α-Hispanolol sensitizes hepatocellular carcinoma cells to TRAIL-induced apoptosis via death receptor up-regulation

Toxicol Appl Pharmacol. 2015 Aug 1;286(3):168-77. doi: 10.1016/j.taap.2015.04.012. Epub 2015 Apr 28.

Abstract

Hispanolone derivatives have been previously described as anti-inflammatory and antitumoral agents. However, their effects on overcoming Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance remain to be elucidated. In this study, we analyzed the cytotoxic effects of the synthetic hispanolone derivative α-hispanolol (α-H) in several tumor cell lines, and we evaluated the induction of apoptosis, as well as the TRAIL-sensitizing potential of α-H in the hepatocellular carcinoma cell line HepG2. Our data show that α-H decreased cell viability in a dose-dependent manner in HeLa, MDA-MB231, U87 and HepG2 cell lines, with a more prominent effect in HepG2 cells. Interestingly, α-H had no effect on non-tumoral cells. α-H induced activation of caspase-8 and caspase-9 and also increased levels of the proapoptotic protein Bax, decreasing antiapoptotic proteins (Bcl-2, X-IAP and IAP-1) in HepG2 cells. Specific inhibition of caspase-8 abrogated the cascade of caspase activation, suggesting that the extrinsic pathway has a critical role in the apoptotic events induced by α-H. Furthermore, combined treatment of α-H with TRAIL enhanced apoptosis in HepG2 cells, activating caspase-8 and caspase-9. This correlated with up-regulation of both the TRAIL death receptor DR4 and DR5. DR4 or DR5 neutralizing antibodies abolished the effect of α-H on TRAIL-induced apoptosis, suggesting that sensitization was mediated through the death receptor pathway. Our results demonstrate that α-H induced apoptosis in the human hepatocellular carcinoma cell line HepG2 through activation of caspases and induction of the death receptor pathway. In addition, we describe a novel function of α-H as a sensitizer on TRAIL-induced apoptotic cell death in HepG2 cells.

Keywords: Apoptosis; Caspase 8; Death receptors; Hispanolone derivatives; TRAIL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Carcinoma, Hepatocellular / metabolism*
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Diterpenes / chemistry
  • Diterpenes / pharmacology*
  • Dose-Response Relationship, Drug
  • HeLa Cells
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / metabolism*
  • Receptors, TNF-Related Apoptosis-Inducing Ligand / biosynthesis*
  • TNF-Related Apoptosis-Inducing Ligand / toxicity*
  • Up-Regulation / drug effects
  • Up-Regulation / physiology

Substances

  • Diterpenes
  • Receptors, TNF-Related Apoptosis-Inducing Ligand
  • TNF-Related Apoptosis-Inducing Ligand
  • TNFRSF10A protein, human
  • TNFSF10 protein, human
  • hispanolone