The recently ermerging disease COVID-19 is caused by the new SARS-CoV-2 virus first detected in the city of Wuhan, China. From there it has been rapidly spreading inside and outside China. With initial death rates around 4%, COVID-19 patients at longer distances from Wuhan showed reduced mortality as was previously observed for the SARS coronavirus. However, the new coronavirus spreads more strongly, as it sheds long before onset of symptoms or may be transmitted by people without symptoms. Rapid development of a protective vaccine against COVID-19 is therefore of paramount importance. Here we demonstrate that recombinantly expressed receptor binding domain (RBD) of the spike protein homologous to SARS binds to ACE2, the viral receptor. Higly repetitive display of RBD on immunologically optimized virus-like particles derived from cucumber mosaic virus resulted in a vaccine candidate (RBD-CuMVTT) that induced high levels of specific antibodies in mice which were able to block binding of spike protein to ACE2 and potently neutralized the SARS-CoV-2 virus in vitro.
Platelet-derived growth factor-B (PDGF-B) promotes tumor metastasis by inducing tumor cell growth, invasion, and angiogenesis in several cancers. However, the roles of PDGF-B in gastric carcinoma are largely unknown. We established two gastric carcinoma cell lines, SGC7901 and BGC823, to stably overexpress PDGF-B by lentiviral vectors, and determined their growth, invasion and angiogenesis. Overexpression of PDGF-B significantly enhanced the cell proliferation, invasion and angiogenesis of both SGC7901 and BGC823 cells, accompanied with increased activation of AKT, which is a downstream target of PDGF signaling pathway. Consequently, an AKT kinase inhibitor abolished the PDGF-B overexpression-mediated up-regulation of growth, invasion and angiogenesis. These results indicate that PDGF-B signaling may promote the metastasis of gastric carcinoma through AKT signaling. Targeting the PDGF-B pathway may be an alternative strategy for the development of therapies for gastric cancers.
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