Therapeutic HDAC inhibition in hypermutant diffuse intrinsic pontine glioma

Constitutional mismatch repair deficiency (CMMRD) is a cancer predisposition syndrome associated with the development of hypermutant pediatric high-grade glioma, and confers a poor prognosis. While therapeutic histone deacetylase (HDAC) inhibition of diffuse intrinsic pontine glioma (DIPG) has been reported; here, we use a clinically relevant biopsy-derived hypermutant DIPG model (PBT-24FH) and a CRISPR-Cas9 induced genetic model to evaluate the efficacy of HDAC inhibition against hypermutant DIPG. We screened PBT-24FH cells for sensitivity to a panel of HDAC inhibitors (HDACis) in vitro, identifying two HDACis associated with low nanomolar IC50s, quisinostat (27 nM) and romidepsin (2 nM). In vivo, quisinostat proved more efficacious, inducing near-complete tumor regression in a PBT-24FH flank model. RNA sequencing revealed significant quisinostat-driven changes in gene expression, including upregulation of neural and pro-inflammatory genes. To validate the observed potency of quisinostat in vivo against additional hypermutant DIPG models, we tested quisinostat in genetically-induced mismatch repair (MMR)-deficient DIPG flank tumors, demonstrating that loss of MMR function increases sensitivity to quisinostat in vivo. Here, we establish the preclinical efficacy of quisinostat against hypermutant DIPG, supporting further investigation of epigenetic targeting of hypermutant pediatric cancers with the potential for clinical translation. These findings support further investigation of HDAC inhibitors against pontine high-grade gliomas, beyond only those with histone mutations, as well as against other hypermutant central nervous system tumors.

HDAC inhibitor quisinostat prevents estrogen deficiency-induced bone loss by suppressing bone resorption and promoting bone formation in mice

Postmenopausal osteoporosis (PMOP) is a metabolic skeletal disorder characterized by reduced bone mass and impaired bone microarchitecture resulting in increased bone fragility and fracture risk. PMOP is primarily caused by excessive osteoclastogenesis induced by estrogen deficiency. Quisinostat (Qst) is a potent hydroxamate-based second-generation inhibitor of histone deacetylases (HDACs) that can inhibit osteoclast differentiation in vitro, and protect mice from titanium particle-induced osteolysis in vivo. However, whether Qst has therapeutic potential against PMOP remains unclear. In the present study, we evaluated the therapeutic efficacy of Qst on PMOP, using a murine model of ovariectomy (OVX)-induced osteoporosis. We examined the body weight, femur length, and histology of major organs, and showed that Qst did not cause obvious toxicity in mice. Micro-computed tomography and histological analyses revealed that Qst treatment prevented OVX-induced trabecular bone loss both in femurs and vertebrae. Moreover, ELISA showed that Qst decreased the serum levels of the osteoclastic bone resorption marker CTX-1, whereas increased the levels of the osteoblastic bone formation marker Osteocalcin in OVX mice. Consistent with the CTX-1 results, TRAP staining showed that Qst suppressed OVX-induced osteoclastogenesis. Mechanistically, we showed that Qst suppressed RANKL-induced osteoclast differentiation in part by inhibiting p65 nuclear translocation. Collectively, our results demonstrated that Qst can ameliorate estrogen deficiency-induced osteoporosis by inhibiting bone resorption and promoting bone formation in vivo. In summary, our study provided the first preclinical evidence to support Qst as a potential therapeutic agent for PMOP prevention and treatment.

Quisinostat mediated autophagy is associated with differentiation in neuroblastoma SK-N-SH cells

Neuroblastoma (NB) is the most common childhood cancer that arises from the sympathetic nervous system. NB is characterized by poor prognosis. One of the strategies to control NB is activating the differentiation process in undifferentiated NB cells. Many differentiating agents including 13-cis-retinoic acid (RA) led to disappointing results. In the current study, we investigated the effect of Quisinostat/JNJ-26481585(JNJ) on NB SK-N-SH cells differentiation. The SK-N-SH cell differentiation was observed by morphology and neurite length measurement. The cell cycle arrest was determined by FACS analysis. The relative levels of autophagy marker LC3-II, neuronal markers βIII-tubulin and Eno-2, cell cycle related proteins cyclin D1 and CDK 4 were detected by western blotting. JNJ induces differentiation in SK-N-SH cells, as evident by the morphological features and expression of neuronal markers, βIII-tubulin and Eno-2. Cell cycle arrest at G1 phase was confirmed by a decrease in the expression of cyclin D1 and CDK 4. Furthermore, we also observed that autophagy plays an important role in JNJ induced cell differentiation of SK-N-SH cells. We demonstrated that autophagy is induced upon JNJ treatment and is important for the neuronal differentiation of human SK-N-SH cells.

Inhibition of osteoclastogenesis by histone deacetylase inhibitor Quisinostat protects mice against titanium particle-induced bone loss

Periprosthetic osteolysis (PPO) and subsequent aseptic loosening are major long-term complications after total joint arthroplasty and have become the first causes for further revision surgery. Since PPO is primarily caused by excessive bone resorption stimulated by released wear particles, osteoclast-targeted therapy is considered to be of great potential for PPO prevention and treatment. Accumulating evidences indicated that inhibition of histone deacetylases (HDACs) may represent a novel approach to suppress osteoclast differentiation. However, different inhibitors of HDACs were shown to exhibit distinct safety profiles and efficacy in inhibiting osteoclastogenesis. Quisinostat (Qst) is a hydroxamate-based histone deacetylase inhibitor, and exerts potent anti-cancer activity. However, its effect on osteoclastogenesis and its therapeutic potential in preventing PPO are still unclear. In this study, we found that Qst suppressed RANKL-induced production of TRAP-positive mature osteoclasts, expression of osteoclast-specific genes, formation of F-actin rings, and bone resorption activity at a nanomolar concentration as low as 2 nM in vitro. Furthermore, we found that as low as 30 μg/kg of Qst was sufficient to exert preventive effect on titanium particle-induced osteolysis in the murine calvarial osteolysis model. Mechanistically, we found that Qst suppressed osteoclastogenesis by interfering with NF-κB and c-Fos/NFATc1 pathways. Thus, our study revealed that Qst may serve as a potential therapeutic agent for prevention and treatment of PPO and other osteoclast-mediated diseases.

Comment on "Preclinical assessment of histone deacetylase inhibitor quisinostat as a therapeutic agent against esophageal squamous cell carcinoma"

Recently, we read a paper "Preclinical assessment of histone deacetylase inhibitor quisinostat as a therapeutic agent against esophageal squamous cell carcinoma" published in Investigational New Drugs. Quisinostat may be a promising drug candidate for the treatment of esophageal squamous cell carcinoma. However, some problems existing in the methods part of this paper are worthy of comment.

Death by histone deacetylase inhibitor quisinostat in tongue squamous cell carcinoma via apoptosis, pyroptosis, and ferroptosis

Tongue cancer is one of the most common oral malignancies. Quisinostat is a histone deacetylase inhibitor with antitumor activity. The aim of this study was to evaluate the effects of quisinostat on the viability of tongue squamous cell carcinoma (TSCC) cells (CAL-27, TCA-8113) in vitro and in vivo. Cell viability, cell morphological observation, scratch wound-healing assay, transwell migration assay, transmission electron microscope, flow cytometry and cellular reactive oxygen species were assessed in vitro. The results showed that quisinostat can significantly inhibit the viability, growth and migration of TSCC cells. And quisinostat could significantly induce TSCC cells apoptosis, pyroptosis, and ferroptosis. Quisinostat significantly inhibited tumor tissue growth in animal experiments. Up-regulation of the expression of Bax, cleaved-caspase3, caspase-1, p53, phospho-p53 and down-regulated of the expression of caspase-3, Bcl-2, GPX4 in cell lines and tumor tissues of nude mice were observed by Western blotting analysis. Up-regulation of the expression of caspase-1, Bax, cleaved-caspase3, p53 and down-regulated of the expression of ki67, caspase-3, Bcl-2, GPX4 in tumor tissues of nude mice were observed by immunohistochemistry. TUNEL analysis showed that quisinostat could increase the apoptosis rate in the tumor tissues of nude mice. Up-regulation of the expression of p53 and down-regulated expression of GPX4 in cell lines were observed by immunofluorescent staining, and the expression locations of p53 and GPX4 proteins in TSCC cells were observed. Based on these findings, quisinostat may be a potential drug for the treatment of tongue squamous cell carcinoma.

Histone deacetylase (HDAC) inhibitors and doxorubicin combinations target both breast cancer stem cells and non-stem breast cancer cells simultaneously

PURPOSE

Breast cancer stem cells (CSCs) are a small subpopulation of cancer cells that have high capability for self-renewal, differentiation, and tumor initiation. CSCs are resistant to chemotherapy and radiotherapy, and are responsible for cancer recurrence and metastasis.

METHODS

By utilizing a panel of breast cancer cells and mammospheres culture as cell-based screening platforms, we performed high-throughput chemical library screens to identify agents that are effective against breast CSCs and non-CSCs. The hit molecules were paired with conventional chemotherapy to evaluate the combinatorial treatment effects on breast CSCs and non-CSCs.

RESULTS

We identified a total of 193 inhibitors that effectively targeting both breast CSCs and non-CSCs. We observed that histone deacetylase inhibitors (HDACi) synergized conventional chemotherapeutic agents (i.e., doxorubicin and cisplatin) in targeting breast CSCs and non-CSCs simultaneously. Further analyses revealed that quisinostat, a potent inhibitor for class I and II HDACs, potentiated doxorubicin-induced cytotoxicity in both breast CSCs and non-CSCs derived from the basal-like (MDA-MB-468 and HCC38), mesenchymal-like (MDA-MB-231), and luminal-like breast cancer (MCF-7). It was also observed that the basal-like breast CSCs and non-CSCs were more sensitive to the co-treatment of quisinostat with doxorubicin compared to that of the luminal-like breast cancer subtype.

CONCLUSION

In conclusion, this study demonstrates the potential of HDACi as therapeutic options, either as monotherapy or in combination with chemotherapeutics against refractory breast cancer.

A high-throughput screening identifies histone deacetylase inhibitors as therapeutic agents against medulloblastoma

BACKGROUND

Medulloblastoma is the most frequently occurring malignant brain tumor in children. Current treatment strategies for medulloblastoma include aggressive surgery, cranio-spinal irradiation and adjuvant chemotherapy. Because current treatments can cause severe long-term side effects and are not curative, successful treatment remains a challenge.

METHODS

In this study, we employed a high-throughput cell viability assay to screen 12,800 compounds and to identify drug candidates with anti-proliferative properties for medulloblastoma cells. We also tested these compounds for attenuating medulloblastoma tumor development using mouse xenografts.

RESULTS

We identified two histone deacetylase inhibitors (dacinostat and quisinostat) with anti-proliferative properties for medulloblastoma cells. We showed that both compounds induce cytotoxicity, trigger cell apoptosis, and block cell cycle progression at the G2/M phase. In addition, dacinostat and quisinostat attenuated xenograft medulloblastoma growth in mice.

CONCLUSIONS

Our findings suggest that histone deacetylase inhibitors are potent therapeutic agents against medulloblastoma.

Improved early development of porcine cloned embryos by treatment with quisinostat, a potent histone deacetylase inhibitor

Recently, the modification of the epigenetic status of somatic cell nuclear transfer (SCNT) embryos by treatment with histone deacetylase inhibitors (HDACis) has made it possible to alter epigenetic traits and improve the developmental competence of these embryos. In the current study, we examined the effects of an HDACi, quisinostat (JNJ), on the in vitro development of porcine cloned embryos and their epigenetic nuclear reprogramming status. SCNT embryos were cultured under various conditions, and we found that treatment with 100 nM JNJ for 24 h post activation could improve blastocyst formation rates compared to the control (P < 0.05). Therefore, this was chosen as the optimal condition and used for further investigations. To explore the effects of JNJ on the nuclear reprogramming of early stage embryos and how it improved cloning efficiency, immunofluorescence staining and quantitative real-time PCR were performed. From the pseudo-pronuclear to 2-cell stages, the levels of acetylation of histone 3 at lysine 9 (AcH3K9) and acetylation of histone 4 at lysine 12 (AcH4K12) increased, and global DNA methylation levels revealed by anti-5-methylcytosine (5-mC) antibody staining were decreased in the JNJ-treated group compared to the control (P < 0.05). However, JNJ treatment failed to alter AcH3K9, AcH4K12, or 5-mC levels at the 4-cell embryo stage. Moreover, JNJ treatment significantly upregulated the expression of the development-related genes OCT4, SOX2, and NANOG, and reduced the expression of genes related to DNA methylation (DNMT1, DNMT3a, and DNMT3b) and histone acetylation (HDAC1, HDAC2, and HDAC3). Together, these results suggest that treatment of SCNT embryos with JNJ could promote their developmental competence by altering epigenetic nuclear reprogramming events.

Acetylation of intragenic histones on HPV16 correlates with enhanced HPV16 gene expression

We report that many histone modifications are unevenly distributed over the HPV16 genome in cervical cancer cells as well as in HPV16-immortalized keratinocytes. For example, H3K36me3 and H3K9Ac that are common in highly expressed cellular genes and over exons, were more common in the early than in the late region of the HPV16 genome. In contrast, H3K9me3, H4K20me3, H2BK5me1 and H4K16Ac were more frequent in the HPV16 late region. Furthermore, a region encompassing the HPV16 early polyadenylation signal pAE displayed high levels of histone H3 acetylation. Histone deacetylase (HDAC) inhibitors caused a 2- to 8-fold induction of HPV16 early and late mRNAs in cervical cancer cells and in immortalized keratinocytes, while at the same time increasing the levels of acetylated histones in the cells and on the HPV16 genome specifically. We concluded that increased histone acetylation on the HPV16 genome correlates with increased HPV16 gene expression.