Irradiated triple-negative breast cancer co-culture produces a less oncogenic extracellular matrix.

Triple-negative breast cancer is the most common and most deadly cancer among women. Radiation is a mainstay of treatment, administered after surgery, and used in the hope that any remaining cancer cells will be destroyed. While the cancer cell response is normally the focus of radiation therapy, little is known about the tumor microenvironment response after irradiation. It is widely reported that increased collagen expression and deposition are associated with cancer progression and poor prognosis in breast cancer patients. Aside from the classical fibrotic response, ratios of collagen isoforms have not been studied in a radiated tumor microenvironment. Here, we created one healthy co-culture of stromal fibroblasts and adipose-derived stem cells, and one triple-negative breast cancer co-culture, made of stromal fibroblasts, adipose derived stem cells, and triple-negative breast cancer cells. After irradiation, growth and decellularization of co-cultures, we reseeded the breast cancer cells for 24 h and analyzed the samples using mass spectrometry. Proteomic analysis revealed that collagen VI, a highly oncogenic collagen isoform linked to breast cancer, was decreased in the irradiated cancer co-culture. This indicates that the anti-cancer impact of radiation may be not only cell ablative, but also influential in creating a less oncogenic microenvironment