High-fat diet blocks the inhibition of skin carcinogenesis and reductions in protein kinase C by moderate energy restriction
✍ Scribed by Diane F. Birt; Tracy Barnett; Parviz M. Pour; James Copenhaver
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 536 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0899-1987
No coin nor oath required. For personal study only.
✦ Synopsis
The aim of this investigation was to determine the impact of dietary energy restriction (ER) with control (C) and high-fat (HF) diets on two-stage skin carcinogenesis and on the expression of specific isoforms of protein kinase C (PKC). Skin carcinogenesis was initiated on SENCAR mice with 10 nmol of 7,12-dimethylbenz[a]anthracene (DMBA) in 0.2 mL of acetone and then promoted with twice weekly treatments of 3.2 nmol of 12-0-tetradecanoylphorbol-13-acetate (TPA) in 0.2 mL of acetone for 18 wk. The experimental diets fed during TPA treatment and for 10 wk after the last TPA treatment were formulated with C (10% calories from fat) and HF (42% calories from fat) levels for freely fed groups. These diets were restricted by 20% (20% EWC and 20% EWHF) and by 40% (40% EWC and 40% EWHF). Papilloma incidence was reduced in the mice fed the 20% EWC, 40% EWC, and 40% EW HF diets in comparison with the C, HF, and 20% EWHF groups. Carcinoma incidence was also reduced in these groups. PKC a and 6 were assessed by western blot analysis in the epidermises of mice pre-fed the six diets for 8-10 wk (without DMBA or TPA treatment). PKC a was reduced in the particulate fraction by 3244% in the 20% EWC, 40% EWC, and 40% EWHF groups (P c 0.005). PKC 5 was reduced by 24-31 % in the cytosol of mice fed the 20% EWC diet and in the particulate fraction of mice fed the 40% EWC diet (P c 0.05). The HF diet was able to block the inhibition of skin carcinogenesis and the reduction in the expression of PKC in the epidermis by 20% ER but not by 40% ER.