NCTD promotes Birinapant-mediated anticancer activity in breast cancer cells by downregulation of c-FLIP
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Li Zhao1,*, Guoshan Yang1,*, Hao Bai2, Minghui Zhang3, Dongcheng Mou1
1Department of General Surgery, The First Hospital of Tsinghua University, Beijing, China
2Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
3School of Medicine Tsinghua University, Beijing, China
*These authors contributed equally to this work
Dongcheng Mou, email: email@example.com
Keywords: SMAC mimetic, norcantharidin, breast cancer, c-FLIP
Received: August 04, 2016 Accepted: February 20, 2017 Published: March 02, 2017
Second mitochondria-derived activator of caspases (SMAC) mimetics is a class of new anticancer agents. However, most cancers exhibit de novo or acquired resistance to SMAC mimetics, posting a problem for broad applications in clinic, and highlighting the necessity of exploring combinational strategies to circumvent SMAC mimetic-resistance. We here showed that Norcantharidin, a drug that is currently being used in cancer treatment, significantly enhanced SMAC mimetic Birinapant-mediated cell viability inhibition and robustly promoted apoptosis in established breast carcinoma cell lines, as well as in primary breast carcinoma cells. Mechanistically, we revealed that Norcantharidin effectively reduced the levels of two major protein isoforms of cellular FLICE-like inhibitor protein(c-FLIP), namely c-FLIP long (c-FLIPL) and c-FLIP short (c-FLIPS). Moreover, Norcantharidin markedly enhanced Birinapant-triggered caspase-8/caspase-3 cascade. Inhibition of caspase-8 activity by a synthetic peptide Z-IETD-FMK significantly attenuated cell death induction by the combination, suggesting that caspase-8 plays a critical role in the anticancer action. In conclusion, our study suggests that the combination of SMAC mimetics with Norcantharidin represents a novel strategy in breast cancer therapy and warrants further studies.
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