Get access

Autophagy stimulates apoptosis in HER2-overexpressing breast cancers treated by lapatinib

Authors

  • Xingmei Zhu,

    1. Department of Pharmaceutical Chemistry, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Lin Wu,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Hongyu Qiao,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Tenglong Han,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Suning Chen,

    1. Department of Pharmacy, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Xueying Liu,

    1. Department of Pharmaceutical Chemistry, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Ru Jiang,

    1. Department of Pharmaceutical Chemistry, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Yifang Wei,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Dayun Feng,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Yuan Zhang,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Yongzheng Ma,

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author
  • Shengyong Zhang,

    Corresponding author
    1. Department of Pharmaceutical Chemistry, The Fourth Military Medical University, Xi'an, Shaanxi, China
    • Correspondence to: Prof. Jian Zhang, The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, No. 169 Changle West Road, 710032 Xi'an, China.

      E-mail: biozhangj@hotmail.com

      Correspondence to: Prof. Shengyong Zhang, Department of Pharmaceutical Chemistry, The Fourth Military Medical University, No. 169 Changle West Road, 710032 Xi'an, China.

      E-mail: syzhang@fmmu.edu.cn

    Search for more papers by this author
  • Jian Zhang

    1. The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, The Fourth Military Medical University, Xi'an, Shaanxi, China
    Search for more papers by this author

  • The authors report no conflicts of interest.
  • Zhu and Wu contributed equally to this work.

ABSTRACT

HER2-overexpressing breast cancers often show hyperactivation of the HER2/AKT/mTOR signaling pathway. Lapatinib is an oral dual tyrosine kinase inhibitor (TKI) that targets both EGFR and HER2 to inhibit the proliferation of breast cancer cells. However, it is obscure whether and how lapatinib could induce autophagy in breast cancer cells, an important cell response with drug treatment. In this study, we investigated the apoptosis and the autophagy in the HER2-overexpressing breast cancer cells BT474 and AU565 treated with lapatinib, and further examined their relationship. Lapatinib inhibited the proliferation and the rate of DNA synthesis in HER2-positive cells, as observed by MTT, colony formation and EDU assays. Lapatinib not only induced apoptosis accompanied by an increased expression of cleaved Caspase-3 and cleaved PARP, but it also induced autophagy in vitro, as confirmed by electron microscopy (EM), acridine orange (AO) staining and LC3-II expression. Meanwhile, lapatinib inhibited the phosphorylation of HER2, AKT, mTOR, and p70S6K, whereas that of AMPK was activated. When the cells were pre-incubated with 3-Methyladenine (3-MA), the specific autophagy inhibitor, the growth inhibitory ratio and apoptosis rate were frustrated, whereas colony formation and DNA synthesis ability were encouraged. In addition, 3-MA application could up-regulate Caspase-3 and PARP expression, compared with the treatment with lapatinib alone. The addition of 3-MA could attenuate the inhibitory role on HER2/AKT/mTOR pathway and the active role on AMPK that was raised by lapatinib. Therefore, lapatinib simultaneously induced both apoptosis and autophagy in the BT474 and AU565 cells, and in these settings, autophagy facilitates apoptosis. J. Cell. Biochem. 114: 2643–2653, 2013. © 2013 Wiley Periodicals, Inc.

Get access to the full text of this article

Ancillary