In recent decades, studies on the functional features of Se nanoparticles (SeNP) have gained great popularity due to their high biocompatibility, stability, and pronounced selectivity. A large number of works prove the anticarcinogenic effect of SeNP. In this work, the molecular mechanisms regulating the cytotoxic effects of SeNP, obtained by laser ablation, were studied by the example of four human cancer cell lines: A-172 (glioblastoma), Caco-2, (colorectal adenocarcinoma), DU-145 (prostate carcinoma), MCF-7 (breast adenocarcinoma). It was found that SeNP had different concentration-dependent effects on cancer cells of the four studied human lines. SeNP at concentrations of less than 1 μg/mL had no cytotoxic effect on the studied cancer cells, with the exception of the A-172 cell line, for which 0.5 μg/mL SeNP was the minimum concentration affecting its metabolic activity. It was shown that SeNP concentration-dependently caused cancer cell apoptosis, but not necrosis. In addition, it was found that SeNP enhanced the expression of pro-apoptotic genes in almost all cancer cell lines, with the exception of Caco-2 and activated various pathways of adaptive and pro-apoptotic signaling pathways of UPR. Different effects of SeNP on the expression of ER-resident selenoproteins and selenium-containing glutathione peroxidases and thioredoxin reductases, depending on the cell line, were established. In addition, SeNP triggered Ca2+ signals in all investigated cancer cell lines. Different sensitivity of cancer cell lines to SeNP can determine the induction of the process of apoptosis in them through regulation of the Ca2+ signaling system, mechanisms of ER stress, and activation of various expression patterns of genes encoding pro-apoptotic proteins.

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Norepinephrine is one of the key neurotransmitters in the hippocampus, but its role in the functioning of the neuroglial networks remains unclear. Here we show that norepinephrine suppresses NH4Cl‐induced oscillations of the intracellular Ca2+ concentration ([Ca2+]i) in hippocampal neurons. We found that the inhibitory effect of norepinephrine against ammonium‐induced [Ca2+]i oscillations is mediated by activation of alpha‐2 adrenergic receptors. Furthermore, UK 14,304, an agonist of alpha‐2 adrenergic receptors, evokes a biphasic [Ca2+]i elevation in a minor population of astrocytes. This elevation consists of an initial fast, peak‐shaped [Ca2+]i rise, mediated by Giβγ subunit and subsequent PLC‐induced mobilization of Ca2+ from internal stores, and a plateau phase, mediated by a Ca2+ influx from the extracellular medium through store‐operated and TRPC3 channels. We show the correlation between the Ca2+ response in astrocytes and suppression of [Ca2+]i oscillations in neurons. The inhibitory effect of UK 14,304 is abolished in the presence of gallein, an inhibitor of Gβγ‐signaling. In turn, application of the agonist in the presence of the PLC inhibitor decreases the frequency and amplitude of [Ca2+]i oscillations in neurons but does not suppress them. The same effect is observed in the presence of bicuculline, a GABA(A) receptor antagonist. We demonstrate that UK 14,304 application increases the frequency and amplitude of slow outward chloride currents in neurons, indicating the release of GABA by astrocytes. Thus, our findings indicate that the activation of astrocytic alpha‐2 adrenergic receptors stimulates GABA release from astrocytes via Giβγ subunit‐associated signaling pathway, contributing to the suppression of neuronal activity.