Modified Panax ginseng extract regulates autophagy by AMPK signaling in A549 human lung cancer cells

Oncol Rep. 2017 Jun;37(6):3287-3296. doi: 10.3892/or.2017.5590. Epub 2017 Apr 20.

Abstract

Panax ginseng has been used worldwide as a traditional medicine for the treatment of cancer and other diseases. The antiproliferative activity of ginseng has been increased after enzymatic processing of ginseng saponin, which may result in the accumulation of minor saponins, such as Rh2, Rg3, compound K and protopanaxatriol type (PPT) in modified regular ginseng extract (MRGX). In the present study, the anticancer activity and the associated mechanisms of MRGX were investigated using A549 human lung cancer cells. To elucidate the mechanisms underlying the effects of MRGX, we performed a microarray analysis of gene expression in the A549 cells. Molecular mechanisms that were associated with the anticancer activity of MRGX were studied, with a special focus on the autophagy-related multiple signaling pathways in lung cancer cells. Microarray analyses elucidated autophagy-related genes affected by MRGX. Administration of MRGX at 100 µg/ml induced punctate cytoplasmic expression of LC3, Beclin-1 and ATG5 and increased expression of endogenous LC3-II whereas 50 µg/ml did not inhibit the proliferation of A549 cells. Compared to the control cells, in cells treated with MRGX at 100 µg/ml, the level of p-Akt was increased, while that of mTOR-4EBP1 was decreased. Downregulation of mTOR and 4EBP1 in the MRGX-treated cells was found not to be a p-Ulk (S757)-dependent pathway, but a p-Ulk (S317)-dependent autophagic pathway, using AMPK. These data suggest that MRGX regulates AMPK and induces autophagy in lung cancer cells.

MeSH terms

  • A549 Cells
  • AMP-Activated Protein Kinases / genetics
  • Adaptor Proteins, Signal Transducing / genetics
  • Autophagy / drug effects
  • Autophagy / genetics*
  • Beclin-1 / genetics
  • Cell Cycle Proteins
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Lung Neoplasms / drug therapy*
  • Lung Neoplasms / genetics
  • Lung Neoplasms / pathology
  • Microtubule-Associated Proteins / genetics
  • Panax / chemistry
  • Phosphoproteins / genetics
  • Plant Extracts / administration & dosage*
  • Plant Extracts / chemistry
  • Saponins / genetics
  • Saponins / metabolism
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / genetics

Substances

  • Adaptor Proteins, Signal Transducing
  • Beclin-1
  • Cell Cycle Proteins
  • EIF4EBP1 protein, human
  • MAP1LC3A protein, human
  • Microtubule-Associated Proteins
  • Phosphoproteins
  • Plant Extracts
  • Saponins
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • AMP-Activated Protein Kinases
  • PRKAA1 protein, human