Antitumor effects of a novel histone deacetylase inhibitor NK-HDAC-1 on breast cancer

Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors

SMADs are the canonical intracellular effector proteins of the TGF-β (transforming growth factor-β). SMADs translocate from plasma membrane receptors to the nucleus regulated by many SMAD-interacting proteins through phosphorylation and other post-translational modifications that govern their nucleocytoplasmic shuttling and subsequent transcriptional activity. The signaling pathway of TGF-β/SMAD exhibits both tumor-suppressing and tumor-promoting phenotypes in epithelial-derived solid tumors. Collectively, the pleiotropic nature of TGF-β/SMAD signaling presents significant challenges for the development of effective cancer therapies. Here, we review preclinical studies that evaluate the efficacy of inhibitors targeting major SMAD-regulating and/or -interacting proteins, particularly enzymes that may play important roles in epithelial or mesenchymal compartments within solid tumors.

Inhibition of histone deacetylases attenuates tumor progression and improves immunotherapy in breast cancer

Breast cancer is one of the common malignancies with poor prognosis worldwide. The treatment of breast cancer patients includes surgery, radiation, hormone therapy, chemotherapy, targeted drug therapy and immunotherapy. In recent years, immunotherapy has potentiated the survival of certain breast cancer patients; however, primary resistance or acquired resistance attenuate the therapeutic outcomes. Histone acetyltransferases induce histone acetylation on lysine residues, which can be reversed by histone deacetylases (HDACs). Dysregulation of HDACs via mutation and abnormal expression contributes to tumorigenesis and tumor progression. Numerous HDAC inhibitors have been developed and exhibited the potent anti-tumor activity in a variety of cancers, including breast cancer. HDAC inhibitors ameliorated immunotherapeutic efficacy in cancer patients. In this review, we discuss the anti-tumor activity of HDAC inhibitors in breast cancer, including dacinostat, belinostat, abexinostat, mocetinotat, panobinostat, romidepsin, entinostat, vorinostat, pracinostat, tubastatin A, trichostatin A, and tucidinostat. Moreover, we uncover the mechanisms of HDAC inhibitors in improving immunotherapy in breast cancer. Furthermore, we highlight that HDAC inhibitors might be potent agents to potentiate immunotherapy in breast cancer.

Promising Chemotherapy for Malignant Pediatric Brain Tumor in Recent Biological Insights

Brain tumors are the most widespread malignancies in children around the world. Chemotherapy plays a critical role in the treatment of these tumors. Although the current chemotherapy process has a remarkable outcome for a certain subtype of brain tumor, improving patient survival is still a major challenge. Further intensive treatment with conventional non-specific chemotherapy could cause additional adverse reactions without significant advancement in survival. Recently, patient derived brain tumor, xenograft, and whole genome analysis using deep sequencing technology has made a significant contribution to our understanding of cancer treatment. This realization has changed the focus to new agents, targeting the molecular pathways that are critical to tumor survival or proliferation. Thus, many novel drugs targeting epigenetic regulators or tyrosine kinase have been developed. These selective drugs may have less toxicity in normal cells and are expected to be more effective than non-specific chemotherapeutics. This review will summarize the latest novel targets and corresponding candidate drugs, which are promising chemotherapy for brain tumors according to the biological insights.

SAHA attenuates rotenone-induced toxicity in primary microglia and HT-22 cells

Rotenone is an industrial and environmental toxicant that has been strongly associated with neurodegeneration. It is clear that rotenone induces inflammatory and oxidative stress; however, information on the role of histone acetylation in neurotoxicity is limited. Epigenetic alterations, neuroinflammation, and oxidative stress play a role in the progression of neurodegeneration and can be caused by exposure to environmental chemicals, such as rotenone. Histone modifications, such as methylation and acetylation, play an important role in mediating epigenetic changes. Therefore, we here investigated the effects of histone acetylation on rotenone-induced inflammation and oxidative stress in both primary mouse microglia and hippocampal HT-22 cells using the pan-histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA). Our results showed that SAHA suppressed the inflammatory response by decreasing nuclear factor kappa B and inducible nitric oxide synthase expression. Additionally, SAHA inhibited the rotenone-induced elevation of interleukin 6 and tumor necrosis factor α levels in both cell lines. Furthermore, SAHA improved the rotenone-induced antioxidant status by mitigating the decrease in cellular glutathione levels. Additionally, SAHA prevented the rotenone-induced increase in the HDAC activity in microglial and hippocampal HT-22 cells. Together, our results showed that SAHA reduced rotenone-induced inflammatory and oxidative stress, suggesting a role for histone deacetylation in environmental-related neurotoxicity.

Bone sarcoma patient-derived xenografts are faithful and stable preclinical models for molecular and therapeutic investigations

Standard therapy of osteosarcoma (OS) and Ewing sarcoma (EW) rests on cytotoxic regimes, which are largely unsuccessful in advanced patients. Preclinical models are needed to break this impasse. A panel of patient-derived xenografts (PDX) was established by implantation of fresh, surgically resected osteosarcoma (OS) and Ewing sarcoma (EW) in NSG mice. Engraftment was obtained in 22 of 61 OS (36%) and 7 of 29 EW (24%). The success rate in establishing primary cell cultures from OS was lower than the percentage of PDX engraftment in mice, whereas the reverse was observed for EW; the implementation of both in vivo and in vitro seeding increased the proportion of patients yielding at least one workable model. The establishment of in vitro cultures from PDX was highly efficient in both tumor types, reaching 100% for EW. Morphological and immunohistochemical (SATB2, P-glycoprotein 1, CD99, caveolin 1) studies and gene expression profiling showed a remarkable similarity between patient’s tumor and PDX, which was maintained over several passages in mice, whereas cell cultures displayed a lower correlation with human samples. Genes differentially expressed between OS original tumor and PDX mostly belonged to leuykocyte-specific pathways, as human infiltrate is gradually replaced by murine leukocytes during growth in mice. In EW, which contained scant infiltrates, no gene was differentially expressed between the original tumor and the PDX. A novel therapeutic combination of anti-CD99 diabody C7 and irinotecan was tested against two EW PDX; both drugs inhibited PDX growth, the addition of anti-CD99 was beneficial when chemotherapy alone was less effective. The panel of OS and EW PDX faithfully mirrored morphologic and genetic features of bone sarcomas, representing reliable models to test therapeutic approaches.

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

Background

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

Methods

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

Results

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

Conclusion

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

Biological Effect of a Hybrid Anticancer Agent Based on Kinase and Histone Deacetylase Inhibitors on Triple-Negative (MDA-MB231) Breast Cancer Cells

We examined the effects of the histone deacetylase inhibitor (HDACi) suberoylanilide hydroxamic acid (SAHA) combined with the vascular endothelial growth factor receptor-1/2 inhibitor (3Z)-5-hydroxy-3-(1H-pyrrol-2-ylmethylidene)-2,3-dihydro-1H-indol-2-one on MDA-MB-231 breast cancer cells (triple-negative) in the form of both a cocktail of the separate compounds and a chemically synthesized hybrid (N-hydroxy-N'-[(3Z)-2-oxo-3-(1H-pyrrol-2-ylmethylidene)-2,3-dihydro-1H-indol-5-yl]octanediamide). Comparative flow cytometric and Western blot analyses were performed on cocktail- and hybrid-treated cells to evaluate cell cycle distribution, autophagy/apoptosis modulation, and mitochondrial metabolic state in order to understand the cellular basis of the cytotoxic effect. Cell cycle analysis showed a perturbation of the rate of progression through the cycle, with aspects of redistribution of cells over different cycle phases for the two treatments. In addition, the results suggest that the two distinct classes of compounds under investigation could induce cell death by different preferential pathways, i.e., autophagy inhibition (the cocktail) or apoptosis promotion (the hybrid), thus confirming the enhanced potential of the hybrid approach vs. the combination approach in finely tuning the biological activities of target cells and also showing the hybrid compound as an additional promising drug-like molecule for the prevention or therapy of “aggressive” breast carcinoma.