Abstract
Triple negative breast cancer (TNBC) is associated with a poor prognosis, has limited treatment options, and is prone to chemoresistance. Adipocytes that are near cancer cells have an activated phenotype, and are known as cancer-associated adipocytes (CAAs). CAAs can drive cancer progression through multiple mechanisms, including the secretion of adipokines. Whether adipokines influence the chemoresistance of cancer cells has not been fully elucidated. Previous work in the Mackenzie Cancer Research Group identified adipokines which were upregulated when adipocytes and breast cancer cells were co-cultured in a transwell system; namely osteopontin (OPN) and matrix metalloproteinase-3 (MMP-3). The aims of this study were to: (1) establish and characterise a 3D model of TNBC using cell lines, and (2) to use this 3D model to test the hypothesis that CAA-secreted adipokines OPN and MMP-3 alter TNBC response to two clinically relevant chemotherapy agents, carboplatin and paclitaxel.
Three TNBC cell lines (MDA-MB-468, HS578T, BT549) were cultured in 3D gelatin methacryloyl (GelMA) hydrogels, and underwent cell viability, metabolic activity and cell count characterisation. This model was then used to determine IC50 concentrations of carboplatin and paclitaxel for MDA-MB-468, MDA-MB-231 and HS578T cell lines. Finally, cell-laden hydrogels were exposed to OPN or MMP-3 prior to treatment with chemotherapy. Cell viability and metabolic activity assays were performed to investigate treatment response, with and without adipokine exposure. In addition, rheological assays were performed to investigate potential remodelling of the GelMA hydrogel by TNBC cells and/or adipokines.
Exposure of MDA-MB-468 cells to OPN prior to carboplatin treatment reduced the effects of carboplatin on cell viability. No other significant changes in chemoresistance were seen in response to adipokine exposure. Rheology experiments revealed differences in the compressive moduli of the 3D GelMA hydrogels containing different TNBC cell lines. This study provides preliminary characterisation of a panel of TNBC cell lines within a 3D GelMA hydrogel model, and begins to elucidate the effects of CAA-derived factors on chemotherapy response. It also highlights the need for optimisation of 3D cell culture models and assays to investigate the relationship between stromal factors and treatment response in breast cancer.