D-Limonene modulates inflammation, oxidative stress and Ras-ERK pathway to inhibit murine skin tumorigenesis

Hum Exp Toxicol. 2012 Aug;31(8):798-811. doi: 10.1177/0960327111434948. Epub 2012 Feb 8.

Abstract

D-Limonene, a common monoterepene has been shown to have antiproliferative, apoptosis-inducing and chemopreventive effects. In the present study, we have investigated the effects of D-limonene on the growth of 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin tumor development. We found that D-limonene (50 and 100 mg/kg body weight) treatments to the mouse skin significantly reduced the TPA-induced (a) edema and hyperplasia (p < 0.001); (b) expression of cyclooxygenase-2; (c) ornithine decarboxylase activity (p < 0.001); and (d) [(3)H] thymidine incorporation into DNA (p < 0.001). In addition, treatment of D-limonene effectively restored the level of reduced glutathione, glutathione peroxidase, glutathione reductase, glutathione S-transferase, catalase and malondialdehyde production in TPA-treated mouse skin. In a two-stage skin tumorigenesis study, D-limonene significantly reduced the tumor burden (p < 0.005) and tumor incidence as compared to DMBA/TPA-treated mice. D-Limonene treatment also extended the latency period of tumor development from 4 to 9 weeks. D-Limonene treatment decreased the expression level of Ras, Raf and phosphorylation of extracellular signal-regulated protein kinase 1/2 in DMBA/TPA-induced tumors. A decrease in the expression of Bcl-2 and an increase in Bax expression were also observed in tumor tissues of mice treated with D-limonene. Taken together, our findings suggest that D-limonene may exert its chemopreventive activity through the inhibition of inflammation, oxidative stress and Ras-signaling as well as the induction of pro-apoptotic state during TPA-mediated promotion of DMBA-induced skin cancer in mouse model.

MeSH terms

  • 9,10-Dimethyl-1,2-benzanthracene
  • Animals
  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use*
  • Carcinogens
  • Catalase / metabolism
  • Cyclohexenes / pharmacology
  • Cyclohexenes / therapeutic use*
  • Cyclooxygenase 2 / metabolism
  • Female
  • Glutathione / metabolism
  • Inflammation / drug therapy*
  • Inflammation / pathology
  • Limonene
  • Mice
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Oxidative Stress / drug effects
  • Signal Transduction / drug effects
  • Skin Neoplasms / chemically induced
  • Skin Neoplasms / metabolism
  • Skin Neoplasms / pathology
  • Skin Neoplasms / prevention & control*
  • Terpenes / pharmacology
  • Terpenes / therapeutic use*
  • Tetradecanoylphorbol Acetate
  • raf Kinases / metabolism
  • ras Proteins / metabolism

Substances

  • Antineoplastic Agents
  • Carcinogens
  • Cyclohexenes
  • Terpenes
  • 9,10-Dimethyl-1,2-benzanthracene
  • Limonene
  • Catalase
  • Ptgs2 protein, mouse
  • Cyclooxygenase 2
  • raf Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • ras Proteins
  • Glutathione
  • Tetradecanoylphorbol Acetate