Breast organoid suspension cultures maintain long-term estrogen receptor expression and responsiveness

Organoid cultures offer a powerful technology to investigate many different aspects of development, physiology, and pathology of diverse tissues. Unlike standard tissue culture of primary breast epithelial cells, breast organoids preserve the epithelial lineages and architecture of the normal tissue. However, existing organoid culture methods are tedious, difficult to scale, and do not robustly retain estrogen receptor (ER) expression and responsiveness in long-term culture. Here, we describe a modified culture method to generate and maintain organoids as suspension cultures. This method improves organoid growth and uniformity over the traditional Matrigel dome embedding method while still maintaining the fidelity of the three major epithelial lineages. Using this adopted method, we are able to isolate and culture hormone sensing (HS) cells alone that retain ER responsiveness upon estrogen stimulation in long-term culture. This culture system presents a valuable opportunity to study the events involved in initiation and evolution of ER-positive breast cancer.