Calcium exerts antiproliferative effects on cellular targets through the promotion of differentiation and apoptosis. We investigated the influence of calcium on the formation of colonic aberrant crypt foci (ACFs), which were induced by exposure to azoxymethane (AOM) followed by dextran sodium sulfate (DSS), in ICR mice. Six-week-old ICR mice received 3 (weeks 0–2) intraperitoneal injections of AOM (10 mg/kg BW), followed by treatment with 2% DSS via drinking water for a week to induce preneoplastic lesions. The mice were then divided into 3 groups: the control (AOM/DSS), AOM/DSS + 1.0% Ca, and AOM/DSS + 2.0% Ca groups. Calcium (1.0 or 2.0%) was administered via drinking water for 12 weeks. After sacrificing the mice, the total numbers of aberrant crypts (ACs) and ACFs were measured in the colonic mucosa after methylene blue staining. The control group displayed 11.58 ± 2.43 ACFs/colon, which were composed of a total of 30.42 ± 5.18 ACs/colon. The number of ACFs with more than 3 ACs, which are likely to progress to colon cancer, was 2.37 ± 0.68. Compared to the control, 1.0% or 2.0% calcium treatment significantly decreased the number of total ACFs and ACs in a concentration-dependent manner. The decrease in ACFs or ACs after calcium treatment was associated with decreases in cell proliferation and β-catenin expression and an increase in apoptosis in colonic mucosal cells. These results suggest that calcium may exert a protective effect against colon cancer by inhibiting the development of ACFs/ACs in ICR mice.

Abstract
 Introduction
 Materials and Methods
  Materials
  Animals
  Experimental design and carcinogen treatment
  Sample collection
  Blood analysis
  Histopathological examination
  Aberrant crypt and ACF counts
  Immunohistochemistry of PCNA and β-catenin
  TUNEL assay
  Statistical analysis
 Results
  Final body weights and blood analysis
  Total AC and ACF counts
  Histopathology
  Changes in proliferation and apoptosis
  Immunohistochemistry of β-catenin
 Discussion
 References

• Yun-Jung Myung(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University)
• Ja-Kyung Seol(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)
• Young-Won Yun(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)
• Beom-Jun Lee(College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungbuk National University) Corresponding author