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Rhabdomyosarcoma (RMS) is the most common childhood soft tissue sarcoma. For the alveolar subtype (ARMS), the presence of the PAX3::FOXO1 fusion gene and/or metastases are strong predictors of poor outcome. Metastatic PAX3::FOXO1+ ARMS often responds to chemotherapies initially, only to subsequently relapse and become resistant with most patients failing to survive beyond 8 years post-diagnosis. No curative intent phase II or phase III clinical trial has been available for patients in the past 10 years (ARST0921). Thus, metastatic ARMS represents a significantly unmet clinical need. Chemotherapy resistance in ARMS has previously been attributed to PAX3::FOXO1-mediated cell cycle checkpoint adaptation, which is mediated by an HDAC3-SMARCA4-miR-27a-PAX3::FOXO1 circuit that can be disrupted by HDAC3 inhibition. In this study, we investigated the therapeutic efficacy of combining the epigenetic regulator entinostat, a Class I Histone Deacetylase (HDAC1-3) inhibitor, with RMS-specific chemotherapies in patient derived xenograft (PDX) models of RMS. We identified single agent, additive or synergistic relationships between relapse-specific chemotherapies and clinically relevant drug exposures of entinostat in three PAX3::FOXO1+ ARMS mouse models. This preclinical data provides further rationale for clinical investigation of entinostat, already known to be well tolerated in a pediatric phase I clinical trial (ADVL1513).

Background: Despite initial success with FLT3 inhibitors (FLT3is), outcomes for FLT3-ITD acute myeloid leukemia (AML) patients remain unsatisfactory, underscoring the need for more effective treatment options. Epigenetic modifications, such as histone acetylation, contribute to AML's onset and persistence, advocating the potential for epigenetic therapies. However, the poor specificity of pan-histone deacetylase inhibitors (HDACis) leads to undesirable adverse effects, prompting the need for isoform-specific HDACis. This study aims to explore the antileukemic activities and mechanisms of IHCH9033, a novel class I HDACi, alone or combined with FLT3i in FLT3-ITD AML. Methods: The viability of AML cell lines and primary AML cells treated with HDACis alone or in combination with FLT3i was detected by MTT or CCK8 assay. Flow cytometry was utilized to examine cell apoptosis, cell cycle progression and ROS production. RNA sequencing analysis, RT-qPCR, western blotting, and co-immunoprecipitation assays were employed to elucidate the molecule mechanisms. The in vivo anti-leukemia efficacy was tested in xenografted mice models derived from FLT3-ITD cell lines and primary AML patients. Results: Here, we identified IHCH9033, a novel selective class I HDACi, which exhibited an increased antitumor effect in FLT3-ITD AML through effectively eliminating leukemia burden and overcoming resistance to FLT3i. Mechanically, IHCH9033 selectively inhibited DNA repair in FLT3-ITD AML cells, leading to the accumulation of DNA damage that eventually resulted in cell cycle arrest and apoptosis. Additionally, IHCH9033 induced HSP90 acetylation, FLT3 ubiquitination, and proteasomal degradation of FLT3, thereby inhibiting FLT3 downstream signaling. Notably, IHCH9033 maintained its potency in both FLT3i-resistant AML cell lines and primary-resistant patient samples, and exerted strong synergy with the FLT3i quizartinib, leading to tumor regression in FLT3-ITD/TKD AML xenografts. In patient-derived xenografts, the treatment with IHCH9033, both alone and in combination, led to nearly complete eradication of the AML burden, without significant adverse effects. Conclusions: Our study shows that IHCH9033, a novel class I HDACi with a desirable pharmacological profile, is a promising drug candidate for FLT3-ITD AML, and suggests a strategy of combining class I HDACis and FLT3is in AML clinical trials to increase efficacy and overcome resistance, thus potentially providing a curative treatment option. [ABSTRACT FROM AUTHOR]

Recently, the curcumin derivative CU17 possessing HDAC inhibitory activity has been shown to synergistically enhance the anti-proliferative activity of Gem against lung cancer cells. Nevertheless, the mechanism(s) underlying the synergistic anti-cancer effect remains to be investigated. This study aimed to investigate the mechanisms that underpin the anti-cancer activity of the combined Gem and CU17 against NSCLC A549 cells both in vitro and in mouse xenograft models. CU17 was successfully synthesized and subsequently investigated for its combination effects with Gem on inductions of cell cycle arrest and apoptosis in A549 cells. The combination treatment substantially decreased cell survival through S phase prolongation and G2/M phase cell cycle arrest via up-regulating the expressions of p21 and p53 proteins. Additionally, CU17 potentiated the apoptotic effect of Gem in A549 cells by increasing the Bax/Bcl-2 ratio. The co-treatment resulted in an up-regulation of pERK1/2 and Ac-H3 expression. An in vivo study demonstrated that CU17 significantly improved the anti-cancer effect of Gem in nude mice utilizing A549 cell xenografts. The hematoxylin and eosin (H&E) staining results indicated that CU17 decreased the toxicity of Gem to the liver, kidneys, and spleen. Overall, CU17 enhanced the effectiveness of Gem while decreasing its toxicity. This compound shows promise as a chemosensitizer for NSCLC treatment with Gem. [ABSTRACT FROM AUTHOR]

The human genome is like a museum of ancient retroviral infections. It contains a large number of endogenous retroviruses (ERVs) that bear witness to past integration events. About 5,000 of them are so-called long terminal repeat 12 (LTR12) elements. Compared with 20,000 human genes, this is a remarkable number. Although LTR12 elements can act as promoters or enhancers of cellular genes, the function of most of these retroviral elements has remained unclear. In our mini-review, we show that different LTR12 elements share many similarities, including common transcription factor binding sites. Furthermore, we summarize novel insights into the epigenetic mechanisms governing their silencing and activation. Specific examples of genes and pathways that are regulated by LTR12 loci are used to illustrate the regulatory network built by these repetitive elements. A particular focus is on their role in the regulation of antiviral immune responses, tumor cell proliferation, and senescence. Finally, we describe how a targeted activation of this fascinating ERV family could be used for diagnostic or therapeutic purposes. [ABSTRACT FROM AUTHOR]

Abstract Background Targeting oncogenic histone modification by histone deacetylase inhibitors (HDACis) demonstrates promising prospects in clinical cancer treatment, whereas a notable proportion of patients cannot benefit from HDACi therapy. This study aims to explore how HDACi influences the tumor microenvironment, in order to identify potential targets for reversing the resistance to HDACi therapies. Methods Macrophage infiltration was compared between HDACi-responding and HDACi-nonresponding cancer patients. The impact of HDACis on the phagocytic capacity of macrophages was investigated through macrophage-tumor cell co-culture system. CD47 expression in tumor cell lines and patient-derived organoids was evaluated by quantitative polymerase chain reaction (QPCR) and flow cytometry. Mechanistic studies were conducted through co-immunoprecipitation (co-IP) and chromatin immunoprecipitation (ChIP). The synergistic effect of HDACis and CD47 neutralizing antibody was assessed in subcutaneous murine tumor models. Bioinformatics approaches were adopted to analyze how macrophage infiltration determines the prognostic significance of CD47 expression in cancer patients. Results High macrophage infiltration is a determinant of therapeutic non-response to HDACi, cancer patients who did not respond to HDACi exhibit massive infiltration of tumor-associated macrophages (TAMs). TAM depletion reversed the resistance to HDACi therapy. Mechanistically, HDACi impaired the phagocytic capacity of macrophages against tumor cells through epigenetically upregulating CD47 expression. Reciprocally, HDACi-upregulated CD47 polarized macrophages towards a pro-tumor M2 phenotype through SIRPα ligation. In tumor-bearing mice, HDACi monotherapy only marginally delayed tumor progression, while the concurrent neutralization of CD47 exhibited potent anti-tumor effect through re-educating TAMs towards a tumoricidal phenotype. In cancer patients, CD47 was found to determine the prognostic significance of TAMs. Conclusions Our study offers a rationale for targeting macrophage infiltration or blocking CD47 to sensitize HDACi therapies in cancer patients.

Abstract Leukemia remains a major therapeutic challenge in clinical oncology. Despite significant advancements in treatment modalities, leukemia remains a significant cause of morbidity and mortality worldwide, as the current conventional therapies are accompanied by life-limiting adverse effects and a high risk of disease relapse. Histone deacetylase inhibitors have emerged as a promising group of antineoplastic agents due to their ability to modulate gene expression epigenetically. In this review, we explore these agents, their mechanisms of action, pharmacokinetics, safety and clinical efficacy, monotherapy and combination therapy strategies, and clinical challenges associated with histone deacetylase inhibitors in leukemia treatment, along with the latest evidence and ongoing studies in the field. In addition, we discuss future directions to optimize the therapeutic potential of these agents.

Purpose: Gastrointestinal (GI) injury is one of the serious problems of total-body irradiation (TBI). However, no fundamental treatment for TBI and other radiation-induced GI injury has yet been established. Valproic acid (VPA) administration reduces mortality in mice subjected to total-body irradiation (TBI) with X-rays. This study aimed to evaluate the effects of VPA on GI injury induced by TBI in mice. Materials and methods: Mice were subjected to TBI with X-rays to induce GI injury. Changes in survival and weight were observed after VPA administration. The small intestine was then sampled at 0, 1, 3, 7, and 10 d after irradiation for histological and immunohistological evaluation and measurement of myeloperoxidase (MPO) activity and inflammatory cytokine levels (IL-1β). Results: VPA (200 and 600 mg/kg) increased survival rate and reduced weight loss in model mice. IL-1β expression 1 d after irradiation was significantly lower in the VPA group than that in the vehicle group. Furthermore, the increase in MPO activity at 3 and 7 d after irradiation was significantly suppressed by VPA administration. Histological examination (hematoxylin and eosin staining) revealed that 600 mg/kg VPA inhibited inflammatory cell infiltration. Immunostaining for the proliferating cell nuclear antigen involved in cell proliferation showed that VPA suppressed the irradiation-induced decrease in cell proliferative capacity. Conclusions: Treatment with VPA in mice with GI injury caused by TBI suppressed inflammatory responses in small intestinal mucosal cells. These results suggest that VPA may be a useful therapeutic agent against TBI-induced small intestinal mucositis. [ABSTRACT FROM AUTHOR]

Enhancement of neuronal plasticity by small-molecule therapeutics protects cognitive skills and also ameliorates progressive neurodegenerative pathologies like Alzheimer's disease (AD) and dementia. One such compound, a novel histone deacetylase 2 (HDAC2) inhibitor named JRM-28, was shown here to enhance dendritic strength, augment spine density, and upregulate post-synaptic neurotransmission in hippocampal neurons. The molecular basis for this effect correlates with JRM-28-induced upregulation of the transcription of cAMP response element-binding protein(CREB), induction of its transcriptional activity, and subsequent stimulation of expressions of CREB-dependent plasticity-associated genes, such as those encoding N-methyl-D-aspartate (NMDA) receptor subunit NR2A and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluR1. Specifically, JRM-28 stimulated the NMDA- and AMPA-receptor-sensitive ionotropic calcium influx in hippocampal neurons. Interestingly, JRM-28 did not induce NMDA- and AMPA-sensitive calcium influx in hippocampal neurons once the expression of CREB was knocked down by creb siRNA, suggesting the critical role of CREB in JRM-28-mediated upregulation of synaptic plasticity. Finally, JRM-28 upregulated CREB mRNA, CREB-dependent plasticity-associated markers, and ionotropic calcium influx in iPSC-derived AD human neurons, indicating its therapeutic implications in the amelioration of AD pathologies. [ABSTRACT FROM AUTHOR]

Tucidinostat has been approved by the Chinese FDA for relapsed/refractory Peripheral T cell lymphoma (PTCL), but its efficacy in newly diagnosed PTCL has not been confirmed. In this study, we aimed to compare the efficacy of tucidinostat combined with CHOP-like (C + CHT) versus CHOP-like alone (CHT) in newly diagnosed PTCL patients. Of the PTCL patients, 109 were newly diagnosed. Patients in the C + CHT group who achieved objective response received tucidinostat maintenance therapy. A total of 36 pairs (n = 72) were matched at a ratio of 1:1 using propensity scoring. The matching criteria included: whether the Prognostic index for the peripheral T-cell lymphoma-not otherwise specified subtype (PIT) was ≥ 2, the pathological subtype, age > 60 years, and gender (matching tolerance = 0.024). A significantly higher objective response rate (ORR) (P = 0.016), 2-year progression-free survival (PFS) (P = 0.026), and 2-year survival rate (P = 0.017) was observed for the C + CHT group as compared to the CHT group. After propensity score matching (PSM), the C + CHT group as compared to the CHT group displayed significantly longer PFS (P = 0.035) and overall survival (OS) (P = 0.029). For the C + CHT group in the per-protocol set, the effect values showed a significant benefit in terms of both PFS (P = 0.027) and OS (P = 0.019). Common grade 3–4 haematological adverse events (AEs), had comparable incidence in each group; while common non-haematological AEs, including elevated AST and ALT were higher in the C + CHT group than in the CHT group. Our study suggests that the tucidinostat with CHOP-like regimen and sequential tucidinostat maintenance after objective remission provides a promising therapeutic approach for treating newly diagnosed PTCL patients. [ABSTRACT FROM AUTHOR]

Summary: Ovarian cancer is the fifth leading cause of cancer related death in the United States. Cisplatin is a platinum-based anti-cancer drug used against ovarian cancer that enters malignant cells and then damages DNA causing cell death. Typically, ovarian cancer cells become resistant to cisplatin making it necessary to increase subsequent dosage, which usually leads to side-effects including irreversible damage to kidney and auditory system tissue. Ovarian cancer resistance is often associated with upregulation of histone deacetylase (HDAC) enzymes that cause DNA to adopt a closed configuration which reduces the ability of cisplatin to target and damage DNA. Compound B, a platinum(IV) complex with two axial phenylbutyrate (PBA) HDAC inhibitor ligands attached to a cisplatin core, can simultaneously inhibit HDAC activity and damage DNA causing decreased cancer cell viability in cisplatin-sensitive (A2780) and -resistant (A2780cis) ovarian cancer cell lines. However, compound B was not previously evaluated in vivo. As simultaneously inhibiting HDAC-mediated resistance with cisplatin treatment could potentiate the platinum drug's effect, we first confirmed the anti-cancer effect of compound B in the A2780 and A2780cis cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide spectrophotometric assay. Then, we used zebrafish embryo and transgenic animal models to comparatively analyze the effect of cisplatin, compound B, and controls on general organismal, auditory, and renal system toxicity, and cancer metastasis. We found that lower dosages of compound B (0.3 or 0.6 µM) than of cisplatin (2.0 µM) could cause similar or decreased levels of general, auditory, and renal tissue toxicity, and at 0.6 µM, compound B reduces cancer metastasis more than 2.0 µM cisplatin. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancer (TNBC) presents a significant challenge for treatment due to its aggressive nature and the lack of effective therapies. This study developed dual inhibitors against cell division cycle 25 (CDC25) and histone deacetylases (HDACs) for TNBC treatment. CDC25 phosphatases are crucial for activating cyclin-dependent kinases (CDKs), the master regulators of cell cycle progression. HDACs regulate various biological processes by deacetylating histone and non-histone proteins, affecting gene expression, chromatin structure, cell differentiation, and proliferation. Dysregulations of HDAC and CDC25 are associated with several human malignancies. We generated a group of dual inhibitors for CDC25 and HDAC by combining the molecular structures of CDC25 (quinoline-5,8-dione) and HDAC (hydroxamic acid or benzamide) pharmacophores. The newly developed compounds were evaluated against various solid-tumor, leukemia, and non-malignant breast epithelial cells. Among the synthesized compounds, 18A emerged as a potent inhibitor, demonstrating significant cytotoxicity against TNBC cells, superior to its effects on other cancer types while sparing non-malignant cells. 18A possessed similar HDAC inhibitory activity as MS-275 and potently suppressed CDC25 activity in vitro and the CDK1 dephosphorylation in cells. Additionally, 18A hindered the progression of S and G2/M phases, triggered DNA damage, and induced apoptosis. These findings underscore the potential of 18A as a targeted therapy for TNBC and warrants further preclinical development. [ABSTRACT FROM AUTHOR]

Leukemia remains a major therapeutic challenge in clinical oncology. Despite significant advancements in treatment modalities, leukemia remains a significant cause of morbidity and mortality worldwide, as the current conventional therapies are accompanied by life-limiting adverse effects and a high risk of disease relapse. Histone deacetylase inhibitors have emerged as a promising group of antineoplastic agents due to their ability to modulate gene expression epigenetically. In this review, we explore these agents, their mechanisms of action, pharmacokinetics, safety and clinical efficacy, monotherapy and combination therapy strategies, and clinical challenges associated with histone deacetylase inhibitors in leukemia treatment, along with the latest evidence and ongoing studies in the field. In addition, we discuss future directions to optimize the therapeutic potential of these agents. [ABSTRACT FROM AUTHOR]

Diffuse intrinsic pontine glioma (DIPG) remains a significant therapeutic challenge due to the lack of effective and safe treatment options. This study explores the potential of combining histone deacetylase (HDAC) and carbonic anhydrase 9 (CA9) inhibitors in treating DIPG. Analysis of RNA sequencing data and tumor tissue from patient samples for the expression of the carbonic anhydrase family and hypoxia signaling pathway activity revealed clinical relevance for targeting CA9 in DIPG. A synergy screen was conducted using CA9 inhibitor SLC-0111 and HDAC inhibitors panobinostat, vorinostat, entinostat, and pyroxamide. The combination of SLC-0111 and pyroxamide demonstrated the highest synergy and was selected for further analysis. Combining SLC-0111 and pyroxamide effectively inhibited DIPG cell proliferation, reduced cell migration and invasion potential, and enhanced histone acetylation, leading to decreased cell population in S Phase. Additionally, the combination therapy induced a greater reduction in intracellular pH than either agent alone. Data from this study suggest that the combination of SLC-0111 and pyroxamide holds promise for treating experimental DIPG, and further investigation of this combination therapy in preclinical models is warranted to evaluate its potential as a viable treatment for DIPG. [ABSTRACT FROM AUTHOR]

Abstract Rhabdomyosarcoma (RMS) is the most common childhood soft tissue sarcoma. For the alveolar subtype (ARMS), the presence of the PAX3::FOXO1 fusion gene and/or metastases are strong predictors of poor outcome. Metastatic PAX3::FOXO1 + ARMS often responds to chemotherapies initially, only to subsequently relapse and become resistant with most patients failing to survive beyond 8 years post-diagnosis. No curative intent phase II or phase III clinical trial has been available for patients in the past 10 years (ARST0921). Thus, metastatic ARMS represents a significantly unmet clinical need. Chemotherapy resistance in ARMS has previously been attributed to PAX3::FOXO1-mediated cell cycle checkpoint adaptation, which is mediated by an HDAC3-SMARCA4-miR-27a-PAX3::FOXO1 circuit that can be disrupted by HDAC3 inhibition. In this study, we investigated the therapeutic efficacy of combining the epigenetic regulator entinostat, a Class I Histone Deacetylase (HDAC1-3) inhibitor, with RMS-specific chemotherapies in patient derived xenograft (PDX) models of RMS. We identified single agent, additive or synergistic relationships between relapse-specific chemotherapies and clinically relevant drug exposures of entinostat in three PAX3::FOXO1 + ARMS mouse models. This preclinical data provides further rationale for clinical investigation of entinostat, already known to be well tolerated in a pediatric phase I clinical trial (ADVL1513).

Histone deacetylase (HDAC) inhibitors promote differentiation through post-translational modifications of histones. BML-281, an HDAC6 inhibitor, has been known to prevent tumors, acute dextran sodium sulfate-associated colitis, and lung injury. However, the neurogenic differentiation effect of BML-281 is poorly understood. In this study, we investigated the effect of BML-281 on neuroblastoma SH-SY5Y cell differentiation into mature neurons by immunocytochemistry (ICC), reverse transcriptase PCR (RT-PCR), quantitative PCR (qPCR), and western blotting analysis. We found that the cells treated with BML-281 showed neurite outgrowth and morphological changes into mature neurons under a microscope. It was confirmed that the gene expression of neuronal markers (NEFL, MAP2, Tuj1, NEFH, and NEFM) was increased with certain concentrations of BML-281. Similarly, the protein expression of neuronal markers (NeuN, Synaptophysin, Tuj1, and NFH) was upregulated with BML-281 compared to untreated cells. Following treatment with BML-281, the expression of Wnt5α increased, and downstream pathways were activated. Interestingly, both Wnt/Ca2+ and Wnt/PCP pathways activated and regulated PKC, Cdc42, RhoA, Rac1/2/3, and p-JNK. Therefore, BML-281 induces the differentiation of SH-SY5Y cells into mature neurons by activating the non-canonical Wnt signaling pathway. From these results, we concluded that BML-281 might be a novel drug to differentiation into neuronal cells through the regulation of Wnt signaling pathway to reduce the neuronal cell death. Headings: BML-281 promotes neuronal differentiation. BML-281 modulates Wnt/Ca2+ and Wnt/PCP pathway. Non-canonical Wnt pathway regulates the cell differentiation. [ABSTRACT FROM AUTHOR]

Cancer, a chronic disease characterized by uncontrolled cell development, kills millions of people globally. The WHO reported over 10 million cancer deaths in 2020. Anticancer medications destroy healthy and malignant cells. Cancer treatment induces neuropathy. Anticancer drugs cause harm to spinal cord, brain, and peripheral nerve somatosensory neurons, causing chemotherapy-induced neuropathic pain. The chemotherapy-induced mechanisms underlying neuropathic pain are not fully understood. However, neuroinflammation has been identified as one of the various pathways associated with the onset of chemotherapy-induced neuropathic pain. The neuroinflammatory processes may exhibit varying characteristics based on the specific type of anticancer treatment delivered. Neuroinflammatory characteristics have been observed in the spinal cord, where microglia and astrocytes have a significant impact on the development of chemotherapy-induced peripheral neuropathy. The patient's quality of life might be affected by sensory deprivation, loss of consciousness, paralysis, and severe disability. High cancer rates and ineffective treatments are associated with this disease. Recently, histone deacetylases have become a novel treatment target for chemotherapy-induced neuropathic pain. Chemotherapy-induced neuropathic pain may be treated with histone deacetylase inhibitors. Histone deacetylase inhibitors may be a promising therapeutic treatment for chemotherapy-induced neuropathic pain. Common chemotherapeutic drugs, mechanisms, therapeutic treatments for neuropathic pain, and histone deacetylase and its inhibitors in chemotherapy-induced neuropathic pain are covered in this paper. We propose that histone deacetylase inhibitors may treat several aspects of chemotherapy-induced neuropathic pain, and identifying these inhibitors as potentially unique treatments is crucial to the development of various chemotherapeutic combination treatments. [ABSTRACT FROM AUTHOR]

Chidamide (CS055/HBI-8000, tucidinostat) has shown promising effects in the clinical treatment of various hematologic tumors. Diffuse large B-cell lymphoma (DLBCL) has shown highly heterogeneous biological characteristics. There are complex mechanisms of the role of chidamide in DLBCL for in-depth study. It is essential to probe further into the mechanism of drug-tumor interactions as a guide to clinical application and to understand the occurrence and progression of DLBCL. In vitro and in vivo models were utilized to determine the effects of chidamide on signaling pathways involved in the DLBCL tumor microenvironment. The experimental results show that chidamide inhibited the proliferation of DLBCL cell lines in a dose- and time-dependent manner, and down-regulated the expression of NOTCH1 and NFATC1 in DLBCL cells as well as decreased the concentration of IL-10 in the supernatant. In addition, chidamide significantly lowered the expression of PD1 or TIM3 on CD4+T cells and CD8+T cells and elevated the levels of IL-2, IFN-γ, and TNF-α in the serum of animal models, which augmented the function of circulating T cells and tumor-infiltrating T cells and ultimately significantly repressed the growth of tumors. These findings prove that chidamide can effectively inhibit the cell activity of DLBCL cell lines by inhibiting the activation of NOTCH1 and NFATC1 signaling pathways. It can also improve the abnormal DLBCL microenvironment in which immune escape occurs, and inhibit immune escape. This study provides a new therapeutic idea for the exploration of individualized precision therapy for patients with malignant lymphoma. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Belinostat therapy followed by hematopoietic stem cell transplantation is a promising salvage strategy for heavily pretreated patients with peripheral T‐cell lymphoma. Effective treatments for peripheral T‐cell lymphoma in the relapsed and refractory (r/r) setting are limited. However, with the development and approval of innovative therapies, effective therapeutic options are becoming available for this patient population. This case report describes the treatment course of a patient with multiple r/r nodal follicular T‐helper cell lymphoma of angioimmunoblastic type. Treatment with the histone deacetylase inhibitor belinostat as bridging, enabled allogeneic stem cell transplantation and resulted in a durable complete hematologic response for at least 21 months post‐transplantation. [ABSTRACT FROM AUTHOR]

Epigenetic editing is thriving as a robust tool for manipulating transcriptional regulation and cell fate. Despite its regulatory role in gene downregulation, epigenetic editing with histone deacetylation has been sparsely studied, especially in the context of cancer. In this current study, we have reconstructed a dCas9-HDAC8-EGFP fusion to perform histone deacetylation on the promoter of the ESR1, TERT and CDKN1C genes for the first time in breast cancer cell lines MCF-7 and MDA-MB-231 as well as in HEK293T cells. Our results demonstrated that dCas9-HDAC8-EGFP in combination with appropriate gRNAs were able to downregulate the expression of the ESR1, TERT and CDKN1C genes transcriptionally by specifically depleting the H3K9ac level on the recruitment loci. The addition of histone deacetylase inhibitors was found to neutralize the outcomes of dCas9-HDAC8-EGFP-induced epigenetic editing. Furthermore, we observed a significant downregulation of full length ERα expression in epigenetically edited MCF-7 cells with consequential alteration in cellular response toward estradiol and tamoxifen treatment due to dCas9-HDAC8-EGFP mediated epigenetic editing of the ESR1 gene. Overall, dCas9-HDAC8-EGFP is a novel circuit that enabled downregulation of crucial genes with cellular outcome in breast cancer cells by preferentially inducing H3K9 deacetylation of specific promoter regions.

Abstract Background Mammalian or mechanistic target of rapamycin complex 1 (mTORC1) is an effective therapeutic target for diseases such as cancer, diabetes, aging, and neurodegeneration. However, an efficient tool for monitoring mTORC1 inhibition in living cells or tissues is lacking. Results We developed a genetically encoded mTORC1 sensor called TORSEL. This sensor changes its fluorescence pattern from diffuse to punctate when 4EBP1 dephosphorylation occurs and interacts with eIF4E. TORSEL can specifically sense the physiological, pharmacological, and genetic inhibition of mTORC1 signaling in living cells and tissues. Importantly, TORSEL is a valuable tool for imaging-based visual screening of mTORC1 inhibitors. Using TORSEL, we identified histone deacetylase inhibitors that selectively block nutrient-sensing signaling to inhibit mTORC1. Conclusions TORSEL is a unique living cell sensor that efficiently detects the inhibition of mTORC1 activity, and histone deacetylase inhibitors such as panobinostat target mTORC1 signaling through amino acid sensing.

Lianru Zhang,1,2,* Jie Xiao,1,2,* Yishan Li,1,2,* Baorui Liu,1,2 Li Xie1,2 1The Comprehensive Cancer Center of Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, People’s Republic of China; 2Clinical Cancer Institute of Nanjing University, Nanjing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Li Xie; Baorui Liu, The Comprehensive Cancer Center of Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, 210008, People’s Republic of China, Email xieli@njglyy.com; baoruiliu@nju.edu.cnPurpose: As one of the most important breakthroughs in cancer therapy, immune checkpoint inhibitors have greatly prolonged survival of patients with breast cancer. However, their application and efficacy are limited, especially for advanced HER2-negative breast cancer. It has been reported that epigenetic modulation of the histone deacetylase (HDAC) inhibitor chidamide, as well as immune microenvironment modulation of radiotherapy are potentially synergistic with immunotherapy. Thus, the combination of chidamide, radiotherapy and immunotherapy is expected to improve prognosis of patients with advanced HER2-negative breast cancer.Patients and Methods: This is a single-arm, open, prospective clinical trial investigating the efficacy and safety of the combination of HDAC inhibitor chidamide, anti-PD-1 antibody sintilimab, and the novel immuno-radiotherapy, which aims to enhance efficacy of immunotherapy, in subsequent lines of therapy of HER2-negative breast cancer. Our study will include 35 patients with advanced breast cancer that has failed endocrine therapy and first-line chemotherapy. Participants will receive 30 mg of chidamide twice a week, 200 mg of sintilimab once every 3 weeks, combined with immuno-radiotherapy. Radiotherapy will be centrally 8 Gy for at least one lesion, and at least 1 Gy for the other lesions. We will complete three fractions of radiotherapy in one cycle. The primary endpoint is progression-free survival, and secondary endpoints are objective response rate, disease control rate and safety. Moreover, biomarkers including cytokines and lymphocyte subgroups will be explored.Conclusion: As a single-arm clinical trial, the analysis of the influence of each single treatment is limited. Besides, our study is an open study, which involves neither randomization nor blinding. In spite of the abovementioned limitations, this prospective clinical trial will give an insight into subsequent lines of therapy of HER2-negative advanced breast cancer, prolong the survival or achieve long remission for these participants, and identify potential responders.Keywords: HDAC inhibitor, sintilimab, radiation, HER2-negative breast cancer

Background: Mammalian or mechanistic target of rapamycin complex 1 (mTORC1) is an effective therapeutic target for diseases such as cancer, diabetes, aging, and neurodegeneration. However, an efficient tool for monitoring mTORC1 inhibition in living cells or tissues is lacking. Results: We developed a genetically encoded mTORC1 sensor called TORSEL. This sensor changes its fluorescence pattern from diffuse to punctate when 4EBP1 dephosphorylation occurs and interacts with eIF4E. TORSEL can specifically sense the physiological, pharmacological, and genetic inhibition of mTORC1 signaling in living cells and tissues. Importantly, TORSEL is a valuable tool for imaging-based visual screening of mTORC1 inhibitors. Using TORSEL, we identified histone deacetylase inhibitors that selectively block nutrient-sensing signaling to inhibit mTORC1. Conclusions: TORSEL is a unique living cell sensor that efficiently detects the inhibition of mTORC1 activity, and histone deacetylase inhibitors such as panobinostat target mTORC1 signaling through amino acid sensing. [ABSTRACT FROM AUTHOR]

In recent years, histone deacetylase (HDAC) has become one of the hottest and most effective targets for the treatment of cancer. In this work, we designed and synthesized a series of novel o-aminobenzamide based HDAC inhibitors and evaluated their antitumor properties in vitro. All 23 compounds obtained showed micromolar IC50 values against A549 cells proliferation, and the most effective compound was 8 u (IC50 = 0.165 μM). In vitro, 8 u showed potent antiproliferative activity against another three cancer cell lines, outperforming the approved drug Chidamide. Enzyme inhibition and western blot assays confirmed that 8 u was a selective inhibitor of HDAC1-3 isoforms. 8 u was able to induce apoptosis of A549 cells and arrest the tumor cells in G2/M phase. Moreover, 8 u significantly mitigated the migration A549 cells. All these results suggest that 8 u deserves further biological studies. [ABSTRACT FROM AUTHOR]

Angioimmunoblastic T-cell lymphoma (AITL) is one of the sub-types of peripheral T-cell lymphomas (PTCLs) that are remarkably refractory and has the potential to have a poor prognosis. The treatment process includes a wide range of treatment modalities, from anthracycline-based regimens that have been used for years to novel agents, such as histone deacetylase inhibitor romidepsin and belinostat. Increased treatment response rates and prolonged survival have been reported in studies with belinostat. Similarly, in this case report, we wanted to share a patient of an advanced age and with a high IPI score, whom we had treated in many treatment lines and maintained a long‑term treatment response by administering belinostat. [ABSTRACT FROM AUTHOR]

Background: Synovial sarcoma (SS) is an SS18‐SSX fusion gene‐driven soft tissue sarcoma with mesenchymal characteristics, associated with a poor prognosis due to frequent metastasis to a distant organ, such as the lung. Histone deacetylase (HDAC) inhibitors (HDACis) are arising as potent molecular targeted drugs, as HDACi treatment disrupts the SS oncoprotein complex, which includes HDACs, in addition to general HDACi effects. To provide further molecular evidence for the advantages of HDACi treatment and its limitations due to drug resistance induced by the microenvironment in SS cells, we examined cellular responses to HDACi treatment in combination with two‐dimensional (2D) and 3D culture conditions. Methods: Using several SS cell lines, biochemical and cell biological assays were performed with romidepsin, an HDAC1/2 selective inhibitor. SN38 was concomitantly used as an ameliorant drug with romidepsin treatment. Cytostasis, apoptosis induction, and MHC class I polypeptide‐related sequence A/B (MICA/B) induction were monitored to evaluate the drug efficacy. In addition to the conventional 2D culture condition, spheroid culture was adopted to evaluate the influence of cell‐mass microenvironment on chemoresistance. Results: By monitoring the cellular behavior with romidepsin and/or SN38 in SS cells, we observed that responsiveness is diverse in each cell line. In the apoptotic inducible cells, co‐treatment with SN38 enhanced cell death. In nonapoptotic inducible cells, cytostasis and MICA/B induction were observed, and SN38 improved MICA/B induction further. As a novel efficacy of SN38, we revealed TWIST1 suppression in SS cells. In the spheroid (3D) condition, romidepsin efficacy was severely restricted in TWIST1‐positive cells. We demonstrated that TWIST1 downregulation restored romidepsin efficacy even in spheroid form, and concomitant SN38 treatment along with romidepsin reproduced the reaction. Conclusions: The current study demonstrated the benefits and concerns of using HDACi for SS treatment in 2D and 3D culture conditions and provided molecular evidence that concomitant treatment with SN38 can overcome drug resistance to HDACi by suppressing TWIST1 expression. [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cells (hiPSCs) possess the potential to differentiate toward vascular cells including endothelial cells (ECs), pericytes, and smooth muscle cells. Epigenetic mechanisms including DNA methylation and histone modification play a crucial role in regulating lineage differentiation and specification. Herein, we utilized a three-stage protocol to induce differentiation of mesoderm, vascular progenitors, and ECs from hiPSCs and investigated the regulatory effects of histone acetylation on the differentiation processes. We found that the expression of several histone deacetylases (HDACs), including HDAC1, HDAC5, and HDAC7, were greatly upregulated at the second stage and downregulated at the third stage. Interestingly, although HDAC1 remained in the nucleus during the EC differentiation, HDAC5 and HDAC7 displayed cytosol/nuclear translocation during the differentiation process. Inhibition of HDACs with sodium butyrate (NaBt) or BML210 could hinder the differentiation of vascular progenitors at the second stage and facilitate EC induction at the third stage. Further investigation revealed that HDAC may modulate the stepwise EC differentiation via regulating the expression of endothelial transcription factors ERG, ETS1, and MEF2C. Opposite to the expression of EC markers, the smooth muscle/pericyte marker ACTA2 was upregulated at the second stage and downregulated at the third stage by NaBt. The stage-specific regulation of ACTA2 by HDAC inhibition was likely through regulating the expression of TGFβ2 and PDGFB. This study suggests that HDACs play different roles at different stages of EC induction by promoting the commitment of vascular progenitors and impeding the later stage differentiation of ECs.

Abstract Background Histone acetylation, which is regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), plays a crucial role in the control of gene expression. HDAC inhibitors (HDACi) have shown potential in cancer therapy; however, the specific roles of HDACs in early embryos remain unclear. Moreover, although some pan-HDACi have been used to maintain cellular undifferentiated states in early embryos, the specific mechanisms underlying their effects remain unknown. Thus, there remains a significant knowledge gap regarding the application of selective HDACi in early embryos. Results To address this gap, we treated early embryos with two selective HDACi (MGCD0103 and T247). Subsequently, we collected and analyzed their transcriptome data at different developmental stages. Our findings unveiled a significant effect of HDACi treatment during the crucial 2-cell stage of zygotes, leading to a delay in embryonic development after T247 and an arrest at 2-cell stage after MGCD0103 administration. Furthermore, we elucidated the regulatory targets underlying this arrested embryonic development, which pinpointed the G2/M phase as the potential period of embryonic development arrest caused by MGCD0103. Moreover, our investigation provided a comprehensive profile of the biological processes that are affected by HDACi, with their main effects being predominantly localized in four aspects of zygotic gene activation (ZGA): RNA splicing, cell cycle regulation, autophagy, and transcription factor regulation. By exploring the transcriptional regulation and epigenetic features of the genes affected by HDACi, we made inferences regarding the potential main pathways via which HDACs affect gene expression in early embryos. Notably, Hdac7 exhibited a distinct response, highlighting its potential as a key player in early embryonic development. Conclusions Our study conducted a comprehensive analysis of the effects of HDACi on early embryonic development at the transcriptional level. The results demonstrated that HDACi significantly affected ZGA in embryos, elucidated the distinct actions of various selective HDACi, and identified specific biological pathways and mechanisms via which these inhibitors modulated early embryonic development.

Divisions at the periphery and midzone of mitochondria are two fission signatures that determine the fate of mitochondria and cells. Pharmacological induction of excessively asymmetric mitofission-associated cell death (MFAD) by switching the scission position from the mitochondrial midzone to the periphery represents a promising strategy for anticancer therapy. By screening a series of pan-inhibitors, we identified pracinostat, a pan-histone deacetylase (HDAC) inhibitor, as a novel MFAD inducer, that exhibited a significant anticancer effect on colorectal cancer (CRC) in vivo and in vitro. Pracinostat increased the expression of cyclin-dependent kinase 5 (CDK5) and induced its acetylation at residue lysine 33, accelerating the formation of complex CDK5/CDK5 regulatory subunit 1 and dynamin-related protein 1 (Drp1)-mediated mitochondrial peripheral fission. CRC cells with high level of CDK5 (CDK5-high) displayed midzone mitochondrial division that was associated with oncogenic phenotype, but treatment with pracinostat led to a lethal increase in the already-elevated level of CDK5 in the CRC cells. Mechanistically, pracinostat switched the scission position from the mitochondrial midzone to the periphery by improving the binding of Drp1 from mitochondrial fission factor (MFF) to mitochondrial fission 1 protein (FIS1). Thus, our results revealed the anticancer mechanism of HDACi pracinostat in CRC via activating CDK5-Drp1 signaling to cause selective MFAD of those CDK5-high tumor cells, which implicates a new paradigm to develop potential therapeutic strategies for CRC treatment.

Abstract Background Prostate cancer (PCa) is the most common malignancy diagnosed in men. Immune checkpoint blockade (ICB) alone showed disappointing results in PCa. It is partly due to the formation of immunosuppressive tumor microenvironment (TME) could not be reversed effectively by ICB alone. Methods We used PCa cell lines to evaluate the combined effects of CN133 and anti-PD-1 in the subcutaneous and osseous PCa mice models, as well as the underlying mechanisms. Results We found that CN133 could reduce the infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and CN133 combination with anti-PD-1 could augment antitumor effects in the subcutaneous PCa of allograft models. However, anti-PD-1 combination with CN133 failed to elicit an anti-tumor response to the bone metastatic PCa mice. Mechanistically, CN133 could inhibit the infiltration of PMN-MDSCs in the TME of soft tissues by downregulation gene expression of PMN-MDSC recruitment but not change the gene expression involved in PMN-MDSC activation in the CN133 and anti-PD-1 co-treatment group relative to the anti-PD-1 alone in the bone metastatic mice model. Conclusions Taken together, our work firstly demonstrated that combination of CN133 with anti-PD-1 therapy may increase the therapeutic efficacy to PCa by reactivation of the positive immune microenvironment in the TME of soft tissue PCa.

The robust integrity of the retinal pigment epithelium (RPE), which contributes to the outer brain retina barrier (oBRB), is compromised in several retinal degenerative and vascular disorders, including diabetic macular edema (DME). This study evaluates the role of a new generation of histone deacetylase inhibitor (HDACi), ITF2357, in regulating outer blood-retinal barrier function and investigates the underlying mechanism of action in inhibiting TNFα-induced damage to RPE integrity. Using the immortalized RPE cell line (ARPE-19), ITF2357 was found to be non-toxic between 50 nM and 5 μM concentrations. When applied as a pre-treatment in conjunction with an inflammatory cytokine, TNFα, the HDACi was safe and effective in preventing epithelial permeability by fortifying tight junction (ZO-1, -2, -3, occludin, claudin-1, -2, -3, -5, -19) and adherens junction (E-cadherin, Nectin-1) protein expression post-TNFα stress. Mechanistically, ITF2357 depicted a late action at 24 h via attenuating IKK, IκBα, and p65 phosphorylation and ameliorated the expression of IL-1β, IL-6, and MCP-1. Also, ITF2357 delayed IκBα synthesis and turnover. The use of Bay 11-7082 and MG132 further uncovered a possible role for ITF2357 in non-canonical NF-κB activation. Overall, this study revealed the protection effects of ITF2357 by regulating the turnover of tight and adherens junction proteins and modulating NF-κB signaling pathway in the presence of an inflammatory stressor, making it a potential therapeutic application for retinal vascular diseases such as DME with compromised outer blood-retinal barrier. [ABSTRACT FROM AUTHOR]

Histone deacetylase inhibitors (iHDACs) have been extensively studied as enhancers of therapeutic protein production in recombinant Chinese hamster ovary (CHO) (rCHO) cell cultures. However, the addition of iHDACs reduces the viable cell concentration (VCC) in rCHO cell cultures, thereby reducing their potential to enhance therapeutic protein production. To mitigate the negative effects of iHDACs on VCC, screening using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR‐associated protein 9 (Cas9)‐based single‐gene knockout (KO) library in rCHO cells was performed in the presence of CI994, a member of iHDACs, and 10 potential KO genes that enhanced the VCC of CI994‐treated rCHO cells were identified. Among these, Bcor was validated as a promising KO target that improved VCC without negatively affecting the specific productivity in the presence of CI994. Bcor KO increased the VCC and therapeutic protein concentrations in both batch and fed‐batch cultures in the presence of CI994. Taken together, these findings highlight the potential of the whole‐genome CRISPR/Cas9‐based single‐gene KO cell library to identify KO target genes for the development of iHDAC‐resistant rCHO cells for enhanced therapeutic protein production. [ABSTRACT FROM AUTHOR]

Background: Histone acetylation, which is regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), plays a crucial role in the control of gene expression. HDAC inhibitors (HDACi) have shown potential in cancer therapy; however, the specific roles of HDACs in early embryos remain unclear. Moreover, although some pan-HDACi have been used to maintain cellular undifferentiated states in early embryos, the specific mechanisms underlying their effects remain unknown. Thus, there remains a significant knowledge gap regarding the application of selective HDACi in early embryos. Results: To address this gap, we treated early embryos with two selective HDACi (MGCD0103 and T247). Subsequently, we collected and analyzed their transcriptome data at different developmental stages. Our findings unveiled a significant effect of HDACi treatment during the crucial 2-cell stage of zygotes, leading to a delay in embryonic development after T247 and an arrest at 2-cell stage after MGCD0103 administration. Furthermore, we elucidated the regulatory targets underlying this arrested embryonic development, which pinpointed the G2/M phase as the potential period of embryonic development arrest caused by MGCD0103. Moreover, our investigation provided a comprehensive profile of the biological processes that are affected by HDACi, with their main effects being predominantly localized in four aspects of zygotic gene activation (ZGA): RNA splicing, cell cycle regulation, autophagy, and transcription factor regulation. By exploring the transcriptional regulation and epigenetic features of the genes affected by HDACi, we made inferences regarding the potential main pathways via which HDACs affect gene expression in early embryos. Notably, Hdac7 exhibited a distinct response, highlighting its potential as a key player in early embryonic development. Conclusions: Our study conducted a comprehensive analysis of the effects of HDACi on early embryonic development at the transcriptional level. The results demonstrated that HDACi significantly affected ZGA in embryos, elucidated the distinct actions of various selective HDACi, and identified specific biological pathways and mechanisms via which these inhibitors modulated early embryonic development. [ABSTRACT FROM AUTHOR]

Tight junction (TJ) protein cingulin (CGN) and transcription factor forkhead box protein O1 (FOXO1) contribute to the development of various cancers. Histone deacetylase (HDAC) inhibitors have a potential therapeutic role for some cancers. HDAC inhibitors affect the expression of both CGN and FOXO1. However, the roles and regulatory mechanisms of CGN and FOXO1 are unknown in non-small cell lung cancer (NSCLC) and normal human lung epithelial (HLE) cells. In the present study, to investigate the effects of CGN and FOXO1 on the malignancy of NSCLC, we used A549 cells as human lung adenocarcinoma and primary human lung epithelial (HLE) cells as normal lung tissues and performed the knockdown of CGN and FOXO1 by siRNAs. Furthermore, to investigate the detailed mechanisms in the antitumor effects of HDAC inhibitors for NSCLC via CGN and FOXO1, A549 cells and HLE cells were treated with the HDAC inhibitors trichostatin A (TSA) and Quisinostat (JNJ-2648158). In A549 cells, the knockdown of CGN increased bicellular TJ protein claudin-2 (CLDN-2) via mitogen-activated protein kinase/adenosine monophosphate-activated protein kinase (MAPK/AMPK) pathways and induced cell migration, while the knockdown of FOXO1 increased claudin-4 (CLDN-4), decreased CGN, and induced cell proliferation. The knockdown of CGN and FOXO1 induced cell metabolism in A549 cells. TSA and Quisinostat increased CGN and tricellular TJ protein angulin-1/lipolysis-stimulated lipoprotein receptor (LSR) in A549. In normal HLE cells, the knockdown of CGN and FOXO1 increased CLDN-4, while HDAC inhibitors increased CGN and CLDN-4. In conclusion, the knockdown of CGN via FOXO1 contributes to the malignancy of NSCLC. Both HDAC inhibitors, TSA and Quisinostat, may have potential for use in therapy for lung adenocarcinoma via changes in the expression of CGN and FOXO1. [ABSTRACT FROM AUTHOR]

Oncolytic viruses have two anticancer functions: direct oncolysis and elicitation of antitumor immunity. We previously developed a novel fusogenic oncolytic vaccinia virus (FUVAC) from a non‐fusogenic vaccinia virus (VV) and, by remodeling the tumor immune microenvironment, we demonstrated that FUVAC induced stronger oncolysis and antitumor immune responses compared with non‐fusogenic VV. These functions depend strongly on cell–cell fusion induction. However, FUVAC tends to have decreased fusion activity in cells with low virus replication efficacy. Therefore, another combination strategy was required to increase cell–cell fusion in these cells. Histone deacetylase (HDAC) inhibitors suppress the host virus defense response and promote viral replication. Therefore, in this study, we selected an HDAC inhibitor, trichostatin A (TSA), as the combination agent for FUVAC to enhance its fusion‐based antitumor potential. TSA was added prior to FUVAC treatment of murine tumor B16‐F10 and CT26 cells. TSA increased the replication of both FUVAC and parental non‐fusogenic VV. Moreover, TSA enhanced cell–cell fusion and FUVAC cytotoxicity in these tumor cells in a dose‐dependent manner. Transcriptome analysis revealed that TSA‐treated tumors showed altered expression of cellular component‐related genes, which may affect fusion tolerance. In a bilateral tumor‐bearing mouse model, combination treatment of TSA and FUVAC significantly prolonged mouse survival compared with either treatment alone or in combination with non‐fusogenic VV. Our findings demonstrate that TSA is a potent enhancer of cell–cell fusion efficacy of FUVAC. [ABSTRACT FROM AUTHOR]

Rotator cuff (RC) muscle fatty infiltration (FI) is an important factor that determines the clinical outcome of patients with RC repair. There is no effective treatment for RC muscle FI at this time. The goal of this study is to define the role Trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor in regulating muscle fibro/adipogenic progenitors (FAPs) adipogenesis and treating muscle fatty degeneration after massive RC tears in a mouse model. We hypothesize that TSA reduces muscle FI after massive RC tears. HDAC activity was measured in FAPs in RC muscle after tendon/nerve transection or sham surgery. FAPs were treated with TSA for 2 weeks and FAP adipogenesis was evaluated with perilipin and Oil Red O staining, as well as reverse transcript-polymerase chain reaction for adipogenesis-related genes. About 0.5 mg/kg TSA or dimethyl sulfoxide was administered to C57B/L6 mice with massive rotator cuff tears through daily intraperitoneal injection for 6 weeks. Supraspinatus muscles were harvested for biochemical and histology analysis. We found that FAPs showed significantly higher HDAC activity after RC tendon/nerve transection. TSA treatment significantly reduced HDAC activity and inhibited adipogenesis of FAPs. TSA also abolished the role of bone morphogenetic protein-7 in inducing FAP adipogenesis and promoted FAP brown/beige adipose tissue (BAT) differentiation. TSA injection significantly increased histone H3 acetylation and reduced FI of rotator cuff muscles after massive tendon tears. Results from this study showed that TSA can regulate FAP adipogenesis and promote FAP BAT differentiation epigenetically. HDAC inhibition may be a new treatment strategy to reduce muscle FI after RC tears and repair.

Abstract Hepatocellular carcinoma (HCC) is a malignancy with high morbidity and mortality but lacks effective treatments thus far. Although the emergence of immune checkpoint inhibitors in recent years has shed light on the treatment of HCC, a considerable number of patients are still unable to achieve durable and ideal clinical benefits. Therefore, refining the combination of immune checkpoint inhibitors (ICIs) to enhance the therapeutic effect has become a global research hotspot. Several histone deacetylase 2 inhibitors have shown advantages in ICIs in many solid cancers, except for HCC. Additionally, the latest evidence has shown that histone deacetylase 2 inhibition can regulate PD-L1 acetylation, thereby blocking the nuclear translocation of PD-L1 and consequently enhancing the efficacy of PD-1/PD-L1 inhibitors and improving anti-cancer immunity. Moreover, our team has recently discovered a novel HDAC2 inhibitor (HDAC2i), valetric acid (VA), that possesses great potential in HCC treatment as a monotherapy. Thus, a new combination strategy, combining HDAC2 inhibitors with ICIs, has emerged with significant development value. This perspective aims to ignite enthusiasm for exploring the application of ideal HDAC2 inhibitors with solid anti-tumor efficacy in combination with immunotherapy for HCC.

Combinations of nucleoside analog(s) and DNA alkylating agent(s) are used for cancer treatment as components of pre-transplant regimens used in hematopoietic stem cell transplantation. Their efficacies are enhanced by combining drugs with different mechanisms of action, which also allows a reduction in the individual drug dosages and thus potentially in toxicity to the patient. We hypothesized that addition of SAHA and olaparib, an HDAC- and a PARP-inhibitor, respectively, to the established combination of fludarabine, clofarabine and busulfan would enhance AML cell cytotoxicity. Exposure of the AML cell lines KBM3/Bu2506, MV4-11, MOLM14 and OCI-AML3 to the 5-drug combination resulted in synergistic cytotoxicity with combination indexes < 1. Increased protein acetylation and decreased poly(ADP-ribosyl)ation were observed, as expected. Activation of apoptosis was suggested by cleavage of Caspase 3 and PARP1, DNA fragmentation, increased reactive oxygen species, and decreased mitochondrial membrane potential. The reduction in poly(ADP-ribosyl) ation was independent of caspase activation. Several proteins involved in DNA damage response and repair were downregulated, which may be contributing factors for the observed synergism. The increased phosphorylation of DNAPKcs suggests inhibition of its kinase activity and diminution of its role in DNA repair. A similar synergism was observed in patient-derived cell samples. These findings will be important in designing clinical trials using these drug combinations as pretransplant conditioning regimens for AML patients. [ABSTRACT FROM AUTHOR]

Background: Prostate cancer (PCa) is the most common malignancy diagnosed in men. Immune checkpoint blockade (ICB) alone showed disappointing results in PCa. It is partly due to the formation of immunosuppressive tumor microenvironment (TME) could not be reversed effectively by ICB alone. Methods: We used PCa cell lines to evaluate the combined effects of CN133 and anti-PD-1 in the subcutaneous and osseous PCa mice models, as well as the underlying mechanisms. Results: We found that CN133 could reduce the infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), and CN133 combination with anti-PD-1 could augment antitumor effects in the subcutaneous PCa of allograft models. However, anti-PD-1 combination with CN133 failed to elicit an anti-tumor response to the bone metastatic PCa mice. Mechanistically, CN133 could inhibit the infiltration of PMN-MDSCs in the TME of soft tissues by downregulation gene expression of PMN-MDSC recruitment but not change the gene expression involved in PMN-MDSC activation in the CN133 and anti-PD-1 co-treatment group relative to the anti-PD-1 alone in the bone metastatic mice model. Conclusions: Taken together, our work firstly demonstrated that combination of CN133 with anti-PD-1 therapy may increase the therapeutic efficacy to PCa by reactivation of the positive immune microenvironment in the TME of soft tissue PCa. [ABSTRACT FROM AUTHOR]

Background: Glioblastoma (GBM) is the most common brain tumor with an overall survival (OS) of less than 30% at two years. Valproic acid (VPA) demonstrated survival benefits documented in retrospective and prospective trials, when used in combination with chemo-radiotherapy (CRT). Purpose: The primary goal of this study was to examine if the differential alteration in proteomic expression pre vs. post-completion of concurrent chemoirradiation (CRT) is present with the addition of VPA as compared to standard-of-care CRT. The second goal was to explore the associations between the proteomic alterations in response to VPA/RT/TMZ correlated to patient outcomes. The third goal was to use the proteomic profile to determine the mechanism of action of VPA in this setting. Materials and Methods: Serum obtained pre- and post-CRT was analyzed using an aptamer-based SOMAScan® proteomic assay. Twenty-nine patients received CRT plus VPA, and 53 patients received CRT alone. Clinical data were obtained via a database and chart review. Tests for differences in protein expression changes between radiation therapy (RT) with or without VPA were conducted for individual proteins using two-sided t-tests, considering p-values of <0.05 as significant. Adjustment for age, sex, and other clinical covariates and hierarchical clustering of significant differentially expressed proteins was carried out, and Gene Set Enrichment analyses were performed using the Hallmark gene sets. Univariate Cox proportional hazards models were used to test the individual protein expression changes for an association with survival. The lasso Cox regression method and 10-fold cross-validation were employed to test the combinations of expression changes of proteins that could predict survival. Predictiveness curves were plotted for significant proteins for VPA response (p-value < 0.005) to show the survival probability vs. the protein expression percentiles. Results: A total of 124 proteins were identified pre- vs. post-CRT that were differentially expressed between the cohorts who received CRT plus VPA and those who received CRT alone. Clinical factors did not confound the results, and distinct proteomic clustering in the VPA-treated population was identified. Time-dependent ROC curves for OS and PFS for landmark times of 20 months and 6 months, respectively, revealed AUC of 0.531, 0.756, 0.774 for OS and 0.535, 0.723, 0.806 for PFS for protein expression, clinical factors, and the combination of protein expression and clinical factors, respectively, indicating that the proteome can provide additional survival risk discrimination to that already provided by the standard clinical factors with a greater impact on PFS. Several proteins of interest were identified. Alterations in GALNT14 (increased) and CCL17 (decreased) (p = 0.003 and 0.003, respectively, FDR 0.198 for both) were associated with an improvement in both OS and PFS. The pre-CRT protein expression revealed 480 proteins predictive for OS and 212 for PFS (p < 0.05), of which 112 overlapped between OS and PFS. However, FDR-adjusted p values were high, with OS (the smallest p value of 0.586) and PFS (the smallest p value of 0.998). The protein PLCD3 had the lowest p-value (p = 0.002 and 0.0004 for OS and PFS, respectively), and its elevation prior to CRT predicted superior OS and PFS with VPA administration. Cancer hallmark genesets associated with proteomic alteration observed with the administration of VPA aligned with known signal transduction pathways of this agent in malignancy and non-malignancy settings, and GBM signaling, and included epithelial–mesenchymal transition, hedgehog signaling, Il6/JAK/STAT3, coagulation, NOTCH, apical junction, xenobiotic metabolism, and complement signaling. Conclusions: Differential alteration in proteomic expression pre- vs. post-completion of concurrent chemoirradiation (CRT) is present with the addition of VPA. Using pre- vs. post-data, prognostic proteins emerged in the analysis. Using pre-CRT data, potentially predictive proteins were identified. The protein signals and hallmark gene sets associated with the alteration in the proteome identified between patients who received VPA and those who did not, align with known biological mechanisms of action of VPA and may allow for the identification of novel biomarkers associated with outcomes that can help advance the study of VPA in future prospective trials. [ABSTRACT FROM AUTHOR]

Divisions at the periphery and midzone of mitochondria are two fission signatures that determine the fate of mitochondria and cells. Pharmacological induction of excessively asymmetric mitofission-associated cell death (MFAD) by switching the scission position from the mitochondrial midzone to the periphery represents a promising strategy for anticancer therapy. By screening a series of pan-inhibitors, we identified pracinostat, a pan-histone deacetylase (HDAC) inhibitor, as a novel MFAD inducer, that exhibited a significant anticancer effect on colorectal cancer (CRC) in vivo and in vitro. Pracinostat increased the expression of cyclin-dependent kinase 5 (CDK5) and induced its acetylation at residue lysine 33, accelerating the formation of complex CDK5/CDK5 regulatory subunit 1 and dynamin-related protein 1 (Drp1)-mediated mitochondrial peripheral fission. CRC cells with high level of CDK5 (CDK5-high) displayed midzone mitochondrial division that was associated with oncogenic phenotype, but treatment with pracinostat led to a lethal increase in the already-elevated level of CDK5 in the CRC cells. Mechanistically, pracinostat switched the scission position from the mitochondrial midzone to the periphery by improving the binding of Drp1 from mitochondrial fission factor (MFF) to mitochondrial fission 1 protein (FIS1). Thus, our results revealed the anticancer mechanism of HDACi pracinostat in CRC via activating CDK5-Drp1 signaling to cause selective MFAD of those CDK5-high tumor cells, which implicates a new paradigm to develop potential therapeutic strategies for CRC treatment. [Display omitted] • Identification pracinostat as a mitofission-associated cell death inducer in CRC. • Pracinostat induces CDK5/Drp1-mediated mitochondrial peripheral fission. • Pracinostat selectively suppresses tumor cells with CDK5-high. • Pracinostat induces peripheral mitofission by improving the binding of Drp1 to FIS1. [ABSTRACT FROM AUTHOR]

Neuroblastoma arises when immature neural precursor cells do not mature into specialized cells. Although retinoic acid (RA), a pro-differentiation agent, improves the survival of low-grade neuroblastoma, resistance to retinoic acid is found in high-grade neuroblastoma patients. Histone deacetylases (HDAC) inhibitors induce differentiation and arrest the growth of cancer cells; however, HDAC inhibitors are FDA-approved mostly for liquid tumors. Therefore, combining histone deacetylase (HDAC) inhibitors and retinoic acid can be explored as a strategy to trigger the differentiation of neuroblastoma cells and to overcome resistance to retinoic acid. Based on this rationale, in this study, we linked evernyl group and menadione-triazole motifs to synthesize evernyl-based menadione-triazole hybrids and asked if the hybrids cooperate with retinoic acid to trigger the differentiation of neuroblastoma cells. To answer this question, we treated neuroblastoma cells using evernyl-based menadione-triazole hybrids (6a–6i) or RA or both and examined the differentiation of neuroblastoma cells. Among the hybrids, we found that compound 6b inhibits class-I HDAC activity, induces differentiation, and RA co-treatments increase 6b-induced differentiation of neuroblastoma cells. In addition, 6b reduces cell proliferation, induces expression of differentiation-specific microRNAs leading to N-Myc downregulation, and RA co-treatments enhance the 6b-induced effects. We observed that 6b and RA trigger a switch from glycolysis to oxidative phosphorylation, maintain mitochondrial polarization, and increase oxygen consumption rate. We conclude that in evernyl-based menadione-triazole hybrid, 6b cooperates with RA to induce differentiation of neuroblastoma cells. Based on our results, we suggest that combining RA and 6b can be pursued as therapy for neuroblastoma. Schematic representation of RA and 6b in inducing differentiation of neuroblastoma cells [ABSTRACT FROM AUTHOR]