GROWTH AND METASTASIS OF HUMAN BREAST CARCINOMAS WITH MATRIGEL IN ATHYMIC MICE

Immunodeficient athymic mice with human tumor xenografts provide an im portant in vivo experimental model for cancer research. However, only a limited number of tumor types grow in these animals. For human breas t carcinomas, the incidence of tumor-take is 6-15%. Recently, increase d incidence of xenograft development in mice has been reported for var ious human tumors when the tumors were coinjected with Matrigel. We st udied the development of human breast carcinoma xenografts in athymic mice with and without coinjection of Matrigel. Tumors developed in onl y 7.3% of enzyme-dispersed tumors injected subcutaneously in saline so lution alone. None of these tumors metastasized to distant sites. On t he other hand, 50% of enzyme-dispersed tumors coinjected with Matrigel developed xenografts; four out of five of these tumors metastasized t o distant sites. Our data from the recent study suggest that, in athym ic mice, Matrigel not only enhanced breast tumor growth but also facil itated tumor metastasis.