Role of HSP27/HSPB1 on the stress induced by cadmium

ALVAREZ OLMEDO D.; NADIN S.; SOTTILE M.; CHUNHUA SHI; BIAGGIO V.S.; GOMEZ N.

Bogotá

Conferencia; Second Latin America Chapter Conference of Cell Stress Society International; 2016

Cell Stress Society International and Pontificia Universidad Javeriana

Introduction and aims: Cadmium (Cd) is a non-essential carcinogenic metal that can harm human health. Typically, exposure occurs through diet, smoking, occupational environment and environmental pollution. Although toxic effects of Cd are well characterized in humans, the molecular mechanisms involving oxidative radical formation with the subsequent downstream effects are not fully understood. HSP27 has been shown to protect cells from oxidative damage and apoptosis, therefore in this work we investigated one of the mechanisms involved in Cd toxicity and the participation of HSP27 in preventing Cd-induced cellular toxicity and death. Methodology: HeLa wild type and HeLa 2.2 cells (stably downregulated for HSP27) were exposed to different CdCl2 solutions (0-100 µM), for 1-24 hr. Reactive oxygen species (ROS) and peroxynitrite (PN) were measured using fluorescent probes. Lipid peroxidation was measured with tiobarbituric acid; nitric oxide (NO) analyzed using Griess reagent. Protein nitration was determined by immunofluorescence (IF) with nitrotyrosine antibody. DNA damage was determined by alkaline comet assay and western blot with H2AX antibody. Metabolic activity was measured by CCK-8 and apoptosis by Annexin V. Results: The harmful effects of Cd correlated with the induction of oxidative stress markers: ROS, PN production, lipid peroxidation, and protein nitration. NO bioavailability, necessary for PN production, was reduced by Cd (50-100 µM) while 100 µM Cd produced PN and reduced the levels of intracellular HSP27. Furthermore, SIN-1 (a PN donor) also decreased HSP27 levels. Cd induced DNA damage and a reduction of cell metabolic activity. HSP27 downregulation sensitized the cells toward Cd toxicity; Cdinduced cell death was counteracted with pharmacological inhibitors of NO or by pretreatment of the cells with recombinant HSP27 (rHSP27), which protected cell viability. Conclusion: Our findings showed a relationship between Cd-induced toxicity and peroxynitrite production. Toxic doses of Cd reduced HSP27 levels. Downregulation of HSP27 sensitized cells to Cd, therefore rHSP27 may be considered a potential therapeutic agent to counteract Cd toxicity.