Upregulation Of ANXA2 Research Articles

Epicardial adipose tissue volume and annexin A2/fetuin-A signalling are linked to coronary calcification in advanced coronary artery disease: Computed tomography and proteomic biomarkers from the EPICHEART study

Background & aimsThe role of epicardial adipose tissue (EAT) in the pathophysiology of late stage-coronary artery disease (CAD) has not been investigated. We explored the association of EAT volume and its proteome with advanced coronary atherosclerosis. MethodsThe EPICHEART Study prospectively enrolled 574 severe aortic stenosis patients referred to cardiac surgery. Before surgery, EAT volume was quantified by computed tomography (CT). During surgery, epicardial, mediastinal (MAT) and subcutaneous (SAT) adipose tissue samples were collected to explore fat phenotype by analyzing the proteomic profile using SWATH-mass spectrometry; pericardial fluid and peripheral venous blood were also collected. CAD presence was defined as coronary artery stenosis ≥50% in invasive angiography and by CT-derived Agatston coronary calcium score (CCS). ResultsEAT volume adjusted for body fat was associated with higher CCS, but not with the presence of coronary stenosis. In comparison with mediastinal and subcutaneous fat depots, EAT exhibited a pro-calcifying proteomic profile in patients with CAD characterized by upregulation of annexin-A2 and downregulation of fetuin-A; annexin-A2 protein levels in EAT samples were also positively correlated with CCS. We confirmed that the annexin-A2 gene was overexpressed in EAT samples of CAD patients and positively correlated with CCS. Fetuin-A gene was not detected in EAT samples, but systemic fetuin-A was higher in CAD than in non-CAD patients, suggesting that fetuin-A was locally downregulated. ConclusionsIn an elderly cohort of stable patients, CCS was associated with EAT volume and annexin-A2/fetuin-A signaling, suggesting that EAT might orchestrate pro-calcifying conditions in the late phases of CAD.

Annexin A2 upregulation protects human retinal endothelial cells from oxygen-glucose deprivation injury by activating autophagy.

Retinal neovascularization is a common pathological change in multiple diseases of the eyes and the upregulation of annexin A2 (A2) under a hypoxic and ischemic microenvironment has been demonstrated to be a key factor in the pathological process. However, the underlying mechanism by which A2 regulates retinal neovascularization remains unclear. In the present study, oxygen-glucose deprivation (OGD) was used to mimic the hypoxic and ischemic microenvironment, to observe the role of A2 in retinal neovascularization regulation by focusing on autophagy. The results showed that OGD treatment significantly increased the mRNA and protein levels of A2 in human retinal endothelial cells (HRECs), which was dependent on activation of hypoxia inducible factor (HIF)-1α signaling. The OGD-induced activation of autophagy was attenuated when A2 was silenced, but increased when A2 was overexpressed, suggesting that A2 upregulation contributed to OGD-induced cell autophagy activation. Furthermore, knockdown of A2 decreased cell viability and promoted cell apoptosis under OGD conditions. Overexpression of A2 increased cell viability and reduced cell apoptosis under OGD conditions, and inhibiting autophagy using an inhibitor, reversed these changes, suggesting that upregulation of A2 by OGD serves a cytoprotective role by inducing cell autophagy in HRECs. Taken together, the results of the present study suggested that promoting retinal endothelial cell survival by autophagy activation via the HIF-1α signaling pathway in a hypoxic and ischemic microenvironment may underlie the mechanism by which A2 regulates retinal neovascularization. The present study is the first study to demonstrate the novel role of A2 during retinal neovascularization under pathological conditions, to the best of our knowledge. Therefore, A2 may serve as a potential therapeutic target for treating neovascularization-associated conditions of the eye.

Abstract A09: Effects of Podocalyxin on neural stem/progenitor cells

Abstract Podocalyxin (PODXL) is a highly glycosylated and sialylated protein found mainly on podocytes and up-regulated in various types of tumors. Known to be a marker of hematopoietic progenitors and pluripotent stem cells, PODXL is also increasingly considered a marker of malignancy in several aggressive tumor types. Though the exact role of PODXL in tumors is not yet established, it has increasingly been shown in vitro to be involved in cell migration and invasion. We found Podxl to be highly expressed in murine tumorigenic neural stem/progenitor cells. To investigate effects of elevated Podxl levels in neural stem/progenitor cells (NSPs), Podxl or an empty control construct were over-expressed in these cells. Podxl-overexpressing NSPs did not form brain tumors upon intracranial transplantations, indicating that high levels of this gene alone are not sufficient for tumorigenesis. In vitro studies however revealed how Podxl might contribute to the development and /or maintenance of tumors. Podxl overexpression had a positive effect on cell number, sphere formation and cell viability. To find out how Podxl exerts its pro-survival effects, the proteome of Podxl-overexpressing and empty control NSPs was analysed by mass spectrometry. These experiments revealed an up-regulation of Annexin A2, a calcium-regulated phospholipid binding protein interacting with the cytoskeleton and extracellular matrix. In addition to elevated Annexin A2 protein levels, we also found increased transcript levels indicating that PODXL stimulates expression of the Annexin A2 gene. NSPs lacking Annexin A2 and overexpressing Podxl are less viable than wild type Podxl-overexpressing NSPs, suggesting that PODXL-mediated pro-survival effects can at least in part be explained by increased Annexin A2 levels. We are now investigating how Podxl and Annexin A2 mechanistically interact to enhance cell viability Citation Format: Isabelle V. Leefa Chong San, Gaelle Prost, Ulrike Nuber. Effects of Podocalyxin on neural stem/progenitor cells. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A09.

Up regulation of annexin A2 on murine H22 hepatocarcinoma cells induced by cartilage polysaccharide

In this study, we investigated the antitumor effect of a tumor vaccine prepared from H22 hepatocarcinoma cells induced by cartilage polysaccharide. We found out there were specific antigens which combined with antigen-specific antibodies from immune murine serum. Results of western blot analysis showed that about 36kDa make specific antibodies appeared specific antibodies in antiserum of immune mice, whereas the best immune effects became visible at the induction time of 48h. Analyses of 2-dimensional electrophoresis identified the specific antigen was annexin A2, which was a glycosylated protein that contained a glycosylation site, closely related to oncogenesis, cancer development, invasion and metastasis. Proteomics indicated that both quantity and conformation of annexin A2 were changed after induced by cartilage polysaccharide. Lastly, we found there was a major increase of annexin A2 mRNA on H22 cells induced by cartilage polysaccharide. In summary, our data suggested that annexin A2, a specific antigen played a key role in antitumor immune response and activating the immune system. It would be a potential type of tumor vaccine which provided new ideas for tumor immunoprophylaxis.

Up-regulation of annexin A2 in cholangiocarcinoma caused by Opisthorchis viverrini and its implication as a prognostic marker

Cholangiocarcinoma (CCA), or cancer of the bile ducts, is primarily associated with infection with the liver fluke Opisthorchis viverrini in northeast Thailand. The disease is associated with late presentation, poses challenges for diagnosis and has a high mortality rate – features that highlight the need for tumor markers. At present, there are no specific tumor markers that can indicate the early stages and status of CCA. Proteomic analysis of the proteins expressed on the surface of tumor cells is particularly difficult since proteome-wide analysis of surface membrane proteins has thus far been hampered by the lack of effective strategies to profile hydrophobic membrane proteins. In this study, a sequential protein extraction was utilized to overcome this problem. Membrane protein was extracted from four CCA cell lines with different tumor forming capabilities. The non-tumor H69 biliary cell line was used as a control. Two-dimensional-PAGE followed by MALDI-TOF-MS was used to identify differentially expressed proteins. Among 20 up-regulated membrane proteins identified in the CCA cell lines was ANXA2, a participant in tumor invasion and metastasis in other cancers. Accordingly, ANXA2 was verified in human subjects by probing, using a commercial anti-mouse monoclonal antibody and a tissue microarray of CCA (301 diagnosed cases), where it was found to associate with one of several tumor progression stages as reflected by lymphatic invasion ( P = 0.014) and metastasis ( P = 0.026). Patients with high expression of ANXA2 had a significantly shorter survival time ( P = 0.011). ANXA2 expression in tumors may be useful for predicting the poor outcome of CCA patients.

Proteomic analysis of differential proteins related to the neuropathic pain and neuroprotection in the dorsal root ganglion following its chronic compression in rats

The aim of the study was to identify the differential protein expressions related to neuropathic pain and neuroprotection in the dorsal root ganglion (DRG) following chronic compression of DRG (CCD) in rats. We conducted a proteomics study of L(4) and L(5) DRG after CCD for 28 days. A total of 98 protein spots were detected with significant changes in their expression levels after CCD and 15 protein spots were identified by the matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. Of these proteins, annexin A2, protein kinase C epsilon (PKCepsilon), glyceraldehyde-3-phosphate dehydrogenases (GAPDH), and heat shock protein 70 (HSP70) were up-regulated significantly compared with the normal control. These four proteins and p11, which was annexin A2 light chain, were further examined by Western blotting. The results of Western blotting and the proteomic analysis showed consistent data. Moreover, real-time quantitative RT-PCR experiments indicated that CCD-induced increase in protein levels was associated with an up-regulation of annexin A2 and PKCepsilon gene expression. In conclusion, this study highlights the molecular process in DRG underlying neuropathic pain. CCD is associated with the up-regulation of annexin A2 and PKCepsilon and their related genes. The up-regulation of GAPDH and HSP70 suggests that there exist concurrent processes of nervous injury and neuroprotection in the course of neuropathic pain.

Upregulation of annexin A2 in H 2O 2-induced premature senescence as evidenced by 2D-DIGE proteome analysis

Human diploid fibroblasts undergo premature senescence after treatment with sublethal concentration of H 2O 2. We report the first proteomic study of microsomal proteins in the context of H 2O 2-induced premature senescence by using 2D-DIGE approach. Twelve different proteins with altered abundance at day 3 after treatment with H 2O 2 were identified. Among them, we demonstrated a re-localization of annexin A2 in plasma membrane.