quantity is a common problem in cytology research and anti-tumor drug development. A simple and low-cost method was developed to determine monolayer and adherent-growth cell quantities. The cell nucleus is located in the cytoplasm, and is independent. Thus, the nucleus cannot make contact even if the cell density is heavy. This phenomenon is the foundation of accurate cell-nucleus recognition. The cell nucleus is easily recognizable in images after fluorescent staining because it is independent. A one-to-one relationship exists between the nucleus and the cell; therefore, this method can be used to determine the quantity of proliferating cells. Results indicated that the activity of the histone deacetylase inhibitor Z1 was effective after this method was used. The nude-mouse xenograft model also revealed the potent anti-tumor activity of Z1. This research presents a new anti-tumor-drug evaluation method.

Histone deacetylase inhibitor trichostatin A enhances anti-tumor effects of docetaxel or erlotinib in A549 cell line

BACKGROUND AND OBJECTIVE

Histone deacetylase (HDAC) inhibitors represent a promising class of potential anticancer agents for treatment of human malignancies. In this study, we investigated the effect of trichostatin A (TSA), one such HDAC inhibitor, in combination with docetaxel (TXT), a cytotoxic chemotherapy agent or erlotinib, a novel molecular target therapy drug, on lung cancer A549 cells.

METHODS

A549 cells were treated with TXT, erlotinib alone or in combination with TSA, respectively. Cell viability, apoptosis, and cell cycle distribution were evaluated using MTT (3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide) assay, Hochst33258 staining and flow cytometry. Moreover, immunofluorescent staining and Western blot analysis were employed to examine alterations of α-tubulin, heat shock protein 90 (hsp90), epidermal growth factor receptor (EGFR), and caspase-3 in response to the different exogenous stimuli.

RESULTS

Compared with single-agent treatment, co-treatment of A549 cells with TSA/TXT or TSA/erlotinib synergistically inhibited cell proliferation, induced apoptosis, and caused cell cycle delay at the G2/M transition. Treatment with TSA/TXT or TSA/erlotinib led to a significant increase of cleaved caspase-3 expression, also resulting in elevated acetylation of α-tubulin or hsp90 and decreased expression of EGFR, which was negatively associated with the level of acetylated hsp90.

CONCLUSIONS

Synergistic anti-tumor effects are observed between TXT or erlotinib and TSA on lung cancer cells. Such combinations may provide a more effective strategy for treating human lung cancer.

Sustained Low-Dose Treatment with the Histone Deacetylase Inhibitor LBH589 Induces Terminal Differentiation of Osteosarcoma Cells

Histone deacetylase inhibitors (HDACi) were identified nearly four decades ago based on their ability to induce cellular differentiation. However, the clinical development of these compounds as cancer therapies has focused on their capacity to induce apoptosis in hematologic and lymphoid malignancies, often in combination with conventional cytotoxic agents. In many cases, HDACi doses necessary to induce these effects result in significant toxicity. Since osteosarcoma cells express markers of terminal osteoblast differentiation in response to DNA methyltransferase inhibitors, we reasoned that the epigenetic reprogramming capacity of HDACi might be exploited for therapeutic benefit. Here, we show that continuous exposure of osteosarcoma cells to low concentrations of HDACi LBH589 (Panobinostat) over a three-week period induces terminal osteoblast differentiation and irreversible senescence without inducing cell death. Remarkably, transcriptional profiling revealed that HDACi therapy initiated gene signatures characteristic of chondrocyte and adipocyte lineages in addition to marked upregulation of mature osteoblast markers. In a mouse xenograft model, continuous low dose treatment with LBH589 induced a sustained cytostatic response accompanied by induction of mature osteoblast gene expression. These data suggest that the remarkable capacity of osteosarcoma cells to differentiate in response to HDACi therapy could be exploited for therapeutic benefit without inducing systemic toxicity.