The neuroprotective effect of treatment of valproic Acid in acute spinal cord injury

OBJECTIVE

Valproic acid (VPA), as known as histone deacetylase inhibitor, has neuroprotective effects. This study investigated the histological changes and functional recovery from spinal cord injury (SCI) associated with VPA treatment in a rat model.

METHODS

Locomotor function was assessed according to the Basso-Beattie-Bresnahan scale for 2 weeks in rats after receiving twice daily intraperitoneal injections of 200 mg/kg VPA or the equivalent volume of normal saline for 7 days following SCI. The injured spinal cord was then examined histologically, including quantification of cavitation.

RESULTS

Basso-Beattie-Bresnahan scale scores in rats receiving VPA were significantly higher than in the saline group (p<0.05). The cavity volume in the VPA group was significantly reduced compared with the control (saline-injected) group (p<0.05). The level of histone acetylation recovered in the VPA group, while it was significantly decreased in the control rats (p<0.05). The macrophage level was significantly decreased in the VPA group (p<0.05).

CONCLUSION

VPA influences the restoration of hyperacetylation and reduction of the inflammatory reaction resulting from SCI, and is effective for histology and motor function recovery.

Treatment strategies for Hodgkin lymphoma recurring following autologous hematopoietic stem cell transplantation

Hodgkin lymphoma (HL) represents one of the great success stories in hematology going from a uniformly fatal disease, to one that is curable in the vast majority of cases. Despite this success, some patients experience relapse. To address this unmet need a variety of agents, classes of drugs, and strategies have demonstrated activity in HL recurring after autologous hematopoietic stem cell transplantation. These include chemotherapeutics (gemcitabine-based combinations, bendamustine), histone deacetylase (HDAC) inhibitors (panobinostat), immunomodulatory agents (lenalidomide), mTOR inhiobitors (everolimus), monoclonal antibodies (rituximab), and antibody-drug conjugates (brentuximab vedotin) as well the potential of long-term disease control via allogeneic transplantation. Such advances reflect our increased understanding of the biology of HL and hold promise for continued improved outcomes for those suffering with this condition.

Molecular mechanism of SAHA on regulation of autophagic cell death in tamoxifen-resistant MCF-7 breast cancer cells

OBJECTIVE

Tamoxifen is currently used for the treatment of estrogen receptor-positive breast cancer patients, but acquired resistance to tamoxifen is a critical problem in breast cancer therapy. Suberoylanilide hydroxamic acid (SAHA) is a prototype of the newly developed HDAC inhibitor. The aim of this study is to investigate the anticancer effects of SAHA in tamoxifen-resistant MCF-7 (TAMR/MCF-7) cells.

METHODS

Cytotoxicity, apoptosis and autophagic cell death induced by SAHA were studied. A TAMR/MCF-7 cells xenograft model was established to investigate the inhibitory effect of SAHA on tumor growth in vivo.

RESULTS

SAHA inhibited the proliferation of TAMR/MCF-7 cells in a dose-dependent manner. SAHA significantly reduced the expression of HDAC1, 2, 3, 4 and 7 and increased acetylated histone H3 and H4. Although SAHA induced G2/M phase arrest of cell cycle, apoptotic cell death was very low, which is correlated with the slight change in the activation of caspases and PARP cleavage. Interestingly, expression of the autophagic cell death markers, LC3-II and beclin-1, was significantly increased in TAMR/MCF-7 cells treated with SAHA. Autophagic cell death induced by SAHA was confirmed by acridine orange staining and transmission electron microscopy (TEM) in TAMR/MCF-7 cells. In mice bearing the TAMR/MCF-7 cell xenografts, SAHA significantly reduced the tumor growth and weight, without apparent side effects.

CONCLUSION

These results suggest that SAHA can induce caspase-independent autophagic cell death rather than apoptotic cell death in TAMR/MCF-7 cells. SAHA-mediated autophagic cell death is a promising new strategy to treatment of tamoxifen-resistant human breast cancer.

Improved Histone Deacetylase Inhibitors as Therapeutics for the Neurodegenerative Disease Friedreich's Ataxia: A New Synthetic Route

Friedreich's ataxia (FRDA) is caused by transcriptional repression of the nuclear FXN gene encoding the essential mitochondrial protein frataxin. Based on the hypothesis that the acetylation state of the histone proteins is responsible for gene silencing in FRDA, previous work in our lab identified a first generation of HDAC inhibitors (pimelic o-aminobenzamides), which increase FXN mRNA in lymphocytes from FRDA patients. Importantly, these compounds also function in a FRDA mouse model to increase FXN mRNA levels in the brain and heart. While the first generation of HDAC inhibitors hold promise as potential therapeutics for FRDA, they have two potential problems: less than optimal brain penetration and metabolic instability in acidic conditions. Extensive optimization focusing on modifying the left benzene ring, linker and the right benzene ring lead to a novel class of HDAC inhibitors that have optimized pharmacological properties (increased brain penetration and acid stability) compared to the previous HDAC inhibitors. This article will describe the chemical synthesis and pharmacological properties of these new HDAC inhibitors.

Histone deacetylase inhibitors: molecular mechanisms of action and clinical trials as anti-cancer drugs

Histone deacetylase (HDAC) inhibitors are a relatively new class of anti-cancer agents that play important roles in epigenetic or non-epigenetic regulation, inducing death, apoptosis, and cell cycle arrest in cancer cells. Recently, their use has been clinically validated in cancer patients resulting in the approval of two HDAC inhibitors, vorinostat and depsipetide, by the FDA. Also, clinical trials of several HDAC inhibitors for use as anti-cancer drugs (alone or in combination with other anti-cancer therapeutics) are ongoing. However, the molecular mechanisms underlying the response to HDAC inhibitors in cancer patients are not fully understood. In this review, we summarize our understanding of the molecular and biological events that underpin the anticancer effects of HDAC inhibitors and the outcomes of recent clinical trials involving these drugs.

Exploiting cellular pathways to develop new treatment strategies for AML

The standard approaches to the treatment of acute myeloid leukemia (AML) have been predominantly based on cytarabine and anthracyclines. Yet, the outcomes associated with AML continue to be poor, especially for those patients who are older or carry higher-risk disease. In recent years, extensive research has led to the development and study of novel agents which target AML by diverse and varied mechanisms. Among these are targeted therapeutics such as kinase inhibitors and oligonucleotide constructs. These aim to suppress the production or activity of proteins, such as FLT3 and BCL2, among others, and thus disrupt related signaling cascades essential for leukemogenesis and proliferation. In addition, other agents like flavopiridol appear to target the myeloid blast by various mechanisms including suppression of cyclin-dependent kinases and interference with nucleotide synthesis. Another class of novel therapies includes inhibitors of histone deacetylase, which cause growth arrest and apoptosis through histone acetylation and resultant conformational changes. Clinical trials are now studying these and other agents alone and in combination with traditional cytotoxic therapies, with some encouraging results. In this review, we aim to provide a summary of the preclinical and clinical investigations of selected promising agents currently under study.

Sodium butyrate activates Notch1 signaling, reduces tumor markers, and induces cell cycle arrest and apoptosis in pheochromocytoma

BACKGROUND

Pheochromocytoma is a neuroendocrine (NE) tumor of the adrenal medulla for which surgical resection is the only therapy. However, 10-46% of tumors are metastatic or have malignant features, and are often inoperable. Our lab has demonstrated the importance of the Notch1 signaling pathway in NE neoplasia, indicating that this pathway could be a target for emergent treatments in pheochromocytoma. It has recently become clear that histone deacetylase (HDAC) inhibitors influence Notch1 signaling. We hypothesized that the HDAC inhibitor Sodium Butyrate (NaB) might activate Notch1 in pheochromocytoma resulting in altered tumor cell proliferation.

METHODS

Pheochromocytoma (PC-12) cells were treated with increasing concentrations of NaB. MTT cellular proliferation assay was used to determine the effect of NaB on PC-12 cell growth. Expression of Notch1, NE markers, and cell cycle proteins was studied using Western analysis.

RESULTS

Untreated PC-12 cells lack Notch1 activity. Treatment with NaB led to a dose-dependent induction of Notch1 signaling, reduction of NE markers ASCL1 and CgA, and a significant reduction in cellular proliferation. Levels of expression of cyclin D1, p21, cleaved PARP, and cleaved caspase 3 proteins indicated the presence of cell cycle arrest and apoptosis following NaB treatment.

CONCLUSION

NaB activated Notch1 signaling, inhibited cellular proliferation, reduced NE markers, and induced cell cycle arrest and apoptosis in pheochromocytoma cells. This data indicates that activation of Notch1 signaling is a promising potential therapy or palliative measure for pheochromocytoma that warrants further investigation.