Colorectal cancer is one of the most common types of cancer in men and women who consume a Western diet. We investigated the inhibitory effect of selenium (sodium selenite, Na2SeO3) and selenium nanoparticles (nano-Se) on experimental colon carcinogenesis in ICR mice. After a 1-week acclimation, 6-week-old mice received three intraperitoneal (i.p.) injections (experimental week 0-2) of azoxymethane (AOM, 10 mg/kg body weight, b.w.), followed by 2% dextran sodium sulfate (DSS)-containing drinking water for the next 1 week. The three groups (10 mice/group) were orally administered either distilled water (control), selenium (1.7 ppm), or nano-Se (1.7 ppm) daily for 8 weeks. The numbers of aberrant crypt foci (ACF), aberrant crypt (AC), and tumorous lesions were measured in colonic mucosa. Se and nano-Se treatments significantly decreased the number of ACF, AC, and tumorous lesions compared with the control. However, there was no significant difference between the selenium and nano-Se groups. The glutathione peroxidase (GSH-Px) activity in the liver and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in serum, were high in the selenium and nano-Se groups, while thiobarbituric acid reactive substance (TBARS) level was low in both Se and nano-Se groups when compared with that in the control group. These findings indicate that selenium and nano-Se showed similar protective effects against colon carcinogenesis by inhibiting the development of ACF and tumorous lesions in mice.

Abstract
 INTRODUCTION
 MATERIALS AND METHODS
  Materials
  Animals and diet
  Experimental design
  Sample collection
  Aberrant crypt foci (ACF), aberrant crypt (AC), andtumorous lesion count
  GSH-Px activity
  Serum thiobarbituric acid reactive substances (TBARS)levels
  2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavengingactivity in serum
  Statistical analysis
 RESULTS
  Body weight of mice
  ACF, AC, and tumorous lesion count
  Liver GSH-Px
  Serum TBARS content
  Serum DPPH radical scavenging capacity
 DISCUSSION
 REFERENCES

• Do-Youn Jang(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University)
• Sung-June Kim(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University)
• Jae-Hwang Jeong(Department of Biotechnology and Biomedicine, Chungbuk Province College)
• Sang Yoon Nam(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University)
• Jong-Soo Kim(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University)
• Young Won Yun(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University) Corresponding Author
• Beom Jun Lee(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University) Corresponding Author