Histone deacetylase inhibition mitigates cognitive deficits and astrocyte dysfunction induced by amyloid-ß (Aß) oligomers.

BACKGROUND AND PURPOSE: Inhibitors of histone deacetylases (iHDACs) are promising drugs for neurodegenerative diseases. We have evaluated the therapeutic potential of the new iHDAC LASSBio-1911 in Aß oligomer (AßO) toxicity models and astrocytes, key players in neuroinflammation and Alzheimer's disease (AD). EXPERIMENTAL APPROACH: Astrocyte phenotype and synapse density were evaluated by flow cytometry, Western blotting, immunofluorescence and qPCR, in vitro and in mice. Cognitive function was evaluated by behavioural assays using a mouse model of intracerebroventricular infusion of AßO. KEY RESULTS: LASSBio-1911 modulates reactivity and synaptogenic potential of cultured astrocytes and improves synaptic markers in cultured neurons and in mice. It prevents AßO-triggered astrocytic reactivity in mice and enhances the neuroprotective potential of astrocytes. LASSBio-1911 improves behavioural performance and rescues synaptic and memory function in AßO-infused mice. CONCLUSION AND IMPLICATIONS: These results contribute to unveiling the mechanisms underlying astrocyte role in AD and provide the rationale for using astrocytes as targets to new drugs for AD.

Modulation of Viability, Proliferation, and Stemness by Rosmarinic Acid in Medulloblastoma Cells: Involvement of HDACs and EGFR.

Medulloblastoma (MB) is a heterogeneous group of malignant pediatric brain tumors, divided into molecular groups with distinct biological features and prognoses. Currently available therapy often results in poor long-term quality of life for patients, which will be afflicted by neurological, neuropsychiatric, and emotional sequelae. Identifying novel therapeutic agents capable of targeting the tumors without jeopardizing patients' quality of life is imperative. Rosmarinic acid (RA) is a plant-derived compound whose action against a series of diseases including cancer has been investigated, with no side effects reported so far. Previous studies have not examined whether RA has effects in MB. Here, we show RA is cytotoxic against human Daoy (IC50 = 168 µM) and D283 (IC50 = 334 µM) MB cells. Exposure to RA for 48 h reduced histone deacetylase 1 (HDAC1) expression while increasing H3K9 hyperacetylation, reduced epidermal growth factor (EGFR) expression, and inhibited EGFR downstream targets extracellular-regulated kinase (ERK)1/2 and AKT in Daoy cells. These modifications were accompanied by increased expression of CDKN1A/p21, reduced expression of SOX2, and a decrease in proliferative rate. Treatment with RA also reduced cancer stem cell markers expression and neurosphere size. Taken together, our findings indicate that RA can reduce cell proliferation and stemness and induce cell cycle arrest in MB cells. Mechanisms mediating these effects may include targeting HDAC1, EGFR, and ERK signaling, and promoting p21 expression, possibly through an increase in H3K9ac and AKT deactivation. RA should be further investigated as a potential anticancer agent in experimental MB.

Marine Cyanobacteria as Sources of Lead Anticancer Compounds: A Review of Families of Metabolites with Cytotoxic, Antiproliferative, and Antineoplastic Effects.

The marine environment is highly diverse, each living creature fighting to establish and proliferate. Among marine organisms, cyanobacteria are astounding secondary metabolite producers representing a wonderful source of biologically active molecules aimed to communicate, defend from predators, or compete. Studies on these molecules' origins and activities have been systematic, although much is still to be discovered. Their broad chemical diversity results from integrating peptide and polyketide synthetases and synthases, along with cascades of biosynthetic transformations resulting in new chemical structures. Cyanobacteria are glycolipid, macrolide, peptide, and polyketide producers, and to date, hundreds of these molecules have been isolated and tested. Many of these compounds have demonstrated important bioactivities such as cytotoxicity, antineoplastic, and antiproliferative activity with potential pharmacological uses. Some are currently under clinical investigation. Additionally, conventional chemotherapeutic treatments include drugs with a well-known range of side effects, making anticancer drug research from new sources, such as marine cyanobacteria, necessary. This review is focused on the anticancer bioactivities of metabolites produced by marine cyanobacteria, emphasizing the identification of each variant of the metabolite family, their chemical structures, and the mechanisms of action underlying their biological and pharmacological activities.

In vitro effects of the 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide on Giardia intestinalis trophozoites.

Giardiasis is an intestinal disease caused by the parasite protozoan Giardia intestinalis. For more than five decades, the treatment of this disease has been based on compounds such as nitroimidazoles and benzimidazoles. The parasite's adverse effects and therapeutic failure are largely recognized. Therefore, it is necessary to develop new forms of chemotherapy treatment against giardiasis. Lysine deacetylases (KDACs), which remove an acetyl group from lysine residues in histone and non-histone proteins as tubulin, are found in the Giardia genome and can become an interesting option for giardiasis treatment. In the present study, we evaluated the effects of 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide, a new class I/II KDAC inhibitor, on G. intestinalis growth, cytoskeleton, and ultrastructure organization. This compound decreased parasite proliferation and viability and displayed an IC50 value of 179 nM. Scanning electron microscopy revealed the presence of protrusions on the cell surface after treatment. In addition, the vacuoles containing concentric membranous lamella and glycogen granules were observed in treated trophozoites. The cell membrane appeared deformed just above these vacuoles. Alterations on the microtubular cytoskeleton of the parasite were not observed after drug exposure. The number of diving cells with incomplete cytokinesis increased after treatment, indicating that the compound can interfere in the late steps of cell division. Our results indicate that 4-[(10H-phenothiazin-10-yl)methyl]-N-hydroxybenzamide should be explored to develop new therapeutic compounds for treating giardiasis.

PaDef (Persea americana var. drymifolia), a Plant Antimicrobial Peptide, Triggers Apoptosis, and Induces Global Epigenetic Modifications on Histone 3 in an Acute Lymphoid Leukemia Cell Line.

In recent years, it has been recognized that epigenetic alterations play an important role in the development and maintenance of cancer, including leukemias. Furthermore, it is known that these alterations are involved in the emergence of resistance to conventional chemotherapeutics. Consequently, molecules with an anticancer activity whose activity is ruled by epigenetic modifications are attractive to search for new therapies against cancer. The plant antimicrobial peptides have been widely evaluated as molecules with anticancer activity; however, the analysis of the epigenetic regulation induced by these molecules associated with this activity is scarce and still is an unexplored field. In this work, we show that the PaDef defensin, a plant antimicrobial peptide from Mexican avocado fruit (Persea americana var. drymifolia) is cytotoxic for Jurkat cell line from acute lymphoid leukemia cells, through an apoptotic process. PaDef inhibited cell viability in a concentration-dependent manner, with an IC50 = 47.3 µM. Treatment of Jurkat cells with PaDef (IC50) induced cell death by apoptosis dependent on caspases 8 and 9; besides, it was related to an increase in the production of reactive oxygen species and the loss of mitochondrial membrane potential. Interestingly, the inhibition of caspase activation by inhibitors of caspases 8 and 9 does not revert the reduction in viability, suggesting that other mechanisms, in addition to caspase activity, could be participating in the PaDef cytotoxic effect. Also, the modifications in the histone 3 tails induced by PaDef in Jurkat cells were evaluated, specifically acetylation and methylation. PaDef increased global histone 3 acetylation and lysine 9 specific marks (2-fold and up to 4-fold, respectively). These effects correlated with the reduction of the Histone Deacetylase activity (HDAC, ∼50%). Based on methylation marks, PaDef treatment increased lysine 9 di- and tri-methylation tags (2-fold in both cases). The epigenetic modulation induced by PaDef on Jurkat cells could be related to the chromatin compaction-decompaction promoting gene expression or repression; however, further studies are necessary to correlate these marks with the transcription of specific genes. Therefore, the study of new molecules that may have anticancer activity through epigenetic modulation is interesting.

Effects of sodium valproate on the chromatin of Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae) under in vitro culture conditions.

Sodium valproate (VPA) is a classic anticonvulsive, a histone deacetylase inhibitor, and a chromatin remodeling inducer. When injected into specimens of Triatoma infestans, a vector of Chagas disease, VPA affects the chromatin supraorganization of chromocenter heterochromatin in only a few cells of the Malpighian tubules. To test whether this result was explained by the inaccessibility of all of the organ's cells to the drug, we investigated the nuclear phenotypes and global acetylation of lysine 9 in histone H3 (H3K9ac) in Malpighian tubules cultivated in vitro for 1-24 h in the presence of 0.05 mM-1 mM VPA. The present results revealed that the chromatin decondensation event in the chromocenter body, which was detected only under low VPA concentrations up to a 4-h treatment, was not frequent during organ culture, similar to the results for injected insects. Cultivation of T. infestans Malpighian tubules in vitro for 24 h revealed inadequate for cell preservation even in the absence of the drug. Immunofluorescence signals for H3K9ac following VPA treatment showed a slightly increased intensity in the euchromatin, but were never detected in the chromocenter bodies, except with great intensity at their periphery, where the 18S rDNA is located. In conclusion, when VPA affects the chromocenter heterochromatin in this animal cell model, it occurs through a pathway that excludes a classic global H3K9ac mark. Investigation of nonhistone proteins associated with histone methylation marks is still required to further explain the differential response of T. infestans chromatin to VPA.

Inhibition of phospholipase D2 augments histone deacetylase inhibitor-induced cell death in breast cancer cells.

BACKGROUND: Histone deacetylase (HDAC) inhibitors are promising anticancer drugs but their effect on tumor treatment has been disappointing mainly due to the acquisition of HDAC inhibitor resistance. However, the mechanisms underlying such resistance remain unclear. METHODS: In this study, we performed Western blot, q-PCR, and promoter assay to examine the expression of HDAC inhibitor-induced phospholipase D2 (PLD2) in MDA-MB231and MDA-MB435 breast cancer cells. Apoptosis and proliferation were analyzed by flow cytometry. In addition to invasion and migration assay, angiogenesis was further measured using in vitro tube formation and chick embryo chorioallantoic membrane model. RESULTS: HDAC inhibitors including suberoylanilide hydroxamic acid (SAHA), trichostatin, and apicidin, induce expression of PLD2 in a transcriptional level. SAHA upregulates expression of PLD2 via protein kinase C-ζ in breast cancer cells and increases the enzymatic activity of PLD. The combination treatment of SAHA with PLD2 inhibitor significantly enhances cell death in breast cancer cells. Phosphatidic acid, a product of PLD activity, prevented apoptosis promoted by cotreatment with SAHA and PLD2 inhibitor, suggesting that SAHA-induced PLD2 expression and subsequent activation of PLD2 might confers resistance of breast cancer cells to HDAC inhibitor. The combinational treatment of the drugs significantly suppressed invasion, migration, and angiogenesis, compared with that of either treatment. CONCLUSION: These findings provide further insight into elucidating the advantages of combination therapy with HDAC and PLD2 inhibitors over single-agent strategies for the treatment of cancer.

Histone Deacetylase Inhibitors as Therapeutic Interventions on Cervical Cancer Induced by Human Papillomavirus.

The role of epigenetic modifications on the carcinogenesis process has received a lot of attention in the last years. Among those, histone acetylation is a process regulated by histone deacetylases (HDAC) and histone acetyltransferases (HAT), and it plays an important role in epigenetic regulation, allowing the control of the gene expression. HDAC inhibitors (HDACi) induce cancer cell cycle arrest, differentiation, and cell death and reduce angiogenesis and other cellular events. Human papillomaviruses (HPVs) are small, non-enveloped double-stranded DNA viruses. They are major human carcinogens, being intricately linked to the development of cancer in 4.5% of the patients diagnosed with cancer worldwide. Long-term infection of high-risk (HR) HPV types, mainly HPV16 and HPV18, is one of the major risk factors responsible for promoting cervical cancer development. In vitro and in vivo assays have demonstrated that HDACi could be a promising therapy to HPV-related cervical cancer. Regardless of some controversial studies, the therapy with HDACi could target several cellular targets which HR-HPV oncoproteins could be able to deregulate. This review article describes the role of HDACi as a possible intervention in cervical cancer treatment induced by HPV, highlighting the main advances reached in the last years and providing insights for further investigations regarding those agents against cervical cancer.

Insights into structural features of HDAC1 and its selectivity inhibition elucidated by Molecular dynamic simulation and Molecular Docking.

Histone deacetylases (HDACs) are a family of proteins whose main function is the removal of acetyl groups from lysine residues located on histone and non-histone substrates, which regulates gene transcription and other activities in cells. HDAC1 dysfunction has been implicated in cancer development and progression; thus, its inhibition has emerged as a new therapeutic strategy. Two additional metal binding sites (Site 1 and Site 2) in HDACs have been described that are primarily occupied by potassium ions, suggesting a possible structural role that affects HDAC activity. In this work, we explored the structural role of potassium ions in Site 1 and Site 2 and how they affect the interactions of compounds with high affinities for HDAC1 (AC1OCG0B, Chlamydocin, Dacinostat and Quisinostat) and SAHA (a pan-inhibitor) using molecular docking and molecular dynamics (MD) simulations in concert with a Molecular-Mechanics-Generalized-Born-Surface-Area (MMGBSA) approach. Four models were generated: one with a potassium ion (K+) in both sites (HDAC1k), a second with K+ only at site 1 (HDAC1ks1), a third with K+ only at site 2 (HDAC1ks2) and a fourth with no K+ (HDAC1wk). We found that the presence or absence of K+ not only impacted the structural flexibility of HDAC1, but also its molecular recognition, consistent with experimental findings. These results could therefore be useful for further structure-based drug design studies addressing new HDAC1 inhibitors.

Short- and long-term effects of nicotine and the histone deacetylase inhibitor phenylbutyrate on novel object recognition in zebrafish.

RATIONALE: Zebrafish have a sophisticated color- and shape-sensitive visual system, so we examined color cue-based novel object recognition in zebrafish. We evaluated preference in the absence or presence of drugs that affect attention and memory retention in rodents: nicotine and the histone deacetylase inhibitor (HDACi) phenylbutyrate (PhB). OBJECTIVES: The objective of this study was to evaluate whether nicotine and PhB affect innate preferences of zebrafish for familiar and novel objects after short- and long-retention intervals. METHODS: We developed modified object recognition (OR) tasks using neutral novel and familiar objects in different colors. We also tested objects which differed with respect to the exploratory behavior they elicited from naïve zebrafish. RESULTS: Zebrafish showed an innate preference for exploring red or green objects rather than yellow or blue objects. Zebrafish were better at discriminating color changes than changes in object shape or size. Nicotine significantly enhanced or changed short-term innate novel object preference whereas PhB had similar effects when preference was assessed 24 h after training. Analysis of other zebrafish behaviors corroborated these results. CONCLUSIONS: Zebrafish were innately reluctant or prone to explore colored novel objects, so drug effects on innate preference for objects can be evaluated changing the color of objects with a simple geometry. Zebrafish exhibited recognition memory for novel objects with similar innate significance. Interestingly, nicotine and PhB significantly modified innate object preference.