Experimental therapy of malignant gliomas using the inhibitor of histone deacetylase MS-275

Inhibitors of histone deacetylases are promising compounds for the treatment of cancer but have not been systematically explored in malignant brain tumors. Here, we characterize the benzamide MS-275, a class I histone deacetylase inhibitor, as potent drug for experimental therapy of glioblastomas. Treatment of four glioma cell lines (U87MG, C6, F98, and SMA-560) with MS-275 significantly reduced cell growth in a concentration-dependent manner (IC(90), 3.75 micromol/L). Its antiproliferative effect was corroborated using a bromodeoxyuridine proliferation assay and was mediated by G(0)-G(1) cell cycle arrest (i.e., up-regulation of p21/WAF) and apoptotic cell death. Implantation of enhanced green fluorescent protein-transfected F98 glioma cells into slice cultures of rat brain confirmed the cytostatic effect of MS-275 without neurotoxic damage to the organotypic neuronal environment in a dose escalation up to 20 micromol/L. A single intratumoral injection of MS-275 7 days after orthotopic implantation of glioma cells in syngeneic rats confirmed the chemotherapeutic efficacy of MS-275 in vivo. Furthermore, its propensity to pass the blood-brain barrier and to increase the protein level of acetylated histone H3 in brain tissue identifies MS-275 as a promising candidate drug in the treatment of malignant gliomas.     

组蛋白去乙酰化酶抑制剂对乳腺癌细胞株MCF-7增殖周期的影响

目的 研究组蛋白去乙酰化酶抑制剂对乳腺癌细胞株增殖周期的影响.方法 培养乳腺癌细胞株MCF-7,用TSA、SAHA、CS055、MS-275 4种不同类型的组蛋白去乙酰化酶抑制剂分别作用于细胞,于24、48、72、96 h用MTT比色法观察细胞生长情况,初筛出高效的抑制剂.用所选出的抑制剂的不同浓度处理细胞,流式细胞术检测S期细胞的比例和周期素Cyclin D1、Cyclin A2,并进行统计分析.结果 在TSA、SAHA、CS055和MS-275 4种不同类型的组蛋白去乙酰化酶抑制剂中,SAHA显示出较强的抑制能力(P＜0.05);在一定时间和浓度范围内,其抑制能力有明显的时效关系;在抑制剂作用下,S期细胞比例和周期素Cyclin A2表达下降,Cyclin D1表达上升(P均＜0.05).结论 组蛋白去乙酰化酶抑制剂SAHA是乳腺癌细胞增殖的高效抑制剂,其抑制作用有一定的时效关系;周期素Cyclin D1、Cyclin A2参与了抑制剂对细胞增殖周期的调控.     

HDAC Inhibition Suppresses Primary Immune Responses,Enhances Secondary Immune Responses,and Abrogates Autoimmunity During Tumor Immunotherapy

Histone deacetylase inhibitors (HDACi) can modulate innate antiviral responses and render tumors more susceptible to oncolytic viruses (OVs); however, their effects on adaptive immunity in this context are largely unknown. Our present study reveals an unexpected property of the HDACi MS-275 that enhances viral vector-induced lymphopenia leading to selective depletion of bystander lymphocytes and regulatory T cells while allowing expansion of antigen-specific secondary responses. Coadministration of vaccine plus drug during the boosting phase focuses the immune response on the tumor by suppressing the primary immune response against the vaccine vector and enhancing the secondary response against the tumor antigen. Furthermore, improvement of T cell functionality was evident suggesting that MS-275 can orchestrate a complex array of effects that synergize immunotherapy and viral oncolysis. Surprisingly, while MS-275 dramatically enhanced efficacy, it suppressed autoimmune pathology, profoundly improving the therapeutic index.     

丁酸钠诱导骨髓间充质干细胞向心肌样细胞分化

背景:组蛋白乙酰化是诱导骨髓间充质干细胞向心肌样细胞分化的机制之一。目的:观察组蛋白去乙酰化酶抑制剂丁酸钠对体外培养的骨髓间充质干细胞向心肌样细胞分化的影响,并分析其诱导分化的机制。方法:分离、培养大鼠骨髓间充质干细胞,并进行鉴定。取第2代骨髓间充质干细胞,应用1mmol/L丁酸钠诱导其向心肌样细胞分化。结果与结论:实验分离培养的骨髓间充质干细胞高表达CD90,CD29;低表达CD45,CD31。加入丁酸钠后细胞增殖能力及组蛋白去乙酰化酶活性明显降低,但未发生明显凋亡现象,表明丁酸钠具有低毒性的特征。real-timePCR检测显示,经丁酸钠诱导后细胞GATA-4,MEF-2c,β-MHC等心肌细胞早期标志基因表达率明显增高(P<0.05)。Westernblot检测发现,经丁酸钠诱导后细胞心肌细胞特异性蛋白连接蛋白43和肌钙蛋白T的表达明显增高。免疫荧光测得的肌钙蛋白T表达结果与Westernblot一致。说明丁酸钠能够有效诱导骨髓间充质干细胞向心肌样细胞分化,其机制可能与抑制组蛋白去乙酰化酶活性,增强组蛋白的乙酰化有关。     

Histone deacetylase inhibitors induce G2-checkpoint arrest and apoptosis in cisplatinum-resistant ovarian cancer cells associated with overexpression of the Bcl-2-related protein Bad

Trichostatin A produces predominantly G(1) cell-cycle blockade and differentiation of the cisplatinum-sensitive A2780 ovarian cancer cell line. Given the propensity of ovarian tumors to become resistant to cisplatinum, often leading to cross-resistance to other agents, we have extended these observations by examining how the emergence of resistant phenotypes in A2780 cells affects the actions of histone deacetylase (HDAC) inhibitors. Trichostatin A exposure (100 ng/mL, 24 hours) induced ultrastructural differentiation of the "intrinsically" cisplatinum-resistant A2780-9M subline, with the reappearance of intercellular junctions and lumina containing primitive microvilli. Similar trichostatin A exposure in the acquired resistance A2780CP cells produced minimal differentiation consisting of occasional weak intercellular junctions. Independent of the differences in trichostatin A-induced differentiation, in both resistant sublines trichostatin A produced a similar reduction in cell viability, by >90%, within 5 days of treatment. Diminished viability in both A2780-9M and CP cells was associated with the absence of cell cycle arrest in G1, resulting in predominant G2-checkpoint arrest accompanied by a 10- to 20-fold increase in Annexin V binding and the reemergence of apoptosis. Similar cell cycle arrests and apoptosis were also observed using other HDAC inhibitors and in other resistant ovarian cancer cell lines (OVCAR-3 and SK-OV-3). Trichostatin A-induced apoptosis in resistant cells is in sharp contrast to its effects on the parental cisplatinum-sensitive A2780 and normal MRC-5 fibroblast cell lines (predominant cycle arrest in G1 with no detectable apoptosis). Western immunoblot analysis indicated trichostatin A triggers apoptosis in resistant ovarian cancer cells via p53-independent activation of the intrinsic "mitochondrial" pathway, commensurate with induction of the Bcl-2-related protein Bad. These results suggest cisplatinum resistance alters the effects of HDAC inhibition through a shift in cell cycle arrest from the G1 to the G2 checkpoint and reactivation of the intrinsic mitochondrial apoptotic cascade.     

HDACi promotes inflammatory remodeling of the tumor microenvironment to enhance epitope spreading and antitumor immunity

Adoptive cell therapy (ACT) with tumor-specific memory T cells has shown increasing efficacy in regressing solid tumors. However, tumor antigen heterogeneity represents a longitudinal challenge for durable clinical responses due to the therapeutic selective pressure for immune escape variants. Here, we demonstrated that delivery of the class I histone deacetylase inhibitor MS-275 promoted sustained tumor regression by synergizing with ACT in a coordinated manner to enhance cellular apoptosis. We found that MS-275 altered the tumor inflammatory landscape to support antitumor immunoactivation through the recruitment and maturation of cross-presenting CD103⁺ and CD8⁺ DCs and depletion of Tregs. Activated endogenous CD8⁺ T cell responses against nontarget tumor antigens were critically required for the prevention of tumor recurrence. Importantly, MS-275 altered the immunodominance hierarchy by directing epitope spreading toward the endogenous retroviral tumor–associated antigen p15E. Our data suggest that MS-275 in combination with ACT multimechanistically enhanced epitope spreading and promoted long-term clearance of solid tumors.     

Carfilzomib interacts synergistically with histone deacetylase inhibitors in mantle cell lymphoma cells in vitro and in vivo

Interactions between the proteasome inhibitor carfilzomib and the histone deacetylase (HDAC) inhibitors vorinostat and SNDX-275 were examined in mantle cell lymphoma (MCL) cells in vitro and in vivo. Coadministration of very low, marginally toxic carfilzomib concentrations (e.g., 3-4 nmol/L) with minimally lethal vorinostat or SNDX-275 concentrations induced sharp increases in mitochondrial injury and apoptosis in multiple MCL cell lines and primary MCL cells. Enhanced lethality was associated with c-jun-NH,-kinase (JNK) 1/2 activation, increased DNA damage (induction of λH2A.X), and ERK1/2 and AKT1/2 inactivation. Coadministration of carfilzomib and histone deacetylase inhibitors (HDACI) induced a marked increase in reactive oxygen species (ROS) generation and G(2)-M arrest. Significantly, the free radical scavenger tetrakis(4-benzoic acid) porphyrin (TBAP) blocked carfilzomib/HDACI-mediated ROS generation, λH2A.X formation, JNK1/2 activation, and lethality. Genetic (short hairpin RNA) knockdown of JNK1/2 significantly attenuated carfilzomib/HDACI-induced apoptosis, but did not prevent ROS generation or DNA damage. Carfilzomib/HDACI regimens were also active against bortezomib-resistant MCL cells. Finally, carfilzomib/vorinostat coadministration resulted in a pronounced reduction in tumor growth compared with single agent treatment in an MCL xenograft model associated with enhanced apoptosis, λH2A.X formation, and JNK activation. Collectively, these findings suggest that carfilzomib/HDACI regimens warrant attention in MCL.     

Butyric acid prodrugs are histone deacetylase inhibitors that show antineoplastic activity and radiosensitizing capacity in the treatment of malignant gliomas

Histone modification has emerged as a promising approach to cancer therapy. We explored the efficacy of a novel class of histone deacetylase inhibitors in the treatment of malignant gliomas. Treatment of glioma cell lines with two butyric acid derivatives, pivaloylomethyl butyrate (AN-9) and butyroyloxymethyl butyrate (AN-1), induced hyperacetylation, increased p21(Cip1) expression, inhibited proliferation, and enhanced apoptosis. Histone deacetylase inhibitor-induced apoptosis was mediated primarily by caspase-8. Treatment of cells with AN-1 or AN-9 for 24 hours before exposure to gamma-irradiation potentiated further caspase-8 activity and resultant apoptosis. Clonogenic survival curves revealed marked reductions in cell renewal capacity of U251 MG cells exposed to combinations of AN-1 and radiation. Preliminary in vivo experiments using human glioma cell lines grown as xenografts in mouse flanks suggest in vivo efficacy of AN-9. The data suggest that novel butyric acid prodrugs provide a promising treatment strategy for malignant gliomas as single agents and in combination with radiation therapy.     

MK1775, a selective Wee1 inhibitor, shows single-agent antitumor activity against sarcoma cells

Wee1 is a critical component of the G(2)-M cell-cycle checkpoint control and mediates cell-cycle arrest by regulating the phosphorylation of CDC2. Inhibition of Wee1 by a selective small molecule inhibitor MK1775 can abrogate G(2)-M checkpoint, resulting in premature mitotic entry and cell death. MK1775 has recently been tested in preclinical and clinical studies of human carcinoma to enhance the cytotoxic effect of DNA-damaging agents. However, its role in mesenchymal tumors, especially as a single agent, has not been explored. Here, we studied the cytotoxic effect of MK1775 in various sarcoma cell lines and patient-derived tumor explants ex vivo. Our data show that MK1775 treatment at clinically relevant concentrations leads to unscheduled entry into mitosis and initiation of apoptotic cell death in all sarcomas tested. In MK1775-treated cells, CDC2 activity was enhanced, as determined by decreased inhibitory phosphorylation of tyrosine-15 residue and increased expression of phosphorylated histone H3, a marker of mitotic entry. The cytotoxic effect of Wee1 inhibition on sarcoma cells seems to be independent of p53 status as all sarcoma cell lines with different p53 mutation were highly sensitive to MK1775 treatment. Finally, in patient-derived sarcoma samples, we showed that MK1775 as a single agent causes significant apoptotic cell death, suggesting that Wee1 inhibition may represent a novel approach in the treatment of sarcomas.     

HDAC inhibitors attenuate the development of hypersensitivity in models of neuropathic pain

Histone deacetylase inhibitors (HDACIs) interfere with the epigenetic process of histone acetylation and are known to have analgesic properties in models of chronic inflammatory pain. The aim of this study was to determine whether these compounds could also affect neuropathic pain. Different class I HDACIs were delivered intrathecally into rat spinal cord in models of traumatic nerve injury and antiretroviral drug–induced peripheral neuropathy (stavudine, d4T). Mechanical and thermal hypersensitivity was attenuated by 40% to 50% as a result of HDACI treatment, but only if started before any insult. The drugs globally increased histone acetylation in the spinal cord, but appeared to have no measurable effects in relevant dorsal root ganglia in this treatment paradigm, suggesting that any potential mechanism should be sought in the central nervous system. Microarray analysis of dorsal cord RNA revealed the signature of the specific compound used (MS-275) and suggested that its main effect was mediated through HDAC1. Taken together, these data support a role for histone acetylation in the emergence of neuropathic pain.     

A novel histone deacetylase (HDAC) inhibitor MHY219 induces apoptosis via up-regulation of androgen receptor expression in human prostate cancer cells

Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents that act by inhibiting cancer cell proliferation and inducing apoptosis in various cancer cell lines. To investigate the anticancer effect of a novel histone deacetylase (HDAC) inhibitor MHY219, its efficacy was compared to that of suberoylanilide hydroxamic acid (SAHA) in human prostate cancer cells. The anticancer effects of MHY219 on cell viability, HDAC enzyme activity, cell cycle regulation, apoptosis and other biological assays were performed. MHY219 was shown to enhance the cytotoxicity on DU145 cells (IC₅₀, 0.36 μM) when compared with LNCaP (IC₅₀, 0.97 μM) and PC3 cells (IC₅₀, 5.12 μM). MHY219 showed a potent inhibition of total HDAC activity when compared with SAHA. MHY219 increased histone H3 hyperacetylation and reduced the expression of class I HDACs (1, 2 and 3) in prostate cancer cells. MHY219 effectively increased the sub-G1 fraction of cells through p21 and p27 dependent pathways in DU145 cells. MHY219 significantly induced a G2/M phase arrest in DU145 and PC3 cells and arrested the cell cycle at G0/G1 phase in LNCaP cells. Furthermore, MHY219 effectively increased apoptosis in DU145 and LNCaP cells, but not PC3 cells, according to Annexin V/PI staining and Western blot analysis. These results indicate that MHY219 is a potent HDAC inhibitor that targets regulating multiple aspects of cancer cell death and might have preclinical value in human prostate cancer chemotherapy, warranting further investigation.