BACKGROUND: The intricate mechanisms that associate obesity with triple-negative breast cancer (TNBC) remain to be disclosed. Considering that obesity is linked with an increased bioavailability of the insulin-like growth factor 1 (IGF1), we evaluated whether IGF1 triggers aggressive features in TNBC cells and the molecular paths involved. METHODS: Gene expression and Chromatin Immunoprecipitation experiments, ELISA, immunoblotting, immunoprecipitation and immunofluorescence assays, combined with two-dimensional and three-dimensional in vitro model-based studies, were used to investigate the molecular mechanisms through which IGF1 may promote proliferative and motile responses in TNBC cells and reprogram normal fibroblasts into cancer-associated fibroblasts (CAFs)-like cells. The translational relevance of the results obtained was supported by bioinformatics analyses leveraging data from extensive TNBC patient databases. RESULTS: We found that the cytokine interleukin-1β (IL-1β) mediates certain IGF1 actions within the tumor microenvironment, hence facilitating the TNBC landscape. Mechanistically, we assessed that the IGF1/IGF1 receptor (IGFIR) axis induces the collagen VI-dependent activation of discoidin domain receptor 1 (DDR1) and the subsequent increase of the G protein estrogen receptor (GPER), toward IL-1β regulation and secretion. Consequently, IL-1β promoted both the autocrine stimulation of TNBC cells and the differentiation of normal fibroblasts into cancer-associated fibroblasts (CAFs)-like cells, which in turn achieved a proliferative profile and enhanced the motility of TNBC cells. CONCLUSIONS: IL-1β may be considered as a therapeutic target in more comprehensive approaches in obese TNBC patients exhibiting high IGF-1 bioavailability.