Induction of colorectal tumors in rats by sulfated polysaccharides.

Some sulfated polysaccharides, such as d-CGN, APS, and DSS, have carcinogenicity to the rat colorectum. These materials first induced colitis, secondly squamous metaplasia, and finally tumors at the colorectum. Initially, colitis was located in the columnar epithelium of the rectum and extended proximally thereafter. Squamous metaplasia persisted in almost all experimental rats and progressed irreversibly. The tumors were adenoma, adenocarcinoma, squamous cell papilloma, and squamous cell carcinoma. Macrophages containing these materials were observed in the lamina propria mucosa and submucosa of the colorectum. There were differences in the molecular weight of the substances and their tumor incidences. However, with regard to their carcinogenicity, these sulfated polysaccharides were inferred to be similar to each other in their target organs and process of tumor development. Consequently, these sulfated polysaccharides may be one entity of carcinogenic sulfates.