Computer-aided drug discovery/design methods have played a major role in the development of therapeutically important small molecules for over three decades. These methods are broadly classified as either structure-based or ligand-based methods. Structure-based methods are in principle analogous to high-throughput screening in that both target and ligand structure information is imperative. Structure-based approaches include ligand docking, pharmacophore, and ligand design methods. The article discusses theory behind the most important methods and recent successful applications. Ligand-based methods use only ligand information for predicting activity depending on its similarity/dissimilarity to previously known active ligands. We review widely used ligand-based methods such as ligand-based pharmacophores, molecular descriptors, and quantitative structure-activity relationships. In addition, important tools such as target/ligand data bases, homology modeling, ligand fingerprint methods, etc., necessary for successful implementation of various computer-aided drug discovery/design methods in a drug discovery campaign are discussed. Finally, computational methods for toxicity prediction and optimization for favorable physiologic properties are discussed with successful examples from literature.

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Computational Methods in Drug Discovery

Transforming growth factor beta (TGF-β) is a ubiquitous and essential regulator of cellular and physiologic processes including proliferation, differentiation, migration, cell survival, angiogenesis, and immunosurveillance. Alterations in the TGF-β signaling pathway, including mutation or deletion of members of the signaling pathway and resistance to TGF-β-mediated inhibition of proliferation are frequently observed in human cancers. Although these alterations define a tumor suppressor role for the TGF-β pathway in human cancer, TGF-β also mediates tumor-promoting effects, either through differential effects on tumor and stromal cells or through a fundamental alteration in the TGF-β responsiveness of the tumor cells themselves. TGF-β and members of the TGF-β signaling pathway are being evaluated as prognostic or predictive markers for cancer patients. Ongoing advances in understanding the TGF-β signaling pathway will enable targeting of this pathway for the chemoprevention and treatment of human cancers.

Role of Transforming Growth Factor Beta in Human Cancer

The host stromal response to an invasive epithelial carcinoma is frequently called a desmoplastic reaction (DR) and is a universal feature of pancreatic ductal adenocarcinoma (PDA). This DR is characterized by a complex interplay between the normal host epithelial cells, invading tumor cells, stromal fibroblasts, inflammatory cells, proliferating endothelial cells, an altered extracellular matrix, and growth factors activating oncogenic signaling pathways by autocrine and paracrine mechanisms. Hence, the tumor microenvironment is a dynamic process promoting tumor growth and invasion through mechanisms likely to include anoikis resistance, genomic instability, and drug resistance. Cell coculture models, murine models (xenograft and genetic), and gene expression profiling studies on human PDA biopsies have identified several key molecules, such as collagen type I, fibronectin, laminin, matrix metalloproteinases (MMP) and their inhibitors (tissue inhibitors of MMP), growth factors (transforming growth factor β, platelet-derived growth factor, connective tissue growth factor, and hepatocyte growth factor), chemokines, and integrins as constituents of the DR. Despite these findings, it is unclear which molecular-cellular events initiate and drive desmoplasia in PDA. Accumulating evidence indicates that pancreatic stellate cells when activated switch to a myofibroblast phenotype that produces components of the extracellular matrix, MMPs, and tissue inhibitors of MMPs by activating the mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) pathway. Based on current evidence, several therapeutic strategies are been evaluated on identified potential therapeutic targets. This review summarizes our current understanding of the mechanisms that potentially drive the DR in PDA and future possibilities for therapeutic targeting of this critical process. [Mol Cancer Ther 2007;6(4):1186–97]

https://mct.aacrjournals.org/content/molcanther/6/4/1186.full.pdf

Tumor-stroma interactions in pancreatic ductal adenocarcinoma

Chronic myeloid leukaemia (CML) is caused by a defined genetic abnormality that generates BCR-ABL, a constitutively active tyrosine kinase. It is widely believed that BCR-ABL activates Akt signalling that suppresses the forkhead O transcription factors (FOXO), supporting the proliferation or inhibiting the apoptosis of CML cells. Although the use of the tyrosine kinase inhibitor imatinib is a breakthrough for CML therapy, imatinib does not deplete the leukaemia-initiating cells (LICs) that drive the recurrence of CML. Here, using a syngeneic transplantation system and a CML-like myeloproliferative disease mouse model, we show that Foxo3a has an essential role in the maintenance of CML LICs. We find that cells with nuclear localization of Foxo3a and decreased Akt phosphorylation are enriched in the LIC population. Serial transplantation of LICs generated from Foxo3a(+/+) and Foxo3a(-/-) mice shows that the ability of LICs to cause disease is significantly decreased by Foxo3a deficiency. Furthermore, we find that TGF-beta is a critical regulator of Akt activation in LICs and controls Foxo3a localization. A combination of TGF-beta inhibition, Foxo3a deficiency and imatinib treatment led to efficient depletion of CML in vivo. Furthermore, the treatment of human CML LICs with a TGF-beta inhibitor impaired their colony-forming ability in vitro. Our results demonstrate a critical role for the TGF-beta-FOXO pathway in the maintenance of LICs, and strengthen our understanding of the mechanisms that specifically maintain CML LICs in vivo.

TGF-β-FOXO signalling maintains leukaemia-initiating cells in chronic myeloid leukaemia

A repeater and associated method of use includes at least one antenna element for communicating in one direction and at least one antenna element for communicating in another direction. A radio frequency uplink path and a radio frequency downlink path are coupled between the antennas. At least one of the radio frequency uplink path or the radio frequency downlink path includes an adaptive cancellation circuit. The adaptive cancellation circuit is configured to generate a cancellation signal without requiring an injected signal. The cancellation signal, when added to a radio frequency signal in the respective uplink and downlink paths, substantially reduces feedback signals present in the radio frequency signal.

Repeaters for wireless communication systems

Pyrazole-based inhibitors of the transforming growth factor-β type I receptor kinase domain (TβR-I) are described Examination of the SAR in both enzyme- and cell-based in vitro assays resulted in the emergence of two subseries featuring differing selectivity versus p38 MAP kinase A common binding mode at the active site has been established by successful cocrystallization and X-ray analysis of potent inhibitors with the TβR-I receptor kinase domain

Synthesis and Activity of New Aryl- and Heteroaryl-Substituted Pyrazole Inhibitors of the Transforming Growth Factor-β Type I Receptor Kinase Domain

A diversity antenna assembly for use with portable radiotelephones includes plural antennas physically connected by a non-conducting member to effect simplicity of deployment of the antenna assembly. The antennas are spatially separated to provide space diversity to minimize the deleterious effects of Rayleigh fading.

Edward C R Smith

Papers

Synthesis and Activity of New Aryl- and Heteroaryl-Substituted Pyrazole Inhibitors of the Transforming Growth Factor-β Type I Receptor Kinase Domain

Diversity antenna assembly for portable radiotelephones