Mesenchymal stem cell-derived extracellular vesicles may promote breast cancer cell dormancy

Disseminated breast cancer cells have the capacity to metastasise to the bone marrow and reside in a dormant state within the mesenchymal stem cell (MSC) niche. Research has focussed on paracrine signalling factors, such as soluble proteins, within the microenvironment. However, it is now clear extracellular vesicles (EVs) secreted by resident MSCs into this microenvironment also play a key role in the initiation of dormancy. Dormancy encourages reduced cell proliferation and migration, whilst upregulating cell adhesion, thus retaining the cancer cells within the bone marrow microenvironment. Here, MCF7 breast cancer cells were treated with MSC-derived EVs, resulting in reduced migration in 2D and 3D culture, with reduced cell proliferation and enhanced adhesion, collectively supporting cancer cell dormancy.