Abstract P2-09-21: Teriflunomide, an immunomodulatory drug, exerts anticancer activity in triple-negative breast cancer (TNBC) cells via modulation of multiple cell signal pathways

Abstract

Abstract Background: Breast cancer is the most diagnosed female cancer and the second leading cause of cancer death in the United States. Triple negative breast cancer (TNBC), a special subtype, defined as breast cancer lacking estrogen, progesterone and HER-2 receptors, showed clinically aggressive features and was associated with poor prognosis. TNBC is resistant to endocrine or HER-2 targeted therapies, and only conventional chemotherapeutic regimens were accepted as the treatment guidelines. Therefore, searching for novel pharmaceutical agents for TNBC is urgent and a hot spot in present clinical research. Teriflunomide, an orally available immunomodulatory drug, approved for treatment of multiple sclerosis (MS) by FDA, has demonstrated the potential application in cancer therapy, such as chronic lymphocytic leukemia (CLL), prostate cancer and melanoma. Therefore, we assessed the therapeutic value of teriflunomide in TNBC cells. Methodology/Principal Findings: In this study, we showed that teriflunomide treatment resulted in a dose- and time-dependent inhibition of proliferation in three TNBC cell lines: MDA-MB-231, MDA-MB-468 and BT549. Meanwhile, the agent could also induce loss of clonogenic survival in dose-dependent fashion in TNBC cells. The analysis of cell cycle distribution by flow cytometry revealed that teriflunomide for 48 h entrapped TNBC cells in S-phase with concomitant reduction in both G1- and G2/M-phase. Furthermore, by Annexin-V/PI staining, we showed high doses of teriflunomide for 2 days led to significant necrosis and minor apoptosis in TNBC cells. Additionally, the effect of teriflunomide on TNBC cell migration and invasion was also tested using Boyden chamber assays. Short-term treatment of teriflunomide decreased the cell motility and invasiveness considerably in a concentration-dependent manner. When evaluated for underlying mechanisms, teriflunomide was found to modulate multiple cell signaling pathways in three TNBC cell lines. First, teriflunomide inhibited expression of proteins linked to cell proliferation, such as cyclin D1 and c-Myc. Second, teriflumomide delayed cell cycle transition by up-regulating cyclin A, along with p27 down-regulation and unchanged cyclin B1. Third, teriflunomide regulated the cell survival proteins, such as up-regulation of BAX and down-regulation of Bcl-Xl, by activation of MAPK pathway. Fourth, teriflunomide suppressed the marker signals involved in epithelial–mesenchymal transition(EMT) and invasion and inhibited activation of FAK/Src complex. Fifth, teriflunomide down-regulated growth factor receptors involved in TNBC growth maintenance, such as EGFR, IGF1R and FGFR4. Conclusion/Significance: Teriflunomide, although an anti-inflammatory agent, is a potent inhibitor of TNBC cells through modulation of multiple signaling pathways and may be of therapeutic benefit for TNBC in clinical practice. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-21.