pyrimidinones and cambinol

Neuro-inflammation accompanies numerous neurological disorders and conditions where it can be associated with a progressive neurodegenerative pathology. In a similar manner, alterations in sphingolipid metabolism often accompany or are causative features in degenerative neurological conditions. These include dementias, motor disorders, autoimmune conditions, inherited metabolic disorders, viral infection, traumatic brain and spinal cord injury, psychiatric conditions, and more. Sphingolipids are major regulators of cellular fate and function in addition to being important structural components of membranes. Their metabolism and signaling pathways can also be regulated by inflammatory mediators. Therefore, as certain sphingolipids exert distinct and opposing cellular roles, alterations in their metabolism can have major consequences. Recently, regulation of bioactive sphingolipids by neuro-inflammatory mediators has been shown to activate a neuronal NADPH oxidase 2 (NOX2) that can provoke damaging oxidation. Therefore, the sphingolipid-regulated neuronal NOX2 serves as a mechanistic link between neuro-inflammation and neurodegeneration. Moreover, therapeutics directed at sphingolipid metabolism or the sphingolipid-regulated NOX2 have the potential to alleviate neurodegeneration arising out of neuro-inflammation.

Topics: AIDS Dementia Complex; Animals; Biological Products; Brain Diseases, Metabolic, Inborn; Drug Discovery; Encephalitis, Viral; Enzyme Activation; Enzyme Replacement Therapy; Humans; Inflammation; NADPH Oxidase 2; Naphthalenes; Nerve Tissue Proteins; Neurodegenerative Diseases; Neurons; Oxidation-Reduction; Pyrimidinones; Reactive Oxygen Species; Sphingolipids; Zika Virus Infection

Sirtuins are a family of NAD+-dependent deacetylases (class III histone deacetylases). Seven mammalian sirtuins, SIRT1-7, are identified, as the functions and locations differ greatly. SIRT1 and SIRT2 locate in nucleus and cytoplasm, while SIRT3-5 in mitochondria. Sirtuins are not only involved in many important biological processes such as apoptosis, cellular senescence, endocrine signaling, glucose homeostasis, aging, and longevity, it can also control circadian clocks and mitochondrial biogenesis. Small molecules that can modulate the sirtuins activity have been shown to have potentials for treating many human diseases such as type II diabetes, cancer, rheumatoid arthritis, cardiovascular and other age-relating diseases. Some polyphenolic natural products such as Resveratrol, Fisetin, and Quercetin have demonstrated health benefits due to their SIRT1 activation effects. Some structurally diverse synthetic compounds, such as SRT1720, SRT1460, Selisistat (EX 527), and AGK2 were used as small molecular SIRT modulators (IC50 = 0.04-100 μM) to treat ischemic stroke, myocardial infarction, neurodegenerative diseases, cancer, aging, and obesity. In order to get better understanding of how the small molecules interact with the sirtuin, the small molecules that having SIRT inhibitory or activation effect, found by HTS or other modern medicinal chemistry techniques, are reviewed in this article.

Topics: Humans; Imidazoles; Naphthalenes; Neoplasms; Neurodegenerative Diseases; Polyphenols; Pyrimidinones; Resveratrol; Sirtuins; Small Molecule Libraries; Stilbenes; Triterpenes

Breast cancer (BC) is a heterogeneous disease with different intrinsic subtypes. The most aggressive subtype of BC-triple-negative breast cancer (TNBC) is characterized by high heterogeneity and metastasis rate, poor prognosis and lack of therapeutic targets due to the absence of estrogen receptor, progesterone receptor and human epidermal growth factor receptor 2. Targeted therapies have been approved for many other cancers and even other subtypes of BC, but treatment options for TNBC are still mainly limited to chemotherapy. Therefore, new, more effective treatment regimens are needed. Combined chemotherapy with two or more active agents is considered a promising anti-neoplasm tool in order to achieve better therapeutic response and reduce therapy-related adverse effects. The study demonstrated an antagonistic effect commonly used in TNBC therapy cytostatic drug-paclitaxel (PAX) and sirtuin inhibitor: cambinol (CAM) in BT-549, MDA-MB-468 and HCC1937 TNBC cell lines. The type of pharmacological interaction was determined by a precise and rigorous pharmacodynamic method-isobolographic analysis. The cytotoxic and anti-proliferative effects of CAM used alone or combined with PAX were determined utilizing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-bromo-2'-deoxyuridine (BrdU) assays, respectively. Induction of apoptosis in TNBC cell lines after PAX and CAM treatment applied individually or in combination was determined by flow cytometry (FACS) as a number of cells with active caspase-3. It has been observed that both agents used separately inhibit cell proliferation and induce apoptosis; however, applying them in combination ameliorated antiproliferative and pro-apoptotic effects in all analyzed TNBC cell lines. Our results demonstrate that CAM and PAX used in combination act antagonistically, limiting anti-cancer efficacy and showing the importance of preclinical testing.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; Humans; Naphthalenes; Paclitaxel; Pyrimidinones; Sirtuins; Triple Negative Breast Neoplasms

Multidrug resistance (MDR) counteracts the efficiency of sorafenib, an important first-line therapy for hepatocellular carcinoma (HCC). Sirtuins (SIRTs) 1 and 2 are associated with tumor progression and MDR. We treated 2D and 3D cultures (which mimic the features of in vivo tumors) from HCC cells with sorafenib alone or in the presence of SIRTs 1 and 2 inhibitors (cambinol or EX-527; combined treatments). Cultures subjected to combined treatments showed a greater fall in cellular viability, proliferation (PCNA, cyclin D1 and Ki-67 expression and cell cycle analysis), migration and invasion when compared with cultures treated only with sorafenib. Similarly, combined treatments produced more apoptosis (annexin V/PI, caspase-3/7 activity) than sorafenib alone. Since cell cycle dysregulation and apoptotic blockage are reported mechanisms of MDR, the modulation found in PCNA, cyclin D1, Ki-67 and caspase-3/7 proteins by cambinol and EX-527 are probably playing a role in enhancing the sensitivity of HCC cell lines to sorafenib. EX-527 reduced MRP3 and BCRP expression in sorafenib-treated HCC cells. Since ABC transporters contribute to MDR, MRP3 and BCRP could be also influencing in the response of HCC cells to sorafenib. Overall, 2D and 3D cultures behave similarly except that 3D cultures were less sensitive to treatments, reinforcing the clinical relevance of the current study. Findings presented in this manuscript support a potential application for SIRTs 1 and 2 inhibitors since we demonstrated that these compounds enhance the inhibitory effect of sorafenib upon treatment of hepatocellular carcinoma cells lines.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; ATP Binding Cassette Transporter, Subfamily G, Member 2; Carbazoles; Carcinoma, Hepatocellular; Cell Cycle Proteins; Cell Movement; Cell Proliferation; Drug Resistance, Neoplasm; Hep G2 Cells; Histone Deacetylase Inhibitors; Humans; Liver Neoplasms; Multidrug Resistance-Associated Proteins; Naphthalenes; Neoplasm Invasiveness; Neoplasm Proteins; Pyrimidinones; Signal Transduction; Sirtuin 1; Sirtuin 2; Sorafenib; Spheroids, Cellular

We have previously reported that cambinol (DDL-112), a known inhibitor of neutral sphingomyelinase-2 (nSMase2), suppressed extracellular vesicle (EV)/exosome production in vitro in a cell model and reduced tau seed propagation. The enzyme nSMase2 is involved in the production of exosomes carrying proteopathic seeds and could contribute to cell-to-cell transmission of pathological protein aggregates implicated in neurodegenerative diseases such as Parkinson's disease (PD). Here, we performed in vivo studies to determine if DDL-112 can reduce brain EV/exosome production and proteopathic alpha synuclein (αSyn) spread in a PD mouse model.. The acute effects of single-dose treatment with DDL-112 on interleukin-1β-induced extracellular vesicle (EV) release in brain tissue of Thy1-αSyn PD model mice and chronic effects of 5 week DDL-112 treatment on behavioral/motor function and proteinase K-resistant αSyn aggregates in the PD model were determined.. In the acute study, pre-treatment with DDL-112 reduced EV/exosome biogenesis and in the chronic study, treatment with DDL-112 was associated with a reduction in αSyn aggregates in the substantia nigra and improvement in motor function. Inhibition of nSMase2 thus offers a new approach to therapeutic development for neurodegenerative diseases with the potential to reduce the spread of disease-specific proteopathic proteins.

Topics: alpha-Synuclein; Animals; Brain; Disease Models, Animal; Enzyme Inhibitors; Exosomes; Mice, Transgenic; Naphthalenes; Parkinson Disease; Protein Aggregates; Pyrimidinones; Sirtuins; Sphingomyelin Phosphodiesterase

Breast cancer (BC) is the leading cause of death in women all over the world. Currently, combined chemotherapy with two or more agents is considered a promising anti-cancer tool to achieve better therapeutic response and to reduce therapy-related side effects. In our study, we demonstrated an antagonistic effect of cytostatic agent-cisplatin (CDDP) and histone deacetylase inhibitor: cambinol (CAM) for breast cancer cell lines with different phenotypes: estrogen receptor positive (MCF7, T47D) and triple negative (MDA-MB-231, MDA-MB-468). The type of pharmacological interaction was assessed by an isobolographic analysis. Our results showed that both agents used separately induced cell apoptosis; however, applying them in combination ameliorated antiproliferative effect for all BC cell lines indicating antagonistic interaction. Cell cycle analysis showed that CAM abolished cell cycle arrest in S phase, which was induced by CDDP. Additionally, CAM increased cell proliferation compared to CDDP used alone. Our data indicate that CAM and CDDP used in combination produce antagonistic interaction, which could inhibit anti-cancer treatment efficacy, showing importance of preclinical testing.

Topics: Apoptosis; Breast Neoplasms; Cell Cycle; Cisplatin; Drug Antagonism; Female; Histone Deacetylase Inhibitors; Humans; MCF-7 Cells; Models, Biological; Naphthalenes; Pyrimidinones

The accumulation of glucosylceramide (GlcCer), which is synthesized by UDP-glucose ceramide glucosyltransferase (UGCG), is associated with several diseases, including Gaucher disease and Parkinson's disease. Since the inhibition of UGCG can be used to treat diseases caused by GlcCer accumulation, several UGCG inhibitors have been developed. In this study, we report on the inhibition of UGCG activity by cambinol, a sirtuin inhibitor. Unlike conventional UGCG inhibitors, cambinol has no structural similarity to GlcCer. LC-ESI MS/MS analysis revealed that the cellular GlcCer levels were reduced by cambinol with an increase in ceramide, the GlcCer precursor. Histidine 193 plays an important role in the inhibition of UGCG via a known UGCG inhibitor, D-PDMP. However, cambinol was found to inhibit UGCG activity in a histidine 193-independent manner. This study provides insights into the mechanism of inhibition of UGCG activity by cambinol, and provides a basis for the development of a cambinol-based novel UGCG inhibitor.

Topics: Animals; Cell Line; Enzyme Inhibitors; Glucosylceramides; Glucosyltransferases; Humans; Intracellular Space; Mice; Naphthalenes; Pyrimidinones; Sirtuins

Methyltrioxorhenium mediated oxidative addition/elimination nucleophilic substitution yielded alkylamino and arylamino cambinol derivatives characterized by anti-proliferative activity against wild-type and p53 mutated MGH-U1 and RT112 bladder cancer cell lines. Some of the novel compounds showed an activity higher than that of the lead compound. The reaction was highly regioselective, affording for the first time a panel of C-2 cambinol substitution products. Aliphatic primary and secondary amines, and primary aromatic amines, were used as nitrogen centered nucleophiles. Surprisingly, the antiproliferative activity of C-2 substituted cambinol derivatives was not correlated to the induction of p53 protein, as evaluated by the analysis of the cell viability on wild-type and p53 mutated cancer cell lines, and further confirmed by western blot analyses. These data suggest that they exert their antiproliferative activity by a mechanism completely different from cambinol.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Humans; Molecular Structure; Naphthalenes; Oxidation-Reduction; Pyrimidinones; Structure-Activity Relationship; Urinary Bladder Neoplasms

Sirtuins (SIRTs) 1 and 2 deacetylases are overexpressed in hepatocellular carcinoma (HCC) and are associated with tumoral progression and multidrug resistance (MDR). In this study we analyzed whether SIRTs 1 and 2 activities blockage was able to affect cellular survival and migration and to modulate p53 and FoxO1 acetylation in HepG2 and Huh7 cells. Moreover, we analyzed ABC transporters P-glycoprotein (P-gp) and multidrug resistance-associated protein 3 (MRP3) expression. We used cambinol and EX-527 as SIRTs inhibitors. Both drugs reduced cellular viability, number of colonies and cellular migration and augmented apoptosis. In 3D cultures, SIRTs inhibitors diminished spheroid growth and viability. 3D culture was less sensitive to drugs than 2D culture. The levels of acetylated p53 and FoxO1 increased after treatments. Drugs induced a decrease in ABC transporters mRNA and protein levels in HepG2 cells; however, only EX-527 was able to reduce MRP3 mRNA and protein levels in Huh7 cells. This is the first work demonstrating the regulation of MRP3 by SIRTs. In conclusion, both drugs decreased HCC cells survival and migration, suggesting SIRTs 1 and 2 activities blockage could be beneficial during HCC therapy. Downregulation of the expression of P-gp and MRP3 supports the potential application of SIRTs 1 and 2 inhibitions in combination with conventional chemotherapy.

Topics: Acetylation; Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B; Carbazoles; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Survival; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; Liver Neoplasms; Multidrug Resistance-Associated Proteins; Naphthalenes; Neoplasm Proteins; Protein Processing, Post-Translational; Pyrimidinones; Sirtuin 1; Sirtuin 2

Targeting of molecular pathways involved in the cell-to-cell propagation of pathological tau species is a novel approach for development of disease-modifying therapies that could block tau pathology and attenuate cognitive decline in patients with Alzheimer's disease and other tauopathies. We discovered cambinol through a screening effort and show that it is an inhibitor of cell-to-cell tau propagation. Our in vitro data demonstrate that cambinol inhibits neutral sphingomyelinase 2 (nSMase2) enzyme activity in dose response fashion, and suppresses extracellular vesicle (EV) production while reducing tau seed propagation. Our in vivo testing with cambinol shows that it can reduce the nSMase2 activity in the brain after oral administration. Our molecular docking and simulation analysis reveals that cambinol can target the DK-switch in the nSMase2 active site.

Topics: Animals; Biosensing Techniques; Brain; Cell-Free System; Enzyme Inhibitors; Extracellular Vesicles; HEK293 Cells; Humans; Mice, Inbred C57BL; Models, Molecular; Naphthalenes; Permeability; Protein Domains; Pyrimidinones; Sphingomyelin Phosphodiesterase; tau Proteins; Tissue Extracts

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Antibodies; Disease Models, Animal; Disease Progression; Entorhinal Cortex; Humans; Mice; Models, Biological; Naphthalenes; Pyrimidinones; tau Proteins; Treatment Failure

The enzyme sphingomyelinase (SMase) is an important biomarker for several diseases such as Niemann Pick's, atherosclerosis, multiple sclerosis, and HIV. We present a two-component colorimetric SMase activity assay that is more sensitive and much faster than currently available commercial assays. Herein, SMase-triggered release of cysteine from a sphingomyelin (SM)-based liposome formulation with 60 mol % cholesterol causes gold nanoparticle (AuNP) aggregation, enabling colorimetric detection of SMase activities as low as 0.02 mU/mL, corresponding to 1.4 pM concentration. While the lipid composition offers a stable, nonleaky liposome platform with minimal background signal, high specificity toward SMase avoids cross-reactivity of other similar phospholipases. Notably, use of an SM-based liposome formulation accurately mimics the natural in vivo substrate: the cell membrane. We studied the physical rearrangement process of the lipid membrane during SMase-mediated hydrolysis of SM to ceramide using small- and wide-angle X-ray scattering. A change in lipid phase from a liquid to gel state bilayer with increasing concentration of ceramide accounts for the observed increase in membrane permeability and consequent release of encapsulated cysteine. We further demonstrated the effectiveness of the sensor in colorimetric screening of small-molecule drug candidates, paving the way for the identification of novel SMase inhibitors in minutes. Taken together, the simplicity, speed, sensitivity, and naked-eye readout of this assay offer huge potential in point-of-care diagnostics and high-throughput drug screening.

Topics: Animals; Biphenyl Compounds; Cattle; Colorimetry; Desipramine; Enzyme Inhibitors; Liposomes; Molecular Structure; Naphthalenes; Particle Size; Pyrimidinones; Sphingomyelin Phosphodiesterase; Surface Properties

Ceramide is a bioactive lipid that plays an important role in stress responses leading to apoptosis, cell growth arrest and differentiation. Ceramide production is due in part to sphingomyelin hydrolysis by sphingomyelinases. In brain, neutral sphingomyelinase 2 (nSMase2) is expressed in neurons and increases in its activity and expression have been associated with pro-inflammatory conditions observed in Alzheimer's disease, multiple sclerosis and human immunodeficiency virus (HIV-1) patients. Increased nSMase2 activity translates into higher ceramide levels and neuronal cell death, which can be prevented by chemical or genetic inhibition of nSMase2 activity or expression. However, to date, there are no soluble, specific and potent small molecule inhibitor tool compounds for in vivo studies or as a starting point for medicinal chemistry optimization. Moreover, the majority of the known inhibitors were identified using bacterial, bovine or rat nSMase2. In an attempt to identify new inhibitor scaffolds, two activity assays were optimized as screening platform using the recombinant human enzyme. First, active hits were identified using a fluorescence-based high throughput compatible assay. Then, hits were confirmed using a 14C sphingomyelin-based direct activity assay. Pharmacologically active compounds and approved drugs were screened using this strategy which led to the identification of cambinol as a novel uncompetitive nSMase2 inhibitor (Ki = 7 μM). The inhibitory activity of cambinol for nSMase2 was approximately 10-fold more potent than for its previously known target, silence information regulator 1 and 2 (SIRT1/2). Cambinol decreased tumor necrosis factor-α or interleukin-1 β-induced increases of ceramide and cell death in primary neurons. A preliminary study of cambinol structure and activity allowed the identification of the main structural features required for nSMase2 inhibition. Cambinol and its analogs may be useful as nSMase2 inhibitor tool compounds to prevent ceramide-dependent neurodegeneration.

Topics: Animals; Cattle; Cell Death; Cell Survival; Ceramides; Cytokines; Dendrites; Drug Evaluation, Preclinical; Enzyme Assays; Enzyme Inhibitors; Fluorescence; HEK293 Cells; Hippocampus; Humans; Interleukin-1beta; Naphthalenes; Neurons; Neuroprotective Agents; Pyrimidinones; Radioactivity; Rats, Sprague-Dawley; Recombinant Proteins; Sphingomyelin Phosphodiesterase; Structure-Activity Relationship; Tumor Necrosis Factor-alpha

Sirtuins are a family of NAD(+)-dependent protein deacetylases that play critical roles in epigenetic regulation, stress responses, and cellular aging in eukaryotic cells. In an effort to identify small molecule inhibitors of sirtuins for potential use as chemotherapeutics as well as tools to modulate sirtuin activity, we previously identified a nonselective sirtuin inhibitor called cambinol (IC50 ≈ 50 μM for SIRT1 and SIRT2) with in vitro and in vivo antilymphoma activity. In the current study, we used saturation transfer difference (STD) NMR experiments with recombinant SIRT1 and 20 to map parts of the inhibitor that interacted with the protein. Our ongoing efforts to optimize cambinol analogues for potency and selectivity have resulted in the identification of isoform selective analogues: 17 with >7.8-fold selectivity for SIRT1, 24 with >15.4-fold selectivity for SIRT2, and 8 with 6.8- and 5.3-fold selectivity for SIRT3 versus SIRT1 and SIRT2, respectively. In vitro cytotoxicity studies with these compounds as well as EX527, a potent and selective SIRT1 inhibitor, suggest that antilymphoma activity of this compound class may be predominantly due to SIRT2 inhibition.

Topics: Antineoplastic Agents; Apoptosis; Drug Discovery; Isoxazoles; Magnetic Resonance Spectroscopy; Naphthalenes; Pyrazolones; Pyrimidinones; Sirtuins; Structure-Activity Relationship

The Wnt signaling pathway is often chronically activated in diverse human tumors, and the Frizzled (FZD) family of receptors for Wnt ligands, are central to propagating oncogenic signals in a β-catenin-dependent and independent manner. SIRT1 is a class III histone deacetylase (HDAC) that deacetylates histone and non-histone proteins to regulate gene transcription and protein function. We previously demonstrated that SIRT1 loss of function led to a significant decrease in the levels of Dishevelled (Dvl) proteins. To further explore this connection between the sirtuins and components of the Wnt pathway, we analyzed sirtuin-mediated regulation of FZD proteins. Here we explore the contribution of sirtuin deacetylases in promoting constitutive Wnt pathway activation in breast cancer cells. We demonstrate that the use of small molecule inhibitors of SIRT1 and SIRT2, and siRNA specific to SIRT1, all reduce the levels of FZD7 mRNA. We further demonstrate that pharmacologic inhibition of SIRT1/2 causes a marked reduction in FZD7 protein levels. Additionally, we show that β-catenin and c-Jun occupy the 7 kb region upstream of the transcription start site of the FZD7 gene, and SIRT1 inhibition leads to a reduction in the occupancy of both β-catenin and c-Jun at points along this region. This work uncovers a new mechanism for the regulation of FZD7 and provides a critical new link between the sirtuins and FZD7, one of the earliest nodal points from which oncogenic Wnt signaling emanates. This study shows that inhibition of specific sirtuins may provide a unique strategy for inhibiting the constitutively active Wnt pathway at the level of the receptor.

Topics: beta Catenin; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Female; Frizzled Receptors; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; Naphthalenes; Promoter Regions, Genetic; Protein Binding; Pyrimidinones; RNA, Messenger; Sirtuin 1; Sirtuin 2

Sirtuins (SIRT1-7) are NAD(+)-dependent histone deacetylases (HDACs) that play an important role in the control of metabolism and proliferation and the development of age-associated diseases like oncologic, cardiovascular and neurodegenerative diseases. Cambinol was originally described as a compound inhibiting the activity of SIRT1 and SIRT2, with efficient anti-tumor activity in vivo. Here, we studied the effects of cambinol on microbial sensing by mouse and human immune cells and on host innate immune responses in vivo. Cambinol inhibited the expression of cytokines (TNF, IL-1β, IL-6, IL-12p40, and IFN-γ), NO and CD40 by macrophages, dendritic cells, splenocytes and whole blood stimulated with a broad range of microbial and inflammasome stimuli. Sirtinol, an inhibitor of SIRT1 and SIRT2 structurally related to cambinol, also decreased macrophage response to TLR stimulation. On the contrary, selective inhibitors of SIRT1 (EX-527 and CHIC-35) and SIRT2 (AGK2 and AK-7) used alone or in combination had no inhibitory effect, suggesting that cambinol and sirtinol act by targeting more than just SIRT1 and SIRT2. Cambinol and sirtinol at anti-inflammatory concentrations also did not inhibit SIRT6 activity in in vitro assay. At the molecular level, cambinol impaired stimulus-induced phosphorylation of MAPKs and upstream MEKs. Going well along with its powerful anti-inflammatory activity, cambinol reduced TNF blood levels and bacteremia and improved survival in preclinical models of endotoxic shock and septic shock. Altogether, our data suggest that pharmacological inhibitors of sirtuins structurally related to cambinol may be of clinical interest to treat inflammatory diseases.

Topics: Animals; Apoptosis; Benzamides; Blotting, Western; Cell Proliferation; Cells, Cultured; Cytokines; Flow Cytometry; Humans; Immunity, Innate; Inflammation; Klebsiella Infections; Klebsiella pneumoniae; Macrophages; Mice; Mice, Inbred BALB C; Mitogen-Activated Protein Kinases; Naphthalenes; Naphthols; Pyrimidinones; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Shock, Septic; Sirtuins

Several lines of evidence indicate that Sirt1, a class III histone deacetylase (HDAC) is implicated in the initiation and progression of malignancies and thus gained attraction as druggable target. Since data on the role of Sirt1 in pancreatic ductal adenocarcinoma (PDAC) are sparse, we investigated the expression profile and prognostic significance of Sirt1 in vivo as well as cellular effects of Sirt1 inhibition in vitro.. Sirt1 expression was analyzed by immunohistochemistry in a large cohort of PDACs and correlated with clinicopathological and survival data. Furthermore, we investigated the impact of overexpression and small molecule inhibition on Sirt1 in pancreatic cancer cell culture models including combinatorial treatment with chemotherapy and EGFR-inhibition. Cellular events were measured quantitatively in real time and corroborated by conventional readouts including FACS analysis and MTT assays.. We detected nuclear Sirt1 expression in 36 (27.9%) of 129 PDACs. SIRT1 expression was significantly higher in poorly differentiated carcinomas. Strong SIRT1 expression was a significant predictor of poor survival both in univariate (p = 0.002) and multivariate (HR 1.65, p = 0.045) analysis. Accordingly, overexpression of Sirt1 led to increased cell viability, while small molecule inhibition led to a growth arrest in pancreatic cancer cells and impaired cell survival. This effect was even more pronounced in combinatorial regimens with gefitinib, but not in combination with gemcitabine.. Sirt1 is an independent prognosticator in PDACs and plays an important role in pancreatic cancer cell growth, which can be levered out by small molecule inhibition. Our data warrant further studies on SIRT1 as a novel chemotherapeutic target in PDAC.

Topics: Aged; Aged, 80 and over; Carcinoma, Pancreatic Ductal; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Follow-Up Studies; Gefitinib; Gene Expression Regulation, Neoplastic; Humans; Middle Aged; Naphthalenes; Neoplasm Grading; Neoplasm Metastasis; Neoplasm Staging; Niacinamide; Pancreatic Neoplasms; Prognosis; Pyrimidinones; Quinazolines; Sirtuin 1

Sirtuins (SIRT1-7) are a highly conserved family of NAD(+)-dependent enzymes that control the activity of histone and nonhistone regulatory proteins. SIRT1 is purposed to promote longevity and to suppress the initiation of some cancers. Nevertheless, SIRT1 is reported to function as a tumor suppressor as well as an oncogenic protein. Our data show that compared with normal liver or surrounding tumor tissue, SIRT1 is strongly overexpressed in human hepatocellular carcinoma (HCC). In addition, human HCC cell lines (Hep3B, HepG2, HuH7, HLE, HLF, HepKK1, skHep1) were screened for the expression of the sirtuin family members and only SIRT1 was consistently overexpressed compared with normal hepatocytes. To determine its effect on HCC growth, SIRT1 activity was inhibited either with lentiviruses expressing short hairpin RNAs or with the small molecule inhibitor, cambinol. Knockdown or inhibition of SIRT1 activity had a cytostatic effect, characterized by an altered morphology, impaired proliferation, an increased expression of differentiation markers, and cellular senescence. In an orthotopic xenograft model, knockdown of SIRT1 resulted in 50% fewer animals developing tumors and cambinol treatment resulted in an overall lower tumor burden. Taken together, our data show that inhibition of SIRT1 in HCC cells impairs their proliferation in vitro and tumor formation in vivo. These data suggest that SIRT1 expression positively influences the growth of HCC and support further studies aimed to block its activity alone or in combination as a novel treatment strategy.

Topics: Animals; Carcinoma, Hepatocellular; Cell Cycle; Cell Line, Tumor; Disease Models, Animal; Female; Gene Expression; Gene Knockdown Techniques; Humans; Liver Neoplasms; Mice; Naphthalenes; Pyrimidinones; Sirtuin 1; Transplantation, Heterologous

In several inflammatory conditions such as rheumatoid arthritis or sepsis, the regulatory mechanisms of inflammation are inefficient and the excessive inflammatory response leads to damage to the host. Sirtuins are class III histone deacetylases that modulate the activity of several transcription factors that are implicated in immune responses. In this study, we evaluated the impact of sirtuin inhibition on the activation of lipopolysaccharide (LPS)-stimulated J774 macrophages by assessing the production of inflammatory cytokines. The pharmacologic inhibition of sirtuins decreased the production of tumour necrosis factor-alpha (TNF-α) interleukin 6 (IL-6) and Rantes. The reduction of cytokine production was associated with decreased nuclear factor kappa B (NF-κB) activity and inhibitor kappa B alpha (IκBα) phosphorylation while no impact was observed on the phosphorylation status of p38 mitogen-activated kinase (p38 MAPK). This work shows that sirtuin pharmacologic inhibitors are a promising tool for the treatment of inflammatory conditions.

Topics: Animals; Cell Line; Chemokine CCL5; Cytokines; Histone Deacetylase Inhibitors; Inflammation; Interleukin-6; Lipopolysaccharides; Macrophages; Mice; Mitogen-Activated Protein Kinase Kinases; Naphthalenes; NF-kappa B; Phosphorylation; Pyrimidinones; Sirtuins; Tumor Necrosis Factor-alpha

Sirtuins and hypoxia-inducible transcription factors (HIF) have well-established roles in regulating cellular responses to metabolic and oxidative stress. Recent reports have linked these two protein families by demonstrating that sirtuins can regulate the activity of HIF-1 and HIF-2. Here we investigated the role of SIRT1, a NAD+-dependent deacetylase, in the regulation of HIF-1 activity in hypoxic conditions. Our results show that in hepatocellular carcinoma (HCC) cell lines, hypoxia did not alter SIRT1 mRNA or protein expression, whereas it predictably led to the accumulation of HIF-1α and the up-regulation of its target genes. In hypoxic models in vitro and in in vivo models of systemic hypoxia and xenograft tumor growth, knockdown of SIRT1 protein with shRNA or inhibition of its activity with small molecule inhibitors impaired the accumulation of HIF-1α protein and the transcriptional increase of its target genes. In addition, endogenous SIRT1 and HIF-1α proteins co-immunoprecipitated and loss of SIRT1 activity led to a hyperacetylation of HIF-1α. Taken together, our data suggest that HIF-1α and SIRT1 proteins interact in HCC cells and that HIF-1α is a target of SIRT1 deacetylase activity. Moreover, SIRT1 is necessary for HIF-1α protein accumulation and activation of HIF-1 target genes under hypoxic conditions.

Topics: Animals; Benzamides; Blotting, Western; Carcinoma, Hepatocellular; Cell Hypoxia; Cell Line, Tumor; Female; Gene Expression Regulation, Neoplastic; Hep G2 Cells; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Liver Neoplasms, Experimental; Mice; Mice, Knockout; Mice, Nude; Naphthalenes; Naphthols; Protein Binding; Pyrimidinones; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Sirtuin 1; Transcriptional Activation; Transplantation, Heterologous; Tumor Burden

Histone deacetylase (HDAC) inhibitors have shown promise in the treatment of resistant and refractory tumors including neuroblastoma. The goal of the study was to compare the efficacy of a class III HDAC inhibitor (cambinol) to a class I and II inhibitor (vorinostat).. In vitro efficacy of vorinostat and cambinol, alone or in combination with doxorubicin, was assessed by 2-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide calorimetric assay using both wild-type (WT) and doxorubicin-resistant (DoxR) SK-N-SH neuroblastoma cells. In vivo efficacy was determined using the same drug combinations in nude mice bearing xenograft implants of WT and DoxR cells on opposite flanks.. Vorinostat and cambinol were efficacious against WT and DoxR neuroblastoma cells in vitro. In WT cells, the potency of the doxorubicin itself overshadowed any effect of cotherapy with vorinostat or cambinol. The effect of vorinostat and/or cambinol on the DoxR cells was constant across progressively increasing doses of doxorubicin. In the in vivo model, the efficacy of doxorubicin itself (88% reduction in tumor volume) again overshadowed any effect of cotreatment with vorinostat or cambinol on the WT tumors. However, in the DoxR tumors, doxorubicin alone had no efficacy, but cotreatment with either cambinol or vorinostat suppressed tumor growth (70% and 91% reduction in tumor volume, respectively).. Both the class III HDAC inhibitor cambinol and the class I/II HDAC inhibitor vorinostat have efficacy against SK-N-SH neuroblastoma cells, including those resistant to doxorubicin.

Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Mice; Mice, Nude; Naphthalenes; Neoplasm Proteins; Neuroblastoma; Pyrimidinones; Tumor Stem Cell Assay; Vorinostat; Xenograft Model Antitumor Assays

The N-Myc oncoprotein is a critical factor in neuroblastoma tumorigenesis which requires additional mechanisms converting a low-level to a high-level N-Myc expression. N-Myc protein is stabilized when phosphorylated at Serine 62 by phosphorylated ERK protein. Here we describe a novel positive feedback loop whereby N-Myc directly induced the transcription of the class III histone deacetylase SIRT1, which in turn increased N-Myc protein stability. SIRT1 binds to Myc Box I domain of N-Myc protein to form a novel transcriptional repressor complex at gene promoter of mitogen-activated protein kinase phosphatase 3 (MKP3), leading to transcriptional repression of MKP3, ERK protein phosphorylation, N-Myc protein phosphorylation at Serine 62, and N-Myc protein stabilization. Importantly, SIRT1 was up-regulated, MKP3 down-regulated, in pre-cancerous cells, and preventative treatment with the SIRT1 inhibitor Cambinol reduced tumorigenesis in TH-MYCN transgenic mice. Our data demonstrate the important roles of SIRT1 in N-Myc oncogenesis and SIRT1 inhibitors in the prevention and therapy of N-Myc-induced neuroblastoma.

Topics: Animals; Binding Sites; Cell Line, Tumor; Cell Proliferation; Dual Specificity Phosphatase 6; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Feedback, Physiological; Gene Expression Regulation, Neoplastic; Mice; Mice, Transgenic; Naphthalenes; Neuroblastoma; Phosphorylation; Promoter Regions, Genetic; Protein Stability; Proto-Oncogene Proteins c-myc; Pyrimidinones; Random Allocation; Sirtuin 1; Sp1 Transcription Factor; Tumor Burden

The tenovins and cambinol are two classes of sirtuin inhibitor that exhibit antitumor activity in preclinical models. This report describes modifications to the core structure of cambinol, in particular by incorporation of substituents at the N1-position, which lead to increased potency and modified selectivity. These improvements have been rationalized using molecular modeling techniques. The expected functional selectivity in cells was also observed for both a SIRT1 and a SIRT2 selective analog.

Topics: Amino Acid Sequence; Cell Line, Tumor; Humans; Molecular Sequence Data; Naphthalenes; Pyrimidinones; Sirtuins; Substrate Specificity

Megakaryocytic cells (Mks) undergo endomitosis and become polyploid. Mk ploidy correlates with platelet production. We previously showed that nicotinamide (NIC) greatly increases Mk ploidy in cultures of human mobilized peripheral blood CD34(+) cells. This study aims to examine the generality of NIC effects, NIC's impact on Mk ultrastructure, and potential mechanisms for the increased ploidy.. We used electron microscopy to examine Mk ultrastructure and flow cytometry to evaluate NIC effects on Mk differentiation and ploidy in mobilized peripheral blood CD34(+) cell cultures under diverse megakaryopoietic conditions. Mk ploidy and NAD(H) content were evaluated for NIC and other NAD(+) precursors. We tested additional inhibitors of the sirtuin (or SIRT) 1 and SIRT2 histone/protein deacetylases and, after treatment with NIC, evaluated changes in the acetylation of SIRT1/2 targets.. NIC increased ploidy under diverse culture conditions and did not alter Mk ultrastructure; 6.25 mM NIC increased NAD(+) levels fivefold. Quinolinic acid increased NAD(+) similar to that for 1 mM NIC, but yielded a much smaller ploidy increase. Similar increases in Mk ploidy were obtained using NIC or the SIRT1/2 inhibitor cambinol, while the SIRT2 inhibitor AGK2 moderately increased ploidy. SIRT1/2 inhibition in cells treated with NIC was evidenced by increased acetylation of nucleosomes and p53. Greater p53 acetylation with NIC was associated with increased binding of p53 to its consensus DNA binding sequence.. NIC greatly increases Mk ploidy under a wide range of conditions without altering Mk morphology. Inhibition of SIRT1 and/or SIRT2 is primarily responsible for NIC effects on Mk maturation.

Topics: Acetylation; Aneugens; Apoptosis; Cell Culture Techniques; Cells, Cultured; Consensus Sequence; Cytokines; DNA; Humans; Megakaryocytes; NAD; Naphthalenes; Niacinamide; Nucleosomes; Polyploidy; Protein Binding; Protein Processing, Post-Translational; Pyrimidinones; Sirtuin 1; Sirtuin 2; Tumor Suppressor Protein p53

SIRT1 and other NAD-dependent deacetylases have been implicated in control of cellular responses to stress and in tumorigenesis through deacetylation of important regulatory proteins, including p53 and the BCL6 oncoprotein. Hereby, we describe the identification of a compound we named cambinol that inhibits NAD-dependent deacetylase activity of human SIRT1 and SIRT2. Consistent with the role of SIRT1 in promoting cell survival during stress, inhibition of SIRT1 activity with cambinol during genotoxic stress leads to hyperacetylation of key stress response proteins and promotes cell cycle arrest. Treatment of BCL6-expressing Burkitt lymphoma cells with cambinol as a single agent induced apoptosis, which was accompanied by hyperacetylation of BCL6 and p53. Because acetylation inactivates BCL6 and has the opposite effect on the function of p53 and other checkpoint pathways, the antitumor activity of cambinol in Burkitt lymphoma cells may be accomplished through a combined effect of BCL6 inactivation and checkpoint activation. Cambinol was well tolerated in mice and inhibited growth of Burkitt lymphoma xenografts. Inhibitors of NAD-dependent deacetylases may constitute novel anticancer agents.

Topics: Acetylation; Animals; Antineoplastic Agents; Burkitt Lymphoma; Cell Line, Tumor; DNA-Binding Proteins; Enzyme Inhibitors; Histone Deacetylase Inhibitors; Humans; Mice; Naphthalenes; Proto-Oncogene Proteins c-bcl-6; Pyrimidinones; Sirtuin 1; Sirtuin 2; Sirtuins; Tubulin; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays