Ergosterol peroxide activates Foxo3-mediated cell death signaling by inhibiting AKT and c-Myc in human hepatocellular carcinoma cells

Oncotarget. 2016 Jun 7;7(23):33948-59. doi: 10.18632/oncotarget.8608.

Abstract

Sterols are the important active ingredients of fungal secondary metabolites to induce death of tumor cells. In our previous study, we found that ergosterol peroxide (5α, 8α-epidioxiergosta-6, 22-dien-3β-ol), purified from Ganoderma lucidum, induced human cancer cell death. Since the amount of purified ergosterol peroxide is not sufficient to perform in vivo experiments or apply clinically, we developed an approach to synthesize ergosterol peroxide chemically. After confirming the production of ergosterol peroxide, we examined the biological functions of the synthetic ergosterol peroxide. The results showed that ergosterol peroxide induced cell death and inhibited cell migration, cell cycle progression, and colony growth of human hepatocellular carcinoma cells. We further examined the mechanism associated with this effect and found that treatment with ergosterol peroxide increased the expression of Foxo3 mRNA and protein in HepG2 cells. The upstream signal proteins pAKT and c-Myc, which can inhibit Foxo3 functions, were clearly decreased in HepG2 cells treated with ergosterol peroxide. The levels of Puma and Bax, pro-apoptotic proteins, were effectively enhanced. Our results suggest that ergosterol peroxide stimulated Foxo3 activity by inhibiting pAKT and c-Myc and activating pro-apoptotic protein Puma and Bax to induce cancer cell death.

Keywords: Foxo3; Puma; c-Myc; ergosterol peroxide; pAKT.

MeSH terms

  • Antineoplastic Agents, Phytogenic / chemical synthesis
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / metabolism
  • Carcinoma, Hepatocellular / drug therapy*
  • Carcinoma, Hepatocellular / enzymology
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / pathology
  • Cell Movement / drug effects
  • Cell Proliferation / drug effects
  • Dose-Response Relationship, Drug
  • Down-Regulation
  • Ergosterol / analogs & derivatives*
  • Ergosterol / chemical synthesis
  • Ergosterol / pharmacology
  • Forkhead Box Protein O3 / genetics
  • Forkhead Box Protein O3 / metabolism*
  • Hep G2 Cells
  • Humans
  • Liver Neoplasms / drug therapy*
  • Liver Neoplasms / enzymology
  • Liver Neoplasms / genetics
  • Liver Neoplasms / pathology
  • Phosphorylation
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Signal Transduction / drug effects*
  • Time Factors
  • bcl-2-Associated X Protein / genetics
  • bcl-2-Associated X Protein / metabolism

Substances

  • Antineoplastic Agents, Phytogenic
  • Apoptosis Regulatory Proteins
  • BAX protein, human
  • BBC3 protein, human
  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • MYC protein, human
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-myc
  • bcl-2-Associated X Protein
  • Proto-Oncogene Proteins c-akt
  • ergosterol-5,8-peroxide
  • Ergosterol