Inhibition Of Histone Deacetylase Activity Research Articles

Photocaged Histone Deacetylase Inhibitors as Prodrugs in Targeted Cancer Therapy.

Histone deacetylases (HDACs) play a key role in the control of transcription, cell proliferation, and migration. FDA-approved histone deacetylase inhibitors (HDACi) demonstrate clinical efficacy in the treatment of different T-cell lymphomas and multiple myeloma. However, due to unselective inhibition, they display a wide range of adverse effects. One approach to avoiding off-target effects is the use of prodrugs enabling a controlled release of the inhibitor in the target tissue. Herein, we describe the synthesis and biological evaluation of HDACi prodrugs with photo-cleavable protecting groups masking the zinc-binding group of the established HDACi DDK137 (I) and VK1 (II). Initial decaging experiments confirmed that the photocaged HDACi pc-I could be deprotected to its parent inhibitor I. In HDAC inhibition assays, pc-I displayed only low inhibitory activity against HDAC1 and HDAC6. After irradiation with light, the inhibitory activity of pc-I strongly increased. Subsequent MTT viability assays, whole-cell HDAC inhibition assays, and immunoblot analysis confirmed the inactivity of pc-I at the cellular level. Upon irradiation, pc-I demonstrated pronounced HDAC inhibitory and antiproliferative activities which were comparable to the parent inhibitor I. Additionally, only phototreated pc-I was able to induce apoptosis in Annexin V/PI and caspase-Glo 3/7 assays, making pc-I a valuable tool for the development of light-activatable HDACi.

Sulforaphane Potentiates Gemcitabine-Mediated Anti-Cancer Effects against Intrahepatic Cholangiocarcinoma by Inhibiting HDAC Activity

Intrahepatic cholangiocarcinoma (iCCA), the second most common primary liver cancer, has high mortality rates because of its limited treatment options and acquired resistance to chemotherapy. Sulforaphane (SFN), a naturally occurring organosulfur compound found in cruciferous vegetables, exhibits multiple therapeutic properties, such as histone deacetylase (HDAC) inhibition and anti-cancer effects. This study assessed the effects of the combination of SFN and gemcitabine (GEM) on human iCCA cell growth. HuCCT-1 and HuH28 cells, representing moderately differentiated and undifferentiated iCCA, respectively, were treated with SFN and/or GEM. SFN concentration dependently reduced total HDAC activity and promoted total histone H3 acetylation in both iCCA cell lines. SFN synergistically augmented the GEM-mediated attenuation of cell viability and proliferation by inducing G2/M cell cycle arrest and apoptosis in both cell lines, as indicated by the cleavage of caspase-3. SFN also inhibited cancer cell invasion and decreased the expression of pro-angiogenic markers (VEGFA, VEGFR2, HIF-1α, and eNOS) in both iCCA cell lines. Notably, SFN effectively inhibited the GEM-mediated induction of epithelial-mesenchymal transition (EMT). A xenograft assay demonstrated that SFN and GEM substantially attenuated human iCCA cell-derived tumor growth with decreased Ki67+ proliferative cells and increased TUNEL+ apoptotic cells. The anti-cancer effects of every single agent were markedly augmented by concomitant use. Consistent with the results of in vitro cell cycle analysis, G2/M arrest was indicated by increased p21 and p-Chk2 expression and decreased p-Cdc25C expression in the tumors of SFN- and GEM-treated mice. Moreover, treatment with SFN inhibited CD34-positive neovascularization with decreased VEGF expression and GEM-induced EMT in iCCA-derived xenografted tumors. In conclusion, these results suggest that combination therapy with SFN with GEM is a potential novel option for iCCA treatment.

Improving binary crow search algorithm for feature selection

Abstract The feature selection (FS) process has an essential effect in solving many problems such as prediction, regression, and classification to get the optimal solution. For solving classification problems, selecting the most relevant features of a dataset leads to better classification accuracy with low training time. In this work, a hybrid binary crow search algorithm (BCSA) based quasi-oppositional (QO) method is proposed as an FS method based on wrapper mode to solve a classification problem. The QO method was employed in tuning the value of flight length in the BCSA which is controlling the ability of the crows to find the optimal solution. To evaluate the performance of the proposed method, four benchmark datasets have been used which are human intestinal absorption, HDAC8 inhibitory activity (IC50), P-glycoproteins, and antimicrobial. Accordingly, the experimental results are discussed and compared against other standard algorithms based on the accuracy rate, the average number of selected features, and running time. The results have proven the robustness of the proposed method relied on the high obtained value of accuracy (84.93–95.92%), G-mean (0.853–0.971%), and average selected features (4.36–11.8) with a relatively low computational time. Moreover, to investigate the effectiveness of the proposed method, Friedman test was used which declared that the performance supremacy of the proposed BCSA-QO with four datasets was very evident against BCSA and CSA by selecting the minimum relevant features and producing the highest accuracy classification rate. The obtained results verify the usefulness of the proposed method (BCSA-QO) in the FS with classification in terms of high classification accuracy, a small number of selected features, and low computational time.

Anticancer effects of the HDAC inhibitor, 3β,6β‑dihydroxyurs‑12‑en‑27‑oic acid, in MCF‑7 breast cancer cells via the inhibition of Akt/mTOR pathways.

Astilbechinensis (A.chinensis) is a perennial herb that is used to treat chronic bronchitis and pain. The anticancer activity of 3β,6β‑dihydroxyurs‑12‑en‑27‑oic acid (ACT‑3), a major component isolated from A.chinensis, has not yet been investigated in detail. The purpose of the present study was to investigate the histone deacetylase (HDAC) inhibitory and anticancer activities of ACT‑3 compared with suberoylanilide hydroxamic acid (SAHA) in MCF‑7 human breast cancer cells. The purity of ACT‑3 was determined using high‑performance liquid chromatography. In the present study, the effects of ACT‑3 on anticancer effects of MCF‑7 cells were determined by measuring the level of apoptotic cell death and cell cycle regulator using flow cytometry analysis and western blot analysis, respectively. The effects of ACT‑3 on HDAC enzyme activity were measured using assay kits. ACT‑3 and SAHA increased the levels of acetylated histone H3 and reduced the levels of HDAC1 and HDAC3 in MCF‑7 cells. ACT‑3 significantly decreased the cell viability in a concentration‑dependent manner and induced different morphological changes at high concentrations. ACT‑3 and SAHA significantly inhibited the colony formation in MCF‑7 cells. ACT‑3 inhibited total HDAC activity in a dose‑dependent manner. ACT‑3 significantly reduced the expression levels of cyclin D1 and cyclin‑dependent kinase 4, and upregulated the expression levels of p21WAF1 and p53. A significant increase in the G1 phase cell population was observed in MCF‑7 cells and ACT‑3 induced apoptosis by reducing the ratio of B‑cell lymphoma‑2 (Bcl‑2)/Bcl‑2‑associated X (Bax) and releasing cleaved caspase 9. Additionally, ACT‑3 significantly increased autophagic cell death by inhibiting the serine‑threonine kinase/mammalian target of the rapamycin pathway. Autophagy induction was confirmed via acridine orange staining. ACT‑3 significantly increased the pERK1/2 and p21 in MCF‑7 cells. Thus, the activated ERK pathway played an important role in cell cycle arrest and apoptosis via ERK‑dependent induction of p21 in MCF‑7 cells. These data indicated that ACT‑3 can be used as a promising anticancer agent to overcome the limitations and reduce the side effects of conventional anticancer drugs.

Gut microbiota-derived short-chain fatty acids regulate group 3 innate lymphoid cells in HCC.

Type 3 innate lymphoid cells (ILC3s) are essential for host defense against infection and tissue homeostasis. However, their role in the development of HCC has not been adequately confirmed. In this study, we investigated the immunomodulatory role of short-chain fatty acids (SCFAs) derived from intestinal microbiota in ILC3 regulation. We report that Lactobacillus reuteri was markedly reduced in the gut microbiota of mice with HCC, accompanied by decreased SCFA levels, especially acetate. Additionally, transplantation of fecal bacteria from wild-type mice or L. reuteri could promote an anticancer effect, elevate acetate levels, and reduce IL-17A secretion in mice with HCC. Mechanistically, acetate reduced the production of IL-17A in hepatic ILC3s by inhibiting histone deacetylase activity, increasing the acetylation of SRY (sex-determining region Y)-box transcription factor 13 (Sox13) at site K30, and decreasing expression of Sox13. Moreover, the combination of acetate with programmed death 1/programmed death ligand 1 blockade significantly enhanced antitumor immunity. Consistently, tumor-infiltrating ILC3s correlated with negative prognosis in patients with HCC, which could be functionally mediated by acetate. These findings suggested that modifying bacteria, changing SCFAs, reducing IL-17A-producing ILC3 infiltration, and combining with immune checkpoint inhibitors will contribute to the clinical treatment of HCC.

Evaluation of Anti-inflammatory Activity of Novel HDAC Inhibitors using in vitro Methods

Inflammation is a neighborhood reaction to cell injury that is set apart by fine enlargement, leukocytic invasion, redness, heat, agony, expanding and loss of function. HDAC inhibitors play crucial role in regulation of inflammatory gene expression. The point of the investigation was to assess the anti-inflammatory activity of novel HDAC inhibitors having cinnamyl moiety. In the present study, two cinnamyl sulfonamide hydroxamate (CSH) derivatives (4a and 4b) were evaluated for their anti-inflammatory activity by in vitro methods, includes COX, LOX inhibitory assay, iNOS, MPO and determination of cellular nitrite level. The present study revealed that the newly derived compound 4a have potential anti-inflammatory activity and can serves as lead molecule in drug discovery.

Histone-deacetylase-inhibitory effects of periodontopathic-bacterial metabolites induce human gingival epithelial Ca9-22 cell death.

Dental plaque bacteria produce high concentrations of short-chain fatty acids (SCFAs), as bacterial metabolites. SCFA-treated gingival epithelial cells undergo cell death. Our previous reports demonstrated that butyrate-induced cell death depends on autophagy and reactive oxygen species (ROS). However, the precise mechanisms underlying SCFA-induced gingival epithelial cell death is poorly understood. Butyrate is a strong histone deacetylase (HDAC) inhibitor. Therefore, we determined the involvement of HDAC inhibitory activity in SCFA-induced gingival epithelial cells. Ca9-22 cells were used as an in vitro counterpart of gingival epithelial cells. Ca9-22 cells were treated with HDAC inhibitors in the presence or absence of C646, aP300 histone acetyltransferase (HAT) inhibitor, and compared the number of dead cells, which are measured using SYTOX Green dye. Acetylation levels of histone H3 were examined using western blotting. Changes in transcriptomes during the butyrate and C646 treatment were examined using RNA sequencing analysis. The butyrateor propionate-treatment of Ca9-22 cells induced acetylation of histone H3, while the C646 treatment strongly reduced the elevated acetylation levels. Accordingly, butyrate or propionate-induced cell death was inhibited by the C646 treatment. Similar results were obtained when other HDAC inhibitors were used. Whole transcriptome analysis revealed that the expression of numerous genes was altered by butyrate-induced histone acetylation. Moreover, some autophagy and ROS-related genes found in the altered genes might induce cell death. This study suggests the need for HDAC-inhibitory activity of bacterial metabolites to induce cell death, and the effects might enhance autophagy and ROS production.

Development of QSRR model for hydroxamic acids using PCA-GA-BP algorithm incorporated with molecular interaction-based features.

As a potent zinc chelator, hydroxamic acid has been applied in the design of inhibitors of zinc metalloenzyme, such as histone deacetylases (HDACs). A series of hydroxamic acids with HDAC inhibitory activities were subjected to the QSRR (Quantitative Structure-Retention Relationships) study. Experimental data in combination with calculated molecular descriptors were used for the development of the QSRR model. Specially, we employed PCA (principal component analysis) to accomplish dimension reduction of descriptors and utilized the principal components of compounds (16 training compounds, 4 validation compounds and 7 test compounds) to execute GA (genetic algorithm)-BP (error backpropagation) algorithm. We performed double cross-validation approach for obtaining a more convincing model. Moreover, we introduced molecular interaction-based features (molecular docking scores) as a new type of molecular descriptor to represent the interactions between analytes and the mobile phase. Our results indicated that the incorporation of molecular interaction-based features significantly improved the accuracy of the QSRR model, (R2 value is 0.842, RMSEP value is 0.440, and MAE value is 0.573). Our study not only developed QSRR model for the prediction of the retention time of hydroxamic acid in HPLC but also proved the feasibility of using molecular interaction-based features as molecular descriptors.

STAT3 Is a Potential Therapeutic Target for Histone Deacetylase Inhibitor-Resistant Cutaneous T-Cell Lymphoma

Background: Histone deacetylase inhibitors (HDACis), such as vorinostat and romidepsin, are effective treatment agents for various T-cell lymphomas, including cutaneous T-cell lymphoma (CTCL), peripheral T-cell lymphoma, and adult T-cell lymphoma/leukemia. Despite the promising anti-lymphoma activity of HDACis, drug resistance remains a significant clinical problem. Therefore, novel therapeutic strategies are required to overcome HDACi resistance. In this study, we generated HDACi-resistant CTCL cell lines and investigated the mechanisms of HDACi resistance. Aims: This study aimed to identify the mechanism of resistance to HDACis in CTCLs and to explore new therapeutic targets. Methods: The CTCL cell lines MyLa, MJ, and Hut78 were used in this study. Vorinostat-resistant cell lines, namely MyLa resistant, HUT78 resistant, and MJ resistant, were prepared by repeatedly exposing cells to increasing concentrations of vorinostat. To maintain drug resistance, the cells were continuously cultured in a medium containing 2.5 μM vorinostat. Following this, we conducted a comprehensive gene expression analysis using a microarray platform to investigate the deregulated genes in the resistant cell lines. Results: CTCL cell lines resistant to vorinostat were also resistant to romidepsin, suggesting that vorinostat-resistant cell lines showed cross-resistance to other HDACis. Next, we selected genes whose expression was upregulated more than 1.5 times in the three resistant cell lines and performed pathway analysis. Pathway analysis revealed that the upregulated genes were significantly enriched in the cytokine-mediated signaling pathways. Among the upregulated genes, we focused on interleukin-6 signal transducer (IL6ST)/glycoprotein (gp) 130, which forms a heterogeneous complex with IL6 and IL6 receptors, and activates the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway. Furthermore, flow cytometric analysis revealed that surface gp130 expression was significantly upregulated in the resistant cell lines. Moreover, the MyLa-resistant and MJ-resistant cell lines showed increased sensitivity to a gp130 inhibitor (SC144). Gp130 activation could activate the JAK/STAT pathway; therefore, we examined the expression level of the activated forms of STAT3 and p-STAT3 and found that p-STAT3 was significantly upregulated in the resistant cell lines. To investigate whether p-STAT3 upregulation is involved in the development of vorinostat resistance, we performed STAT3 knockdown using siRNA. We confirmed that STAT3 knockdown significantly decreased the survival of the resistant cell lines. Moreover, resistant cell lines showed increased sensitivity to the STAT3-selective inhibitor C188-9. However, compared to the controls, the resistant cell lines showed no difference in their sensitivity towards the JAK1/2 inhibitor ruxolitinib. This suggests that the STAT3 activation occurs not only through the JAK/STAT pathway but also through a pathway that is not mediated by JAK. We also examined the expression level of p-STAT5; however, it was downregulated in the resistant cell lines, which was in contrast to that of p-STAT3. These findings suggest that STAT3 activation, which is mediated by HDAC inhibition, could contribute to the resistance of CTCL to HDACis. Finally, we examined the gp130 and p-STAT3 protein expression in CTCL skin samples, which were obtained from the same patients before and after vorinostat treatment. We found that the gp130 and p-STAT3 expression was significantly increased in the specimens during relapse after vorinostat treatment. Conclusion: Activation of STAT3 in HDACi-resistant CTCL cells was enhanced by gp130, which contributed to their resistance. These results suggest that STAT3 could be the new therapeutic target in HDACi-resistant CTCL and that gp130/STAT3 inhibition could be an important therapeutic strategy. To further elucidate the detailed mechanism of HDACi resistance, analysis of the pathways activating STAT3 without JAK and the target proteins of STAT3 is warranted.

Evaluation of Antitumor and On-Target Activity of HDAC Inhibitors with the Zebrafish Embryo Xenograft Model.

Reliable preclinical drug testing models for cancer research are urgently needed with zebrafish embryo models emerging as a powerful vertebrate model for xenotransplantation studies. Here, we describe the evaluation of toxicity, efficacy, and on-target activity of histone deacetylase (HDAC) inhibitors in a zebrafish embryo yolk sac xenotransplantation model of medulloblastoma and neuroblastoma cells. For this, we performed toxicity assays with our zebrafish drug library consisting of 28 clinically relevant targeted as well as chemotherapeutic drugs with zebrafish embryos. We further engrafted zebrafish embryos with fluorescently labeled pediatric tumor cells (SK-N-BE(2)-C, HD-MB03, or MED8A) and monitored the progression after HDAC inhibitor treatment of xenotransplanted tumors through tumor volume measurements with high-content confocal microscopy in a multi-well format. The on-target activity of HDAC inhibitors was verified through immunohistochemistry staining on paraffin-embedded early larvae. Overall, the zebrafish embryo xenotransplantation model allows for fast and cost-efficient in vivo evaluation of targeted drug toxicity, efficacy, and on-target activity in the field of precision oncology.

Synthesis, antitumor, and apoptosis-inducing activities of novel 5-arylidenethiazolidine-2,4-dione derivatives: Histone deacetylases inhibitory activity and molecular docking study

The antitumor activity of the newly synthesized 5-arylidenethiazolidine-2,4-dione derivatives 18a–f and 19a–f was investigated, compared to doxorubicin (IC50 = 4.17–8.87 μM) and SAHA (IC50 = 2.70–7.11 μM). Among the tested molecules, compounds 18b, 18c, 18f, 19d, and 19e displayed the highest antitumor activity against cancer cell lines (IC50 = 3.16–28.94 μM). Further, compounds 18b, 18c, 18f, and 19d were tested as Histone deacetylases (HDACs) inhibitors compared with Entinostat (IC50 = 0.093–0.75 μM). Compounds 18b, 18c, 18f, and 19d inhibited HDAC1, HDAC2, HDAC8, and HDAC6 enzymes with IC50 values ranging from 0.144 to 1.741 μM. In addition, compound 18b caused apoptosis via a mitochondrial-mediated pathway and led to cell cycle arrest at the G1 phase. It also increased caspases-3 and caspases-7 by 5.2–3.9 and 9.1–3.7 folds, respectively. The molecular docking analysis of compounds 18b and 18c revealed that they could bind to the active sites of HDAC1, HDAC2, HDAC8, and HDAC6 like co-crystallized inhibitors.

Rectal administration of butyrate ameliorates pulmonary fibrosis in mice through induction of hepatocyte growth factor in the colon via the HDAC-PPARγ pathway

Butyrate, given by oral administration or in drinking water, has been shown to improve experimental pulmonary fibrosis (PF) in mice despite of very low bioavailability. The pharmacokinetic-pharmacodynamics disconnection attracts us to explore its anti-PF mechanism in view of the intestinal expression of anti-PF factors. In bleomycin-induced PF in mice, rectal administration of butyrate (500 mg/kg) exhibited a significant anti-PF effect, with a maximum plasma concentration largely lower than the minimum effective concentration (1 mM) at which butyrate inhibited the expression of pro-inflammatory factors by lung epithelial cells and the production of extracellular matrix by lung fibroblasts. The rectal administration of butyrate significantly upregulated the mRNA expression of hepatocyte growth factor (HGF) in the colons of PF mice, but showed no significant effect on the mRNA expression of HGF in the small intestines, lungs and livers. In colon epithelial cells, the monocarboxylate transporter inhibitor α-cyano-4-hydroxycinnamic acid (CHC) abrogated butyrate-induced expression of HGF, indicating that butyrate functions through entering into cells. Butyrate showed no significant effect on the histone acetylation in the promoter region of HGF, suggesting that it promotes HGF expression not by directly affecting the histone deacetylation of HGF but by other pathways. GW9662, the inhibitor of PPARγ, significantly attenuated the effect of butyrate to promote the mRNA expression of HGF. Butyrate was able to enhance the acetylation of PPARγ, and a targeted mutation of lysine at the position 240 (K240) of PPARγ markedly diminished the induction of butyrate on HGF expression, suggesting that butyrate promoted HGF expression in colon epithelial cells by upregulating PPARγ K240 acetylation.In summary, rectal administration of butyrate promotes the expression of HGF in colonic epithelial cells through upregulating PPARγ acetylation via inhibition of HDAC activity. The findings of the present study provide a reasonable explanation for the anti-PF action mode of butyrate based on the ‘lung-gut axis’, and found that intestine-derived butyrate and HGF may be involved in the modulation of the occurrence and progression of PF.

Chidamide works synergistically with Dasatinib by inducing cell-cycle arrest and apoptosis in acute myeloid leukemia cells.

This research aimed to explore whether Chidamide works synergistically with Dasatinib in the therapy of Acute myeloid leukemia (AML) and the potential molecular mechanism. The inhibition rate of the Dasatinib and Chidamide combination was significantly better than that of the single-drug application for HL-60 cells. The combination of Dasatinib and Chidamide significantly enhanced the Abnormal histone deacetylase (HDAC) inhibitory activity of Chidamide in Kasumi-1 and HL-60 cells. In the combined group, the proportion of S phase was significantly decreased, and the proportions of G2/M phase were significantly increased. The inhibitory rate of CD34+ CD38- HL-60 cells or Kasumi-1 cells was elevated when the cells were disposed with both Chidamide and Dasatinib. Dasatinib and Chidamide had synergistic antitumor effect. The combination with Dasatinib enhanced the HDAC inhibitory activity of Chidamide, promoted cell apoptosis and cell-cycle arrest of AML cells, and enhanced the inhibition of leukemia stem cell proliferation.

Valeric acid delays aril breakdown of longan (Dimocarpus longan Lour.) fruit in relation to the regulation of histone deacetylase activity

Aril breakdown results in the loss of nutrition and commodity value, thereby limits the postharvest storage of longan fruit. Histone deacetylases (HDACs) are important epigenetic regulators in many biological processes. Results in the current study showed that application of valeric acid (VA), which belongs to HDAC inhibitors, suppressed longan aril breakdown during postharvest storage. Meanwhile, lower contents of malondialdehyde, H2O2, and O2−., but higher activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) were observed in VA-treated fruit. Western blotting (WB) assay confirmed enhancement of histone H3 and H4 acetylation in VA-treated fruit, suggesting the possible inhibition of HDAC activity by VA. Furthermore, VA regulated DlHDACs expressions, with DlHDA5 and DlHDA8 expressions apposite of WB results. These results revealed that VA inhibited longan aril breakdown through enhancing the reactive oxygen species scavenging ability in relation to HDAC inhibitor activity. Our findings suggested that VA treatment delayed aril breakdown of longan fruit in relation to histone deacetylase-mediated epigenetic regulation and highlighted DlHDA5 and DlHDA8 potentially be important candidates for further research.

Lactate increases stemness of CD8 + T cells to augment anti-tumor immunity

Lactate is a key metabolite produced from glycolytic metabolism of glucose molecules, yet it also serves as a primary carbon fuel source for many cell types. In the tumor-immune microenvironment, effect of lactate on cancer and immune cells can be highly complex and hard to decipher, which is further confounded by acidic protons, a co-product of glycolysis. Here we show that lactate is able to increase stemness of CD8+ T cells and augments anti-tumor immunity. Subcutaneous administration of sodium lactate but not glucose to mice bearing transplanted MC38 tumors results in CD8+ T cell-dependent tumor growth inhibition. Single cell transcriptomics analysis reveals increased proportion of stem-like TCF-1-expressing CD8+ T cells among intra-tumoral CD3+ cells, a phenotype validated by in vitro lactate treatment of T cells. Mechanistically, lactate inhibits histone deacetylase activity, which results in increased acetylation at H3K27 of the Tcf7 super enhancer locus, leading to increased Tcf7 gene expression. CD8+ T cells in vitro pre-treated with lactate efficiently inhibit tumor growth upon adoptive transfer to tumor-bearing mice. Our results provide evidence for an intrinsic role of lactate in anti-tumor immunity independent of the pH-dependent effect of lactic acid, and might advance cancer immune therapy.

Nutrient sensing mechanism of short-chain fatty acids in mastitis control.

Bovine mastitis is a disease that is widespread in dairy cows worldwide, and its impact is significant due to economic losses at all levels of the dairy value chain. For a long time, antibiotics have been the main tool for curing mastitis, however the cure rate is not very high, and sometime side effects may occur. Therefore, an in-depth understanding of mastitis and effective solutions are urgently needed to resolve the problem that in what way to prevent and treat mastitis in order to protect the profitability of dairy farms. The importance of diet in the regulation of health are not novel. Dietary control of the intestinal flora provides a promising approach to prevent or treat certain deadly diseases. Ample amount of studies has been conducted on the role of short-chain fatty acids (SCFAs) in the maintenance of health. SCFAs are the type of dietary substance that has the ability to restore blood-milk barrier permeability, inhibit the development of mammary inflammation, and are also effective epigenomic modifiers with histone deacetylases inhibitory activity. To date, the detailed mechanism of action of SCFAs in treating mastitis is unclear, but preliminary evidences are emerging. To assess the effectiveness of this recommendation, we examined the overall mammary gland health knowledge related to SCFAs by scrutinizing their potential role and evaluating its compatibility with the immunobiology of mammary gland inflammation. We then considered preliminary in vivo and in vitro experiments and analyzed the literature on the subject. Here, we outline the production of SCFAs and its protective effect on the mammary gland, with particular emphasis on their relevance to mastitis. In addition, we also discussed the therapeutic potential of SCFAs for mammary gland inflammation. Expectantly, this theory will provide new perception for the treatment of mastitis and other infectious diseases.

Synthetic Study on Bicyclic Depsipeptides Containing an Intramolecular Disulfide Bond

Bicyclic depsipeptide natural products containing an intramolecular disulfide bond are potent histone deacetylase (HDAC) inhibitors. Among them, FK228 (romidepsin) is approved for treating cutaneous T-cell lymphoma and peripheral T-cell lymphoma. This study focused on developing a new synthesis method for producing this class of natural products for use as HDAC inhibitors with high efficacy and low toxicity. In this paper, the total syntheses of FK228 as well as spiruchostatins A and B are described. The synthesis routes include a convergent way to assemble seco-acids via the amide condensation of amine segments with carboxylic acid segments. The syntheses of C4- and C7-modified FK228 analogs (FK-A1 to FK-A8) are also described. The evaluation of HDAC and cell growth inhibitory activities of the synthesized analogs revealed novel aspects of their structure-activity relationship. Potent and highly isoform-selective HDAC1 inhibitors were identified. Furthermore, the analogs showed phosphatidylinositol 3-kinase (PI3K) inhibitory activity. Structural optimization of the analogs as HDAC/PI3K dual inhibitors led to the identification of FK-A11 as the most potent analog.

Synthesis and anticancer activity of novel histone deacetylase inhibitors that inhibit autophagy and induce apoptosis

The combination of histone deacetylase (HDAC) and autophagy inhibitor has been considered as a novel cancer therapeutic strategy. To find novel HDAC inhibitors that can inhibit autophagy, several new series of oxazole- and thiazole-based HDAC inhibitors were designed and synthesized by replacing the phenyl cap in SAHA with 5-phenyloxazoles and 5-phenylthiazoles. The representative oxazole derivative, compound 21, showed better enzymatic inhibitory activity than SAHA (vorinostat). Compound 21 induced G2/M cell cycle arrest and its antiproliferative activity is 10-fold better than SAHA in multiple tumor cell lines. Western blot analysis showed that compound 21 can markedly increase the acetylation levels of tubulin, histone H3, and histone H4. Contrary to SAHA, compound 21 was found to inhibit autophagy. Additionally, compound 21 induced cell apoptosis via the Bax/Bcl-2 and caspase-3 pathways. Ultimately, compound 21 exhibited higher oral antitumor potency than SAHA in a A549 xenograft model. Our results indicated that compound 21 may be further developed as a promising anticancer agent.

Histone Deacetylases Cooperate with NF-κB to Support the Immediate Migratory Response after Zebrafish Pronephros Injury.

Acute kidney injury (AKI) is commonly associated with severe human diseases, and often worsens the outcome in hospitalized patients. The mammalian kidney has the ability to recover spontaneously from AKI; however, little progress has been made in the development of supportive treatments. Increasing evidence suggest that histone deacetylases (HDAC) and NF-κB promote the pathogenesis of AKI, and inhibition of Hdac activity has a protective effect in murine models of AKI. However, the role of HDAC at the early stages of recovery is unknown. We used the zebrafish pronephros model to study the role of epigenetic modifiers in the immediate repair response after injury to the tubular epithelium. Using specific inhibitors, we found that the histone deacetylase Hdac2, Hdac6, and Hdac8 activities are required for the repair via collective cell migration. We found that hdac6, hdac8, and nfkbiaa expression levels were upregulated in the repairing epithelial cells shortly after injury. Depletion of hdac6, hdac8, or nfkbiaa with morpholino oligonucleotides impaired the repair process, whereas the combined depletion of all three genes synergistically suppressed the recovery process. Furthermore, time-lapse video microscopy revealed that the lamellipodia and filopodia formation in the flanking cells was strongly reduced in hdac6-depleted embryos. Our findings suggest that Hdac activity and NF-κB are synergistically required for the immediate repair response in the zebrafish pronephros model of AKI, and the timing of HDAC inhibition might be important in developing supportive protocols in the human disease.

Design, and synthesis of N‐benzyl spiro‐piperidine hydroxamic acid‐based derivatives: Histone deacetylase inhibitory activity and drug‐likeness prediction

AbstractNonselective histone deacetylase (HDAC) inhibitors show dose‐limiting side effects due to the inhibition of multiple, essential HDAC subtypes that can be limited by selective inhibitors. We herein synthesized a new series of N‐benzyl spiro‐piperidinehydroxamic acid‐based derivatives, which have been identified as a zinc‐binding group by combining privileged structures with hydroxamic acid and N‐benzyl spiro‐piperidine. All the synthesized compounds had good antiproliferative activity against various tumor cell lines and were non‐toxic to the normal cells, AD293. Compound with halogen substitution (8i: 2,4‐dichloro and 8k: 2,4‐difluoro) shown 101.5‐ and 108‐fold selectivity towars HDAC6 inhibition over HDAC8 in‐vitro fluorometric‐based assay and compared with Tubastatin A. The obtained in‐vitro results were in agreement with molecular docking studies. The identified novel compounds occupy the catalytic domain of HDAC6 selectively and shed light on the role of both chlorine and fluorine instead of fluorination on benzohydroxamate‐based (ACS Med. Chem. Lett. 2021, 12(11), 1810–1817) structure over class I isoforms. These obtained results can be used in the design of novel, highly selective HDAC6 inhibitors.