Prolonged survival and delayed progression of pancreatic intraepithelial neoplasia in LSL-KrasG12D/+;Pdx-1-Cre mice by vitamin E δ-tocotrienol

Carcinogenesis. 2013 Apr;34(4):858-63. doi: 10.1093/carcin/bgt002. Epub 2013 Jan 9.

Abstract

The highly lethal nature of pancreatic cancer and the increasing recognition of high-risk individuals have made research into chemoprevention a high priority. Here, we tested the chemopreventive activity of δ-tocotrienol, a bioactive vitamin E derivative extracted from palm fruit, in the LSL-Kras(G12D/+);Pdx-1-Cre pancreatic cancer mouse model. At 10 weeks of age, mice (n = 92) were randomly allocated to three groups: (i) no treatment; (ii) vehicle and (iii) δ-tocotrienol (200mg/kg × 2/day, PO). Treatment was continued for 12 months. Mice treated with δ-tocotrienol showed increased median survival from the onset of treatment (11.1 months) compared with vehicle-treated mice (9.7 months) and non-treated mice (8.5 months; P < 0.025). Importantly, none of the mice treated with δ-tocotrienol harbored invasive cancer compared with 10% and 8% in vehicle-treated and non-treated mice, respectively. Furthermore, δ-tocotrienol treatment also resulted in significant suppression of mouse pancreatic intraepithelial neoplasm (mPanIN) progression compared with vehicle-treated and non-treated mice: mPanIN-1: 47-50% (P < 0.09), mPanIN-2: 6-11% (P < 0.001), mPanIN-3: 3-15% (P < 0.001) and invasive cancer: 0-10% (P < 0.001). δ-Tocotrienol treatment inhibited mutant Kras-driven pathways such as MEK/ERK, PI3K/AKT and NF-kB/p65, as well as Bcl-xL and induced p27. δ-Tocotrienol also induced biomarkers of apoptosis such as Bax and activated caspase 3 along with an increase in plasma levels of CK18. In summary, δ-tocotrienol's ability to interfere with oncogenic Kras pathways coupled with the observed increase in median survival and significant delay in PanIN progression highlights the chemopreventative potential of δ-tocotrienol and warrants further investigation of this micronutrient in individuals at high risk for pancreatic cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Biomarkers, Tumor
  • Carcinoma in Situ / drug therapy*
  • Carcinoma in Situ / mortality
  • Carcinoma in Situ / prevention & control
  • Carcinoma, Pancreatic Ductal / drug therapy*
  • Carcinoma, Pancreatic Ductal / mortality
  • Carcinoma, Pancreatic Ductal / prevention & control
  • Caspase 3 / drug effects
  • Disease Models, Animal
  • Disease Progression
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Genotype
  • Homeodomain Proteins / genetics
  • Mice
  • Pancreatic Neoplasms / drug therapy*
  • Pancreatic Neoplasms / mortality
  • Pancreatic Neoplasms / prevention & control
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoinositide-3 Kinase Inhibitors
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins p21(ras) / drug effects
  • Proto-Oncogene Proteins p21(ras) / genetics
  • Survival
  • Trans-Activators / genetics
  • Transcription Factor RelA / antagonists & inhibitors
  • Transcription Factor RelA / metabolism
  • Vitamin E / analogs & derivatives*
  • Vitamin E / pharmacology
  • bcl-X Protein / antagonists & inhibitors
  • bcl-X Protein / metabolism

Substances

  • Bcl2l1 protein, mouse
  • Biomarkers, Tumor
  • Homeodomain Proteins
  • Phosphoinositide-3 Kinase Inhibitors
  • Rela protein, mouse
  • Trans-Activators
  • Transcription Factor RelA
  • bcl-X Protein
  • pancreatic and duodenal homeobox 1 protein
  • Vitamin E
  • tocotrienol, delta
  • Proto-Oncogene Proteins c-akt
  • Extracellular Signal-Regulated MAP Kinases
  • Caspase 3
  • Hras protein, mouse
  • Proto-Oncogene Proteins p21(ras)