Antioxidant tert-butylhydroquinone ameliorates arsenic-induced intracellular damages and apoptosis through induction of Nrf2-dependent antioxidant responses as well as stabilization of anti-apoptotic factor Bcl-2 in human keratinocytes

Free Radic Biol Med. 2016 May:94:74-87. doi: 10.1016/j.freeradbiomed.2016.02.009. Epub 2016 Feb 12.

Abstract

Human skin is a known target site of inorganic arsenic with effects ranging from hyperkeratosis to dermal malignancies. Tert-butylhydroquinone (tBHQ), approved food-grade phenolic antioxidant, is demonstrated to induce remarkable antioxidant activity in a variety of cells and tissues. The present study aimed at the protective effects of tBHQ on arsenic-induced cytotoxicity and apoptosis in human keratinocytes. Our results demonstrated that tBHQ antagonized arsenic-induced decrease of cell viability, generation of reactive oxygen species (ROS) and lipid peroxidation, as well as reduction of antioxidative enzymes superoxide dismutase (SOD) and catalase (CAT) activities. We also found that tBHQ relieved the G2/M phase arrest by arsenic exposure, which was associated with altering the expression of cell cycle regulators cyclin D1 and CDK4. tBHQ treatment further reduced the numbers of arsenic-induced mitochondrial-mediated apoptotic cells, which occurred concomitantly with the effective recovery of mitochondrial membrane potential (ΔΨm) depolarization, the release of cytochrome c releasing from the mitochondrial as well as the survival signal related factor caspase 3 activation. Our experiments then confirmed that tBHQ activated nuclear factor E2-related factor 2 (NRF2) pathway by increasing NRF2 protein in both nucleus and cytoplasm and upregulating NRF2 downstream targets

Nad(p)h: quinine oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1). More interestingly, arsenic-induced decrease of anti-apoptotic factor B-cell lymphoma-2 (Bcl-2) and increase of pro-apoptotic factor Bcl-2-associated X protein (Bax) could all be reversed by tBHQ pretreatment. These results suggested together that tBHQ could ameliorate arsenic-induced cytotoxicity and apoptosis, which might be linked with the induction of Nrf2-dependent antioxidant responses as well as stabilization of anti-apoptotic factor Bcl-2 in human keratinocytes.

Keywords: Apoptosis; Arsenic; Bcl-2; Human keratinocytes; NRF2; Oxidative stress; tBHQ.

MeSH terms

  • Antioxidants / administration & dosage*
  • Apoptosis / drug effects
  • Arsenic / toxicity
  • Catalase / metabolism
  • Cell Survival / drug effects
  • Cyclin D1 / metabolism
  • Cyclin-Dependent Kinase 4 / metabolism
  • Cytoplasm / drug effects
  • Cytoplasm / metabolism
  • Cytoplasm / pathology
  • Heme Oxygenase-1 / metabolism
  • Humans
  • Hydroquinones / administration & dosage*
  • Keratinocytes / drug effects
  • Keratinocytes / metabolism
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mitochondria / pathology
  • NAD(P)H Dehydrogenase (Quinone) / genetics*
  • NAD(P)H Dehydrogenase (Quinone) / metabolism
  • NF-E2-Related Factor 2 / genetics*
  • NF-E2-Related Factor 2 / metabolism
  • Oxidative Stress / drug effects
  • Proto-Oncogene Proteins c-bcl-2 / genetics*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Reactive Oxygen Species / metabolism
  • Superoxide Dismutase / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • Antioxidants
  • BAX protein, human
  • Hydroquinones
  • NF-E2-Related Factor 2
  • NFE2L2 protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • Reactive Oxygen Species
  • bcl-2-Associated X Protein
  • Cyclin D1
  • 2-tert-butylhydroquinone
  • Catalase
  • HMOX1 protein, human
  • Heme Oxygenase-1
  • Superoxide Dismutase
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, human
  • CDK4 protein, human
  • Cyclin-Dependent Kinase 4
  • Arsenic