Target Of Valproic Acid Research Articles

Spatiotemporal protein dynamics during early organogenesis in mouse conceptuses treated with valproic acid

Valproic acid (VPA) is an anti-epileptic medication that increases the risk of neural tube defect (NTD) outcomes in infants exposed during gestation. Previous studies into VPA's mechanism of action have focused on alterations in gene expression and metabolism but have failed to consider how exposure changes the abundance of critical developmental proteins over time. This study evaluates the effects of VPA on protein abundance in the developmentally distinct tissues of the mouse visceral yolk sac (VYS) and embryo proper (EMB) using mouse whole embryo culture. Embryos were exposed to 600 μM VPA at 2 h intervals over 10 h during early organogenesis with the aim of identifying protein pathways relevant to VPA's mechanism of action in failed NTC. Protein abundance was measured through tandem mass tag (TMT) labeling followed by liquid chromatography and mass spectrometry. Overall, there were over 1500 proteins with altered abundance after VPA exposure in the EMB or VYS with 428 of these proteins showing previous gene expression associations with VPA exposure. Limited overlap of significant proteins between tissues supported the conclusion of independent roles for the VYS and EMB in response to VPA. Pathway analysis of proteins with increased or decreased abundance identified multiple pathways with mechanistic relevance to NTC and embryonic development including convergent extension, Wnt Signaling/planar cell polarity, cellular migration, cellular proliferation, cell death, and cytoskeletal organization processes as targets of VPA. Clustering of co-regulated proteins to identify shared patterns of protein abundance over time highlighted 4 h and 6/10 h as periods of divergent protein abundance between control and VPA-treated samples in the VYS and EMB, respectively. Overall, this study demonstrated that VPA temporally alters protein content in critical developmental pathways in the VYS and the EMB during early organogenesis in mice.

Structure-activity relationship read-across and transcriptomics for branched carboxylic acids.

The purpose of this study was to use chemical similarity evaluations, transcriptional profiling, in vitro toxicokinetic data, and physiologically based pharmacokinetic (PBPK) models to support read-across for a series of branched carboxylic acids using valproic acid (VPA), a known developmental toxicant, as a comparator. The chemicals included 2-propylpentanoic acid (VPA), 2-ethylbutanoic acid, 2-ethylhexanoic acid (EHA), 2-methylnonanoic acid, 2-hexyldecanoic acid, 2-propylnonanoic acid (PNA), dipentyl acetic acid or 2-pentylheptanoic acid, octanoic acid (a straight chain alkyl acid), and 2-ethylhexanol. Transcriptomics was evaluated in 4 cell types (A549, HepG2, MCF7, and iCell cardiomyocytes) 6 h after exposure to 3 concentrations of the compounds, using the L1000 platform. The transcriptional profiling data indicate that 2- or 3-carbon alkyl substituents at the alpha position of the carboxylic acid (EHA and PNA) elicit a transcriptional profile similar to the one elicited by VPA. The transcriptional profile is different for the other chemicals tested, which provides support for limiting read-across from VPA to much shorter and longer acids. Molecular docking models for histone deacetylases, the putative target of VPA, provide a possible mechanistic explanation for the activity cliff elucidated by transcriptomics. In vitro toxicokinetic data were utilized in a PBPK model to estimate internal dosimetry. The PBPK modeling data show that as the branched chain increases, predicted plasma Cmax decreases. This work demonstrates how transcriptomics and other mode of action-based methods can improve read-across.

PTPRC, KDM5C, GABBR1 and HDAC1 are the Major Targets of Valproic Acid in Regulation of its Anticonvulsant Pharmacological Effects

Background: Valproic acid (VPA) is a small molecule which is the 3rd most prescribed drug among anticonvulsant therapeutics. Understanding of the pharmacology of VPA targets will help optimally rationalise the therapeutic effects and also minimise the undesired outcomes. Hence this study analysed the human specific targets of VPA and assessed the affinity of VPA to these targets to interpret potential safe therapeutic range for VPA. Materials and Methods: The targets of VPA were identified from the SwissTargetPrediction server and STITCH database and analysed for their affinity with VPA using Autodock vina 1.2.0. The volume of distribution (Vd, L) and the dose of VPA reported in the DrugBank database was used for estimation of the plasma and CSF concentration. The plasma and CSF Concentration Affinity (CA) ratio of VPA against each of the high affinity targets was assessed at variable Vd (0.1 to 0.4 L/kg) to identify the therapeutic safety window of VPA. Results: The plasma/CSF concentration of VPA range from 170 to 7000 μM and 17 to 700 μM respectively. The plasma concentration achieved was within the safety limits (170 to 700 μM) at higher Vd (>10 L), while at lower Vd (<10L), the plasma or CSF concentration achieved was of concern at VPA dose of >1000 mg/day. The plasma concentration at very low Vd (< 2L) was of concern even at dose of 500 mg/day. The affinity of VPA against all its human specific targets ranged from 2.9 to 52.1 mM. The CA ratio of VPA against its high affinity target was observed to be greater than 0.8, indicating potentially significant modulation of these targets. The following four targets showed CA ratio of over 1: PTPRC, KDM5C, GABBR1 and HDAC1, indicating their preferential targeting by VPA. CES1 and SLC22A12 are high affinity targets of VPA which can contribute to its undesired pharmacological effects (CNS oedema and hepatotoxicity). Conclusion: This study offers a novel insight into the anticonvulsant and undesired pharmacology of VPA by specifically identifying the targets involved and recommends an evidence-based approach to personalise dose titration of VPA to achieve optimal therapeutic benefits.

Abstract 1840: Repurposing of valproic acid and simvastatin in pancreatic cancer: in vitro and in vivo synergistic antitumor interaction and sensitization to gemcitabine/nab-paclitaxel via inhibition of TGFβ-EMT signaling pathway

Abstract INTRODUCTION: Metastatic pancreatic ductal adenocarcinoma (PDAC) represents an unmet clinical need because the lack of effective treatment strategies and a very poor prognosis. Here we propose a novel therapeutic strategy, based on the repurposing of valproic acid (VPA), a safe and generic drug with epigenetic modulating activity, and simvastatin (SIM), a widely used generic cholesterol lowering drug, in combination with the standard gemcitabine/nab-paclitaxel (GEM/NP) treatment in metastatic PDAC setting. METHODS: Synergistic anti-tumor effect of the combined treatment was assessed in PANC1, ASPC1, PANC28 and BxPC3 PDAC cell lines in vitro by evaluating combination index, apoptosis, clonogenic capability, tumor spheroids and fibroblasts/tumor cells microtissues growth. Antitumor effect was confirmed in vivo on heterotopic and orthotropic xenograft PANC1 models in athymic mice. Expression and functional role of TGF-β and downstream epithelial-to-mesenchymal-transition (EMT) markers were studied by Ingenuity pathway analysis (IPA), mRNA and protein expression and by cell migration scratch assay. RESULTS: We showed, both in vitro and in vivo, the ability of VPA/SIM combination, used at low dosages, to synergistically improve the anti-proliferative and pro-apoptotic effect of chemotherapy (GEM/NP). Mechanistically, VPA/SIM treatment, alone or in combination with chemotherapy, induced e-Cadherin and impaired vimentin and ZEB-1 expression, functionally linked to the synergistic inhibition of cell migration. In line, IPA highlighted a protein network connecting HDACs and HMGCR, the targets of VPA and SIM respectively, with the two main EMT markers. Notably, the most significantly cancer enriched features associated with this network were “migration of tumor cell lines”, “fibrosis” and “invasion of tumor cell lines”, and TGFβ emerged as a hierarchical dominant network- node. Indeed, VPA/SIM inhibited TGFβ transcription and TGFβ-regulated EMT gene expression in PDAC cells. Consistently we also observed a significant reduction of circulating TGFβ1 levels in mice treated with VPA/SIM in combination with GEM/NP, paralleled by a reduced fibrosis on PDAC xenograft tumor sections, confirming the involvement of TGFβ functional down-modulation in the mechanism of VPA/SIM antitumor synergistic interaction and chemo-sensitization. CONCLUSIONS: Overall, we proposed a novel combination strategy, based on two safe and generic drugs, able to sensitize a widely employed regimen in metastatic PDAC patients, that warrant further clinical evaluation. Citation Format: Maria Serena Roca, federica iannelli, maria rita milone, veronica barile, cristina testa, tania moccia, carlo vitagliano, fabiana tatangelo, di gennaro elena, antonio avallone, francesca bruzzese, alessandra leone, alfredo budillon. Repurposing of valproic acid and simvastatin in pancreatic cancer: in vitro and in vivo synergistic antitumor interaction and sensitization to gemcitabine/nab-paclitaxel via inhibition of TGFβ-EMT signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1840.

Insights into Structural Modifications of Valproic Acid and Their Pharmacological Profile.

Valproic acid (VPA) is a well-established anticonvulsant drug discovered serendipitously and marketed for the treatment of epilepsy, migraine, bipolar disorder and neuropathic pain. Apart from this, VPA has potential therapeutic applications in other central nervous system (CNS) disorders and in various cancer types. Since the discovery of its anticonvulsant activity, substantial efforts have been made to develop structural analogues and derivatives in an attempt to increase potency and decrease adverse side effects, the most significant being teratogenicity and hepatotoxicity. Most of these compounds have shown reduced toxicity with improved potency. The simple structure of VPA offers a great advantage to its modification. This review briefly discusses the pharmacology and molecular targets of VPA. The article then elaborates on the structural modifications in VPA including amide-derivatives, acid and cyclic analogues, urea derivatives and pro-drugs, and compares their pharmacological profile with that of the parent molecule. The current challenges for the clinical use of these derivatives are also discussed. The review is expected to provide necessary knowledgebase for the further development of VPA-derived compounds.

Cell wall integrity is compromised under temperature stress in Schizosaccharomyces pombe expressing a valproic acid-sensitive vas4 mutant

Valproic acid (VPA) is widely used as a eutherapeutic and safe anticonvulsant drug, but the mechanism is not well elucidated. Histone deacetylases (HDACs) were first identified as direct targets of VPA. Many loss-of function mutants in S. pombe have been shown to be VPA sensitive but not sensitive to other HDAC inhibitors, such as sodium butyrate or trichostatin A (TSA). This difference suggests that there are multiple VPA target genes. In the current study, we isolated a VPA-sensitive (vas) mutant, vas4-1, and cloned the VPA target gene vas4+/vrg4+ by performing complementation experiments. The vas4+/vrg4+ gene encodes a putative Golgi GDP-mannose transporter, Vrg4, which is highly homologous with ScVrg4p. Physiological experiments indicated that SpVrg4p is involved in maintaining cell wall integrity (CWI) under high- or low-temperature stress. The results of a coimmunoprecipitation assay suggested that SpVrg4p may be transferred from the ER to the Golgi through SpGot1p loaded COPII vesicles, and both single and double mutations (S263C and A271V) in SpVrg4p compromised this transfer. Our results suggested that CWI in S. pombe is compromised under temperature stress by the VPA-sensitive vas4 mutant.

DOP23 Single-cell RNA sequencing identifies an important role for class I histone-deacetylase enzymes in intestinal myofibroblasts from patients with Crohn’s Disease strictures

Abstract Background Histone-deacetylase (HDAC) enzymes are a broad class of ubiquitously expressed enzymes that modulate histone acetylation, chromatin accessibility and gene expression. In models of Inflammatory bowel disease (IBD), HDAC inhibitors, such as Valproic acid (VPA) are proven anti-inflammatory agents and evidence suggests that they also inhibit fibrosis in non-intestinal organs. However, the role of HDAC enzymes in stricturing Crohn’s disease (CD) has not been characterised; this is key to understanding the molecular mechanism and developing novel therapies. Methods To evaluate HDAC expression in the intestine of SCD patients, we performed unbiased single-cell RNA sequencing (sc-RNA-seq) of over 10,000 cells isolated from full-thickness surgical resection specimens of non-SCD (NSCD; n=2) and SCD intestine (n=3). Approximately, 1000 fibroblasts were identified for further analysis, including a distinct cluster of myofibroblasts. Changes in gene expression were compared between myofibroblasts and other resident intestinal fibroblasts using the sc-RNA-seq analysis pipeline in Partek. Changes in HDAC expression and markers of HDAC activity (H3K27ac) were confirmed by immunohistochemistry in FFPE tissue from patient matched NSCD and SCD intestine (n=14 pairs). The function of HDACs in intestinal fibroblasts in the CCD-18co cell line and primary CD myofibroblast cultures (n=16 cultures) was assessed using VPA, a class I HDAC inhibitor. Cells were analysed using a variety of molecular techniques including ATAC-seq, gene expression arrays, qPCR, western blot and immunofluorescent protein analysis. Results Class I HDAC (HDAC1, p= 2.11E-11; HDAC2, p= 4.28E-11; HDAC3, p= 1.60E-07; and HDAC8, p= 2.67E-03) expression was increased in myofibroblasts compared to other intestinal fibroblasts subtypes. IHC also showed an increase in the percentage of stromal HDAC2 positive cells, coupled with a decrease in the percentage of H3K27ac positive cells, in the mucosa overlying SCD intestine relative to matched NSCD areas. In the CCD-18co cell line and primary myofibroblast cultures, VPA reduced chromatin accessibility at Collagen-I gene promoters and suppressed their transcription. VPA also inhibited TGFB-induced up-regulation of Collagen-I, in part by inhibiting TGFB1|1/SMAD4 signalling. TGFB1|1 was identified as a mesenchymal specific target of VPA and siRNA knockdown of TGFB1|1 was sufficient suppress TGFB-induced up-regulation of Collagen-I. Conclusion In SCD patients, class I HDAC expression is increased in myofibroblasts. Class I HDACs inhibitors impair TGFB-signalling and inhibit Collagen-I expression. Selective targeting of TGFB1|1 offers the opportunity to increase treatment specificity by selectively targeting meschenymal cells.

Valproic acid inhibits interferon-\u03b3 production by NK cells and increases susceptibility to Listeria monocytogenes infection

Valproic acid (VPA) is a drug commonly used for epileptic seizure control. Recently, it has been shown that VPA alters the activation of several immune cells, including Natural Killer (NK) cells, which play an important role in the containment of viruses and intracellular bacteria. Although VPA can increase susceptibility to extracellular pathogens, it is unknown whether the suppressor effect of VPA could affect the course of intracellular bacterial infection. This study aimed to evaluate the role of VPA during Listeria monocytogenes (L.m) infection, and whether NK cell activation was affected. We found that VPA significantly augmented mortality in L.m infected mice. This effect was associated with increased bacterial load in the spleen, liver, and blood. Concurrently, decreased levels of IFN-γ in serum and lower splenic indexes were observed. Moreover, in vitro analysis showed that VPA treatment decreased the frequency of IFN-γ-producing NK cells within L.m infected splenocytes. Similarly, VPA inhibited the production of IFN-γ by NK cells stimulated with IL-12 and IL-18, which is a crucial system for early IFN-γ production in listeriosis. Finally, VPA decreased the phosphorylation of STAT4, p65, and p38, without affecting the expression of IL-12 and IL-18 receptors. Altogether, our results indicate that VPA increases the susceptibility to Listeria monocytogenes infection and suggest that NK cell is one of the main targets of VPA, but further work is needed to ascertain this effect.

Effects of SCN1A and SCN2A polymorphisms on responsiveness to valproic acid monotherapy in epileptic children

PurposeThis study was conducted to explore the influence of genetic variations on responsiveness to valproic acid (VPA) monotherapy among Chinese children with epilepsy. MethodsOne hundred and forty epileptic children taking VPA as monotherapy were enrolled, and at least one-year follow-up was obtained to assess the therapeutic outcome. Twenty-seven single nucleotide polymorphisms (SNPs) within twelve candidate genes correlated with the metabolic enzymes, transporters and targets of VPA were genotyped. The effects of selected polymorphisms on VPA efficacy were identified by binary logistic regression analysis adjusting for potential confounders. ResultsSCN2A rs2304016 (A > G) AG genotype was more common among the VPA-resistant patients in comparison with the VPA-responsive patients (OR = 3.18, 95 % CI = 1.10−9.14, P = 0.032), and in subgroup of focal seizure, lower frequency of VPA resistance was found in epileptic children with SCN1A rs2298771 AG genotype than those with AA genotype (OR = 0.11, 95 % CI = 0.01−0.91, P = 0.040). ConclusionsOur study indicated that SCN2A rs2304016 and SCN1A rs2298771 polymorphisms might be associated with the response to VPA monotherapy in Chinese epileptic children. Further and larger researches are required to validate these results.

Exploring the inhibitory activity of valproic acid against the HDAC family using an MMGBSA approach.

Valproic acid (VPA) is a compound currently used in clinical practice for the treatment of epilepsy as well as bipolar and mood disorders. VPA targets histone deacetylases (HDACs), which participate in the removal of acetyl groups from lysine in several proteins, regulating a wide variety of functions within the organism. An imbalance or malfunction of these enzymes is associated with the development and progression of several diseases, such as cancer and neurodegenerative diseases. HDACs are divided into four classes, but VPA only targets Class I (HDAC1-3 and 8) and Class IIa (HDAC4-5, 7 and 9) HDACs; however, structural and energetic information regarding the manner by which VPA inhibits these HDACs is lacking. Here, the structural and energetic features that determine this recognition were studied using molecular docking and molecular dynamics (MD) simulation. It was found that VPA reaches the catalytic site in HDAC1-3 and 7, whereas in HDAC6, VPA only reaches the catalytic tunnel. In HDAC4, VPA was bound adjacent to L1 and L2, a zone that participates in corepressor binding, and in HDAC8, VPA was bound to the hydrophobic active site channel (HASC), in line with previous reports.

Valproic acid targets HDAC1/2 and HDAC1/PTEN/Akt signalling to inhibit cell proliferation via the induction of autophagy in gastric cancer.

Valproic acid (2-propylpentanoic acid, VPA) has been widely used as an anticonvulsant drug and is a choice drug for seizure treatment. VPA is also used as a short-chain fatty acid HDAC inhibitor that affects proliferation and differentiation and induces cell apoptosis in both solid and haematologic malignancies. Here, we observed that VPA treatment inhibited HDAC1/2 activity and induced autophagy in gastric cancer cells, leading to apoptosis. VPA-induced apoptosis occurred through inhibition of the HDAC1/PTEN/Akt signalling pathway and involved alterations in Bcl-2 and Beclin-1. The antitumour effects of VPA were verified invivo using SGC-7901 xenograft models. Moreover, we evaluated the expression of HDAC1/2 in gastric cancer patient samples and revealed a positive correlation between HDAC1/2 overexpression and poor prognosis. These findings indicate that VPA may serve as a potential therapeutic agent for gastric cancer and that HDAC1/2 might be a promising therapeutic biomarker for the disease.

HDAC inhibitor valproic acid protects heart function through Foxm1 pathway after acute myocardial infarction.

BackgroundEpigenetic histone acetylation is a major event controlling cell functions, such as metabolism, differentiation and repair. Here, we aim to determine whether Valproic acid (VPA), a FDA approved inhibitor of histone deacetylation for bipolar disease, could protect heart against myocardial infarction (MI) injury and elucidate key molecular pathways.MethodsVPA was administrated to MI rats at different time points, onset and after MI injury. Echocardiography, histology, serum biology assays, and gene expression, inhibition, and over-expression were performed to characterize the systolic function, infarct size, gene and signaling pathways.FindingsVPA treatment reduced the infarct size by ~50% and preserved the systolic function of heart after acute MI in rats. Even 60 min after infarction, VPA treatment significantly decreased infarct size. Furthermore, long-term treatment of VPA markedly improved myocardial performance. VPA regulated gene expression essential for cell survival and anti-inflammatory response. Consequently, oxidative stress and cell death were notably reduced after VPA treatment. Moreover, Foxm1 was identified as a potential key target of VPA. Overexpression of Foxm1 provided similar heart protective effect to VPA treatment. Particularly, both VPA treatment and Foxm1 over-expression repressed inflammatory response after MI for heart protection. In contrast, inhibition of Foxm1 activity abolished the cardiac protective effect of VPA. VPA mediated CM protection through Foxm1 upregulation was also identified in a human ESC derived CM hypoxia/reperfusion system.InterpretationVPA treatments significantly reduce cardiac damage after MI and the cardioprotective effect of VPA is likely mediated via Foxm1 pathway.FundThis work was mainly supported by 1R01HL109054.

Adverse placental effects of valproic acid: Studies in perfused human placentas.

In utero exposure to valproic acid (VPA) has been associated with worse pregnancy outcomes compared to all other antiepileptic drugs. We have previously shown that VPA alters the expression of placental transporters for hormones and nutrients invitro and in pregnant mice. Here, our aim was to characterize the effects of short exposure to VPA on the expression of carriers for compounds essential for fetal development in human placentas exvivo, under controlled conditions. Placentas were obtained from cesarean deliveries of women with no known epilepsy. Cotyledons were cannulated and perfused in the absence or the presence of VPA (42, 83, or 166μg/mL; n=6/group) in the maternal perfusate over 180minutes. A customized gene panel array was used to analyze the expression of carrier genes in the perfused cotyledons. We additionally measured in the perfused placentas folic acid concentrations and histone acetylation. VPA significantly altered the mRNA levels of major carriers for folic acid, glucose, choline, thyroid hormones, and serotonin (P<.05) and reduced placental folate concentrations by 25%-35% (P=.059). The effects were observed at therapeutic concentrations sufficient to enhance placental histone acetylation, and some were concentration-dependent. Our results point to the placenta as a novel target of VPA, implying potential involvement of the placenta in VPA's adverse fetal outcomes.

Valproic Acid Sensitizes Hepatocellular Carcinoma Cells to Proton Therapy by Suppressing NRF2 Activation

Although efficacy of combined histone deacetylase (HDAC) inhibitors and conventional photon radiotherapy is being tested in clinical trials, their combined effect with proton beam radiotherapy has yet to be determined. Here, we compared combined effect of valproic acid (VPA), a class I and II HDAC inhibitor and antiepileptic drug with proton and photon irradiation in hepatocellular carcinoma (HCC) cells in vitro and in vivo. We found that VPA sensitized more Hep3B cells to proton than to photon irradiation. VPA prolonged proton-induced DNA damage and augmented proton-induced apoptosis. In addition, VPA further increased proton-induced production of intracellular reactive oxygen species and suppressed expression of nuclear factor erythroid-2-related factor 2 (NRF2), a key transcription factor regulating antioxidant response. Downregulation of NRF2 by siRNA transfection increased proton-induced apoptotic cell death, supporting NRF2 as a target of VPA in radiosensitization. In Hep3B tumor xenograft models, VPA significantly enhanced proton-induced tumor growth delay with increased apoptosis and decreased NRF2 expression in vivo. Collectively, our study highlights a proton radiosensitizing effect of VPA in HCC cells. As NRF2 is an emerging prognostic marker contributing to radioresistance in HCC, targeting NRF2 pathway may impact clinical outcome of proton beam radiotherapy.

Cellular Effects of the Antiepileptic Drug Valproic Acid in Glioblastoma

Background/Aims: Valproic acid (VPA), an anticonvulsant and mood-stabilizing drug is used to treat epileptic seizure of glioblastoma patients. Besides its antiepileptic activity, VPA has been attributed further functions that improve the clinical outcome of glioblastoma patients. Those comprise the inhibition of some histone deacetylase (HDAC) isoforms which reportedly may result in radiosensitization. Retrospective analysis of patient data, however, could not unequivocally confirm a prolonged survival of glioblastoma patients receiving VPA. The present study aimed to identify potential VPA targets at the cellular level. Methods: To this end, the effect of VPA on metabolism, Ca²⁺-, biochemical and electro-signaling, cell-cycling, clonogenic survival and transfilter migration was analyzed in three human glioblastoma lines (T98G, U-87MG, U251) by MTT assay, Ca²⁺ imaging, immunoblotting, patch-clamp recording, flow cytometry, delayed plating colony formation and modified Boyden chamber assays, respectively. In addition, the effect of VPA on clonogenic survival of primary glioblastoma spheroid cultures treated with temozolomide and fractionated radiation was assessed by limited dilution assay. Results: In 2 of 3 glioblastoma lines, clinical relevant concentrations of VPA slightly slowed down cell cycle progression and decreased clonogenic survival. Furthermore, VPA induced Ca²⁺ signaling which was accompanied by pronounced K⁺ channel activity and transfilter cell migration. VPA did not affect metabolic NAD(P)H formation or radioresistance of the glioblastoma lines. Finally, VPA did not impair clonogenic survival or radioresistance of temozolomide-treated primary spheroid cultures. Conclusions: Combined, our in vitro data do not propose a general use of VPA as a radiosensitizer in anti-glioblastoma therapy.

Polymorphisms of ABAT, SCN2A and ALDH5A1 may affect valproic acid responses in the treatment of epilepsy in Chinese.

The clinical efficacy of valproic acid (VPA) varies greatly among epileptic patients. To find the potential genetic factors related to VPA responses, the pharmacogenetics study was conducted. Two hundred and one Chinese Han epileptic patients who were treated by VPA for at least 1 year were recruited. Up to 24 SNPs in 11 candidate genes that correlate with the metabolism, transport or target of VPA were genotyped. Three SNPs, rs1731017 (ABAT), rs2304016 (SCN2A) and rs1054899 (ALDH5A1) were found associated with VPA responses with the p-values of 0.003, 0.007 and 0.048, respectively. Further interaction analysis showed that the interaction between rs17183814 (ABAT) and rs1641022 (SCN2A) was also correlated with the response of VPA (p = 0.006). This study found three SNPs and one interaction among ABAT, SCN2A and ALDH5A1 were significantly associated with VPA response, which indicated that these genes may play important roles in the pharmacological mechanism of VPA.

Energy metabolism regulated by HDAC inhibitor attenuates cardiac injury in hemorrhagic rat model.

A disturbance of energy metabolism reduces cardiac function in acute severe hemorrhagic patients. Alternatively, adequate energy supply reduces heart failure and increases survival. However, the approach to regulating energy metabolism conductive to vital organs is limited, and the underlying molecular mechanism remains unknown. This study assesses the ability of histone deacetylase inhibitors (HDACIs) to preserve cardiac energy metabolism during lethal hemorrhagic injury. In the lethally hemorrhagic rat and hypoxic myocardial cells, energy metabolism and heart function were well maintained following HDACI treatment, as evident by continuous ATP production with normal cardiac contraction. Valproic acid (VPA) regulated the energy metabolism of hemorrhagic heart by reducing lactate synthesis and protecting the mitochondrial ultrastructure and respiration, which were attributable to the inhibition of lactate dehydrogenase A activity and the increased myeloid cell leukemia-1 (mcl-1) gene expression, ultimately facilitating ATP production and consumption. MCL-1, the key target of VPA, mediated this cardioprotective effect under acute severe hemorrhage conditions. Our results suggest that HDACIs promote cardioprotection by improving energy metabolism during hemorrhagic injury and could therefore be an effective strategy to counteract this process in the clinical setting.

Valproic acid enhances the neural differentiation of human placenta derived-mesenchymal stem cells in vitro.

Mesenchymal stem cells (MSCs) are known to express a wide range of markers belonging to all the three lineages: mesodermal, ectodermal and endodermal. Therefore, the possibility of their transdifferentiation towards a neural lineage has been an aspect of active research. In the present study, MSCs were isolated from human placental tissue (P-MSC) and subjected them to neural differentiation. It was found that the P-MSCs differentiated towards neural lineage in appropriate differentiation conditions. However, when a histone deacetylase (HDAC) inhibitor - valproic acid (VPA) - was incorporated in the medium, there was a further increase in their neural differentiation potential. The increase in the number of neurites and neural lineage specific markers was notable. The VPA-treated cells showed a significantly elevated membrane potential compared with the cells grown in only differentiation medium. When the molecular mechanism was studied, the enhancement in the neuronal lineage specification was caused by the inhibition of bone morphogenetic protein (BMP) 2 and an increase in BMP4 under both conditions. The target of VPA (HDAC2) was reduced in the VPA set, whereas HDAC1 remained unchanged. Concurrent reduction in the levels of Stat3 was observed, leading to an upregulation of βIII tubulin, which is a neuronal lineage-specific marker. The components of Notch signalling (i.e. decreased notch 1 and increased notch 3) also supported differentiation towards the neuronal lineage. Thus, the VPA treated P-MSCs can serve as an alternative source for deriving neural cells for use in both research and in clinics. Copyright © 2016 John Wiley & Sons, Ltd.

Prenatal exposure to sodium valproate alters androgen receptor expression in the developing cerebellum in a region and age specific manner in male and female rats

Valproic acid (VPA) is an anti-epileptic drug with teratogenicity activity that has been related to autism. In rodents, exposure to VPA in utero leads to brain abnormalities similar than those reported in the autistic brain. Particularly, VPA reduces the number of Purkinje neurons in the rat cerebellum parallel to cerebellar abnormalities found in autism. Thus, we injected pregnant females on embryonic day 12 either with VPA (600mg/kg, i.p.) or 0.9% saline solution and obtained the cerebellum from their offspring at different postnatal time points. Testosterone has been linked to autism and plays an important role during brain development. Therefore, we identified and analyzed the androgen receptor (AR) by immunohistochemistry and densitometry, respectively. We found VPA decreases AR density in the superficial Purkinje layer only in cerebellar lobule 8 at PN7, but increased it at PN14 compared to control in males. In females, VPA decreased AR density in the superficial Purkinje layer in cerebellar lobule 6 at PN14, but increased it in lobule 9 at the same time point. No differences were found in the deep Purkinje layer of any cerebellar lobule in terms of AR density neither in males nor females. We additionally found a particular AR density decreasing in both superficial and deep regions across development in the majority of cerebellar lobules in males, but in all cerebellar lobules in females. Thus, our results indicate that VPA disrupts the AR ontogeny in the developing cerebellum in an age and region specific manner in male and female rats. Future epigenetic studies including the evaluation of histone deacetylases (HDAC’s) might shed light these results as HDAC’s are expressed by Purkinje neurons, interact with the AR and are VPA targets. This work contributes to the understanding of the cerebellar development and it might help to understand the role of the cerebellum in neurodevelopmental disorders such as autism.

Valproic Acid Limits Pancreatic Recovery after Pancreatitis by Inhibiting Histone Deacetylases and Preventing Acinar Redifferentiation Programs

The mechanisms by which drugs induce pancreatitis are unknown. A definite cause of pancreatitis is due to the antiepileptic drug valproic acid (VPA). On the basis of three crucial observations-that VPA inhibits histone deacetylases (HDACs), HDACs mediate pancreas development, and aspects of pancreas development are recapitulated during recovery of the pancreas after injury-we hypothesized that VPA does not cause injury on its own, but it predisposes patients to pancreatitis by inhibiting HDACs and provoking an imbalance in pancreatic recovery. In an experimental model of pancreatic injury, we found that VPA delayed recovery of the pancreas and reduced acinar cell proliferation. In addition, pancreatic expression of class I HDACs (which are the primary VPA targets) increased in the midphase of pancreatic recovery. VPA administration inhibited pancreatic HDAC activity and led to the persistence of acinar-to-ductal metaplastic complexes, with prolonged Sox9 expression and sustained β-catenin nuclear activation, findings that characterize a delay in regenerative reprogramming. These effects were not observed with valpromide, an analog of VPA that lacks HDAC inhibition. This is the first report, to our knowledge, that VPA shifts the balance toward pancreatic injury and pancreatitis through HDAC inhibition. The work also identifies a new paradigm for therapies that could exploit epigenetic reprogramming to enhance pancreatic recovery and disorders of pancreatic injury.