The Role of Immunoglobulin Superfamily Cell Adhesion Molecules in Cancer Metastasis

Metastasis is a major clinical problem and results in a poor prognosis for most cancers. The metastatic pathway describes the process by which cancer cells give rise to a metastatic lesion in a new tissue or organ. It consists of interconnecting steps all of which must be successfully completed to result in a metastasis. Cell-cell adhesion is a key aspect of many of these steps. Adhesion molecules belonging to the immunoglobulin superfamily (Ig-SF) commonly play a central role in cell-cell adhesion, and a number of these molecules have been associated with cancer progression and a metastatic phenotype. Surprisingly, the contribution of Ig-SF members to metastasis has not received the attention afforded other cell adhesion molecules (CAMs) such as the integrins. Here we examine the steps in the metastatic pathway focusing on how the Ig-SF members, melanoma cell adhesion molecule (MCAM), L1CAM, neural CAM (NCAM), leukocyte CAM (ALCAM), intercellular CAM-1 (ICAM-1) and platelet endothelial CAM-1 (PECAM-1) could play a role. Although much remains to be understood, this review aims to raise the profile of Ig-SF members in metastasis formation and prompt further research that could lead to useful clinical outcomes

A structural analysis of heparin-like glycosaminoglycans using MALDI-TOF mass spectrometry

Abstract. Mass spectrometry (MS) techniques have spear-headed the field of proteomics. Recently, MS has been used to structurally analyse carbohydrates. The heparin/heparan sulfate-like glycosaminoglycans (HLGAGs) present a special set of difficulties for structural analysis because they are highly sulfated and heterogeneous. We have used a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-MS) technique in which heparin fragments are non-covalently bound to basic peptides of a known mass, so as to limit in-source desulfation and hence afford an accurate mass. We examined a range of different sized fragments with varying degrees of sulfation. The potential of combining the MALDI-MS technique with enzymatic digestion to obtain saccharide sequence information on heparin fragments was explored. A disaccharide analysis greatly assists in determining a sequence from MALDI-MS data. Enzymatic digestion followed by MALDI-MS allows structural data on heparin fragments too large for direct MALDI-MS to be obtained. We demonstrate that synthetic sulfated oligosaccharides can also be analysed by MALDI-MS. There are advantages and limitations with this methodology, but until superior MS techniques become readily accessible to biomedical scientists the MALDI-MS method provides a means to structurally analyse HLGAG fragments that have therapeutic potential because of their ability to bind to and functionally regulate a host of clinically important proteins

In vitro expansion of keratinocytes on human dermal fibroblast-derived matrix retains their stem-like characteristics

The long-term expansion of keratinocytes under conditions that avoid xenogeneic components (i.e. animal serum- and feeder cell-free) generally causes diminished proliferation and increased terminal differentiation. Here we present a culture system free of xenogeneic components that retains the self-renewal capacity of primary human keratinocytes. In vivo the extracellular matrix (ECM) of the tissue microenvironment has a major influence on a cell's fate. We used ECM from human dermal fibroblasts, cultured under macromolecular crowding conditions to facilitate matrix deposition and organisation, in a xenogeneic-free keratinocyte expansion protocol. Phospholipase A2 decellularisation produced ECM whose components resembled the core matrix composition of natural dermis by proteome analyses. Keratinocytes proliferated rapidly on these matrices, retained their small size, expressed p63, lacked keratin 10 and rarely expressed keratin 16. The colony forming efficiency of these keratinocytes was enhanced over that of keratinocytes grown on collagen I, indicating that dermal fibroblast-derived matrices maintain the in vitro expansion of keratinocytes in a stem-like state. Keratinocyte sheets formed on such matrices were multi-layered with superior strength and stability compared to the single-layered sheets formed on collagen I. Thus, keratinocytes expanded using our xenogeneic-free protocol retained a stem-like state, but when triggered by confluence and calcium concentration, they stratified to produce epidermal sheets with a potential clinical use

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Recognition of foreign particles by the protochordate Botrylloides leachii / Deirdre R. Coombe

Typescript (photocopy)vi, 184 leaves, [14] leaves of plates : ill.,(part col.) ; 30 cm.Thesis (Ph.D.) Dept. of Zoology, University of Adelaide, 198

Herapin mimetics

Explorations of the therapeutic potential of heparin mimetics, anionic compounds that are analogues of glycosaminoglycans (GAGs), have gone hand-in-hand with the emergence of understanding as to the role of GAGs in many essential biological processes. A myriad of structurally different heparin mimetics have been prepared and examined in many diverse applications. They range in complexity from heterogeneous polysaccharides that have been chemically sulphated to well-defined compounds, designed in part to mimic the natural ligand, but with binding specificity and potency increased by conjugation to non-carbohydrate pharmacophores. The maturity of the field is illustrated by the seven heparin mimetics that have achieved marketing approval and there are several more in late-stage clinical development. An overview of the structural determinants of heparin mimetics is presented together with an indication of their activities. The challenges in developing heparin mimetics as drugs, specificity and potential toxicity issues, are highlighted. Finally, the development path of three structurally very different mimetics, PI-88®, GMI-1070 and RGTAs, each of which is in clinical trials, is described

Feature, Structure and Classification of Adhesion Molecules: An Overview

Cell adhesion molecules allow cells to communicate with each other and with their environment. The interactions between cell adhesion receptors and their ligands orchestrate the assembly of cells into tissues, organs and systems, and lead to the formation of multicellular organisms. Numerous different adhesive events, which may be synergistic or antagonistic, are required for organizing a tissue or a cell behavior. It is the balance between these events that determines the structure of a tissue, or whether cells stay in tight association with other cells or migrate around the body.There are four main families of cell adhesion receptors: the immunoglobulin superfamily, integrins, cadherins and selectins. The cadherins mediate strong cell-cell adhesion and play a fundamental role in morphogenesis and development, while integrins are critical to cell-matrix interactions and cell migration through the extracellular matrix. Immunoglobulin superfamily members contribute to and modulate cell-cell interactions. These three large families contribute to adhesive interactions between many cell types in different tissues. The selectins have three members and they perform a very specific role critical for leukocyte migration from the vasculature

Heparanase: A challenging cancer drug target

Heparanase has been viewed as a promising anti-cancer drug target for almost two decades, but no anti-heparanase therapy has yet reached the clinic. This endoglycosidase is highly expressed in a variety of malignancies, and its high expression is associated with greater tumor size, more metastases, and a poor prognosis. It was first described as an enzyme cleaving heparan sulfate chains of proteoglycans located in extracellular matrices and on cell surfaces, but this is not its only function. It is a multi-functional protein with activities that are enzymatic and non-enzymatic and which take place both outside of the cell and intracellularly. Knowledge of the crystal structure of heparanase has assisted the interpretation of earlier structure-function studies as well as in the design of potential anti-heparanase agents. This review re-examines the various functions of heparanase in light of the structural data. The functions of the heparanase variant, T5, and structure and functions of heparanase-2 are also examined as these heparanase related, but non-enzymatic, proteins are likely to influence the in vivo efficacy of anti-heparanase drugs. The anti-heparanase drugs currently under development predominately focus on inhibiting the enzymatic activity of heparanase, which, in the absence of inhibitors with high clinical efficacy, prompts a discussion of whether this is the best approach. The diversity of outcomes attributed to heparanase and the difficulties of unequivocally determining which of these are due to its enzymatic activity is also discussed and leads us to the conclusion that heparanase is a valid, but challenging drug target for cance

Cross-species analysis of glycosaminoglycan binding proteins reveals some animal models are “more equal” than others

Glycosaminoglycan (GAG) mimetics are synthetic or semi-synthetic analogues of heparin or heparan sulfate, which are designed to interact with GAG binding sites on proteins. The preclinical stages of drug development rely on efficacy and toxicity assessment in animals and aim to apply these findings to clinical studies. However, such data may not always reflect the human situation possibly because the GAG binding site on the protein ligand in animals and humans could differ. Possible inter-species differences in the GAG-binding sites on antithrombin III, heparanase, and chemokines of the CCL and CXCL families were examined by sequence alignments, molecular modelling and assessment of surface electrostatic potentials to determine if one species of laboratory animal is likely to result in more clinically relevant data than another. For each protein, current understanding of GAG binding is reviewed from a protein structure and function perspective. This combinatorial analysis shows chemokine dimers and oligomers can present different GAG binding surfaces for the same target protein, whereas a cleft-like GAG binding site will differently influence the types of GAG structures that bind and the species preferable for preclinical work. Such analyses will allow an informed choice of animal(s) for preclinical studies of GAG mimetic drugs