ABSTRACT
Modern methods of drug discovery and development in recent years make a wide use of computational algorithms. These methods utilise Virtual Screening (VS), which is the computational counterpart of experimental screening. In this manner the in silico models and tools initial replace the wet lab methods saving time and resources. This paper presents the overall design and implementation of a web based scientific workflow system for virtual screening called, the Life Sciences Informatics (LiSIs) platform. The LiSIs platform consists of the following layers: the input layer covering the data file input; the pre-processing layer covering the descriptors calculation, and the docking preparation components; the processing layer covering the attribute filtering, compound similarity, substructure matching, docking prediction, predictive modelling and molecular clustering; post-processing layer covering the output reformatting and binary file merging components; output layer covering the storage component. The potential of LiSIs platform has been demonstrated through two case studies designed to illustrate the preparation of tools for the identification of promising chemical structures. The first case study involved the development of a Quantitative Structure Activity Relationship (QSAR) model on a literature dataset while the second case study implemented a docking-based virtual screening experiment. Our results show that VS workflows utilizing docking, predictive models and other in silico tools as implemented in the LiSIs platform can identify compounds in line with expert expectations. We anticipate that the deployment of LiSIs, as currently implemented and available for use, can enable drug discovery researchers to more easily use state of the art computational techniques in their search for promising chemical compounds. The LiSIs platform is freely accessible (i) under the GRANATUM platform at: http://www.granatum.org and (ii) directly at: http://lisis.cs.ucy.ac.cy.
Subject(s)
High-Throughput Screening Assays , Internet , Medical Informatics , Algorithms , Biological Science Disciplines , Quantitative Structure-Activity RelationshipABSTRACT
The purpose of this work is to determine the molecular mechanisms underlying tamoxifen resistance. We show here that ER-ß is epigenetically silenced in a cell line with acquired tamoxifen resistance (MCF-7/TAM-R) and this could be reversed by 5-AZA-deoxycytidine (5-AZA) and trichostatin-A (TSA) pre-treatment. Subsequent treatment with 4-hydroxy-tamoxifen (4-OHT) induced ER-ß nuclear translocation, upregulated pS2 and p21 levels and reduced cell viability. Transfection with an ER-ß expression vector sensitized MCF-7/TAM-R cells to the growth inhibitory and pro-apoptotic effects of 4-OHT, indicating that ER-ß re-expression alone is sufficient to restore sensitivity to tamoxifen. This novel finding reveals that ER-ß is fundamental in overcoming acquired tamoxifen resistance and provides insights for new therapeutic protocols against breast cancer.
Subject(s)
Antineoplastic Agents, Hormonal/pharmacology , Breast Neoplasms/genetics , Chromatin Assembly and Disassembly/drug effects , Drug Resistance, Neoplasm , Estrogen Receptor beta/genetics , Gene Silencing , Histone Deacetylase Inhibitors/pharmacology , Tamoxifen/analogs & derivatives , Active Transport, Cell Nucleus , Apoptosis/drug effects , Azacitidine/analogs & derivatives , Azacitidine/pharmacology , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Survival/drug effects , Decitabine , Dose-Response Relationship, Drug , Drug Resistance, Neoplasm/drug effects , Drug Resistance, Neoplasm/genetics , Estrogen Receptor beta/metabolism , Female , Gene Expression Regulation, Neoplastic/drug effects , Humans , Hydroxamic Acids/pharmacology , MCF-7 Cells , Tamoxifen/pharmacology , Time Factors , TransfectionABSTRACT
BACKGROUND: Soy phytoestrogens, such as daidzein and its metabolite equol, have been proposed to be responsible for the low breast cancer rate in Asian women. Since the majority of estrogen receptor positive breast cancer patients are treated with tamoxifen, the basic objective of this study is to determine whether equol enhances tamoxifen's anti-tumor effect, and to identify the molecular mechanisms involved. METHODS: For this purpose, we examined the individual and combined effects of equol and tamoxifen on the estrogen-dependent MCF-7 breast cancer cells using viability assays, annexin-V/PI staining, cell cycle and western blot analysis. RESULTS: We found that equol (>50 µM) and 4-hydroxy-tamoxifen (4-OHT; >100 nM) significantly reduced the MCF-7 cell viability. Furthermore, the combination of equol (100 µM) and 4-OHT (10 µM) induced apoptosis more effectively than each compound alone. Subsequent treatment of MCF-7 cells with the pan-caspase inhibitor Z-VAD-FMK inhibited equol- and 4-OHT-mediated apoptosis, which was accompanied by PARP and α-fodrin cleavage, indicating that apoptosis is mainly caspase-mediated. These compounds also induced a marked reduction in the bcl-2:bax ratio, which was accompanied by caspase-9 and caspase-7 activation and cytochrome-c release to the cytosol. Taken together, these data support the notion that the combination of equol and tamoxifen activates the intrinsic apoptotic pathway more efficiently than each compound alone. CONCLUSIONS: Consequently, equol may be used therapeutically in combination treatments and clinical studies to enhance tamoxifen's effect by providing additional protection against estrogen-responsive breast cancers.
