Tumor formation assays

Animal experiments are necessary to confirm and demonstrate the reliability of the results of in vitro assays and to reveal any unexpected effects in the living body. Tumor invasion and metastasis consist of multistep and complex cascades. Moreover, conflictive interactions between cancer cells and host immune system exist in the living body. Therefore, tumor formation assay is an essential technique in tumor biology. Methods used in tumor formation assay include injection and inoculation, and considerable skill is required to perform these basic techniques. Injections and inoculations are categorized according to the target site: intraperitoneal (IP), intravenous (IV), subcutaneous (SC), footpad (FP), and targeted organ inoculation. Tumor cell injections and inoculations are standard methods for the evaluation of the malignant potential of cancer cells. IP injection is a useful and uncomplicated method for drug administration, SC inoculation is used to evaluate tumor growth and size, FP inoculation to estimate lymph nodule metastasis, and IV injection into the tail vein to evaluate the metastatic potential for lung colonization. Using immune-deficiency mice, we can address possible roles of carbohydrate antigens against host immune system. In this chapter, we describe details of the materials and methods that can be used for injection (IP and IV) and inoculation (SC, FP, testis, and prostate) in mice.