Procyanidin B2 3,3″-di-O-gallate induces oxidative stress-mediated cell death in prostate cancer cells via inhibiting MAP kinase phosphatase activity and activating ERK1/2 and AMPK

Mol Carcinog. 2018 Jan;57(1):57-69. doi: 10.1002/mc.22731. Epub 2017 Sep 22.

Abstract

Neoplastic cells exhibit higher oxidative stress compared to normal cells; however, antioxidants based clinical trials have mostly failed. Another attractive therapeutic approach is to further increase the oxidative stress in cancer cells leading to cell death. Herein, we show that Procyanidin B2 3,3″-di-O-gallate (B2G2), the most active constituent of grape seed extract, treatment causes cell death in human prostate cancer (PCa) cells (LNCaP and 22Rv1) via increasing the reactive oxygen species (ROS) generation. Mechanistically, B2G2 treatment decreased the mitochondrial electron transport chain complex III activity leading to enhanced mitochondrial superoxide generation and decreased ATP production in LNCaP cells. Additional molecular studies revealed that B2G2-induced cell death was mediated mainly through ROS-induced sustained activation of ERK1/2, which was due to inhibition of MAP kinase phosphatase (MKP) activity as over-expression of MKP3 in LNCaP cells conferred significant protection against B2G2-induced cell death. Along with ERK1/2, AMP-activated protein kinase α (AMPKα) was also activated by B2G2 treatment, and pre-treatment with AMPKα inhibitor compound C significantly reversed the cytotoxic effects of B2G2 in LNCaP cells. Furthermore, pre-treatment of MKP3 over-expressing LNCaP cells with compound C further reduced the B2G2-induced cell death, suggesting the involvement of AMPKα along with MKP3 and ERK1/2 in the biological effects of B2G2. Together, these results for the first time identified that oxidative stress and MKP3 inhibition play a critical role in B2G2-induced cell death in PCa cells through sustained activation of both ERK1/2 and AMPKα. These results offer a unique opportunity to control this deadly malignancy through B2G2 use.

Keywords: AMP-activated kinase; dual-specificity phosphoprotein phosphatase; extracellular-signal-regulated kinase; oxidative stress; procyanidin B2 3,3″-di-O-gallate; prostate cancer.

MeSH terms

  • AMP-Activated Protein Kinases / metabolism*
  • Anthocyanins / pharmacology*
  • Cell Death / drug effects
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Dual Specificity Phosphatase 6 / metabolism*
  • Enzyme Activation / drug effects
  • Humans
  • Immunoblotting
  • Male
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Oxidative Stress / drug effects*
  • Prostatic Neoplasms / metabolism
  • Prostatic Neoplasms / pathology
  • Reactive Oxygen Species / metabolism

Substances

  • Anthocyanins
  • Reactive Oxygen Species
  • procyanidin B2-3,3'-di-O-gallate
  • MAPK1 protein, human
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • AMP-Activated Protein Kinases
  • PRKAA1 protein, human
  • Dual Specificity Phosphatase 6