Understanding the interaction between obesity and breast cancer

Metastasis accounts for almost 90% of all human cancer related deaths including breast cancer (BC). Obesity is associated with a 30% increased risk of death from BC. In particular, one type of BC called triple negative breast cancer (TNBC) has a worse prognosis in obese women and the mechanism behind this effect is not known. Obese BC patients tend to have larger tumours and do not respond well to therapy in comparison to lean BC patients. Adipocytes can promote metastasis by inducing an epithelial to mesenchymal transition (EMT) but less is known about the role of adipocytes in later stages of metastasis, particularly during the process of mesenchymal to epithelial transition (MET) that might occur at sites of secondary tumor formation. Here, we have investigated the effects of adipocytes on BC progression using a 3-dimensional (3D) co-culture system to better mimic the microenvironment. We found that adipocytes can promote acquisition of epithelial-like characteristics via soluble factors in a manner that could promote secondary tumor formation.