Chronological Changes in Cell Proliferation of Colonic Mucosa in Dimethylhydrazine-induced Colon Carcinogenesis in Rat

Noburu Yokoyama

Department of Surgery, Showa University School of Medicine (Director: Prof. Mitsuo Kusano)

Chronological changes in proliferation of colonic mucosal cells in dimethylhydrazine (DMH)-induced colon carcinogenesis were investigated by using biopsy specimens obtained by serial colonoscopy. The proliferating cell nuclear antigen (PCNA)-labeling index and the proliferation index (P.I.) of colonic mucosa in DMH-treated rats were significantly higher than those in control rats from 12 weeks after the beginning of carcinogen injection until the end of the experiment. PCNA-stained cells in the crypt of the mucosa in DMH-treated rats moved from the base ot the surface with increasing incidence of colon tumors, compared with the control rats. At necropsy, aneuploidy of the mucosa was discovered only in rats with tumors. The PCNA-labeling index (55.3±12.8%) and P.I. (31.2±5.5%) in rats with tumors were significantly higher than those in rats without tumors. These proliferative changes in the mucosa, suggesting that it became a high risk mucosa, imply that these changes may become the parameters for detecting colon cancer.

Key words
1,2-Dimethylhydrazine-induced colon cancer in rat, DNA ploidy, proliferating cell nuclear antigen labeling index

Reprint requests
Noboru Yokoyama Department of Surgery, Showa University School of Medicine
1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142 JAPAN

Accepted
December 6, 1995

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