The question of whether tourism will become the world's largest single industry by the year 2000 is addressed. Although business travel is determined mainly by the economic climate, the volume of ...pleasure travel is influenced by a range of factors: to clarify & quantify their effects, further research is necessary. Despite the current low level of tourism promotion, most people regard holidays as necessary. As working hours decrease, tourism will increase; energy shortages will probably result in "organized" rather than individual tourism. The redistribution of tourist flows from traditional destinations to the less developed countries is likely to occur. Government involvement may increase, particularly if the social role of tourism is recognized. HA.
The absolute bioavailability of many small molecule kinase inhibitors (smKIs) is low. The reasons for low bioavailability are multifaceted and include constraints due to first pass metabolism and ...poor absorption. For smKIs where absorption limits oral bioavailability, low aqueous solubility and high lipophilicity, often in combination with high-dose requirements have been implicated in low and variable absorption, food-effects, and absorption-related drug–drug interactions. The current study has evaluated whether preparation of smKIs as lipophilic salts/ionic liquids in combination with coadministration with lipid-based formulations is able to enhance absorption for examples of this compound class. Lipophilic (docusate) salt forms of erlotinib, gefitinib, ceritinib, and cabozantinib (as example smKIs demonstrating low aqueous solubility and high lipophilicity) were prepared and isolated as workable powder solids. In each case, the lipophilic salt exhibited high and significantly enhanced solubility in lipidic excipients (>100 mg/g) when compared to the free base or commercial salt form. Isolation as the lipophilic salt facilitated smKI loading in model lipid-based formulations at high concentration, increased in vitro solubilization at gastric and intestinal pH and in some cases increased oral absorption (∼2-fold for cabozantinib formulations in rats). Application of a lipophilic salt approach can therefore facilitate the use of lipid-based formulations for examples of the smKI compound class where low solubility limits absorption and is a risk factor for increased variability due to food-effects.
Translation of muscarinic acetylcholine receptor (mAChR) agonists into clinically used therapeutic agents has been difficult due to their poor subtype selectivity. M4 mAChR subtype-selective positive ...allosteric modulators (PAMs) may provide better therapeutic outcomes, hence investigating their detailed pharmacological properties is crucial to advancing them into the clinic. Herein, we report the synthesis and comprehensive pharmacological evaluation of M4 mAChR PAMs structurally related to 1e, Me–C-c, 11CMK-6884 and 18F12. Our results show that small structural changes to the PAMs can result in pronounced differences to baseline, potency (pEC50) and maximum effect (Emax) measures in cAMP assays when compared to the endogenous ligand acetylcholine (ACh) without the addition of the PAMs. Eight selected PAMs were further assessed to determine their binding affinity and potential signalling bias profile between cAMP and β-arrestin 2 recruitment. These rigorous analyses resulted in the discovery of the novel PAMs, 6k and 6l, which exhibit improved allosteric properties compared to the lead compound, and probative in vivo exposure studies in mice confirmed that they maintain the ability to cross the blood-brain barrier, making them more suitable for future preclinical assessment.
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•The M mAChR a promising target for the therapy of neurological diseases such as schizophrenia and Alzheimer's disease.•M4 mAChR PAMs with different allosteric profiles in terms of affinity, co-operativity and allosteric agonism were identified.•Compounds 6k and 6l were found to possess biased signalling profiles between cAMP and β-arrestin 2 recruitment.•Compounds 1e, 6k and 6l were able to cross the blood brain barrier and distribute into the brain parenchyma of mice.
Ewing sarcoma (ES) is a rare and highly malignant cancer that occurs in the bone and surrounding tissue of children and adolescents. The
fusion transcription factor that drives ES pathobiology was ...previously demonstrated to modulate cyclin D1 expression. In this study, we evaluated abemaciclib, a small-molecule CDK4 and CDK6 (CDK4 and 6) inhibitor currently under clinical investigation in pediatric solid tumors, in preclinical models of ES.
Using Western blot, high-content imaging, flow cytometry, ELISA, RNA sequencing, and CpG methylation assays, we characterized the
response of ES cell lines to abemaciclib. We then evaluated abemaciclib
in cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models of ES as either a monotherapy or in combination with chemotherapy.
Abemaciclib induced quiescence in ES cell lines via a G
cell-cycle block, characterized by decreased proliferation and reduction of Ki-67 and FOXM1 expression and retinoblastoma protein (RB) phosphorylation. In addition, abemaciclib reduced DNMT1 expression and promoted an inflammatory immune response as measured by cytokine secretion, antigen presentation, and interferon pathway upregulation. Single-agent abemaciclib reduced ES tumor volume in preclinical mouse models and, when given in combination with doxorubicin or temozolomide plus irinotecan, durable disease control was observed.
Collectively, our data demonstrate that the antitumor effects of abemaciclib in preclinical ES models are multifaceted and include cell-cycle inhibition, DNA demethylation, and immunogenic changes.
Abstract
Low grade gliomas (LGG) are the most common tumors of the central nervous system in children, accounting for about 50% of all brain tumors. They represent a heterogeneous group of grade I ...and II tumors according to the WHO classification. Pediatric LGG, is associated with activation of BRAF through a tandem duplication that results in the KIAA1549-BRAF fusion or through an activating point mutation of BRAF (predominantly V600E). More recent findings suggest that the KIAA1549-BRAF fusion is restricted to Grade 1 tumors (70-90%) whereas BRAF(V600E) occurs more frequently in Grade 2-4 tumors (~23%). Findings for BRAF mutation, similar to other tumors with activated BRAF (e.g. melanoma), and the phase I activity of MEK inhibitor in the PBTC-029 protocol, suggest that activated BRAF may provide a validated drug target. Previous studies from our lab indicate that, in the context of mutant BRAF, inhibition of MEK inhibits TORC1 signaling and may induce a ‘BRCA-like’ phenotype, through depletion of FANCD2. Potentially suppression of TORC1 could have effects on other DNA damage response pathways that could compensate for loss of FANCD2. To understand the consequences of MEK inhibition in the context of BRAF abreation in LGG we surveyed DNA repair genes that may be regulated via the MEK/TORC1 pathway in BRAF mutant cells. The objective of this particular study was to examine the mechanism and significance of MEK inhibition to the repair of DNA damage by the homologous recombination (HR) pathway. For this study, we have used glioma cell lines having BRAF(V600E) mutation; the BT40 cell line was developed from patient-derived astrocytoma xenograft (PDX) model in mice in our lab and AM38c1 and DBTRG-05MG cells were generously provided by T. Nicolades. Annexin binding assay demonstrated that MEKi treatment significantly increased the percentage of apoptosis and necrosis of glioma cells. Human DNA repair PCR Array analysis identified MEKi induced down regulation of genes involved in Base Excision Repair (BER), Nucleotide Excision Repair (NER), Mismatch Repair (MMR) and Double-Strand Break (DSB) repair pathways. DSB repair genes were further validated by real time qPCR analysis. Immunoblot analysis of glioma cell lines indicate that MEKi treatment enhanced the gamma-H2AX levels. To elucidate the mechanism of DSB repair pathway in presence of MEKi, clonogenic assay, nuclear foci formation assay, and GFP reporter assay for homologous recombination (HR) and non-homologous end-joining (NHEJ) are ongoing. Collectively, these findings demonstrate for the first time a previously unknown role for MEKi in treatment of glioma cells that involves inhibition of DNA double-strand break repair pathways. Further, we will examine the mechanism and significance of MEK/ERK and TORC1 signaling axis in regulation of DNA repair genes and its effect on LGG. Understanding how MEK plays a role in DNA repair pathways will be useful in maximizing treatment opportunities for childhood glioma.
Citation Format: Sudipa Saha Roy, Terry Shackleford, Peter Houghton. Therapeutic exploitation of mutant BRAF in childhood glioma abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1431. doi:10.1158/1538-7445.AM2017-1431
Antibodies targeting insulin-like growth factor 1 receptor (IGF-1R) induce objective responses in only 5% to 15% of children with sarcoma. Understanding the mechanisms of resistance may identify ...combination therapies that optimize efficacy of IGF-1R-targeted antibodies. Sensitivity to the IGF-1R-targeting antibody TZ-1 was determined in rhabdomyosarcoma and Ewing sarcoma cell lines. Acquired resistance to TZ-1 was developed and characterized in sensitive Rh41 cells. The BRD4 inhibitor, JQ1, was evaluated as an agent to prevent acquired TZ-1 resistance in Rh41 cells. The phosphorylation status of receptor tyrosine kinases (RTK) was assessed. Sensitivity to TZ-1 in vivo was determined in Rh41 parental and TZ-1-resistant xenografts. Of 20 sarcoma cell lines, only Rh41 was sensitive to TZ-1. Cells intrinsically resistant to TZ-1 expressed multiple (>10) activated RTKs or a relatively less complex set of activated RTKs (∼5). TZ-1 decreased the phosphorylation of IGF-1R but had little effect on other phosphorylated RTKs in all resistant lines. TZ-1 rapidly induced activation of RTKs in Rh41 that was partially abrogated by knockdown of SOX18 and JQ1. Rh41/TZ-1 cells selected for acquired resistance to TZ-1 constitutively expressed multiple activated RTKs. TZ-1 treatment caused complete regressions in Rh41 xenografts and was significantly less effective against the Rh41/TZ-1 xenograft. Intrinsic resistance is a consequence of redundant signaling in pediatric sarcoma cell lines. Acquired resistance in Rh41 cells is associated with rapid induction of multiple RTKs, indicating a dynamic response to IGF-1R blockade and rapid development of resistance. The TZ-1 antibody had greater antitumor activity against Rh41 xenografts compared with other IGF-1R-targeted antibodies tested against this model.
Parkinson's disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily ...consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified Cu(II)(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that Cu(II)(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.
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