A recent expression proteomics study has reported changes in cellular proteome (set of proteins) of human endothelial cells (ECs) induced by caffeine and epigallocatechin-3-gallate (EGCG), the most abundant bioactive compounds in coffee and green tea, respectively. Although both common and differential changes were highlighted by bioinformatics prediction, no experimental validation was performed. Herein, we reanalyzed these proteome datasets and performed protein-protein interactions network analysis followed by functional investigations using various assays to address the relevance of such proteome changes in human ECs functions. Protein-protein interactions network analysis revealed actin-crosslink formation, ubiquitin-proteasome activity and glycolysis as the three main networks among those significantly altered proteins induced by caffeine and EGCG. The experimental data showed predominant increases of actin-crosslink formation, ubiquitin-proteasome activity, and glycolysis (as reflected by increased F-actin and β-actin, declined ubiquitinated proteins and increased intracellular ATP, respectively) in the EGCG-treated cells. Investigations on angiogenesis features revealed that EGCG predominantly reduced ECs proliferation, migration/invasion, endothelial tube formation (as determined by numbers of nodes/junctions and meshes), barrier function (as determined by levels of VE-cadherin, zonula occludens-1 (ZO-1) and transendothelial resistance (TER)), and angiopoietin-2 secretion. However, both caffeine and EGCG had no effects on matrix metalloproteinase-2 (MMP-2) secretion. These data indicate that EGCG exhibits more potent effects on human ECs functions to induce actin-crosslink, ubiquitin-proteasome activity and glycolysis, and to suppress angiogenesis processes that commonly occur in various diseases, particularly cancers.
Keywords: Actin crosslink; Angiogenesis; Angiopoietin; Glycolysis; Proteasome; Ubiquitin.
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