Time-dependent dual mode of action of COX-2 inhibition on mouse serum corticosterone levels.

To elucidate the effect of cyclooxygenase-2 (COX-2) inhibition on corticosterone release, mice were divided into a group receiving NS398, a selective COX-2 inhibitor at a dose of 3 mg/kg for seven days, and a group receiving NS398 for fourteen days. After this time, the mice were sacrificed, and blood serum was collected. An ELISA protocol was used to analyze serum corticosterone levels. Short-term COX-2 inhibition increased corticosterone levels, while long-term inhibition lowered them. The exact schedule of experiments was repeated after the lipopolysaccharide (LPS) Escherichia coli challenge in mice to check the influence of stress stimuli on the tested parameters. In this case, we observed increases in corticosterone levels, significant in a seven-day pattern. These results indicate that corticosterone levels are regulated through a COX-2-dependent mechanism in mice.

The BCL-2 inhibitor APG-2575 resets tumor-associated macrophages toward the M1 phenotype, promoting a favorable response to anti-PD-1 therapy via NLRP3 activation.

The main challenges in the use of immune checkpoint inhibitors (ICIs) are ascribed to the immunosuppressive tumor microenvironment and the lack of sufficient infiltration of activated CD8+ T cells. Transforming the tumor microenvironment (TME) from "cold" to "hot" and thus more likely to potentiate the effects of ICIs is a promising strategy for cancer treatment. We found that the selective BCL-2 inhibitor APG-2575 can enhance the antitumor efficacy of anti-PD-1 therapy in syngeneic and humanized CD34+ mouse models. Using single-cell RNA sequencing, we found that APG-2575 polarized M2-like immunosuppressive macrophages toward the M1-like immunostimulatory phenotype with increased CCL5 and CXCL10 secretion, restoring T-cell function and promoting a favorable immunotherapy response. Mechanistically, we demonstrated that APG-2575 directly binds to NF-κB p65 to activate NLRP3 signaling, thereby mediating macrophage repolarization and the activation of proinflammatory caspases and subsequently increasing CCL5 and CXCL10 chemokine production. As a result, APG-2575-induced macrophage repolarization could remodel the tumor immune microenvironment, thus improving tumor immunosuppression and further enhancing antitumor T-cell immunity. Multiplex immunohistochemistry confirmed that patients with better immunotherapeutic efficacy had higher CD86, p-NF-κB p65 and NLRP3 levels, accompanied by lower CD206 expression on macrophages. Collectively, these data provide evidence that further study on APG-2575 in combination with immunotherapy for tumor treatment is required.

Phytotoxicity of nitrobenzene bioaccumulation in rice seedlings: Nitrobenzene inhibits growth, induces oxidative stress, and reduces photosynthetic pigment synthesis.

Nitrobenzene (NB) has been used in numerous industrial and agricultural fields as an organic compound intermediate. NB has mutagenicity and acute toxicity, and is typically a toxic pollutant in industrial wastewater worldwide. To evaluate its phytotoxicity, we treated rice (Oryza sativa) with different concentrations of NB (0, 5, 25, 50, 75, and 100 mg L-1). NB inhibited growth indices of rice (shoot and root length, fresh shoot and root weight, and dry shoot and root weight) as NB treatment concentrations increased. High concentrations (>25 mg L-1) of NB significantly inhibited rice root and shoot growth; root growth was more susceptible to NB. NB treatment could damage the structure and reduce the activity of rice seedling roots. The result of high performance liquid chromatography (HPLC) indicated that the bioaccumulation of NB in rice seedlings had a dose-dependent effect on the growth inhibition. NB reduced the photosynthetic pigment content and the expression levels of chlorophyll synthesis genes. NB treatment increased active oxygen radicals, electrical conductivity, malondialdehyde (MDA), proline, and soluble sugar contents. The expressions of antioxidant enzyme genes were induced by NB stress, and exhibited a phenomenon of initial increase followed by decrease. When the NB concentration was higher than 50 mg L-1, the gene expression levels decreased rapidly. This study provides insight into the association between exposure to NB and its phytotoxic effects on rice seedlings, and assesses the potential risk of NB bioaccumulation for crops that require a large amount of irrigation water.

Up-Regulation of Cyclooxygenase-2 (COX-2) Expression by Temozolomide (TMZ) in Human Glioblastoma (GBM) Cell Lines.

TMZ-resistance remains a main limitation in glioblastoma (GBM) treatment. TMZ is an alkylating agent whose cytotoxicity is modulated by O6-methylguanine-DNA methyltransferase (MGMT), whose expression is determined by MGMT gene promoter methylation status. The inflammatory marker COX-2 has been implicated in GBM tumorigenesis, progression, and stemness. COX-2 inhibitors are considered a GBM add-on treatment due to their ability to increase TMZ-sensitivity. We investigated the effect of TMZ on COX-2 expression in GBM cell lines showing different COX-2 levels and TMZ sensitivity (T98G and U251MG). ß-catenin, MGMT, and SOX-2 expression was analyzed. The effects of NS398, COX-2 inhibitor, alone or TMZ-combined, were studied evaluating cell proliferation by the IncuCyte® system, cell cycle/apoptosis, and clonogenic potential. COX-2, ß-catenin, MGMT, and SOX-2 expression was evaluated by RT-PCR, Western blotting, and immunofluorescence and PGE2 by ELISA. Our findings, sustaining the role of COX-2/PGE2 system in TMZ-resistance of GBM, show, for the first time, a relevant, dose-dependent up-regulation of COX-2 expression and activity in TMZ-treated T98G that, in turn, correlated with chemoresistance. Similarly, all the COX-2-dependent signaling pathways involved in TMZ-resistance also resulted in being up-modulated after treatment with TMZ. NS398+TMZ was able to reduce cell proliferation and induce cell cycle arrest and apoptosis. Moreover, NS398+TMZ counteracted the resistance in T98G preventing the TMZ-induced COX-2, ß-catenin, MGMT, and SOX-2 up-regulation.

The P300 acetyltransferase inhibitor C646 promotes membrane translocation of insulin receptor protein substrate and interaction with the insulin receptor.

Inhibition of P300 acetyltransferase activity by specific inhibitor C646 has been shown to improve insulin signaling. However, the underlying molecular mechanism of this improvement remains unclear. In this study, we analyzed P300 levels of obese patients and found that they were significantly increased in liver hepatocytes. In addition, large amounts of P300 appeared in the cytoplasm. Inhibition of P300 acetyltransferase activity by C646 drastically increased tyrosine phosphorylation of the insulin receptor protein substrates (IRS1/2) without affecting the tyrosine phosphorylation of the beta subunit of the insulin receptor (IRß) in hepatocytes in the absence of insulin. Since IRS1/2 requires membrane translocation and binding to inositol compounds for normal functions, we also examined the role of acetylation on binding to phosphatidylinositol(4,5)P2 and found that IRS1/2 acetylation by P300 reduced this binding. In contrast, we show that inhibition of IRS1/2 acetylation by C646 facilitates IRS1/2 membrane translocation. Intriguingly, we demonstrate that C646 activates IRß's tyrosine kinase activity and directly promotes IRß interaction with IRS1/2, leading to the tyrosine phosphorylation of IRS1/2 and subsequent activation of insulin signaling even in the absence of insulin. In conclusion, these data reveal the unique effects of C646 in activating insulin signaling in patients with obesity and diabetes.

Blockade of Cycloxygenase-2 ameliorates sepsis induced immune-suppression by regulating myeloid-derived suppressor cells.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) and cyclooxy-genase-2 (COX-2)/Prostaglandin E2 (PGE2) axis are important contributors to sepsis-induced immune-suppression. The purpose of present study is to explore whether COX-2 inhibitor can improve immunological disorder after sepsis via regulating MDSCs. METHODS: A ''two-hit'' model reflecting clinical sepsis development was performed. Cecal ligation and puncture (CLP) and Legionella pneumophila infection were used as the first and the second hit, respectively. NS398, a selective COX-2 inhibitor, was utilized to treat septic mice. The motality, bacterial counts in the lung, systematic inflammatory reaction and CD4 + T cells response after sepsis were assessed, so as the frequency and function of MDSCs. In some experiments, the number of MDSCs was manipulated by adoptive transfer or neutralizing antibody before induction of secondary infection. RESULTS: Mice surviving CLP showed a marked expansion and activation of MDSCs in spleen, accompanied by suppressed proliferating capability, impaired secreting functionand increased apoptosis of CD4 + T cells. Majority of CLP survivors became succumbed to L. pneumophila invasion, associated with defective bacteria elimination ability. NS398 treatment was found to ameliorate these adverse outcomes significantly. CONCLUSION: MDSCs contribute greatly to the sepsis-induced immune dysfunction. Inhibiting COX-2 may become a promising therapy that targets MDSCs-induced immunosuppression.

Synthesis, biological evaluation, and molecular docking of new series of antitumor and apoptosis inducers designed as VEGFR-2 inhibitors.

Based on quinazoline, quinoxaline, and nitrobenzene scaffolds and on pharmacophoric features of VEGFR-2 inhibitors, 17 novel compounds were designed and synthesised. VEGFR-2 IC50 values ranged from 60.00 to 123.85 nM for the new derivatives compared to 54.00 nM for sorafenib. Compounds 15a, 15b, and 15d showed IC50 from 17.39 to 47.10 µM against human cancer cell lines; hepatocellular carcinoma (HepG2), prostate cancer (PC3), and breast cancer (MCF-7). Meanwhile, the first in terms of VEGFR-2 inhibition was compound 15d which came second with regard to antitumor assay with IC50 = 24.10, 40.90, and 33.40 µM against aforementioned cell lines, respectively. Furthermore, Compound 15d increased apoptosis rate of HepG2 from 1.20 to 12.46% as it significantly increased levels of Caspase-3, BAX, and P53 from 49.6274, 40.62, and 42.84 to 561.427, 395.04, and 415.027 pg/mL, respectively. Moreover, 15d showed IC50 of 253 and 381 nM against HER2 and FGFR, respectively.

Fisetin suppresses cigarette smoke extract-induced epithelial to mesenchymal transition of airway epithelial cells through regulating COX-2/MMPs/ß-catenin pathway.

Cigarette smoke exposure leads to upregulation of cyclooxygenase-2 (COX-2), an inducible enzyme that synthesizes prostaglandin E2 (PGE2) and promotes airway inflammation. COX-2 overexpression is frequently implicated in inflammation, invasion, metastasis, and epithelial-mesenchymal transition (EMT). However, its detailed molecular mechanism in cigarette smoke induced EMT is not clear. Further, fisetin, a bioflavonoid, exhibits antioxidant and anti-inflammatory properties, but its effect in modulating COX-2-mediated inflammation and downstream sequelae remains unexplored. Therefore, we have investigated the mechanism of cigarette smoke-induced COX-2-mediated EMT in airway epithelial cells and examined the role of fisetin in controlling this aberration. MTT, trypan blue staining, gelatin zymography, Western blotting, invasion, wound healing, and tumor sphere formation assays in cigarette smoke extract (CSE) and/or fisetin treated airway epithelial cells, and in-silico molecular docking studies were performed. Results revealed that CSE exposure increased the expression and activity of COX-2, MMP-2/9, and ß-catenin and also enhanced expression of EMT markers leading to higher migration and invasion potential of airway epithelial cells. A specific COX-2 inhibitor NS-398 as well as fisetin treatment reversed the expression of EMT biomarkers, reduced the activity of MMP-2/9, and blocked the migration and invasion potential induced by CSE. Further, PGE2 also increased MMPs activity, invasion, and migration potential similar to CSE, which were significantly reversed by fisetin. In-silico studies showed a high binding affinity of fisetin to key EMT associated proteins, validating its anti-EMT potential. Thus, our study firstly unearths the mechanism of CSE-induced EMT in airway epithelial cells via COX-2/MMP/ß-catenin pathway, and secondly, it reveals that fisetin could significantly reverse CSE-induced EMT by inhibiting COX-2, indicating that fisetin could be an effective drug candidate for cigarette smoke-induced lung dysfunction.

The discovery of a novel series of potential ERRα inverse agonists based on p-nitrobenzenesulfonamide template for triple-negative breast cancer in vivo.

Oestrogen related receptor α participated in the regulation of oxidative metabolism and mitochondrial biogenesis, and was overexpressed in many cancers including triple-negative breast cancer. A set of new ERRα inverse agonists based on p-nitrobenzenesulfonamide template were discovered and compound 11 with high potent activity (IC50 = 0.80 µM) could significantly inhibit the transcription of ERRα-regulated target genes. By regulating the downstream signalling pathway, compound 11 could suppress the migration and invasion of the ER-negative MDA-MB-231 cell line. Furthermore, compound 11 demonstrated a significant growth suppression of breast cancer xenograft tumours in vivo (inhibition rate 23.58%). The docking results showed that compound 11 could form hydrogen bonds with Glu331 and Arg372 in addition to its hydrophobic interaction with ligand-binding domain. Our data implied that compound 11 represented a novel and effective ERRα inverse agonist, which had broad application prospects in the treatment of triple-negative breast cancer.

Development of hypoxia-activated PROTAC exerting a more potent effect in tumor hypoxia than in normoxia.

Hypoxia is a hallmark of many solid tumors, and it causes the overexpression of a variety of proteins including the epidermal growth factor receptor (EGFR). Many antitumor prodrugs have been designed to target hypoxia. Here we report the identification of a kind of hypoxia-activated proteolysis targeting chimera (ha-PROTAC) by introducing the hypoxia-activated leaving group (1-methyl-2-nitro-1H-imidazol-5-yl)methyl or 4-nitrobenzyl into the structure of an EGFRDel19-based PROTAC. Among the obtained molecules, ha-PROTAC 13 exhibits a more potent degradation activity for EGFRDel19 in hypoxia than in normoxia in HCC4006 cells. This is the first example of identifying a PROTAC to selectively act on tumors utilizing the characteristic of tumor hypoxia and provides a new approach for PROTAC development.

Investigation of NPB Analogs That Target Phosphorylation of BAD-Ser99 in Human Mammary Carcinoma Cells.

The design and development of a small molecule named NPB [3-{(4(2,3-dichlorophenyl)piperazin-1-yl}{2-hydroxyphenyl)methyl}-N-cyclopentylbenzamide], which specifically inhibited the phosphorylation of BAD at Ser99 in human carcinoma cells has been previously reported. Herein, the synthesis, characterization, and effect on cancer cell viability of NPB analogs, and the single-crystal X-ray crystallographic studies of an example compound (4r), which was grown via slow-solvent evaporation technique is reported. Screening for loss of viability in mammary carcinoma cells revealed that compounds such as 2[(4(2,3-dichlorophenyl)piperazin-1-yl][naphthalen-1-yl]methyl)phenol (4e), 5[(4(2,3-dichlorophenyl)piperazin-1-yl][2-hydroxyphenyl)methyl)uran-2-carbaldehyde (4f), 3[(2-hydroxyphenyl][4(p-tolyl)piperazin-1-yl)methyl)benzaldehyde (4i), and NPB inhibited the viability of MCF-7 cells with IC50 values of 5.90, 3.11, 7.68, and 6.5 µM, respectively. The loss of cell viability was enhanced by the NPB analogs synthesized by adding newer rings such as naphthalene and furan-2-carbaldehyde in place of N-cyclopentyl-benzamide of NPB. Furthermore, these compounds decreased Ser99 phosphorylation of hBAD. Additional in silico density functional theory calculations suggested possibilities for other analogs of NPB that may be more suitable for further development.

Upregulation of the mGlu5 receptor and COX-2 protein in the mouse brain after imipramine and NS398, searching for mechanisms of regulation.

Imipramine belongs to a group of tricyclic antidepressants (TCAs). It has been also documented that its antidepressant activity connects with the modulation of cytosolic phospholipase A2 (cPLA2) and arachidonic acid (AA) turnover. Through this mechanism, imipramine can indirectly modify glutamate (Glu) transmission. Additionally, it has been shown that chronic treatment with imipramine results in the upregulation of the metabotropic glutamate receptor subtype 5 (mGlu5 receptor) in the hippocampus of rats. Our previous study revealed that manipulation of the AA pathway via inhibition of cyclooxygenase-2 (COX-2) by selective COX-2 inhibitor (NS398) could effectively modulate the behavior of mice treated with imipramine. Here, we hypothesized that COX-2 inhibition could similarly to imipramine influence mGlu5 receptor, and thus NS398 can modulate the effect of imipramine on Glu. Moreover, such regulation changes should correspond with alterations in neurotransmission. Increased cPLA activity after imipramine administration may change the activity of the AA pathway and the endocannabinoid metabolism, e.g., 2-Arachidonyl-glycerol (2-AG). To verify the idea, mGlu5 receptor level was investigated in the hippocampus (HC) and prefrontal cortex (PFC) of mice treated for 7 or 14 days with imipramine and/or COX-2 inhibitor: NS398. Western blot and PCR analyses were conducted. Moreover, the excitatory (Glu) and inhibitory (gamma-aminobutyric acid; GABA) neurotransmitters were measured using HPLC and 2-AG using ELISA. A time-dependent change in mGlu5 receptor and COX-2 protein level, COX-2 expression, and 2-AG level in the PFC after imipramine administration was found. Up-regulation of mGlu5 receptor after NS398 was found in HC and PFC. A structure-dependent shift between excitatory vs. inhibitory transmission was detected when NS398 and imipramine were co-administered.

NS398 as a potential drug for autosomal-dominant polycystic kidney disease: Analysis using bioinformatics, and zebrafish and mouse models.

Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by uncontrolled renal cyst formation, and few treatment options are available. There are many parallels between ADPKD and clear-cell renal cell carcinoma (ccRCC); however, few studies have addressed the mechanisms linking them. In this study, we aimed to investigate their convergences and divergences based on bioinformatics and explore the potential of compounds commonly used in cancer research to be repurposed for ADPKD. We analysed gene expression datasets of ADPKD and ccRCC to identify the common and disease-specific differentially expressed genes (DEGs). We then mapped them to the Connectivity Map database to identify small molecular compounds with therapeutic potential. A total of 117 significant DEGs were identified, and enrichment analyses results revealed that they are mainly enriched in arachidonic acid metabolism, p53 signalling pathway and metabolic pathways. In addition, 127 ccRCC-specific up-regulated genes were identified as related to the survival of patients with cancer. We focused on the compound NS398 as it targeted DEGs and found that it inhibited the proliferation of Pkd1-/- and 786-0 cells. Furthermore, its administration curbed cystogenesis in Pkd2 zebrafish and early-onset Pkd1-deficient mouse models. In conclusion, NS398 is a potential therapeutic agent for ADPKD.

Simultaneous CK2/TNIK/DYRK1 inhibition by 108600 suppresses triple negative breast cancer stem cells and chemotherapy-resistant disease.

Triple negative breast cancer (TNBC) remains challenging because of heterogeneous responses to chemotherapy. Incomplete response is associated with a greater risk of metastatic progression. Therefore, treatments that target chemotherapy-resistant TNBC and enhance chemosensitivity would improve outcomes for these high-risk patients. Breast cancer stem cell-like cells (BCSCs) have been proposed to represent a chemotherapy-resistant subpopulation responsible for tumor initiation, progression and metastases. Targeting this population could lead to improved TNBC disease control. Here, we describe a novel multi-kinase inhibitor, 108600, that targets the TNBC BCSC population. 108600 treatment suppresses growth, colony and mammosphere forming capacity of BCSCs and induces G2M arrest and apoptosis of TNBC cells. In vivo, 108600 treatment of mice bearing triple negative tumors results in the induction of apoptosis and overcomes chemotherapy resistance. Finally, treatment with 108600 and chemotherapy suppresses growth of pre-established TNBC metastases, providing additional support for the clinical translation of this agent to clinical trials.

Cyclooxygenase-dependent mechanisms mediate in part the anti-dilatory effects of perivascular adipose tissue in uterine arteries from pregnant rats.

Uterine perivascular adipose tissue (PVAT) contributes to uterine blood flow regulation in pregnancy, at least in part, due to its effects on uterine artery reactivity. We tested the hypothesis that uterine PVAT modulates the balance between the contribution of nitric oxide synthase (NOS)- and cyclooxygenase (COX)-dependent pathways to acetylcholine (ACh)-induced relaxation in isolated uterine arteries. Concentration-response curves to ACh (1 nM - 30 µM) were performed on uterine arteries from pregnant and non-pregnant rats. Arteries were exposed to Krebs-Henseleit solution (control) or PVAT-conditioned media (PVATmedia) in the presence of the following inhibitors: L-NAME (NOS inhibitor), indomethacin (COX inhibitor), SC560 (COX-1 inhibitor), NS398 (COX-2 inhibitor), SQ 29,548 (thromboxane receptor (TP) inhibitor). In arteries incubated with PVATmedia, the presence of indomethacin increased ACh-induced relaxation, reversing the anti-dilatory effect of PVATmedia. NOS inhibition reduced ACh-induced relaxation in uterine arteries from pregnant rats, and exposure to PVATmedia did not change this effect. Selective inhibition of COX-1 but not COX-2 suppressed relaxation responses to ACh in control arteries. The presence of PVATmedia abolished the effect of COX-1 inhibition. Incubation of uterine arteries from pregnant rats with PVATmedia increased production of thromboxane B2 (TxB2, p = 0.01) but thromboxane receptor (TP) inhibition did not affect the anti-dilatory properties of PVATmedia. In conclusion, inhibition of COX signaling suppressed the anti-dilatory effects of PVATmedia, while PVATmedia had no effect on the contribution of the NOS/NO pathway to ACh-induced relaxation in uterine arteries from pregnant rats, indicating that the anti-dilatory effects of uterine PVAT are mediated in part by COX-dependent mechanisms.

Ghrelin Regulates Cyclooxygenase-2 Expression and Promotes Gastric Cancer Cell Progression.

AIM: To research the molecular mechanism of ghrelin in apoptosis, migratory, and invasion of gastric cancer (GC) cells. METHODS: After GC AGS cells were handled with ghrelin (10-8 M), cyclooxygenase-2 inhibitor NS398 (100 µM), and Akt inhibitor perifosine (10uM), the rates of apoptosis were detected by TUNEL assay and flow cytometry assay. We assessed the expressions of PI3K, p-Akt, and COX-2 proteins by making use of Western blot analysis. The cell migratory and invasion were detected by using wound-healing and transwell analysis. RESULTS: The migratory and invasion were increased in ghrelin-treated cells, while the rates of apoptosis were decreased. GC AGS cells treated with ghrelin showed an increase in protein expression of p-Akt, PI3K, and COX-2. After cells were treated with Akt inhibitor perifosine, the protein expression of p-Akt, PI3K, and COX-2 and the cell migratory, invasion, and apoptosis were partly recovered. After cells were treated with cyclooxygenase-2 inhibitor NS398, the protein expression of COX-2 and the cell migratory and invasion were decreased, while the rates of apoptosis were increased. CONCLUSION: Ghrelin regulates cell migration, invasion, and apoptosis in GC cells through targeting PI3K/Akt/COX-2. Ghrelin increases the expression of COX-2 in GC cells by targeting PI3K/Akt. Ghrelin is suggested to be one of the molecular targets in GC.

Design, Synthesis, and Evaluation of o-(Biphenyl-3-ylmethoxy)nitrophenyl Derivatives as PD-1/PD-L1 Inhibitors with Potent Anticancer Efficacy In Vivo.

Two series of novel o-(biphenyl-3-ylmethoxy)nitrophenyl compounds (A1-31 and B1-17) were designed as programmed cell death protein 1 (PD-1)/PD-ligand 1 (PD-L1) inhibitors. All compounds showed significant inhibitory activity with IC50 values ranging from 2.7 to 87.4 nM except compound A17, and compound B2 displayed the best activity. Further experiments showed that B2 bound to the PD-L1 protein without obvious toxicity in Lewis lung carcinoma (LLC) cells. Furthermore, B2 significantly promoted interferon-gamma secretion in a dose-dependent manner in vitro and in vivo. Especially, B2 exhibited potent in vivo anticancer efficacy in an LLC-bearing allograft mouse model at a low dose of 5 mg/kg, which was more active than BMS-1018 (tumor growth inhibition rate: 48.5% vs 17.8%). A panel of immunohistochemistry and flow cytometry assays demonstrated that B2 effectively counteracted PD-1-induced immunosuppression in the tumor microenvironment, thereby triggering antitumor immunity. These results indicate that B2 is a promising PD-1/PD-L1 inhibitor worthy of further development.

Histone acetyltransferase EP300 regulates the proliferation and differentiation of neural stem cells during adult neurogenesis and regenerative neurogenesis in the zebrafish optic tectum.

Zebrafish have a greater capacity for adult neurogenesis and brain regeneration than mammals. In the adult zebrafish optic tectum (OT), neuroepithelial-like stem cells (NE) contribute to adult neurogenesis, whereas radial glia (RG) contribute to neuronal regeneration after the stab wound injury. The molecular mechanisms regulated by acetylated histone play important roles in these events; however, the functions of histone acetyltransferase (HAT) require further elucidation. The aim of this study was to study the proliferation and differentiation of neural stem cells (NSCs) following treatment with C646, a HAT EP300 inhibitor, to identify the functions of HAT in adult neurogenesis and neuronal regeneration. C646 treatment decreased acetylation of histone 3 lysine 9 in the adult OT. Under physiological conditions, C646 promoted NE proliferation and generation of newborn neurons. EP300 inhibition promoted RG proliferation but suppressed the generation of newborn neurons after the injury. EP300 inhibition downregulated the Notch target genes her4 and her6, which was correlated with NE and RG proliferation in the adult OT. EP300 inhibition regulates the proliferation and differentiation of NSCs by inhibiting histone acetylation and Notch target genes expression, suggesting that the functions of HAT in neurogenesis are opposite to those of histone deacetylase.

Is PF-00835231 a Pan-SARS-CoV-2 Mpro Inhibitor? A Comparative Study.

The COVID-19 outbreak continues to spread worldwide at a rapid rate. Currently, the absence of any effective antiviral treatment is the major concern for the global population. The reports of the occurrence of various point mutations within the important therapeutic target protein of SARS-CoV-2 has elevated the problem. The SARS-CoV-2 main protease (Mpro) is a major therapeutic target for new antiviral designs. In this study, the efficacy of PF-00835231 was investigated (a Mpro inhibitor under clinical trials) against the Mpro and their reported mutants. Various in silico approaches were used to investigate and compare the efficacy of PF-00835231 and five drugs previously documented to inhibit the Mpro. Our study shows that PF-00835231 is not only effective against the wild type but demonstrates a high affinity against the studied mutants as well.

Effects of the histone acetylase inhibitor C646 on growth and differentiation of adipose-derived stem cells.

As an important histone acetylase, the transcriptional coactivator P300/CBP affects target gene expression and plays a role in the maintenance of stem cell characteristics and differentiation potential. In this study, we explored the action of a highly effective selective histone acetylase inhibitor, C646, on goat adipose-derived stem cells (gADSCs), and investigated the impact of histone acetylation on the growth characteristics and the differentiation potential of ADSCs. We found that C646 blocked the cell proliferation, arrested the cell cycle, and triggered apoptosis. Notably, immunocytochemistry and western blot analyses showed that the acetylation level of histone H3K9 was increased. Moreover, although real-time quantitative PCR and western blot confirmed that P300 expression was inhibited under these conditions, the expression level of two other histone acetylases, TIP60 and PCAF, was significantly increased. Furthermore, C646 clearly promoted the differentiation of gADSCs into adipocytes and had an impact on their differentiation into neuronal cells. This study provides new insights into the epigenetic regulation of stem cell differentiation and may represent an experimental basis for the comprehension of stem cell characteristics and function. Furthermore, it is of great relevance for the application of adult stem cells to somatic cell cloning, which may improve the efficiency of large livestock cloning and foster the production of transgenic animals.