Cancer-stromal cell interactions in breast cancer brain metastases induce glycocalyx-mediated resistance to HER2-targeting therapies [RNA-seq]

In a 3D coculture with stroma cells derived from breast cancer patients’ brain metastasis, HER2+ breast cancer cells were protected from HER2-targeted therapies, particularly the EGFR/HER2 small molecule inhibitor neratinib. To get insight into how this protection arises, a Synthetic Notch (SynNotch) reporter model allowed to study the effect of direct contact between stroma and cancer cells. To identify stroma-contact specific changes, a SynNotch reporter was used with breast cancer cell lines constitutively expressing mCherry and transiently expressing BFP when in direct contact with BM3 cells engineered with cell surface GFP. Following coculture of organoids in 3D with or without neratinib, cells were dissociated and sorted by Fluorescence-activated cell sorting (FACS) for mCherry+BFP- (breast cancer, non-contact) and mCherry+BFP+ (DP breast cancer, stroma-contact) fractions