Proteomic analysis of plasma from a Tau transgenic mouse

Extracellular Regucalcin: A Potent Suppressor in the Cancer Cell Microenvironment

The regucalcin gene is located on the X chromosome, comprising seven exons and six introns. This gene and protein are expressed in various tissues and cells and is predominantly expressed in human liver, kidney, and adrenal tissues. Regucalcin gene expression is enhanced via a mechanism mediated by several signaling molecules and transcription factors. Regucalcin plays a multifunctional role in cellular regulation in maintaining cell homeostasis. In addition, regucalcin has been implicated in several metabolic disorders and diseases. In particular, regucalcin plays a role as a novel suppressor in several types of cancer patients. Increased expression of regucalcin suppresses the growth of human cancer cells, suggesting its pivotal role in suppressing tumor development. The survival time of cancer patients is prolonged with increased expression of regucalcin in the tumor tissues. The adhesion, migration, invasion, and bone metastatic activity of cancer cells are blocked by the overexpression of regucalcin, promoting dormancy in cancer patients. Interestingly, regucalcin is also found in human serum, suggesting its character as a novel biomarker in various diseases. This extracellular regucalcin has been shown to suppress human cancer cells' growth and bone metastatic activity. Thus, extracellular regucalcin may play a vital role as a suppressor of human cancer activity. Alteration of the serum regucalcin levels in physiological and pathophysiological conditions may influence the activity of cancer cells in the microenvironment. This review will discuss the potential role of extracellular regucalcin in cancer cell activity as a critical suppressor in the cancer microenvironment.

Functional pleiotropy of calcium binding protein Regucalcin in signaling and diseases

Regucalcin (Mr ∼ 33.38 kDa) is a calcium binding protein, discovered in rat liver. In humans, gene for regucalcin is located on chromosome-11 (p11.3-q11.2) consisting of seven exons and six introns. The protein differs from other calcium binding protein in the way that it lacks EF-hand motif of calcium binding domain. It is also called as Senescence Marker Protein-30 (SMP-30) as previously its weight assumes to be 30 kDa and expression of this protein decreases with aging in androgen independent manner. Among vertebrates, it is a highly conserved protein showing gene homology in Drosophila, Xenopus, fireflies and others too. It is primarily expressed in liver and kidney in addition to brain, lungs, and skeletal muscles. Regucalcin acts as a Ca²⁺ regulatory protein and controls various cellular functions in liver and other organs. It suppresses protein phosphatase, protein kinase, DNA and RNA synthesis. Published evidences suggest regucalcin to be a reliable biomarker in various disorders of liver, kidney, brain and ocular. In over expressed state, it subdues apoptosis in cloned rat hepatoma cells and also induces hyperlipidemia and osteoblastogenesis by regulating various factors. Owing to the multi-functionality of regucalcin this review is presented to elaborate its importance in order to understand its involvement in cellular signaling during various pathologies.

Towards frailty biomarkers: Candidates from genes and pathways regulated in aging and age-related diseases

OBJECTIVE

Use of the frailty index to measure an accumulation of deficits has been proven a valuable method for identifying elderly people at risk for increased vulnerability, disease, injury, and mortality. However, complementary molecular frailty biomarkers or ideally biomarker panels have not yet been identified. We conducted a systematic search to identify biomarker candidates for a frailty biomarker panel.

METHODS

Gene expression databases were searched (http://genomics.senescence.info/genes including GenAge, AnAge, LongevityMap, CellAge, DrugAge, Digital Aging Atlas) to identify genes regulated in aging, longevity, and age-related diseases with a focus on secreted factors or molecules detectable in body fluids as potential frailty biomarkers. Factors broadly expressed, related to several "hallmark of aging" pathways as well as used or predicted as biomarkers in other disease settings, particularly age-related pathologies, were identified. This set of biomarkers was further expanded according to the expertise and experience of the authors. In the next step, biomarkers were assigned to six "hallmark of aging" pathways, namely (1) inflammation, (2) mitochondria and apoptosis, (3) calcium homeostasis, (4) fibrosis, (5) NMJ (neuromuscular junction) and neurons, (6) cytoskeleton and hormones, or (7) other principles and an extensive literature search was performed for each candidate to explore their potential and priority as frailty biomarkers.

RESULTS

A total of 44 markers were evaluated in the seven categories listed above, and 19 were awarded a high priority score, 22 identified as medium priority and three were low priority. In each category high and medium priority markers were identified.

CONCLUSION

Biomarker panels for frailty would be of high value and better than single markers. Based on our search we would propose a core panel of frailty biomarkers consisting of (1) CXCL10 (C-X-C motif chemokine ligand 10), IL-6 (interleukin 6), CX3CL1 (C-X3-C motif chemokine ligand 1), (2) GDF15 (growth differentiation factor 15), FNDC5 (fibronectin type III domain containing 5), vimentin (VIM), (3) regucalcin (RGN/SMP30), calreticulin, (4) PLAU (plasminogen activator, urokinase), AGT (angiotensinogen), (5) BDNF (brain derived neurotrophic factor), progranulin (PGRN), (6) α-klotho (KL), FGF23 (fibroblast growth factor 23), FGF21, leptin (LEP), (7) miRNA (micro Ribonucleic acid) panel (to be further defined), AHCY (adenosylhomocysteinase) and KRT18 (keratin 18). An expanded panel would also include (1) pentraxin (PTX3), sVCAM/ICAM (soluble vascular cell adhesion molecule 1/Intercellular adhesion molecule 1), defensin α, (2) APP (amyloid beta precursor protein), LDH (lactate dehydrogenase), (3) S100B (S100 calcium binding protein B), (4) TGFβ (transforming growth factor beta), PAI-1 (plasminogen activator inhibitor 1), TGM2 (transglutaminase 2), (5) sRAGE (soluble receptor for advanced glycosylation end products), HMGB1 (high mobility group box 1), C3/C1Q (complement factor 3/1Q), ST2 (Interleukin 1 receptor like 1), agrin (AGRN), (6) IGF-1 (insulin-like growth factor 1), resistin (RETN), adiponectin (ADIPOQ), ghrelin (GHRL), growth hormone (GH), (7) microparticle panel (to be further defined), GpnmB (glycoprotein nonmetastatic melanoma protein B) and lactoferrin (LTF). We believe that these predicted panels need to be experimentally explored in animal models and frail cohorts in order to ascertain their diagnostic, prognostic and therapeutic potential.

Electrochemical Detection of Plasma Immunoglobulin as a Biomarker for Alzheimer's Disease

The clinical diagnosis and treatment of Alzheimer’s disease (AD) represent a challenge to clinicians due to the variability of clinical symptomatology as well as the unavailability of reliable diagnostic tests. In this study, the development of a novel electrochemical assay and its potential to detect peripheral blood biomarkers to diagnose AD using plasma immunoglobulins is investigated. The immunosensor employs a gold electrode as the immobilizing substrate, albumin depleted plasma immunoglobulin as the biomarker, and polyclonal rabbit Anti-human immunoglobulin (against IgA, IgG, IgM) as the receptor for plasma conjugation. The assay showed good response, sensitivity and reproducibility in differentiating plasma immunoglobulin from AD and control subjects down to 10⁻⁹ dilutions of plasma immunoglobulin representing plasma content concentrations in the pg mL⁻¹ range. The newly developed assay is highly sensitive, less time consuming, easy to handle, can be easily modified to detect other dementia-related biomarkers in blood samples, and can be easily integrated into portable devices.

Alzheimer's disease biomarkers: correspondence between human studies and animal models

Alzheimer's disease (AD) represents an escalating global threat as life expectancy and disease prevalence continue to increase. There is a considerable need for earlier diagnoses to improve clinical outcomes. Fluid biomarkers measured from cerebrospinal fluid (CSF) and blood, or imaging biomarkers have considerable potential to assist in the diagnosis and management of AD. An additional important utility of biomarkers is in novel therapeutic development and clinical trials to assess efficacy and side effects of therapeutic interventions. Because many biomarkers are initially examined in animal models, the extent to which markers translate from animals to humans is an important issue. The current review highlights many existing and pipeline biomarker approaches, focusing on the degree of correspondence between AD patients and animal models. The review also highlights the need for greater translational correspondence between human and animal biomarkers.