Aging reduces the pro-tumorigenic potential of bone marrow cells and influences triple-negative breast cancer progression

To examine the effects of recombinant granulin on human mammary stromal fibroblasts, we cultured immortalized GFP+ normal human mammary fibroblasts in the presence of recombinant human granulin (1ug/ml) or PBS every 24h for 6 days. To generate GRN-independent CAFs, we injected immortalized GFP+ human mammary fibroblasts, MCF7Ras human breast carcinoma cells, and 20% Matrigel subcutaneously into nude mice. Tumors were allowed to form for a period of 45 days. GFP+ fibroblasts were isolated from tumors by mincing the tumors, dissociating, and culturing in the presence of 1 ug/ml puromycin for ~3-4 weeks. CAF purity was confirmed by ensuring that 100% of the population was GFP-positive. We cultured normal human mammary fibroblasts in the presence human granulin (1ug/ml) or PBS control every 24h for 6 days. The analysis showen are for 3 control (control) and 3 granulin-treated (PGRN) fibrobast cultures.