Cr(VI) induces premature senescence through ROS-mediated p53 pathway in L-02 hepatocytes

Abstract

Hexavalent Chromium [Cr(VI)], which can be found of various uses in industries such as metallurgy and textile dying, can cause a number of human disease including inflammation and cancer. Unlike previous research that focused on Cr(VI)-induced oxidative damage and apoptosis, this study placed emphasis on premature senescence that can be induced by low-dose and long-term Cr(VI) exposure. We found Cr(VI) induced premature senescence in L-02 hepatocytes, as confirmed by increase in senescence associated-β-galactosidase (SA-β-Gal) activity. Cr(VI) stabilized p53 through phosphorylation at Ser15 and increased expression of p53-transcriptional target p21. Mechanism study revealed Cr(VI) targeted and inhibited mitochondrial respiratory chain complex (MRCC) I and II to enhance reactive oxygen species (ROS) production. By applying antioxidant Trolox, we also confirmed that ROS mediated p53 activation. A tetracycline-inducible lentiviral expression system containing shRNA to p53 was used to knockout p53. We found p53 could inhibit pro-survival genes B-cell lymphoma-2 (Bcl-2), myeloid leukemia-1 (Mcl-1) and S phase related cell cycle proteins cyclin-dependent kinase 2 (CDK2), Cyclin E to induce premature senescence, and the functional role of ROS in Cr(VI)-induced premature senescence is depend on p53. The results suggest that Cr(VI) has a role in premature senescence by promoting ROS-dependent p53 activation in L-02 hepatocytes.

Cr(VI)‐induced genotoxicity and cell cycle arrest in human osteoblast cell line MG‐63

“…Cr(V) and Cr(IV)]. Moreover, Zhang, Zhang, Zhong and Xiao () found that Cr(VI) stabilized p53 through phosphorylation at Ser15 in L‐02 hepatocytes and increased expression of p53‐transcriptional target p21. The authors also found that Cr(VI) targeted and inhibited mitochondrial respiratory chain complex I and II to enhance ROS production.…”

Chromium-Induced Reactive Oxygen Species Accumulation by Altering the Enzymatic Antioxidant System and Associated Cytotoxic, Genotoxic, Ultrastructural, and Photosynthetic Changes in Plants

“…Chromium-induced cytotoxicity affects essential micronutrient absorption, lipid peroxidation, cell cycle arrest and ultimate cell death in plants [8,22,56,87]. Toxic Cr levels also mediate the stomatal abnormalities, such as the decreased size of stomatal aperture, swelling of guard cells, changes in membrane permeability level, ion flux, and osmotic pressure [22,87,114,115]. These stomatal aberrations significantly influence the a, b, and total chlorophyll contents, stomatal conductance, photosynthetic rate, respiration, and transpiration rate [87,114,115].…”

“…Toxic Cr levels also mediate the stomatal abnormalities, such as the decreased size of stomatal aperture, swelling of guard cells, changes in membrane permeability level, ion flux, and osmotic pressure [22,87,114,115]. These stomatal aberrations significantly influence the a, b, and total chlorophyll contents, stomatal conductance, photosynthetic rate, respiration, and transpiration rate [87,114,115]. Trichomes, which are unicellular outgrowths on the leaf, play a defensive role in plants under stress conditions [116,117].…”

Cr(VI)-Induced Autophagy Protects L-02 Hepatocytes from Apoptosis Through the ROS-AKT-mTOR Pathway

“…Hepatocytes were treated, harvested, washed with ice-cold PBS, and subjected to western blot analysis, as previously described [21]. Briefly, approximately 50 μg protein of each different treatment group was separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to polyvinylidene fluoride (PVDF) membranes.…”

“…Cell culture and drug treatment L-02 hepatocytes were cultured as previously described [21]. The stock solution of Cr(VI) was prepared with phosphate buffered solution (PBS).…”