Because there are currently no reliable predictors for progression of
ductal carcinoma in situ (
DCIS) to invasive disease, nearly all patients receive comprehensive
therapy, leading to over-treatment in many cases. Few in vitro models for studying
DCIS progression have been developed. We report here the successful culture and expansion of primary
DCIS from surgical specimens using a conditional reprogramming protocol. Patients with percutaneous core-needle biopsy demonstrating
DCIS were enrolled in a tissue banking protocol after informed consent was received. Fresh tissue was taken from
lumpectomy or
mastectomy specimens, mechanically and enzymatically dissociated, cultured in
medium conditioned by irradiated mouse fibroblasts and supplemented with rho-associated
protein kinase (ROCK) inhibitor, and characterized by immunocytochemistry. Out of 33
DCIS cases, 58% (19) were expanded for up to 2 months in culture, and 42% (14) were frozen immediately after mechanical dissociation for future growth. The cultures are almost exclusively composed of
cytokeratin 8- and
EpCAM-positive
luminal and
cytokeratin 14-,
cytokeratin 5-, and p63-positive basal mammary epithelial cells, suggesting maintenance of heterogeneity in vitro. Furthermore, as assessed by
luminal and basal marker expression, these cells retain their cellular identities both in the "conditionally reprogrammed" proliferative state and after
conditioned media and ROCK inhibitor withdrawal. When grown to 100 % confluency, the cultures organize into
luminal and basal layers as well as
luminal compartments surrounded by basal cells. Primary cultures of
DCIS derived directly from patient tissues can be generated and may serve as in vitro models for the study of
DCIS.