Introduction. Ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) both arise from inside breast ducts but present a different ability to invade the surrounding tissue. Primary cell cultures are one of the most representative and realistic in vitro models to study what really happens in breast cancer in vivo. Therefore our aim was to establish primary cultures representative of DCIS and IDC as tools to explore the mechanisms underlying a potential transition between these two disease states. Since each culture is new and unique, and there are no commercial cellular models of DCIS, these breast cancer primary cultures must be characterized molecularly and functionally with several different markers and functional assays.

Experimental procedures. From needle-core biopsies of resected human DCIS and IDC tumors, we have grown several epithelial primary cell cultures for at least 15 passages, using the methodology of Stampfer et al. In order to characterize these model cell lines we have investigated: a) Expression and localization of epithelial and mesenchymal markers including cytokeratin-19, epithelial-specific antigen (ESA), ZO-1, cytokeratin-18, carcinogenic embryonic antigen, smooth muscle actin, vimentin; b) Proliferation and senescence assays; c) Flow cytometric determination of aneuploidy; d) Tumor cell migration in scratch-wound assays; e) Invasion assays through modified Boyden chambers; f) Ability to form model acini in three-dimensional cultures.

Results. Our preliminary results reveal some similarities but also several important differences between cells isolated from DCIS in comparison to IDC tumors. One similarity is that DCIS and IDC cell lines examined to date have both been competent to form 3-dimensional acinar-like structures in Matrigel. Key differences include observations of enhanced proliferation and reduced senescence in IDC relative to DCIS cells. In addition, protein factors elaborated preferentially by IDC cells (relative to DCIS cells) promoted migration of normal breast epithelial cells in culture. Conclusions. These assays have helped us to characterize the cells in culture and to define a panel of features compared to reference cell lines. This will help us to easily evaluate future primary cultures to be used for studies on the mechanisms responsible for differential invasiveness in DCIS and IDC.

98th AACR Annual Meeting-- Apr 14-18, 2007; Los Angeles, CA