A Multifaceted Biological Engineering Approach to Breast Cancer Modeling and Drug Delivery

Few targeted therapies are available for patients with triple negative breast cancer (TNBC). We utilized a novel alkaline-lignin-conjugated-poly(lactic-co-glycolic acid) (L-PLGA) nanoparticle drug delivery system (NPDDS) to improve the efficacy of GDC-0623, a targeted therapy that exhibited poor pharmacokinetics in phase I trials. L-PLGA NPs were much smaller than PLGA NPs making them better suited for passive targeting based on the enhanced permeability and retention effect. L-PLGA NPs loaded with GDC-0623 NPs demonstrated a nearly 50% reduction in cell numbers compared to free GDC-0623 and PLGA-GDC NPs when tested in vitro. Western blot of ERK1/2 confirmed that L-PLGA-GDC resulted in greater inhibition of MEK1/2. We are reporting for the first time that GDC-0623 reverses epithelial to mesenchymal transition in TNBC. Another factor to consider in drug response is the tumor-stromal interactions which contribute to disease progression and drug resistance. Here, we take all these factors into consideration with our engineering approach to breast tumor modeling and drug delivery. To understand the effects that components of the ECM have on the cell which alter response to therapy, we examined the differences that collagen I, collagen IV, fibronectin, and laminin have on the cell. Using optical tweezers to test mechanical forces exerted by the cell, we concluded that TNBC cells do not bind matrix proteins with equal affinity and that cells have different stiffness when cultured on these substrates. Additionally, we demonstrated that ECM is a key player in dictating cellular response to therapy. Current models to study breast cancer fail to recapitulate the tumor microenvironment. We designed and optimized an ex vivo human breast tissue (HBT) model for estrogen receptor positive (ER+) and negative (ER-) breast cancer. HBT is a complete tissue with native breast ECM and immune cells. We designed and optimized methods to perform molecular analyses such as immunohistochemistry, immunofluorescence, and qPCR, as well as ECM structural remodeling assays. Confocal microscopy confirmed the presence of macrophages in the model. Our novel model will allow 1) real-time examination of BC-HBT interactions and 2) the isolation of breast cancer-specific factors vs. patient-specific factors on the development and progression of breast cancer