Selective Cancer Cell Apoptosis Induced by FTY720; Evidence for a Bcl-dependent Pathway and Impairment in ERK Activity

Background: FTY720 is a unique immunosuppressant that induces apoptosis in activated lymphocytes, but not in other hematopoietic cells. We conducted the present study to investigate its anticancer effect and molecular pathway in inducing apoptosis using murine breast cancer models.

Materials And Methods: The difference in drug susceptibility to FTY720 between cancer cells and non-cancer cells was examined by MTT assay and cell growth assay. FTY720-induced apoptosis was determined by electron microscopy and DNA electrophoresis, and its molecular pathway was evaluated by Western blot analysis. We then tested in vivo the effect of this agent using two murine breast cancer models.

Results: FTY720 treatment induced selective cancer cell apoptosis in vitro at a concentration of less than 10 microM. In vivo tumor growth was significantly prevented with induction of apoptosis in both models without any severe systemic adverse reactions. The evaluation of intracellular protease activity demonstrated that FTY720-induced apoptosis was mediated by a Fas-independent, Bcl-associated signal transduction pathway. Inhibition of extracellular signal-regulated kinase (ERK) activity may be involved in its underlying mechanism of action.

Conclusion: FTY720 may be a promising candidate for a new anticancer therapy, which potentially induces selective apoptosis in cancer cells.