An Optimized Protocol for Simultaneous Propagation of Patient-derived Organoids and Matching CAFs.

Recurrent hormone receptor-positive (HR+) breast cancer is a leading cause of cancer mortality in women. Recurrence and resistance to targeted therapies have been difficult to study due to the long clinical course of the disease, the complex nature of resistance, and the lack of clinically relevant model systems. Existing models are limited to a few HR+ cell lines, organoid models, and patient-derived xenograft models, all lacking components of the human tumor microenvironment. Furthermore, the low take rate and loss of estrogen receptor (ER) expression in patient-derived organoids (PDOs) has been challenging. Our protocol allows simultaneous isolation of PDOs and matching cancer-associated fibroblasts (CAFs) from primary and metastatic HR+ breast cancers. Importantly, our protocol has a higher take rate and enables long-term culturing of PDOs that retain ER expression. Our matching PDOs and CAFs will provide researchers with a new resource to study the influence of the tumor microenvironment on various aspects of cancer biology such as cell growth and drug resistance in HR+ breast cancer. Key features • Propagation of patient-derived organoids and matching cancer-associated fibroblasts from primary and metastatic hormone receptor (HR+) positive breast cancer. • Optimized media for long-term culturing of HR+ organoids from primary tumors and bone metastasis. • Co-culture model to assess the influence of the tumor stroma on breast cancer progression.