The influence of advanced glycosylation end products (AGE) on endothelial cells was investigated. When human umbilical endothelial cells were cultured with AGE-bovine serum albumin, viable cell number as well as DNA synthesis was significantly stimulated, whereas prostacyclin production by the endothelial cells was decreased. Antisense oligodeoxyribonucleotides against mRNA coding for AGE receptor were found to reverse both the AGE-induced growth stimulation and the inhibition of prostacyclin production in endothelial cells. These results thus suggest that AGE ligand-receptor interactions in endothelial cells can promote angiogenesis and thrombogenesis, leading to the development of diabetic vascular complications.
The molecular basis for the clinical association betweendiabetes mellitusand pancreatic cancer was investigated, using Mia PaCa-2 human pancreatic cancer cells in culture. Advanced glycation endproducts (AGE) prepared with bovine serum albumin and glucose were found to stimulate Mia PaCa-2 cell synthesis of DNA in a dose-dependent manner and also to significantly increase the number of viable cells. Evidence that platelet-derived growth factor-B (PDGF-B) mediates this growth promotion was obtained; AGE upregulated the level of PDGF-B mRNA, and antibodies against PDGF-BB completely neutralized the AGE-induced DNA synthesis. Antisense oligodeoxyribonucleotides complementary to mRNA encoding a receptor for AGE were found to reverse both the PDGF-B upregulation and the AGE-induced DNA synthesis. These results thus indicate that AGE ligand–receptor interactions could play an active part in the progression of pancreatic cancer through the induction of autocrine PDGF-B.
The influence of advanced glycosylation end products (AGE) on bovine retinal pericytes was investigated. When pericytes were cultured with AGE-bovine serum albumin (BSA), pericyte growth was significantly retarded in a dose-dependent manner. They also exhibited an immediate toxicity to pericytes. However, MRC-5 human fibroblasts were totally resistant to AGE-BSA. Moreover, antisense oligonucleotides complementary to mRNA coding for AGE receptor were found to reverse the AGE-induced decrease in viable pericyte number, although the mRNA level was about one order of magnitude lower in pericytes than in the fibroblasts. These results indicate that pericytes may possess a peculiar sensitivity to AGE, and that AGE ligand-receptor interactions may play an important role in the pathogenesis of pericyte loss, the principal change in diabetic microangiopathies.
The influence of endothelial cells on the growth of vascular pericytes was investigated using human umbilical endothelial cell and bovine retinal pericyte co-culture systems. When pericytes were cultured with endothelial cells, the number of viable pericytes increased significantly, regardless of the presence or absence of physical contact between the two cell types, indicating that endothelial cells can induce proliferation of pericytes through certain secreted factor(s). Evidence that endothelin 1 mediates this action was obtained: endothelin 1 added to the medium was able to substitute for the feeder layer of endothelial cells, and an antiserum against endothelin 1 could neutralize the ability of endothelial cells to promote pericyte growth. RNA blot analysis revealed that pericytes express mRNA for type-A endothelin receptor, a high affinity receptor of endothelin 1.
