Triple-negative and triple-positive breast cancer cells reciprocally control their growth and migration via the S100A4 pathway.

The study's aim was to investigate the S100A4-mediated mechanisms of the regulation of tumor cell proliferation and migration in the human triple-positive breast carcinoma cell line MCF-7 (TPBC) and triple-negative breast carcinoma cell line MDA-MB-231 (TNBC). The proliferative activity of TNBC more than doubled during the incubation in the conditioned medium of TPBC. Extracellular S100A4 dose-dependently decreased the proliferative response of TPBC. TPBC negatively impacted the growth of TNBCs during their co-culturing. TPBC significantly decreased the migration activity of the TNBC cells while the S100A4 intracellular level in the TNBC was also decreasing. The decrease in the S100A4 intracellular level occurred due to the protein's monomeric form while the contribution of the dimeric form into the overall S100A4 concentration in TNBC cells increased 1.5-2-fold. The S100A4 pathway in the intercellular communication between TNBC and TPBCs also included the dexamethasone-sensitive mechanisms of S100A4 intra- and extracellular pools regulation.