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2.
Nat Chem ; 15(5): 729-739, 2023 05.
Article in English | MEDLINE | ID: mdl-36997700

ABSTRACT

Non-destructive fluorophore diffusion across cell membranes to provide an unbiased fluorescence intensity readout is critical for quantitative imaging applications in live cells and tissues. Commercially available small-molecule fluorophores have been engineered for biological compatibility, imparting high water solubility by modifying rhodamine and cyanine dye scaffolds with multiple sulfonate groups. The resulting net negative charge, however, often renders these fluorophores cell-membrane-impermeant. Here we report the design and development of our biologically compatible, water-soluble and cell-membrane-permeable fluorophores, termed OregonFluor (ORFluor). By adapting previously established ratiometric imaging methodology using bio-affinity agents, it is now possible to use small-molecule ORFluor-labelled therapeutic inhibitors to quantitatively visualize their intracellular distribution and protein target-specific binding, providing a chemical toolkit for quantifying drug target availability in live cells and tissues.


Subject(s)
Fluorescent Dyes , Water , Fluorescent Dyes/chemistry , Rhodamines/chemistry
4.
ACS Omega ; 7(20): 17083-17097, 2022 May 24.
Article in English | MEDLINE | ID: mdl-35647450

ABSTRACT

The anaplastic lymphoma kinase (ALK) is abnormally expressed and hyperactivated in a number of tumors and represents an ideal therapeutic target. Despite excellent clinical responses to ALK inhibition, drug resistance still represents an issue and novel compounds that overcome drug-resistant mutants are needed. We designed, synthesized, and evaluated a large series of azacarbazole inhibitors. Several lead compounds endowed with submicromolar potency were identified. Compound 149 showed selective inhibition of native and mutant drug-refractory ALK kinase in vitro as well as in a Ba/F3 model and in human ALK+ lymphoma cells. The three-dimensional (3D) structure of a 149:ALK-KD cocrystal is reported, showing extensive interaction through the hinge region and the catalytic lysine 1150.

5.
Eur J Med Chem ; 238: 114488, 2022 Aug 05.
Article in English | MEDLINE | ID: mdl-35665691

ABSTRACT

The Anaplastic Lymphoma Kinase (ALK) is a therapeutic target for personalized medicine in selected cancers. Despite excellent clinical responses to ALK inhibitors, most patients develop drug resistance and relapse. New compounds with alternative binding modes are needed to overcome resistant mutants. Here we describe a medicinal chemistry effort to the design and development of novel ALK inhibitors based on a 4,6-substituted α-carboline scaffold. Active compounds were able to inhibit the gatekeeper L1196M mutant, in several cases better than the wild-type enzyme. Compound 43 showed potent non-ATP-competitive inhibition of wild-type and mutant ALK, including G1202R, in biochemical and cellular assays, as well as in xenograft mouse models.


Subject(s)
Carbolines , Receptor Protein-Tyrosine Kinases , Anaplastic Lymphoma Kinase , Animals , Carbolines/pharmacology , Cell Line, Tumor , Drug Resistance, Neoplasm , Humans , Mice , Mutation , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology
6.
Blood ; 135(24): 2159-2170, 2020 06 11.
Article in English | MEDLINE | ID: mdl-32315394

ABSTRACT

Much of what is known about the neurotrophic receptor tyrosine kinase (NTRK) genes in cancer was revealed through identification and characterization of activating Trk fusions across many tumor types. A resurgence of interest in these receptors has emerged owing to the realization that they are promising therapeutic targets. The remarkable efficacy of pan-Trk inhibitors larotrectinib and entrectinib in clinical trials led to their accelerated, tissue-agnostic US Food and Drug Administration (FDA) approval for adult and pediatric patients with Trk-driven solid tumors. Despite our enhanced understanding of Trk biology in solid tumors, the importance of Trk signaling in hematological malignancies is underexplored and warrants further investigation. Herein, we describe mutations in NTRK2 and NTRK3 identified via deep sequencing of 185 patients with hematological malignancies. Ten patients contained a point mutation in NTRK2 or NTRK3; among these, we identified 9 unique point mutations. Of these 9 mutations, 4 were oncogenic (NTRK2A203T, NTRK2R458G, NTRK3E176D, and NTRK3L449F), determined via cytokine-independent cellular assays. Our data demonstrate that these mutations have transformative potential to promote downstream survival signaling and leukemogenesis. Specifically, the 3 mutations located within extracellular (ie, NTRK2A203T and NTRK3E176D) and transmembrane (ie, NTRK3L449F) domains increased receptor dimerization and cell-surface abundance. The fourth mutation, NTRK2R458G, residing in the juxtamembrane domain, activates TrkB via noncanonical mechanisms that may involve altered interactions between the mutant receptor and lipids in the surrounding environment. Importantly, these 4 activating mutations can be clinically targeted using entrectinib. Our findings contribute to ongoing efforts to define the mutational landscape driving hematological malignancies and underscore the utility of FDA-approved Trk inhibitors for patients with aggressive Trk-driven leukemias.


Subject(s)
Hematologic Neoplasms/genetics , Membrane Glycoproteins/genetics , Point Mutation , Receptor, trkB/genetics , Receptor, trkC/genetics , Animals , Base Sequence , Benzamides/therapeutic use , Cell Line , Drug Resistance, Neoplasm/genetics , Hematologic Neoplasms/drug therapy , Hematologic Neoplasms/metabolism , Humans , Indazoles/therapeutic use , Lipid Metabolism , Membrane Glycoproteins/chemistry , Membrane Glycoproteins/metabolism , Mice , Mutant Proteins/chemistry , Mutant Proteins/genetics , Mutant Proteins/metabolism , Oncogenes , Protein Kinase Inhibitors/therapeutic use , Protein Multimerization/genetics , RNA, Small Interfering/genetics , Receptor, trkB/chemistry , Receptor, trkB/metabolism , Receptor, trkC/chemistry , Receptor, trkC/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism
8.
Nat Med ; 24(12): 1919-1929, 2018 12.
Article in English | MEDLINE | ID: mdl-30397356

ABSTRACT

The anti-hyperglycemic effect of metformin is believed to be caused by its direct action on signaling processes in hepatocytes, leading to lower hepatic gluconeogenesis. Recently, metformin was reported to alter the gut microbiota community in humans, suggesting that the hyperglycemia-lowering action of the drug could be the result of modulating the population of gut microbiota. However, the critical microbial signaling metabolites and the host targets associated with the metabolic benefits of metformin remained elusive. Here, we performed metagenomic and metabolomic analysis of samples from individuals with newly diagnosed type 2 diabetes (T2D) naively treated with metformin for 3 d, which revealed that Bacteroides fragilis was decreased and the bile acid glycoursodeoxycholic acid (GUDCA) was increased in the gut. These changes were accompanied by inhibition of intestinal farnesoid X receptor (FXR) signaling. We further found that high-fat-diet (HFD)-fed mice colonized with B. fragilis were predisposed to more severe glucose intolerance, and the metabolic benefits of metformin treatment on glucose intolerance were abrogated. GUDCA was further identified as an intestinal FXR antagonist that improved various metabolic endpoints in mice with established obesity. Thus, we conclude that metformin acts in part through a B. fragilis-GUDCA-intestinal FXR axis to improve metabolic dysfunction, including hyperglycemia.


Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Gastrointestinal Microbiome/drug effects , Metformin/administration & dosage , Obesity/drug therapy , Receptors, Cytoplasmic and Nuclear/genetics , Bacteroides/drug effects , Bacteroides/pathogenicity , Bile Acids and Salts/metabolism , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/microbiology , Diabetes Mellitus, Type 2/pathology , Diet, High-Fat/adverse effects , Gastrointestinal Microbiome/genetics , Gene Expression Regulation, Bacterial/drug effects , Glucose Intolerance/drug therapy , Glucose Intolerance/genetics , Glucose Intolerance/microbiology , Humans , Hyperglycemia/drug therapy , Hyperglycemia/genetics , Hyperglycemia/microbiology , Hyperglycemia/pathology , Metabolome/drug effects , Metabolome/genetics , Metagenomics/methods , Obesity/genetics , Obesity/microbiology , Obesity/pathology , Ursodeoxycholic Acid/analogs & derivatives
9.
Biochem Pharmacol ; 158: 1-12, 2018 12.
Article in English | MEDLINE | ID: mdl-30248327

ABSTRACT

In its classical genomic mode of action, the aryl hydrocarbon receptor (AhR) acts as a ligand activated transcription factor regulating expression of target genes such as CYP1A1 and CYP1B1. Some ligands may also trigger more rapid nongenomic responses through AhR, including calcium signaling (Ca2+). In the present study we observed that pyrene induced a relatively rapid increase in intracellular Ca2+-concentrations ([Ca2+]i) in human microvascular endothelial cells (HMEC-1) and human embryonic kidney cells (HEK293) that was attenuated by AhR-inhibitor treatment and/or transient AhR knockdown by RNAi. In silico molecular docking based on homology models, suggested that pyrene is not able to bind to the human AhR in the agonist conformation. Instead, pyrene docked in the antagonist conformation of the AhR PAS-B binding pocket, although the interaction differed from antagonists such as GNF-351 and CH223191. Accordingly, pyrene did not induce CYP1A1 or CYP1B1, but suppressed CYP1-expression by benzo[a]pyrene (B[a]P) in HMEC-1 cells, confirming that pyrene act as an antagonist of AhR-induced gene expression. Use of pharmacological inhibitors and Ca2+-free medium indicated that the pyrene-induced AhR nongenomic [Ca2+]i increase was initiated by Ca2+-release from intracellular stores followed by a later phase of extracellular Ca2+-influx, consistent with store operated calcium entry (SOCE). These effects was accompanied by an AhR-dependent reduction in ordered membrane lipid domains, as determined by di-4-ANEPPDHQ staining. Addition of cholesterol inhibited both the pyrene-induced [Ca2+]i-increase and alterations in membrane lipid order. In conclusion, we propose that pyrene binds to AhR, act as an antagonist of the canonical genomic AhR/Arnt/CYP1-pathway, reduces ordered membrane lipid domains, and activates AhR nongenomic Ca2+-signaling from intracellular stores.


Subject(s)
Basic Helix-Loop-Helix Transcription Factors/metabolism , Calcium Signaling/physiology , Pyrenes/metabolism , Pyrenes/pharmacology , Receptors, Aryl Hydrocarbon/metabolism , Azo Compounds/chemistry , Azo Compounds/metabolism , Azo Compounds/pharmacology , Basic Helix-Loop-Helix Transcription Factors/agonists , Basic Helix-Loop-Helix Transcription Factors/antagonists & inhibitors , Basic Helix-Loop-Helix Transcription Factors/chemistry , Binding Sites , Calcium Signaling/drug effects , Endothelial Cells/drug effects , Endothelial Cells/metabolism , HEK293 Cells , Humans , Indoles/chemistry , Indoles/metabolism , Indoles/pharmacology , Molecular Docking Simulation/methods , Protein Structure, Secondary , Purines/chemistry , Purines/metabolism , Purines/pharmacology , Pyrazoles/chemistry , Pyrazoles/metabolism , Pyrazoles/pharmacology , Pyrenes/chemistry , Receptors, Aryl Hydrocarbon/agonists , Receptors, Aryl Hydrocarbon/antagonists & inhibitors , Receptors, Aryl Hydrocarbon/chemistry
10.
Drug Metab Dispos ; 46(7): 1030-1040, 2018 07.
Article in English | MEDLINE | ID: mdl-29691238

ABSTRACT

Rutaecarpine (RUT), evodiamine (EOD), and dehydroevodiamine (DHED) are the three main bioactive indoloquinazoline alkaloids isolated from Euodia rutaecarpa, a widely prescribed traditional Chinese medicine. Here, the structure-activity relationships of these analogs for aryl hydrocarbon receptor (AHR) activation were explored by use of Ahr-deficient (Ahr-/-) mice, primary hepatocyte cultures, luciferase reporter gene assays, in silico ligand-docking studies, and metabolomics. In vitro, both mRNA analysis of AHR target genes in mouse primary hepatocytes and luciferase reporter assays in hepatocarcinoma cell lines demonstrated that RUT, EOD, and DHED significantly activated AHR, with an efficacy order of RUT > DHED > EOD. Ligand-docking analysis predicted that the methyl substitute at the N-14 atom was a key factor affecting AHR activation. In vivo, EOD was poorly orally absorbed and failed to activate AHR, whereas RUT and DHED markedly upregulated expression of the hepatic AHR gene battery in wild-type mice, but not in Ahr-/- mice. Furthermore, RUT, EOD, and DHED were not hepatotoxic at the doses used; however, RUT and DHED disrupted bile acid homeostasis in an AHR-dependent manner. These findings revealed that the methyl group at the N-14 atom of these analogs and their pharmacokinetic behaviors were the main determinants for AHR activation, and suggest that attention should be given to monitoring bile acid metabolism in the clinical use of E. rutaecarpa.


Subject(s)
Bile Acids and Salts/metabolism , Drugs, Chinese Herbal/pharmacology , Evodia/chemistry , Homeostasis/drug effects , Receptors, Aryl Hydrocarbon/metabolism , Alkaloids/pharmacology , Animals , Cell Line, Tumor , Genes, Reporter/drug effects , Hep G2 Cells , Hepatocytes/drug effects , Hepatocytes/metabolism , Humans , Indole Alkaloids/pharmacology , Liver/diagnostic imaging , Liver/metabolism , Male , Mice , Mice, Inbred C57BL , Quinazolines/pharmacology , RNA, Messenger/metabolism , Structure-Activity Relationship , Up-Regulation/drug effects
11.
Proc Natl Acad Sci U S A ; 115(18): E4179-E4188, 2018 05 01.
Article in English | MEDLINE | ID: mdl-29581250

ABSTRACT

Medical castration that interferes with androgen receptor (AR) function is the principal treatment for advanced prostate cancer. However, clinical progression is universal, and tumors with AR-independent resistance mechanisms appear to be increasing in frequency. Consequently, there is an urgent need to develop new treatments targeting molecular pathways enriched in lethal prostate cancer. Lysine-specific demethylase 1 (LSD1) is a histone demethylase and an important regulator of gene expression. Here, we show that LSD1 promotes the survival of prostate cancer cells, including those that are castration-resistant, independently of its demethylase function and of the AR. Importantly, this effect is explained in part by activation of a lethal prostate cancer gene network in collaboration with LSD1's binding protein, ZNF217. Finally, that a small-molecule LSD1 inhibitor-SP-2509-blocks important demethylase-independent functions and suppresses castration-resistant prostate cancer cell viability demonstrates the potential of LSD1 inhibition in this disease.


Subject(s)
Gene Regulatory Networks , Histone Demethylases/metabolism , Neoplasm Proteins/metabolism , Prostatic Neoplasms, Castration-Resistant/enzymology , Cell Survival/drug effects , Cell Survival/genetics , Histone Demethylases/antagonists & inhibitors , Histone Demethylases/genetics , Humans , Hydrazines/pharmacology , Male , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Prostatic Neoplasms, Castration-Resistant/drug therapy , Prostatic Neoplasms, Castration-Resistant/genetics , Prostatic Neoplasms, Castration-Resistant/pathology , Sulfonamides/pharmacology , Trans-Activators/genetics , Trans-Activators/metabolism
12.
Toxicol Sci ; 161(2): 310-320, 2018 02 01.
Article in English | MEDLINE | ID: mdl-29040756

ABSTRACT

FICZ and TCDD, two high-affinity AhR ligands, are reported to have opposite effects on T cell differentiation with TCDD inducing regulatory T cells and FICZ inducing Th17 cells. This dichotomy has been attributed to ligand-intrinsic differences in AhR activation, although differences in sensitivity to metabolism complicate the issue. TCDD is resistant to AhR-induced metabolism and produces sustained AhR activation following a single dose in the µg/kg range, whereas FICZ is rapidly metabolized and AhR activation is transient. Nonetheless, prior studies comparing FICZ with TCDD have generally used the same 10-50 µg/kg dose range, and thus the two ligands would not equivalently activate AhR. We hypothesized that high-affinity AhR ligands can promote CD4+ T cell differentiation into both Th17 cells and Tregs, with fate depending on the extent and duration of AhR activation. We compared the immunosuppressive effects of TCDD and FICZ, along with two other rapidly metabolized ligands (ITE and 11-Cl-BBQ) in an acute alloresponse mouse model. The dose and timing of administration of each ligand was optimized for TCDD-equivalent Cyp1a1 induction. When optimized, all of the ligands suppressed the alloresponse in conjunction with the induction of Foxp3- Tr1 cells on day 2 and the expansion of natural Foxp3+ Tregs on day 10. In contrast, a low dose of FICZ induced transient expression of Cyp1a1 and did not induce Tregs or suppress the alloresponse but enhanced IL-17 production. Interestingly, low doses of the other ligands, including TCDD, also increased IL-17 production on day 10. These findings support the conclusion that the dose and the duration of AhR activation by high-affinity AhR ligands are the primary factors driving the fate of T cell differentiation.


Subject(s)
CD4-Positive T-Lymphocytes/drug effects , Carbazoles/toxicity , Cell Differentiation/drug effects , Polychlorinated Dibenzodioxins/toxicity , Receptors, Aryl Hydrocarbon/metabolism , Animals , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , Dose-Response Relationship, Drug , Female , Humans , Immunity, Cellular/drug effects , Ligands , Mice, Inbred C57BL , Time Factors
13.
Biology (Basel) ; 6(4)2017 Dec 01.
Article in English | MEDLINE | ID: mdl-29194351

ABSTRACT

We previously reported that raloxifene, an estrogen receptor modulator, is also a ligand for the aryl hydrocarbon receptor (AhR). Raloxifene induces apoptosis in estrogen receptor-negative human cancer cells through the AhR. We performed structure-activity studies with seven raloxifene analogs to better understand the structural requirements of raloxifene for induction of AhR-mediated transcriptional activity and apoptosis. We identified Y134 as a raloxifene analog that activates AhR-mediated transcriptional activity and induces apoptosis in MDA-MB-231 human triple negative breast cancer cells. Suppression of AhR expression strongly reduced apoptosis induced by Y134, indicating the requirement of AhR for Y134-induced apoptosis. Y134 also induced apoptosis in hepatoma cells without having an effect on cell cycle regulation. Toxicity testing on zebrafish embryos revealed that Y134 has a significantly better safety profile than raloxifene. Our studies also identified an analog of raloxifene that acts as a partial antagonist of the AhR, and is capable of inhibiting AhR agonist-induced transcriptional activity. We conclude that Y134 is a promising raloxifene analog for further optimization as an anti-cancer agent targeting the AhR.

14.
Cell Mol Gastroenterol Hepatol ; 3(2): 163-173, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28275683

ABSTRACT

In patients with colorectal cancer (CRC) that metastasizes to the liver, there are several key goals for improving outcomes including early detection, effective prognostic indicators of treatment response, and accurate identification of patients at high risk for recurrence. Although new therapeutic regimens developed over the past decade have increased survival, there is substantial room for improvement in selecting targeted treatment regimens for the patients who will derive the most benefit. Recently, there have been exciting developments in identifying high-risk patient cohorts, refinements in the understanding of systemic vs localized drug delivery to metastatic niches, liquid biomarker development, and dramatic advances in tumor immune therapy, all of which promise new and innovative approaches to tackling the problem of detecting and treating the metastatic spread of CRC to the liver. Our multidisciplinary group held a state-of-the-science symposium this past year to review advances in this rapidly evolving field. Herein, we present a discussion around the issues facing treatment of patients with CRC liver metastases, including the relationship of discrete gene signatures with prognosis. We also discuss the latest advances to maximize regional and systemic therapies aimed at decreasing intrahepatic recurrence, review recent insights into the tumor microenvironment, and summarize advances in noninvasive multimodal biomarkers for early detection of primary and recurrent disease. As we continue to advance clinically and technologically in the field of colorectal tumor biology, our goal should be continued refinement of predictive and prognostic studies to decrease recurrence after curative resection and minimize treatment toxicity to patients through a tailored multidisciplinary approach to cancer care.

15.
Toxicol Sci ; 157(1): 246-259, 2017 05 01.
Article in English | MEDLINE | ID: mdl-28186253

ABSTRACT

Nitrated polycyclic aromatic hydrocarbons (NPAHs) and heterocyclic PAHs (HPAHs) are recognized environmental pollutants. However, the health risks of NPAHs and HPAHs to humans and environmental systems are not well-studied. The developmental zebrafish (Danio rerio) model was used to evaluate the toxicity of a structurally diverse set of 27 NPAHs and 10 HPAHs. The individual activity of each compound towards the aryl hydrocarbon receptor (AHR), including the role of the AHR in observed toxicity, and genetic markers of oxidative stress and cardiac toxicity were evaluated. Zebrafish embryos were exposed from 6 to 120 hours post fertilization (hpf), to a broad concentration range of individual compounds, and evaluated for 22 developmental endpoints. The potential role of AHR was determined using the transgenic Tg(cyp1a:nls-egfp) reporter zebrafish line. All compounds were screened computationally through molecular docking using a previously developed AHR models of zebrafish isoforms 1A, 1B, and 2. Some compounds did not induce observable developmental toxic responses, whereas others produced statistically significant concentration-dependent toxicity. The tested compounds also exhibited a range of predicted AHR binding and cyp1a/GFP induction patterns, including cyp1a expression in the liver, vasculature, skin, and yolk, which we determined to be due to distinct isoforms of the AHR, using morpholino oligonucleotide knockdown. Furthermore, we investigated mRNA expression of oxidative and cardiac stress genes at 48 and 120 hpf, which indicated several potential mechanisms-of-action for NPAHs. Overall, we observed a range of developmental toxicities, cyp1a/GFP expression patterns, and gene expression profiles, suggestive of several potential mechanisms of action.


Subject(s)
Heterocyclic Compounds/toxicity , Hydrocarbons, Cyclic/toxicity , Nitrates/chemistry , Teratogens/toxicity , Animals , Animals, Genetically Modified , Cytochrome P-450 CYP1A1/genetics , Gene Knockdown Techniques , Hydrocarbons, Cyclic/chemistry , Oxidative Stress/drug effects , Receptors, Aryl Hydrocarbon/drug effects , Receptors, Aryl Hydrocarbon/genetics , Stress, Physiological/drug effects , Zebrafish
16.
J Nutr Biochem ; 41: 12-19, 2017 03.
Article in English | MEDLINE | ID: mdl-27951515

ABSTRACT

The objective of this study was to assess the underlying mechanisms of mango polyphenol decreased cell proliferation and tumor volume in ductal carcinoma in situ breast cancer. We hypothesized that mango polyphenols suppress signaling along the AKT/mTOR axis while up-regulating AMPK. To test this hypothesis, mango polyphenols (0.8 mg gallic acid equivalents per day) and pyrogallol (0.2 mg/day) were administered for 4 weeks to mice xenografted with MCF10DCIS.com cells subcutaneously (n=10 per group). Tumor volumes were significantly decreased, both mango and pyrogallol groups displayed greater than 50% decreased volume compared to control. There was a significant reduction of phosphorylated protein levels of IR, IRS1, IGF-1R, and mTOR by mango; while pyrogallol significantly reduced the phosphorylation levels of IR, IRS1, IGF-1R, p70S6K, and ERK. The protein levels of Sestrin2, which is involved in AMPK-signaling, were significantly elevated in both groups. Also, mango significantly elevated AMPK phosphorylation and pyrogallol significantly elevated LKB1 protein levels. In an in vitro model, mango and pyrogallol increased reactive oxygen species (ROS) generation and arrested cells in S phase. In silico modeling indicates that pyrogallol has the potential to bind directly to the allosteric binding site of AMPK, inducing activation. When AMPK expression was down-regulated using siRNA in vitro, pyrogallol reversed the reduced expression of AMPK. This indicates that pyrogallol not only activates AMPK, but also increases constitutive protein expression. These results suggest that mango polyphenols and their major microbial metabolite, pyrogallol, inhibit proliferation of breast cancer cells through ROS-dependent up-regulation of AMPK and down-regulation of the AKT/mTOR pathway.


Subject(s)
Antineoplastic Agents, Phytogenic/therapeutic use , Breast Neoplasms/diet therapy , Carcinoma, Intraductal, Noninfiltrating/diet therapy , Dietary Supplements , Gene Expression Regulation, Neoplastic , Plant Extracts/therapeutic use , Polyphenols/therapeutic use , AMP-Activated Protein Kinases/antagonists & inhibitors , AMP-Activated Protein Kinases/chemistry , AMP-Activated Protein Kinases/genetics , AMP-Activated Protein Kinases/metabolism , Animals , Antineoplastic Agents, Phytogenic/analysis , Antineoplastic Agents, Phytogenic/chemistry , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Carcinoma, Intraductal, Noninfiltrating/metabolism , Carcinoma, Intraductal, Noninfiltrating/pathology , Cell Line, Tumor , Cell Proliferation , Dietary Supplements/analysis , Female , Humans , Mangifera , Mice, Nude , Phosphorylation , Plant Extracts/adverse effects , Plant Extracts/chemistry , Polyphenols/adverse effects , Polyphenols/analysis , Protein Processing, Post-Translational , Pyrogallol/adverse effects , Pyrogallol/analysis , Pyrogallol/therapeutic use , RNA Interference , Reactive Oxygen Species/agonists , Reactive Oxygen Species/metabolism , TOR Serine-Threonine Kinases/antagonists & inhibitors , TOR Serine-Threonine Kinases/genetics , TOR Serine-Threonine Kinases/metabolism , Tumor Burden , Xenograft Model Antitumor Assays
17.
Environ Health Perspect ; 125(2): 163-169, 2017 02.
Article in English | MEDLINE | ID: mdl-27517672

ABSTRACT

BACKGROUND: The current single-chemical-as-carcinogen risk assessment paradigm might underestimate or miss the cumulative effects of exposure to chemical mixtures, as highlighted in recent work from the Halifax Project. This is particularly important for chemical exposures in the low-dose range that may be affecting crucial cancer hallmark mechanisms that serve to enable carcinogenesis. OBJECTIVE: Could ongoing low-dose exposures to a mixture of commonly encountered environmental chemicals produce effects in concert that lead to carcinogenesis? A workshop held at the NIEHS in August 2015 evaluated the scientific support for the low-dose mixture hypothesis of carcinogenesis and developed a research agenda. Here we describe the science that supports this novel theory, identify knowledge gaps, recommend future methodologies, and explore preventative risk assessment and policy decision-making that incorporates cancer biology, environmental health science, translational toxicology, and clinical epidemiology. DISCUSSION AND CONCLUSIONS: The theoretical merits of the low-dose carcinogenesis hypothesis are well founded with clear biological relevance, and therefore, the premise warrants further investigation. Expert recommendations include the need for better insights into the ways in which noncarcinogenic constituents might combine to uniquely affect the process of cellular transformation (in vitro) and environmental carcinogenesis (in vivo), including investigations of the role of key defense mechanisms in maintaining transformed cells in a dormant state. The scientific community will need to acknowledge limitations of animal-based models in predicting human responses; evaluate biological events leading to carcinogenesis both spatially and temporally; examine the overlap between measurable cancer hallmarks and characteristics of carcinogens; incorporate epigenetic biomarkers, in silico modelling, high-performance computing and high-resolution imaging, microbiome, metabolomics, and transcriptomics into future research efforts; and build molecular annotations of network perturbations. The restructuring of many existing regulatory frameworks will require adequate testing of relevant environmental mixtures to build a critical mass of evidence on which to base policy decisions. Citation: Miller MF, Goodson WH III, Manjili MH, Kleinstreuer N, Bisson WH, Lowe L. 2017. Low-Dose Mixture Hypothesis of Carcinogenesis Workshop: scientific underpinnings and research recommendations. Environ Health Perspect 125:163-169; http://dx.doi.org/10.1289/EHP411.


Subject(s)
Carcinogens/toxicity , Consensus , Environmental Exposure/statistics & numerical data , Environmental Pollution/statistics & numerical data , Carcinogenesis , Complex Mixtures , Dose-Response Relationship, Drug , Education , Models, Animal , Neoplasms , Risk Assessment
18.
Biochim Biophys Acta ; 1864(12): 1667-1677, 2016 12.
Article in English | MEDLINE | ID: mdl-27596062

ABSTRACT

We report on the molecular interactions of the farnesoid X receptor (FXR) with prenylflavonoids, an emerging class of FXR modulators. FXR is an attractive therapeutic target for mitigating metabolic syndromes (MetS) because FXR activates the inhibitory nuclear receptor, small heterodimer partner (SHP), thereby inhibiting both gluconeogenesis and de novo lipogenesis. We and others have shown that xanthohumol (XN), the principal prenylflavonoid of the hop plant (Humulus lupulus L.), is a FXR agonist based on its ability to affect lipid and glucose metabolism in vivo and to induces FXR target genes in biliary carcinoma cells and HEK293 cells. However, studies are currently lacking to rationalize the molecular mechanisms of FXR modulation by prenylflavonoids. We addressed this deficiency and report the first systematic study of FXR prenylflavonoid interactions. We combined hydrogen deuterium exchange mass spectrometry (HDX-MS) with computational studies for dissecting molecular recognition and conformational impact of prenylflavonoid interactions on the ligand binding domain (LBD) of human FXR. Four prenylflavonoids were tested: xanthohumol, a prenylated chalcone, two prenylated flavonones, namely isoxanthohumol (IX) and 8-prenylnaringenin (8PN), and a semisynthetic prenylflavonoid derivative, tetrahydroxanthohumol (TX). Enhancement of the HDX protection profile data by in silico predicted models of FXR prenylflavonoid complexes resulted in mapping of the prenylflavonoid interactions within the canonical ligand binding pocket. Our findings provide a foundation for the exploration of the chemical scaffolds of prenylated chalcones and flavanones as leads for future structure activity studies of this important nuclear receptor with potential relevance for ameliorating lipid metabolic disorders associated with obesity and MetS.


Subject(s)
Flavonoids/metabolism , Receptors, Cytoplasmic and Nuclear/chemistry , Receptors, Cytoplasmic and Nuclear/metabolism , Cell Line, Tumor , Deuterium Exchange Measurement , Flavonoids/chemistry , HEK293 Cells , Humans , Kinetics , Ligands , Mass Spectrometry , Molecular Docking Simulation , Molecular Dynamics Simulation , Propiophenones/metabolism , Protein Conformation , Receptors, Cytoplasmic and Nuclear/agonists , Spectrometry, Fluorescence
19.
Mol Biol Evol ; 33(10): 2648-58, 2016 10.
Article in English | MEDLINE | ID: mdl-27486223

ABSTRACT

We have identified a fixed nonsynonymous sequence difference between humans (Val381; derived variant) and Neandertals (Ala381; ancestral variant) in the ligand-binding domain of the aryl hydrocarbon receptor (AHR) gene. In an exome sequence analysis of four Neandertal and Denisovan individuals compared with nine modern humans, there are only 90 total nucleotide sites genome-wide for which archaic hominins are fixed for the ancestral nonsynonymous variant and the modern humans are fixed for the derived variant. Of those sites, only 27, including Val381 in the AHR, also have no reported variability in the human dbSNP database, further suggesting that this highly conserved functional variant is a rare event. Functional analysis of the amino acid variant Ala381 within the AHR carried by Neandertals and nonhuman primates indicate enhanced polycyclic aromatic hydrocarbon (PAH) binding, DNA binding capacity, and AHR mediated transcriptional activity compared with the human AHR. Also relative to human AHR, the Neandertal AHR exhibited 150-1000 times greater sensitivity to induction of Cyp1a1 and Cyp1b1 expression by PAHs (e.g., benzo(a)pyrene). The resulting CYP1A1/CYP1B1 enzymes are responsible for PAH first pass metabolism, which can result in the generation of toxic intermediates and perhaps AHR-associated toxicities. In contrast, the human AHR retains the ancestral sensitivity observed in primates to nontoxic endogenous AHR ligands (e.g., indole, indoxyl sulfate). Our findings reveal that a functionally significant change in the AHR occurred uniquely in humans, relative to other primates, that would attenuate the response to many environmental pollutants, including chemicals present in smoke from fire use during cooking.


Subject(s)
Hominidae/genetics , Neanderthals/genetics , Receptors, Aryl Hydrocarbon/genetics , Animals , Basic Helix-Loop-Helix Transcription Factors/genetics , Benzo(a)pyrene , Biological Evolution , Cytochrome P-450 CYP1A1/genetics , Cytochrome P-450 CYP1B1/genetics , DNA/metabolism , Evolution, Molecular , Humans , Ligands , Polycyclic Aromatic Hydrocarbons/metabolism
20.
Mol Nutr Food Res ; 60(9): 1912-23, 2016 09.
Article in English | MEDLINE | ID: mdl-27028006

ABSTRACT

SCOPE: Tannin-rich fruits have been evaluated as alternative prevention strategies for colorectal cancer based on their anti-inflammatory properties. This study compared tannin-rich preparations from mango (rich in gallotannins) and pomegranate (rich in ellagitannins) in the dextran sodium sulfate-induced colitis model. METHODS AND RESULTS: In rats, mango and pomegranate beverages decreased intestinal inflammation and the levels of pro-inflammatory cytokines in mucosa and serum. The mango beverage suppressed the ratio of phosphorylated/total protein expression of the IGF-1R-AKT/mTOR axis and downregulated mRNA expression of Igf1, Insr, and pik3cv. Pomegranate decreased p70S6K and RPS6, as well as Rps6ka2, Map2k2, and Mapk1 mRNA. In silico modeling indicated a high binding of docked of gallic acid to the catalytic domain of IGF-1R, which may suppress the activity of the enzyme. Ellagic acid docked effectively into the catalytic domains of both IGF-1R and EGFR. In vitro assays with lipopolysaccharide-treated CCD-18Co cells using polyphenolic extracts from each beverage, as well as pure compounds, corroborated the predictions made in silico. CONCLUSION: Mango polyphenols inhibited the IGF-1R- AKT/mTOR axis, and pomegranate polyphenols downregulate the mTOR downstream pathway through reductions in ERK1/2. These results suggest that extracts rich in gallo- and ellagitannins act on different molecular targets in the protection against ulcerative colitis.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Colitis/drug therapy , Lythraceae/chemistry , Mangifera/chemistry , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Colitis/chemically induced , Dextran Sulfate/toxicity , Disease Models, Animal , ErbB Receptors/metabolism , Extracellular Signal-Regulated MAP Kinases/metabolism , Fruit and Vegetable Juices , Gene Expression Regulation/drug effects , Humans , Male , Molecular Docking Simulation , Polyphenols/pharmacology , Proto-Oncogene Proteins c-akt/metabolism , Rats, Sprague-Dawley , Receptor, IGF Type 1/chemistry , Receptor, IGF Type 1/metabolism , TOR Serine-Threonine Kinases/antagonists & inhibitors , TOR Serine-Threonine Kinases/genetics , TOR Serine-Threonine Kinases/metabolism
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