This project explores a novel therapeutic approach for breast cancer by combining zebrafish (Danio rerio) xenograft modeling with recombinant DNA technology. Human breast cancer cells are transplanted into zebrafish embryos, creating an in vivo platform to observe tumor behavior in real time. In addition to tumor cell injection, specially designed recombinant DNA structures encoding functional proteins are introduced into the embryos. At 96 hours post-fertilization, embryos are exposed to controlled thermal stress to selectively induce cytotoxic effects in cancer cells. This proof-of-concept study aims to evaluate the potential of thermally activated gene-based therapies and to establish zebrafish as a versatile model in cancer research and drug development.