(4av) Microfluidic Three-Dimensional in Vitro System Enabling An Information-Rich Assay to Investigate Breast Cancer Progression

The earliest stage at which breast cancer can be diagnosed is known as ductal carcinoma in situ (DCIS), which is uncontrolled growth of epithelial cells within breast ducts. This cancer is non-invasive as carcinoma cells have not yet spread into surrounding stromal tissues, but it can proceed to invasive ductal carcinoma (IDC) and stromal alterations have been implicated in initiating this transition. Studies show that one out of every five new breast cancer diagnoses each year is DCIS, and one out of every three women with untreated DCIS will later develop invasive breast cancer. Despite the fact that DCIS is one of the most common breast cancers and it may be life-threatening if it progresses to IDC, the understanding of the mechanisms involved and the identification of potential therapeutic targets are still vague. One reason for this is the lack of a reliable in vitro experimental model. While the transition from DCIS to IDC has been observed clinically and has been recapitulated in mouse models, we lack a good in vitro model that allows screening for inhibitors and furthers our ability to elucidate the underlying molecular mechanisms that govern the transition.

We introduce a simple microfluidic 3D compartmentalized co-culture system that supports the DCIS to IDC transition in vitro. The platform employs microfluidic channels with two input ports to load MCF10-DCIS cells adjacent to stromal fibroblasts, recapitulating the general spatial relationship observed in vivo. The compartmentalized model enables both spatial (distance-dependent transition, i.e., more transition at interface) and temporal (transition from larger clusters) control of the microenvironment. In addition, we present the use of second harmonic generation (SHG) intensity information to measure quantitatively the degree of invasive transition of MCF10-DCIS clusters in the compartmentalized co-culture model. Uniquely, the compartmentalized culture system enables imaging collagen structures that are altered by MCF10-DCIS cells alone because each cell type is in a separate compartment. The arrayed microchannel-based model is compatible with the existing infrastructure and provides a cost effective approach (~ 40 times less sample required) to test for inhibitors of pathways involved in DCIS progression to IDC, allowing a screening approach to the identification of potential therapeutic targets. It is important to note that the model can be easily adapted and generalized to a variety of cell-cell signaling studies.