White tea extract induces apoptosis in non-small cell lung cancer cells: the role of peroxisome proliferator-activated receptor-{gamma} and 15-lipoxygenases

Cancer Prev Res (Phila). 2010 Sep;3(9):1132-40. doi: 10.1158/1940-6207.CAPR-09-0264. Epub 2010 Jul 28.

Abstract

Emerging preclinical data suggests that tea possess anticarcinogenic and antimutagenic properties. We therefore hypothesize that white tea extract (WTE) is capable of favorably modulating apoptosis, a mechanism associated with lung tumorigenesis. We examined the effects of physiologically relevant doses of WTE on the induction of apoptosis in non-small cell lung cancer cell lines A549 (adenocarcinoma) and H520 (squamous cell carcinoma) cells. We further characterized the molecular mechanisms responsible for WTE-induced apoptosis, including the induction of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and the 15-lipoxygenase (15-LOX) signaling pathways. We found that WTE was effective in inducing apoptosis in both A549 and H520 cells, and inhibition of PPAR-gamma with GW9662 partially reversed WTE-induced apoptosis. We further show that WTE increased PPAR-gamma activation and mRNA expression, concomitantly increased 15(S)-hydroxy-eicosatetraenoic acid release, and upregulated 15-LOX-1 and 15-LOX-2 mRNA expression by A549 cells. Inhibition of 15-LOX with nordihydroguaiaretic acid (NGDA), as well as caffeic acid, abrogated WTE-induced PPAR-gamma activation and upregulation of PPAR-gamma mRNA expression in A549 cells. WTE also induced cyclin-dependent kinase inhibitor 1A mRNA expression and activated caspase-3. Inhibition of caspase-3 abrogated WTE-induced apoptosis. Our findings indicate that WTE is capable of inducing apoptosis in non-small cell lung cancer cell lines. The induction of apoptosis seems to be mediated, in part, through the upregulation of the PPAR-gamma and 15-LOX signaling pathways, with enhanced activation of caspase-3. Our findings support the future investigation of WTE as an antineoplastic and chemopreventive agent for lung cancer.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anilides / pharmacology
  • Apoptosis / drug effects*
  • Arachidonate 15-Lipoxygenase / genetics
  • Arachidonate 15-Lipoxygenase / metabolism
  • Arachidonate 15-Lipoxygenase / physiology*
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / metabolism
  • Carcinoma, Non-Small-Cell Lung / pathology*
  • Carcinoma, Non-Small-Cell Lung / prevention & control
  • Catechin / analogs & derivatives
  • Catechin / pharmacology
  • Catechin / therapeutic use
  • Drug Evaluation, Preclinical
  • Gene Expression Regulation, Enzymologic / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Hormone Antagonists / pharmacology
  • Humans
  • Hydroxyeicosatetraenoic Acids / pharmacology
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism
  • Lung Neoplasms / pathology*
  • Lung Neoplasms / prevention & control
  • PPAR gamma / antagonists & inhibitors
  • PPAR gamma / genetics
  • PPAR gamma / metabolism
  • PPAR gamma / physiology*
  • Plant Extracts / pharmacology*
  • Plant Extracts / therapeutic use
  • Tea* / chemistry
  • Tumor Cells, Cultured

Substances

  • 2-chloro-5-nitrobenzanilide
  • Anilides
  • Hormone Antagonists
  • Hydroxyeicosatetraenoic Acids
  • PPAR gamma
  • Plant Extracts
  • Tea
  • 15-hydroxy-5,8,11,13-eicosatetraenoic acid
  • Catechin
  • epigallocatechin gallate
  • Arachidonate 15-Lipoxygenase