An Optimized Protocol of Azoxymethane-Dextran Sodium Sulfate Induced Colorectal Tumor Model in Mice

Since azoxymethane (AOM)-dextran sodium sulfate (DSS) induced tumorigenesis was used to explore inflammation-associated carcinogenesis of sporadic colorectal cancer (CRC), different administration modes of AOM or DSS have been reported. In this article we optimized the protocol of the AOM-DSS modeling using C57BL/6 mice for study on sporadic CRC by intraperitoneal injecting AOM solution at a proper concentration with a 100 μl sterile syringe once, feeding with DSS solution for 7 days in a roll and change DSS solution every day. More than 100 C57BL/6 mice had been treated with the optimized protocol, and all mice were demonstrated suffering from colorectal tumors when sacrificed in 8 to 20 weeks after AOM injection. These tumors mainly occurred in distal segment of colorectum with an increase in tumor density, which was similar to CRC in human beings. Tumor per mouse was high, and variation of tumor number per mouse was low. The histology of tumor developed through the defined stage ranged from precursor lesions, adenomatous lesions, adenomas to adenocarcinomas. The modified protocol of AOM-DSS model is easy, cheap, with high tumor formation rate of colorectal tumors.