Novel Insights into the Molecular Mechanisms Involved in the Neuroprotective Effects of C-Phycocyanin against Brain Ischemia in Rats.

BACKGROUND: Ischemic stroke produces a large health impact worldwide, with scarce therapeutic options. OBJECTIVE: This study aimed to reveal the role of NADPH oxidase and neuroinflammatory genes in the cerebral anti-ischemic effects of C-Phycocyanin (C-PC), the chief biliprotein of Spirulina platensis. METHODS: Rats with either focal cerebral ischemia/reperfusion (I/R) or acute brain hypoperfusion, received C-PC at different doses, or a vehicle, for up to 6 h post-stroke. Neurological, behavioral and histochemical parameters were assessed in I/R rats at 24 h. Cerebral gene expression and hippocampal neuron viability were evaluated in hypoperfused rats at acute (24 h) or chronic phases (30 days), respectively. A molecular docking analysis of NOX2 and C-PC-derived Phycocyanobilin (PCB) was also performed. RESULTS: C-PC, obtained with a purity of 4.342, significantly reduced the infarct volume and neurological deficit in a dose-dependent manner, and improved the exploratory activity of I/R rats. This biliprotein inhibited NOX2 expression, a crucial NADPH oxidase isoform in the brain, and the superoxide increase produced by the ischemic event. Moreover, C-PC-derived PCB showed a high binding affinity in silico with NOX2. C-PC downregulated the expression of pro-inflammatory genes (IFN-γ, IL-6, IL-17A, CD74, CCL12) and upregulated immune suppressive genes (Foxp3, IL-4, TGF-ß) in hypoperfused brain areas. This compound also decreased chronic neuronal death in the hippocampus of hypoperfused rats. CONCLUSION: These results suggest that the inhibition of cerebral NADPH oxidase and the improvement of neuroinflammation are key mechanisms mediating the neuroprotective actions of C-PC against brain ischemia.

Synergic effect of OP449 and FTY720 on oral squamous cell carcinoma.

As SET protein is overexpressed and PP2A activity is reduced in oral squamous cell carcinoma (OSCC), this study aimed to assess the effects induced by OP449, a PP2A activator/SET inhibitor, on OSCC cells in vitro, and its potential either isolated or combined with FTY720, a PP2A activator/sphingosine kinase 1 antagonist, as antitumoral therapy in vivo. SET protein was analyzed in cells by immunoblotting and cancer stem cells by aldehyde dehydrogenase 1 assay (ALDH1). The cytotoxicity of OP449 was determined in five OSCC lineages by resazurin assay. Molecular actions of OP449 in SET targets were determined by immunoblotting. The coefficient of drug interaction (CDI) was used to characterize the synergism of OP449 and FTY720. The xenograft HN12 tumor model in nude mice was used to assess the antitumoral effect of OP449 and/or FTY720. HN12 (metastatic) cells showed higher SET and ALDH1 levels, and together with SCC9 cells were selected for molecular analysis. OP449 altered several SET functions/targets, such as histone H3 acetylation and NFkB. A synergism in cytotoxicity was observed when HN12 and SCC9 cells were pre-treated with 2 µM OP449 in combination with 15 µM FTY720 (CDI = 0.27 ± 0.088). Nude mice bearing xenograft HN12 tumors treated with OP449 and FTY720 showed reduced tumor mass. Moreover, NFkB was reduced in tumors after treatment. OP449 targets several SET functions, not only PP2A inhibition. Besides, OP449 plus FTY720 has a synergistic antitumoral effect on OSCC. Our results suggest new combined therapies and highlight SET and NFκB signaling as targets for OSCC therapy.