No abstract

Galectin-3 staining is highly sensitive for malignancy in follicular patterned thyroid lesions. Diagnostic problems may arise in the presence of Hurthle cell proliferation or minimally invasive follicular carcinoma.

Impaired angiogenesis is one of the features of ischemic diseases. We have previously identified, by screening a phage display peptide library, a peptide that induces angiogenesis in endothelial cells under hypoxic conditions by binding the cell’s membrane heat shock protein GRP78. Protein data base search identified 4 amino acids (HWRR) of that synthetic peptide present on the ADAM15 metalloprotease domain, a protein considered to be involved in neovascularization. Three peptides were synthesized according to the ADAM15 sequence placing HWRR at different positions. Peptide ADoPep1 exhibited significant angiogenic properties under hypoxic conditions as determined by cell proliferation, migration and tube formation. In a mouse hind limb ischemia model, a single injection of the peptide restored blood perfusion. The identified peptide was found to activate GRP78 on endothelial cell membrane and siRNA directed against the GRP78 mRNA interfered with induction of angiogenesis by the peptide. The peptide binding induced a decrease in heat shock protein GRP78 that is overexpressed under hypoxic conditions. The mechanism of peptide-induced angiogenic activity involves inhibition of apoptosis as well as increased Akt phosphorylation and ERK 1/2 activation. The peptide did not induce VEGF receptor-2 protein synthesis and phosphorylation, suggesting a VEGF-independent mechanism of angiogenesis.

Myocardial ischemia is a severe stress condition that causes extensive biochemical changes triggering cardiac cell death. The 78-kDa glucose-regulated protein (GRP78), a heat shock protein present in all cells and a widely used marker of endoplasmic reticulum stress, functions in controlling the structural maturation of nascent glycoproteins. However, GRP78 was also found to be expressed on the cell surface of several cells such as endothelial cells, macrophages, and tumor cells where it functions as a receptor for a variety of ligands in signaling pathways. Recently, we have identified peptides from two different sources that specifically bind GRP78 protein. We have shown that binding of these peptides to endothelial cell surface GRP78 resulted in angiogenesis. In this study, we first established the presence of cell surface GRP78 on cardiac myocytes. Analysis of cardiomyocytes under hypoxia determined the significant increase in cell surface GRP78 in addition to gene expression and total protein. Apoptosis that was significantly increased in cardiomyocytes under hypoxic conditions was inhibited by the presence of the peptide-binding GRP78 during hypoxia. Inhibition of apoptosis was mediated by the binding of the peptide to cardiomyocytes cell surface GRP78 resulting in blocking caspase-3/7 activation. Silencing GRP78 RNA that reduced GRP78 receptor abrogated the peptide activity. Apoptosis of cardiac cells induced by myocardial infarction in a mouse model was also significantly inhibited by the administration of the peptide to mouse hearts. Our findings may make ADoPep1 a useful therapeutic tool for relieving of ischemia.