Vitamin E δ-tocotrienol triggers endoplasmic reticulum stress-mediated apoptosis in human melanoma cells

Sci Rep. 2016 Jul 27:6:30502. doi: 10.1038/srep30502.

Abstract

Malignant melanoma is the leading cause of death from skin cancer. Drug toxicity and resistance represent a serious challange for melanoma treatments. Evidence demonstrates that natural compounds may play a crucial role in cancer prevention, growth and progression. Vitamin E tocotrienols (TT) were shown to possess antitumor activity. Here, we analyzed the effects of δ-TT on melanoma cell growth and the involvement of the endoplasmic reticulum (ER) stress in this activity. The experiments were performed on human melanoma cell lines, BLM and A375. δ-TT exerted a significant proapoptotic effect on both cell lines, involving the intrinsic apoptosis pathway; importantly, this compound did not affect the viability of normal human melanocytes. In melanoma cells, δ-TT exerted its antitumor effect through activation of the PERK/p-eIF2α/ATF4/CHOP, IRE1α and caspase-4 ER stress-related branches. Salubrinal, an inhibitor of the ER stress, counteracted the cytotoxic activity of δ-TT. In vivo experiments performed in nude mice bearing A375 xenografts evidenced that δ-TT reduces tumor volume and tumor mass; importantly, tumor progression was significantly delayed by δ-TT treatment. In conclusion, δ-TT exerts a proapoptotic activity on melanoma cells, through activation of the ER stress-related pathways. δ-TT might represent an effective option for novel chemopreventive/therapeutic strategies for melanoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects*
  • Apoptosis / physiology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Endoplasmic Reticulum Stress / drug effects*
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Melanoma / drug therapy*
  • Melanoma / genetics
  • Melanoma / pathology
  • Melanoma, Cutaneous Malignant
  • Mice, Nude
  • Signal Transduction / drug effects
  • Skin Neoplasms / drug therapy*
  • Skin Neoplasms / genetics
  • Skin Neoplasms / pathology
  • Vitamin E / analogs & derivatives*
  • Vitamin E / pharmacology
  • Xenograft Model Antitumor Assays

Substances

  • Antineoplastic Agents
  • Vitamin E
  • tocotrienol, delta