Cucurbitacin-I induces hypertrophy in H9c2 cardiomyoblasts through activation of autophagy via MEK/ERK1/2 signaling pathway

Toxicol Lett. 2016 Dec 15;264:87-98. doi: 10.1016/j.toxlet.2016.11.003. Epub 2016 Nov 9.

Abstract

Cucurbitacin-I, a natural triterpenoids initially identified in medicinal plants, shows a potent anticancer effect on a variety of cancer cell types. Nevertheless, the cardiotoxicity of cucurbitacin-I has not heretofore been reported. In this study, the mechanisms of cucurbitacin-I-induced cardiotoxicity were examined by investigating the role of MAPK-autophagy-dependent pathways. After being treated with 0.1-0.3μM cucurbitacin-I for 48h, H9c2 cells showed a gradual decrease in the cell viabilities, a gradual increase in cell size, and mRNA expression of ANP and BNP (cardiac hypertrophic markers). Cucurbitacin-I concentration-dependent apoptosis of H9c2 cells was also observed. The increased apoptosis of H9c2 cells was paralleling with the gradually strong autophagy levels. Furthermore, an autophagy inhibitor, 3-MA, was used to block the cucurbitacin-I-stirred autophagy, and then the hypertrophy and apoptosis induced by 0.3μM cucurbitacin-I were significantly attenuated. In addition, cucurbitacin-I exposure also activated the MAPK signaling pathways, including ERK1/2, JNK, and p38 kinases. Interestingly, only the ERK inhibitor U0126, but not the JNK inhibitor SP600125 and p38 MAPK inhibitor SB203580, weakened the induction of 0.3μM cucurbitacin-I in hypertrophy, autophagy and apoptosis. Our findings suggest that cucurbitacin-I can increase the autophagy levels of H9c2 cells, most likely, through the activation of an ERK-autophagy dependent pathway, which results in the hypertrophy and apoptosis of cardiomyocytes.

Keywords: Autophagy; Cardiomyocyte hypertrophy; Cucurbitacin-I; MEK/ERK1/2; U0126.

MeSH terms

  • Atrial Natriuretic Factor / biosynthesis
  • Autophagy / drug effects*
  • Cardiomegaly / chemically induced*
  • Cardiomegaly / pathology
  • Cell Size / drug effects
  • Cell Survival / drug effects
  • Humans
  • Imidazoles / pharmacology
  • MAP Kinase Kinase 4 / antagonists & inhibitors
  • MAP Kinase Kinase Kinases / drug effects*
  • MAP Kinase Signaling System / drug effects*
  • Myoblasts, Cardiac / drug effects*
  • Natriuretic Peptide, Brain / biosynthesis
  • Protein Kinase Inhibitors / pharmacology
  • Pyridines / pharmacology
  • Signal Transduction / drug effects
  • Triterpenes / pharmacology*

Substances

  • Imidazoles
  • Protein Kinase Inhibitors
  • Pyridines
  • Triterpenes
  • Natriuretic Peptide, Brain
  • Atrial Natriuretic Factor
  • MAP Kinase Kinase Kinases
  • MAP Kinase Kinase 4
  • SB 203580
  • cucurbitacin I