Ousting RAGE in melanoma: A viable therapeutic target?

Advanced glycation end products and reactive oxygen species: uncovering the potential role of ferroptosis in diabetic complications

Advanced glycation end products (AGEs) are a diverse range of compounds that are formed when free amino groups of proteins, lipids, and nucleic acids are carbonylated by reactive carbonyl species or glycosylated by reducing sugars. Hyperglycemia in patients with diabetes can cause an overabundance of AGEs. Excess AGEs are generally acknowledged as major contributing factors to the development of diabetic complications because of their ability to break down the extracellular matrix directly and initiate intracellular signaling pathways by binding to the receptor for advanced glycation end products (RAGE). Inflammation and oxidative stress are the two most well-defined pathophysiological states induced by the AGE-RAGE interaction. In addition to oxidative stress, AGEs can also inhibit antioxidative systems and disturb iron homeostasis, all of which may induce ferroptosis. Ferroptosis is a newly identified contributor to diabetic complications. This review outlines the formation of AGEs in individuals with diabetes, explores the oxidative damage resulting from downstream reactions of the AGE-RAGE axis, and proposes a novel connection between AGEs and the ferroptosis pathway. This study introduces the concept of a vicious cycle involving AGEs, oxidative stress, and ferroptosis in the development of diabetic complications.

Role of HMGB1 in Cutaneous Melanoma: State of the Art

High-mobility Group Box 1 (HMGB1) is a nuclear protein that plays a key role in acute and chronic inflammation. It has already been studied in several diseases, among them melanoma. Indeed, HMGB1 is closely associated with cell survival and proliferation and may be directly involved in tumor cell metastasis development thanks to its ability to promote cell migration. This research aims to assess the role of this molecule in the pathogenesis of human melanoma and its potential therapeutic role. The research has been conducted on the PubMed database, and the resulting articles are sorted by year of publication, showing an increasing interest in the last five years. The results showed that HMGB1 plays a crucial role in the pathogenesis of skin cancer, prognosis, and therapeutical response to therapy. Traditional therapies target this molecule indirectly, but future perspectives could include the development of new target therapy against HMGB1, thus adding a new approach to the therapy, which has often shown primary and secondary resistance. This could add a new therapy arm which has to be prolonged and specific for each patient.

Research Progress on the Role of Microglia Membrane Proteins or Receptors in Neuroinflammation and Degeneration

Microglia are intrinsic immune cells of the central nervous system and play a dual role (pro-inflammatory and anti-inflammatory) in the homeostasis of the nervous system. Neuroinflammation mediated by microglia serves as an important stage of ischemic hypoxic brain injury, cerebral hemorrhage disease, neurodegeneration and neurotumor of the nervous system and is present through the whole course of these diseases. Microglial membrane protein or receptor is the basis of mediating microglia to play the inflammatory role and they have been found to be upregulated by recognizing associated ligands or sensing changes in the nervous system microenvironment. They can then allosterically activate the downstream signal transduction and produce a series of complex cascade reactions that can activate microglia, promote microglia chemotactic migration and stimulate the release of proinflammatory factor such as TNF-α, IL-β to effectively damage the nervous system and cause apoptosis of neurons. In this paper, several representative membrane proteins or receptors present on the surface of microglia are systematically reviewed and information about their structures, functions and specific roles in one or more neurological diseases. And on this basis, some prospects for the treatment of novel coronavirus neurological complications are presented.

Molecular Characteristics of RAGE and Advances in Small-Molecule Inhibitors

Receptor for advanced glycation end-products (RAGE) is a member of the immunoglobulin superfamily. RAGE binds and mediates cellular responses to a range of DAMPs (damage-associated molecular pattern molecules), such as AGEs, HMGB1, and S100/calgranulins, and as an innate immune sensor, can recognize microbial PAMPs (pathogen-associated molecular pattern molecules), including bacterial LPS, bacterial DNA, and viral and parasitic proteins. RAGE and its ligands stimulate the activations of diverse pathways, such as p38MAPK, ERK1/2, Cdc42/Rac, and JNK, and trigger cascades of diverse signaling events that are involved in a wide spectrum of diseases, including diabetes mellitus, inflammatory, vascular and neurodegenerative diseases, atherothrombosis, and cancer. Thus, the targeted inhibition of RAGE or its ligands is considered an important strategy for the treatment of cancer and chronic inflammatory diseases.

Deficiency of Mitochondrial Glycerol 3-Phosphate Dehydrogenase Exacerbates Podocyte Injury and the Progression of Diabetic Kidney Disease

Mitochondrial function is essential for bioenergetics, metabolism, and signaling and is compromised in diseases such as proteinuric kidney diseases, contributing to the global burden of kidney failure, cardiovascular morbidity, and death. The key cell type that prevents proteinuria is the terminally differentiated glomerular podocyte. In this study, we characterized the importance of mitochondrial glycerol 3-phosphate dehydrogenase (mGPDH), located on the inner mitochondrial membrane, in regulating podocyte function and glomerular disease. Specifically, podocyte-dominated mGPDH expression was downregulated in the glomeruli of patients and mice with diabetic kidney disease and adriamycin nephropathy. Podocyte-specific depletion of mGPDH in mice exacerbated diabetes- or adriamycin-induced proteinuria, podocyte injury, and glomerular pathology. RNA sequencing revealed that mGPDH regulated the receptor for the advanced glycation end product (RAGE) signaling pathway, and inhibition of RAGE or its ligand, S100A10, protected against the impaired mitochondrial bioenergetics and increased reactive oxygen species generation caused by mGPDH knockdown in cultured podocytes. Moreover, RAGE deletion in podocytes attenuated nephropathy progression in mGPDH-deficient diabetic mice. Rescue of podocyte mGPDH expression in mice with established glomerular injury significantly improved their renal function. In summary, our study proposes that activation of mGPDH induces mitochondrial biogenesis and reinforces mitochondrial function, which may provide a potential therapeutic target for preventing podocyte injury and proteinuria in diabetic kidney disease.

RAGE Signaling in Melanoma Tumors

Despite recent progresses in its treatment, malignant cutaneous melanoma remains a cancer with very poor prognosis. Emerging evidences suggest that the receptor for advance glycation end products (RAGE) plays a key role in melanoma progression through its activation in both cancer and stromal cells. In tumors, RAGE activation is fueled by numerous ligands, S100B and HMGB1 being the most notable, but the role of many other ligands is not well understood and should not be underappreciated. Here, we provide a review of the current role of RAGE in melanoma and conclude that targeting RAGE in melanoma could be an approach to improve the outcomes of melanoma patients.

RAGE and its ligands: from pathogenesis to therapeutics

Receptor for advanced glycation end products (RAGE) is an immunoglobulin-like receptor present on cell surface. RAGE binds to an array of structurally diverse ligands, acts as a pattern recognition receptor (PRR) and is expressed on cells of different origin performing different functions. RAGE ligation leads to the initiation of a cascade of signaling events and is implicated in diseases, such as inflammation, cancer, diabetes, vascular dysfunctions, retinopathy, and neurodegenerative diseases. Because of the significant involvement of RAGE in the progression of numerous diseases, RAGE signaling has been targeted through use of inhibitors and anti-RAGE antibodies as a treatment strategy and therapy. Here in this review, we have summarized the physical and physiological aspects of RAGE biology in mammalian system and the importance of targeting this molecule in the treatment of various RAGE mediated pathologies. Highlights Receptor for advanced glycation end products (RAGE) is a member of immunoglobulin superfamily of receptors and involved in many pathophysiological conditions. RAGE ligation with its ligands leads to initiation of distinct signaling cascades and activation of numerous transcription factors. Targeting RAGE signaling through inhibitors and anti-RAGE antibodies can be promising treatment strategy.

Ca2+-Binding Proteins of the EF-Hand Superfamily: Diagnostic and Prognostic Biomarkers and Novel Therapeutic Targets

A multitude of Ca²⁺-sensor proteins containing the specific Ca²⁺-binding motif (helix-loop-helix, called EF-hand) are of major clinical relevance in a many human diseases. Measurements of troponin, the first intracellular Ca-sensor protein to be discovered, is nowadays the "gold standard" in the diagnosis of patients with acute coronary syndrome (ACS). Mutations have been identified in calmodulin and linked to inherited ventricular tachycardia and in patients affected by severe cardiac arrhythmias. Parvalbumin, when introduced into the diseased heart by gene therapy to increase contraction and relaxation speed, is considered to be a novel therapeutic strategy to combat heart failure. S100 proteins, the largest subgroup with the EF-hand protein family, are closely associated with cardiovascular diseases, various types of cancer, inflammation, and autoimmune pathologies. The intention of this review is to summarize the clinical importance of this protein family and their use as biomarkers and potential drug targets, which could help to improve the diagnosis of human diseases and identification of more selective therapeutic interventions.