Elevated kindlin-2 promotes tumour progression and angiogenesis through the mTOR/VEGFA pathway in melanoma.

BACKGROUND: In our previous study, kindlin-2 promoted skin wound healing and decreased the permeability of neovascularization during angiogenesis. Herein, we explored the biological function and underlying mechanism of kindlin-2 in cutaneous melanoma. METHODS AND RESULTS: Through a series of in vitro assays, we found that high levels of kindlin-2 promoted migration and invasion of melanoma cells without influencing cell proliferation. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analyses showed that upregulated kindlin-2 promoted the cellular epithelial-mesenchymal transition (EMT). Importantly, we found that melanoma cells overexpressing kindlin-2 promoted angiogenesis and VEGFA secretion in vitro and facilitated tumour growth and lung metastasis in vivo. To unveil the underlying mechanism, we conducted Next-generation sequencing (NGS) and differential expression analyses. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that overlapping differentially expressed genes (DEGs) were primarily enriched in the TGF-ß, mTOR and VEGF signalling pathways. Then, we confirmed that the mTOR/VEGFA pathway was activated during the process of kindlin-2-induced melanoma progression and angiogenesis. Moreover, we demonstrated that kindlin-2 was significantly overexpressed in clinical melanoma samples and that a high level of kindlin-2 predicted a poor prognosis. CONCLUSIONS: Taken together, these findings showed that kindlin-2 promotes angiogenesis and tumour progression via the mTOR/VEGFA pathway.

Two free radical pathways mediate chemical hypoxia-induced glutamate release in synaptosomes from the prefrontal cortex.

It has been known that the inhibition of mitochondrial cytochrome c oxidase is one of the earliest events occurring under hypoxia and this inhibition can lead to neuronal damages. Thus, the cytochrome c oxidase inhibitor sodium cyanide (NaCN) is widely used to produce a model of chemical hypoxia by inhibiting this enzyme. However, the downstream signaling pathways of the inhibition of the cytochrome c oxidase remain to be studied. In the present paper, we used sodium cyanide to mimic the inhibition of the mitochondrial cytochrome c oxidase and studied its effect on glutamate release in synaptosomes from the prefrontal cortex using on-line fluorimetry. We also further investigated the mechanisms underlying the enhancing effect of sodium cyanide on glutamate release using pharmacological approaches combined with other techniques. The results showed that sodium cyanide significantly increased glutamate release from synaptosomes of prefrontal cortex; the broad-spectrum free radical scavenger MnTBAP and melatonin completely abolished the effect of sodium cyanide on glutamate release; the H2O2-NMDA receptor pathway mediated one part, whereas the lipid peroxyl radicals-ATP synthase pathway mediated another part of the sodium cyanide-induced glutamate release; scavenging H2O2 and enhancing ATP synthase activity could completely abolish the sodium cyanide-induced glutamate release.