Inhibition of c-Met promoted apoptosis, autophagy and loss of the mitochondrial transmembrane potential in oridonin-induced A549 lung cancer cells

J Pharm Pharmacol. 2013 Nov;65(11):1622-42. doi: 10.1111/jphp.12140. Epub 2013 Sep 15.

Abstract

Objective: Herein, inhibition of hepatocyte growth factor receptor, c-Met, significantly increased cytochrome c release and Bax/Bcl-2 ratio, indicating that c-Met played an anti-apoptotic role. The following experiments are to elucidate this anti-apoptotic mechanism, then the effect of c-Met on autophagy has also been discussed.

Methods: Investigated was the influence of c-Met on apoptosis, autophagy and loss of mitochondrial transmembrane potential (Δψm), and the relevant proteins were examined.

Key findings: First, we found that activation of extracellular signal-regulated kinase (ERK), p53 was promoted by c-Met interference. Subsequent studies indicated that ERK was the upstream effector of p53, and this ERK-p53 pathway mediated release of cytochrome c and up-regulation of Bax/Bcl-2 ratio. Secondly, the inhibition of c-Met augmented oridonin-induced loss of mitochondrial transmembrane potential (Δψm), resulting apoptosis. Finally, the inhibition of c-Met increased oridonin-induced A549 cell autophagy accompanied by Beclin-1 activation and conversion from microtubule-associated protein light chain 3 (LC3)-I to LC3-II. Activation of ERK-p53 was also detected in autophagy process and could be augmented by inhibition of c-Met. Moreover, suppression of autophagy by 3-methyladenine (3-MA) or small interfering RNA against Beclin-1 or Atg5 decreased oridonin-induced apoptosis. Inhibition of apoptosis by pan-caspase inhibitor (z-VAD-fmk) decreased oridonin-induced autophagy as well and Loss of Δψm also occurred during autophagic process.

Conclusion: Thus, inhibiting c-Met enhanced oridonin-induced apoptosis, autophagy and loss of Δψm in A549 cells.

Keywords: SU11274; apoptosis; autophagy; c-Met; c-Met siRNA.

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Amino Acid Chloromethyl Ketones
  • Apoptosis / drug effects*
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects*
  • Autophagy-Related Protein 5
  • Beclin-1
  • Cytochromes c / metabolism
  • Diterpenes, Kaurane / pharmacology*
  • Diterpenes, Kaurane / therapeutic use
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Humans
  • Isodon / chemistry
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / physiopathology
  • Membrane Potential, Mitochondrial / drug effects*
  • Membrane Proteins / metabolism
  • Microtubule-Associated Proteins / metabolism
  • Mitochondria / drug effects*
  • Phytotherapy
  • Plant Extracts / pharmacology
  • Plant Extracts / therapeutic use
  • Proto-Oncogene Proteins c-met / antagonists & inhibitors*
  • RNA, Small Interfering / pharmacology
  • Tumor Suppressor Protein p53 / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • ATG5 protein, human
  • Amino Acid Chloromethyl Ketones
  • Apoptosis Regulatory Proteins
  • Autophagy-Related Protein 5
  • BECN1 protein, human
  • Beclin-1
  • Diterpenes, Kaurane
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Plant Extracts
  • RNA, Small Interfering
  • Tumor Suppressor Protein p53
  • bcl-2-Associated X Protein
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • oridonin
  • 3-methyladenine
  • Cytochromes c
  • Proto-Oncogene Proteins c-met
  • Extracellular Signal-Regulated MAP Kinases
  • Adenine