3D organoid culture of MMTV-PyMT mammary gland tumors

The mammary-specific polyomavirus middle T antigen overexpression mouse model (MMTV-PyMT) is one of the most commonly used models in the cancer research field for multiple reasons, among which the spontaneous development of multifocal luminal tumors, the early tumoral onset, and the primary tumors' morphology resembling those in clinical biopsies. Here we present a method for the derivation of MMTV-PyMT tumor organoids recapitulating the complex structural organization and heterogeneity observed in vivo. The generation of an organotypic culture from MMTV-PyMT primary tumors provides a valid research platform exploitable for a variety of experimental analyses concerning the study of breast cancer progression, the modulation of the tumor-microenvironment or metastases formation. These organoids can be derived from a limited amount of starting material and are easily maintained and expanded in basement membrane extract (BME).