Preclinical study of the antitumor effect of sphingosine-1-phosphate receptor 1 antibody (S1PR1-antibody) against human breast cancer cells.

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite, which regulates a broad range of physiological and pathophysiological processes. The signaling of S1P via its cell surface receptor S1PR1 has been identified to play an important role in carcinogenesis, cancer growth and survival, and tumor metastasis. In this study, we evaluated whether a monoclonal antibody against S1PR1 (S1PR1-antibody) could impose any effect on cell growth of human breast cancer SK-BR-3 and MDA-MB-231 cells. The S1PR1-antibody exhibited cytostatic effect against both cell lines at the concentration of 4000 ng/mL. Co-administration of 4000 ng/mL of the S1PR1-antibody not only potentiated the cytotoxicity of carboplatin towards the MDA-MB-231 cells but also increased the anti-proliferative effect of S1P towards the SK-BR-3 cells. Furthermore, we showed that co-administration of S1P did not sensitize the SK-BR-3 and MDA-MB-231 cells towards carboplatin.