Selenium mediated arsenic toxicity modifies cytotoxicity, reactive oxygen species and phosphorylated proteins

Abstract

The effect of selenium on modulating arsenic cytotoxicity is well known in mammals, but not well understood. Cell cytotoxicity and reactive oxygen species (ROS) changes were performed in combinations of As(III) and selenomethionine (SeMet) toxic mixes on, HEK293, human kidney cells. Cell growth is readily restored from 20% to 60% when switching from 30 μM As(III) as toxin to a mix of 30 μM As(III) and 100 μM SeMet. As(III) alone triggers ROS formation, primarily hydrogen peroxide, in a concentration dependent manner as observed through changes in the fluorescence from 2',7'-dichlorofluorescein diacetate. Importantly, SeMet induces lower ROS levels at the same concentrations used to modulate As(III) cytotoxicity (IC50). Elevated ROS is important to As(III) cytotoxicity and minimizing it is essential to the SeMet modulating function. Changes in cell signaling, through analysis of signaling changes via differential protein phosphorylation to uncover molecular level changes occurring in HEK293 human kidney cells as SeMet modulates the As(III) cytotoxicity. To discover changes in the phosphoproteome, cells were incubated under three conditions: 30 μM As(III), 100 μM SeMet, and 30 μM As(III) + 100 μM SeMet. After total protein isolation the three samples were separated into fractions using size exclusion chromatography by detecting (31)P(+). Each sample was analyzed for the phosphorylated peptides by enzymatic digestion, selective enrichment of phosphorylated peptides via TiO2, followed by nanoLC-ESIMS. Phosphorylated proteins unique to the As(III)-SeMet mixture were then identified. The molecular level changes to the cells show uniquely that the As(III)-SeMet mixture details proteins involved in ROS detoxification, cell cycle arrest, and protein/DNA damage. This study shows that SeMet not only lowers the total amount of ROS in a cell but also confers upon HEK293 cells the ability to detoxify. Thus, SeMet is not only a potent antioxidant in this system, but induces molecular changes that confer survival.

Selenium Alleviates Porcine Nephrotoxicity of Ochratoxin A by Improving Selenoenzyme Expression In Vitro

“…Furthermore, our results showed that selenomethionine blocked OTA-induced ROS production and GSH depletion in PK15 cells in a dose-dependent manner. These results are consistent with that of a previous study, which found that selenomethionine treatment lowered the total amount of ROS generated by As (III) treatment in HEK293 human kidney cells [ 47 ]. Together, the present results strongly suggested that selenomethionine protected PK15 cells against OTA-induced cytotoxicity and apoptosis by improving cellular antioxidant capacity.…”

The Role of Selenium in Arsenic and Cadmium Toxicity: an Updated Review of Scientific Literature

“…Using the comet assay, the researchers also found that nanoSe prevented arsenite-dependent DNA damage [99]. In another in vitro study, an organic Se form (SeMet, 100 μM) protected human kidney cells from arsenite (30 μM)-induced cell cytotoxicity and ROS generation [98]. Inorganic Se administered as selenite (10 μΜ) induced antioxidant, antiautophagic, and antiapoptotic effects in arsenite (10 μΜ)-treated PC12 cells [100].…”

Evaluation of Essential and Toxic Elements in Blood Samples of Male Smokers Having Different Types of Cancers with Reference to Healthy Male Smokers

“…The antagonistic effect of Se on arsenic toxicity has been gradually accepted by the public. In recent years, in vitro research showed that Se can alleviate arsenic toxicity by modifying cytotoxicity, genotoxicity and oxidative stress [46,47]. This is confirmed by a study carried out by Sah and Smits (2012), who suggested dietary Se at 0.6 mg/ kg, improved the antioxidant capacity and counteracted chronic as toxicity in rats [48].…”