Allograft transplantation for Drosophila tumor metastasis studies.

Drosophila has long been a powerful model for cancer research, yet the development of robust metastatic tumor models remains a challenge. Although allograft transplantation offers a promising approach, its use has been limited by technical constraints. Here, we established a reproducible serial transplantation protocol using lgl mutant brain tumors, enabling exponential expansion of tumor material and precise tracking of temporal tumor progression. Extending this approach to other neural stem cell (NSC)-derived tumors, we identified shared metastatic characteristics between lgl and pins mutants. Additionally, we compared tumors of different tissue origins, demonstrating that epithelial tumors, like NSC tumors, can also be serially propagated. Using these models, we showed that tumors metastasize to host organs, establish tumor colonies in the ovaries, distort the gastrointestinal tract and invade the cellular cortex of the adult brain. Overall, our study provides a systematic framework for generating metastatic tumors in adult flies from two distinct tissue origins, establishing organ-specific metastatic patterns and offering a platform for studying tumor-host interactions at secondary organ sites.