DIETARY CALCIUM SALTS AS PROTECTIVE AGENTS AND LAMININ P1 AS A BIOCHEMICAL MARKER IN CHEMICALLY-INDUCED COLON CARCINOGENESIS IN RATS

To evaluate the protective effect of different calcium forms against c olon carcinogenesis, Wistar rats fed a high-fat diet (24%) were supple mented with different chemical forms of dietary calcium and were intra rectally instilled with N-methyl-N-nitrosourea (NMU). Supplemental cal cium was administered at 1.5% mineral (w/w of total diet) complexed wi th either carbonate, gluconate, or lactate in Groups 2, 3, and 4, resp ectively. The tumor incidence of colon cancer was compared with a cont rol group (Group 1), fed the same diet without supplemental calcium. C olon carcinoma incidence was 31, 33, 13, and 7% in Groups 1, 2, 3, and 4, respectively. Calcium had a significant protective effect against carcinogenesis, and the maximum protective effect was observed with gl uconate and lactate forms. Laminin P1 blood level was measured as a tu mor marker. Laminin Pt results were compared with the reference group (Group T), fed a standard diet and not NMU instilled. The serum lamini n P1 level was significantly higher (p = 0.0001) in NMU-instilled Grou ps 1, 2, 3, and 4 (0.24 +/- 0.03, 0.93 +/- 1.43, 0.84 +/- 1.33, and 0. 41 +/- 0.34 mU/ml respectively) than in the Reference Group T (0.10 +/ - 0.05 mU/ml).