Abstract P6-08-02: Developing in vitro models of ductal carcinoma in situ from primary tissue

Abstract

Abstract BACKGROUND: Because there are currently no reliable predictors for progression of ductal carcinoma in situ (DCIS) to invasive disease, nearly all patients receive aggressive 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. MATERIALS AND METHODS: From 2/2014 to 4/2015, patients with percutaneous core needle biopsy demonstrating DCIS were enrolled in a tissue banking protocol after informed consent was received. Under supervision of the surgical pathologist, fresh tissue measuring between 5-15 mm in length was taken from lumpectomy or mastectomy specimens. Tissue was divided such that half was mechanically and enzymatically dissociated and then cultured in medium conditioned by irradiated mouse fibroblasts and supplemented with rho-associated protein kinase (ROCK) inhibitor, and the second half, known as the "mirror image" remained as part of the clinical specimen. RESULTS: Of 49 consented patients, mean age was 59 ± 10 years. 7 were excluded due to final pathology not consistent with DCIS: 4 upstaged to invasive ductal cancer, 2 had microinvasion and 1 showed pleomorphic lobular carcinoma in situ. Of the remaining 42, 9 were failures: 5 tissues were not received in lab and 4 cases were received, but no cells grew in culture. Of the remaining 33 cases of DCIS, 70% (n=23) and 27% (n=9) were nuclear grade 2 and 3 respectively. 91% (n=30) were ER-positive, with H-score ranging between 4 and 300. 19 (58%) were expanded in cell culture for up to two months in culture, and 14 were frozen immediately after mechanical dissociation for future growth. The 19 cell cultures could be cryopreserved and expanded. The cultures are almost exclusively composed of cytokeratin 8- and EpCAM-positive luminal cells 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both in the "conditionally reprogrammed" proliferative state and when conditioned media and ROCK inhibitor were withdrawn. When grown to 100% confluency, the cultures appear to organize into luminal and basal layers as well as luminal compartments surrounded by basal cells. CONCLUSION: Primary cultures of DCIS derived directly from patient tissues may serve as in vitro models for the study of DCIS. Citation Format: McAuliffe PF, Brown DD, Oesterreich S, Lee AV, Johnson RR, McGuire KP, Davidson NE, Brufsky AM, Dabbs DJ. Developing in vitro models of ductal carcinoma in situ from primary tissue. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-08-02.