Towards controlling the crystallisation behaviour of fenofibrate melt: triggers of crystallisation and polymorphic transformation

Fenofibrate (FEN) is a dyslipidemia treatment agent which is poorly soluble in water. FEN has tendency to form polymorphs and its crystallisation behaviour is difficult to predict. The nucleation process can be initiated by mechanical disruption such as ball milling or surface scratching which may result in different crystallisation behaviour to that observed in the unperturbed system. This study has obtained insights into the controllability of FEN crystallisation by means of regulating the exposed surface and growth temperatures during its crystallisation. The availability of an open top surface (OTS) during the crystallisation of the FEN melt resulted in a mixture containing FEN form I and IIa (I ≫ IIa) at room temperature, and in the range 40 to 70 °C. Covering the surface led to significant increases in the yield of form IIa at room temperature and at 40 and 50 °C. These temperatures also yielded the highest amount of form IIa in the OTS samples whilst crystallisation at 70 °C led to only FEN form I crystals regardless of the availability of the free surface. The metastable FEN form IIa transforms to the stable form I under the influence of a mechanical stress. Additionally, the introduction of OTS before the completion of crystallisation of form IIa led to a ‘switch’ of from IIa growth to form I. This study demonstrates that the polymorph selection of FEN can be obtained by the manipulation of the crystallisation conditions

GSTT2 promoter polymorphisms and colorectal cancer risk

BACKGROUND: Glutathione S-transferases are a group of enzymes that participate in detoxification and defense mechanisms against toxic carcinogens and other compounds. These enzymes play an important role in human carcinogenesis. In the present study, we sought to determine whether GSTT2 promoter single nucleotide polymorphisms (SNPs) are associated with colorectal cancer risk. METHODS: A total of 436 colorectal cancer patients and 568 healthy controls were genotyped for three GSTT2 promoter SNPs (-537G>A, -277T>C and -158G>A), using real-time TaqMan assay and direct sequencing. An electrophoretic mobility shift assay (EMSA) was performed to determine the effects of polymorphisms on protein binding to the GSTT2 promoter. RESULTS: The -537A allele (-537G/A or A/A) was significantly associated with colorectal cancer risk (OR = 1.373, p = 0.025), while the -158A allele (-158G/A or A/A) was involved in protection against colorectal cancer (OR = 0.539, p = 0.032). Haplotype 2 (-537A, -277T, -158G) was significantly associated with colorectal cancer risk (OR = 1.386, p = 0.021), while haplotype 4 (-537G, -277C, -158A) protected against colorectal cancer (OR = 0.539, p = 0.032). EMSA data revealed lower promoter binding activity in the -537A allele than its -537G counterpart. CONCLUSION: Our results collectively suggest that SNPs and haplotypes of the GSTT2 promoter region are associated with colorectal cancer risk in the Korean population

Aldo-keto reductases are biomarkers of NRF2 activity and are co-ordinately overexpressed in non-small cell lung cancer

BACKGROUND: Although the nuclear factor-erythroid 2-related factor 2 (NRF2) pathway is one of the most frequently dysregulated in cancer, it is not clear whether mutational status is a good predictor of NRF2 activity. Here we utilise four members of the aldo-keto reductase (AKR) superfamily as biomarkers to address this question. METHODS: Twenty-three cell lines of diverse origin and NRF2-pathway mutational status were used to determine the relationship between AKR expression and NRF2 activity. AKR expression was evaluated in lung cancer biopsies and Cancer Genome Atlas (TCGA) and Oncomine data sets. RESULTS: AKRs were expressed at a high basal level in cell lines carrying mutations in the NRF2 pathway. In non-mutant cell lines, co-ordinate induction of AKRs was consistently observed following activation of NRF2. Immunohistochemical analysis of lung tumour biopsies and interrogation of TCGA data revealed that AKRs are enriched in both squamous cell carcinomas (SCCs) and adenocarcinomas that contain somatic alterations in the NRF2 pathway but, in the case of SCC, AKRs were also enriched in most other tumours. CONCLUSIONS: An AKR biomarker panel can be used to determine NRF2 status in tumours. Hyperactivation of the NRF2 pathway is far more prevalent in lung SCC than previously predicted by genomic analyses

A Computational Approach to Finding Novel Targets for Existing Drugs

Repositioning existing drugs for new therapeutic uses is an efficient approach to drug discovery. We have developed a computational drug repositioning pipeline to perform large-scale molecular docking of small molecule drugs against protein drug targets, in order to map the drug-target interaction space and find novel interactions. Our method emphasizes removing false positive interaction predictions using criteria from known interaction docking, consensus scoring, and specificity. In all, our database contains 252 human protein drug targets that we classify as reliable-for-docking as well as 4621 approved and experimental small molecule drugs from DrugBank. These were cross-docked, then filtered through stringent scoring criteria to select top drug-target interactions. In particular, we used MAPK14 and the kinase inhibitor BIM-8 as examples where our stringent thresholds enriched the predicted drug-target interactions with known interactions up to 20 times compared to standard score thresholds. We validated nilotinib as a potent MAPK14 inhibitor in vitro (IC50 40 nM), suggesting a potential use for this drug in treating inflammatory diseases. The published literature indicated experimental evidence for 31 of the top predicted interactions, highlighting the promising nature of our approach. Novel interactions discovered may lead to the drug being repositioned as a therapeutic treatment for its off-target's associated disease, added insight into the drug's mechanism of action, and added insight into the drug's side effects

FABP7 expression in normal and stab-injured brain cortex and its role in astrocyte proliferation

Reactive gliosis, in which astrocytes as well as other types of glial cells undergo massive proliferation, is a common hallmark of all brain pathologies. Brain-type fatty acid-binding protein (FABP7) is abundantly expressed in neural stem cells and astrocytes of developing brain, suggesting its role in differentiation and/or proliferation of glial cells through regulation of lipid metabolism and/or signaling. However, the role of FABP7 in proliferation of glial cells during reactive gliosis is unknown. In this study, we examined the expression of FABP7 in mouse cortical stab injury model and also the phenotype of FABP7-KO mice in glial cell proliferation. Western blotting showed that FABP7 expression was increased significantly in the injured cortex compared with the contralateral side. By immunohistochemistry, FABP7 was localized to GFAP+ astrocytes (21% of FABP7+ cells) and NG2+ oligodendrocyte progenitor cells (62%) in the normal cortex. In the injured cortex there was no change in the population of FABP7+/NG2+ cells, while there was a significant increase in FABP7+/GFAP+ cells. In the stab-injured cortex of FABP7-KO mice there was decrease in the total number of reactive astrocytes and in the number of BrdU+ astrocytes compared with wild-type mice. Primary cultured astrocytes from FABP7-KO mice also showed a significant decrease in proliferation and omega-3 fatty acid incorporation compared with wild-type astrocytes. Overall, these data suggest that FABP7 is involved in the proliferation of astrocytes by controlling cellular fatty acid homeostasis

Glutathione in Cancer Cell Death

Glutathione (L-γ-glutamyl-L-cysteinyl-glycine; GSH) in cancer cells is particularly relevant in the regulation of carcinogenic mechanisms; sensitivity against cytotoxic drugs, ionizing radiations, and some cytokines; DNA synthesis; and cell proliferation and death. The intracellular thiol redox state (controlled by GSH) is one of the endogenous effectors involved in regulating the mitochondrial permeability transition pore complex and, in consequence, thiol oxidation can be a causal factor in the mitochondrion-based mechanism that leads to cell death. Nevertheless GSH depletion is a common feature not only of apoptosis but also of other types of cell death. Indeed rates of GSH synthesis and fluxes regulate its levels in cellular compartments, and potentially influence switches among different mechanisms of death. How changes in gene expression, post-translational modifications of proteins, and signaling cascades are implicated will be discussed. Furthermore, this review will finally analyze whether GSH depletion may facilitate cancer cell death under in vivo conditions, and how this can be applied to cancer therapy

Safe approaches for camptothecin delivery: Structural analogues and nanomedicines

[EN] Twenty-(S)-camptothecin is a strongly cytotoxic molecule with excellent antitumor activity over a wide spectrum of human cancers. However, the direct formulation is limited by its poor water solubility, low plasmatic stability and severe toxicity, which currently limits its clinical use. As a consequence, two strategies have been developed in order to achieve safe and efficient delivery of camptothecin to target cells: structural analogues and nanomedicines. In this review, we summarize recent advances in the design, synthesis and development of camptothecin molecular derivatives and supramolecular vehicles, following a systematic classification according to structure-activity relationships (structural analogues) or chemical nature (nanomedicines). A series of organic, inorganic and hybrid materials are presented as nanoplatforms to overcome camptothecin restrictions in administration, biodistribution, pharmacokinetics and toxicity. Nanocarriers which respond to a variety of stimuli endogenously (e.g., pH, redox potential, enzyme activity) or exogenously (e.g., magnetic field, light, temperature, ultrasound) seem the best positioned therapeutic materials for optimal spatial and temporal control over drug release. The main goal of this review is to be used as a source of relevant literature for others interested in the field of camptothecin-based therapeutics. To this end, final remarks on the most important formulations currently under clinical trial are provided. (C) 2016 Elsevier B.V. All rights reserved.Financial support of the Spanish Ministry of Economy and Competitiveness (projects MAT2012-39290-C02-02 and SEV-2012-0267) is gratefully acknowledged. Dr. E.M. Rivero thanks the Cursol Foundation for a post-doctoral scholarship.Botella Asuncion, P.; Rivero-Buceta, EM. (2017). Safe approaches for camptothecin delivery: Structural analogues and nanomedicines. Journal of Controlled Release. 247:28-54. https://doi.org/10.1016/j.jconrel.2016.12.023S285424