Reactive oxygen species (ROS) are key signaling molecules that play an important role in the progression of inflammatory disorders. An enhanced ROS generation by polymorphonuclear neutrophils (PMNs) at the site of inflammation causes endothelial dysfunction and tissue injury. The vascular endothelium plays an important role in passage of macromolecules and inflammatory cells from the blood to tissue. Under the inflammatory conditions, oxidative stress produced by PMNs leads to the opening of inter-endothelial junctions and promotes the migration of inflammatory cells across the endothelial barrier. The migrated inflammatory cells not only help in the clearance of pathogens and foreign particles but also lead to tissue injury. The current review compiles the past and current research in the area of inflammation with particular emphasis on oxidative stress-mediated signaling mechanisms that are involved in inflammation and tissue injury.

Reactive Oxygen Species in Inflammation and Tissue Injury

It is well established that organs of future metastasis are not passive receivers of circulating tumour cells, but are instead selectively and actively modified by the primary tumour before metastatic spread has even occurred. Sowing the 'seeds' of metastasis requires the action of tumour-secreted factors and tumour-shed extracellular vesicles that enable the 'soil' at distant metastatic sites to encourage the outgrowth of incoming cancer cells. In this Review, we summarize the main processes and new mechanisms involved in the formation of the pre-metastatic niche.

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Pre-metastatic niches: organ-specific homes for metastases

Carbohydrates are the most abundant natural products. Besides their role in metabolism and as structural building blocks, they are fundamental constituents of every cell surface, where they are involved in vital cellular recognition processes. Carbohydrates are a relatively untapped source of new drugs and therefore offer exciting new therapeutic opportunities. Advances in the functional understanding of carbohydrate-protein interactions have enabled the development of a new class of small-molecule drugs, known as glycomimetics. These compounds mimic the bioactive function of carbohydrates and address the drawbacks of carbohydrate leads, namely their low activity and insufficient drug-like properties. Here, we examine examples of approved carbohydrate-derived drugs, discuss the potential of carbohydrate-binding proteins as new drug targets (focusing on the lectin families) and consider ways to overcome the challenges of developing this unique class of novel therapeutics.

From carbohydrate leads to glycomimetic drugs

Neoplastic transformation results in a wide variety of cellular alterations that impact the growth, survival, and general behavior of affected tissue. Although genetic alterations underpin the development of neoplastic disease, epigenetic changes can exert an equally significant effect on neoplastic transformation. Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of neoplastic progression. Alterations in glycosylation appear to not only directly impact cell growth and survival but also facilitate tumor-induced immunomodulation and eventual metastasis. Many of these changes may support neoplastic progression, and unique alterations in tumor-associated glycosylation may also serve as a distinct feature of cancer cells and therefore provide novel diagnostic and even therapeutic targets.

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Protein Glycosylation in Cancer

A disintegrin and metalloproteinases (ADAMs) are a new gene family of proteins with sequence similarity to the reprolysin family of snake venomases that share the metalloproteinase domain with matrix metalloproteinases (MMPs). They are structurally classified into two groups: the membrane-anchored ADAM and ADAM with thrombospondin motifs (ADAMTS). These molecules are involved in various biological events such as cell adhesion, cell fusion, cell migration, membrane protein shedding and proteolysis. Studies on the biochemical characteristics and biological functions of ADAMs are in progress, and accumulated lines of evidence have shown that some ADAMs are expressed in malignant tumors and participate in the pathology of cancers. The activities of ADAMs are regulated by gene expression, intracytoplasmic and pericellular regulation, activation of the zymogens and inhibition of activities by inhibitors. Many ADAM species, including ADAM8, ADAM9, ADAM10, ADAM12, ADAM15, ADAM17, ADAM19, ADAM28, ADAMTS1, ADAMTS4 and ADAMTS5, are expressed in human malignant tumors. Many of them are involved in the regulation of growth factor activities and integrin functions, leading to promotion of cell growth and invasion, although the precise mechanisms of these are not clear at the present time. In this article, we review recent information about ADAM family members and their implications for cancer cell proliferation and progression.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1349-7006.2007.00434.x

ADAMs in cancer cell proliferation and progression

Inflammation and cancer metastasis are associated with extravasation of leukocytes or tumor cells from blood into tissue. Such movement is believed to follow a coordinated and sequential molecular cascade initiated, in part, by the three members of the selectin family of carbohydrate-binding proteins: E-selectin (CD62E), L-selectin (CD62L) and P-selectin (CD62P). E-selectin is particularly noteworthy in disease by virtue of its expression on activated endothelium and on bone-skin microvascular linings and for its role in cell rolling, cell signaling and chemotaxis. E-selectin, along with L- or P-selectin, mediates cell tethering and rolling interactions through the recognition of sialo-fucosylated Lewis carbohydrates expressed on structurally diverse protein-lipid ligands on circulating leukocytes or tumor cells. Major advances in understanding the role of E-selectin in inflammation and cancer have been advanced by experiments assaying E-selectin-mediated rolling of leukocytes and tumor cells under hydrodynamic shear flow, by clinical models of E-selectin-dependent inflammation, by mice deficient in E-selectin and by mice deficient in glycosyltransferases that regulate the binding activity of E-selectin ligands. Here, the authors elaborate on how E-selectin and its ligands may facilitate leukocyte or tumor cell recruitment in inflammatory and metastatic settings. Antagonists that target cellular interactions with E-selectin and other members of the selectin family, including neutralizing monoclonal antibodies, competitive ligand inhibitors or metabolic carbohydrate mimetics, exemplify a growing arsenal of potentially effective therapeutics in controlling inflammation and the metastatic behavior of cancer.

/pdf/targeting-selectins-and-selectin-ligands-in-inflammation-and-3b708qjlsf.pdf

Targeting selectins and selectin ligands in inflammation and cancer

Prostate tumor cells, which characteristically metastasize to bone, initiate binding interactions with bone marrow endothelium under blood flow conditions through binding interactions with E-selectin. We hypothesized that E-selectin ligands on prostate tumor cells are directly associated with bone-metastatic potential. In this report, we elucidate the identity of E-selectin ligands on human metastatic prostate tumor cells and examine their association with prostate tumor progression and metastasis in vivo. To our surprise, we found that the E-selectin-binding form of P-selectin glycoprotein ligand-1 (PSGL-1) is expressed on the human bone-metastatic prostate tumor MDA PCa 2b cell line. Interestingly, we also found that human prostate tumor cells derived from bone, lymph node, and brain metastases expressed another leukocyte E-selectin ligand, E-selectin ligand-1 (ESL-1). Immunohistochemical analysis of PSGL-1 and ESL-1 in normal prostate tissue and in localized and metastatic prostate tumors revealed that ESL-1 was principally localized to intracellular cell membrane and expressed on all normal and malignant prostate tissue, whereas PSGL-1 was notably detected on the surfaces of bone-metastatic prostate tumor cells. These findings implicate a functional role of PSGL-1 in the bone tropism of prostate tumor cells and establish a new perspective into the molecular mechanism of human prostate tumor metastasis.

https://cancerres.aacrjournals.org/content/canres/65/13/5750.full.pdf

Identification of leukocyte E-selectin ligands, P-selectin glycoprotein ligand-1 and E-selectin ligand-1, on human metastatic prostate tumor cells

Ameliorating Skin-Homing Receptors on Malignant T Cells with a Fluorosugar Analog of N-acetylglucosamine: P-Selectin Ligand Is a More Sensitive Target than E-Selectin Ligand

T cell recruitment into inflamed skin is dependent on skin-homing receptor binding to endothelial (E)- and platelet (P)-selectin. These T cell receptors, or E- and P-selectin ligands, can be targeted by the metabolic fluorosugar inhibitor, 4-F-GlcNAc, to blunt cutaneous inflammation. Compelling new data indicate that, in addition to T cells, NK cells are also recruited to inflamed skin in allergic contact hypersensitivity (CHS) contingent on E- and P-selectin-binding. Using a model of allergic CHS, we evaluated the identity and impact of NK cell E-selectin ligand(s) on inflammatory responses and examined the oral efficacy of 4-F-GlcNAc. We demonstrated that the predominant E-selectin ligands on NK cells are P-selectin glycoprotein ligand-1 and protease-resistant glycolipids. We showed that, unlike the induced E-selectin ligand expression on activated T cells upon exposure to Ag, ligand expression on NK cells was constitutive. CHS responses were significantly lowered by orally administered 4-F-GlcNAc treatment. Although E-selectin ligand on activated T cells was suppressed, ligand expression on NK cells was insensitive to 4-F-GlcNAc treatment. These findings indicate that downregulating effector T cell E- and P-selectin ligand expression directly correlates with anti-inflammatory efficacy and provides new insight on metabolic discrepancies of E-selectin ligand biosynthesis in effector leukocytes in vivo.

/pdf/skin-homing-receptors-on-effector-leukocytes-are-2b4w4rpn94.pdf

Leyla Descheny

Papers

Targeting selectins and selectin ligands in inflammation and cancer

Identification of leukocyte E-selectin ligands, P-selectin glycoprotein ligand-1 and E-selectin ligand-1, on human metastatic prostate tumor cells

Ameliorating Skin-Homing Receptors on Malignant T Cells with a Fluorosugar Analog of N-acetylglucosamine: P-Selectin Ligand Is a More Sensitive Target than E-Selectin Ligand

Skin-Homing Receptors on Effector Leukocytes Are Differentially Sensitive to Glyco-Metabolic Antagonism in Allergic Contact Dermatitis