SPAK mediates KCC3-enhanced cervical cancer tumorigenesis

Authors

  • Min-Hsi Chiu,

    1. Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan
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  • Hsiao-Sheng Liu,

    1. Department of Microbiology and Immunology, National Cheng Kung University, Tainan, Taiwan
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  • Yi-Hui Wu,

    1. Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University and Hospital, Tainan, Taiwan
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  • Meng-Ru Shen,

    1. Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University and Hospital, Tainan, Taiwan
    2. Department of Pharmacology, National Cheng Kung University, Tainan, Taiwan
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  • Cheng-Yang Chou

    Corresponding author
    1. Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University and Hospital, Tainan, Taiwan
    • Correspondence

      C.-Y. Chou, Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University and Hospital, Tainan 70403, Taiwan

      Fax: +886 6 2766185

      Tel: +886 6 2353535 ext. 5608

      E-mail: chougyn@mail.ncku.edu.tw

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Abstract

Ste20-related proline/alanine-rich kinase (SPAK) plays a role in regulating many biological activities, and interacts with K-Cl co-transporter 3 (KCC3); however, the importance of SPAK for KCC3 function has not been demonstrated. Here, we investigated the role of SPAK in KCC3-regulated cell invasiveness and tumor formation. We show that induction of KCC3 expression triggers activation of the NF-κB and SPAK signaling cascades, leading to activation of p38 mitogen-activated protein kinase (MAPK) and matrix metalloproteinase-2 (MMP2). A small interference RNA-mediated reduction in SPAK protein levels suppressed the invasive ability and oncogenic potential of cervical cancer cells, and decreased tumor formation in mouse xenografts. A combination of experimental approaches, including RT-PCR and real-time RT-PCR, gelatin zymography, NF-κB luciferase activity and chromatin immunoprecipitation assays, showed that the induction of KCC3 over-expression increased MMP2 expression and augmented binding of NF-κB to its putative SPAK promoter binding site, suggesting that the SPAK/MMP2 axis is up-regulated by NF-κB. Pharmacological inhibition of NF-κB or MMP2 abrogated KCC3-triggered, SPAK-dependent cell invasiveness. Furthermore, p38 MAPK was identified as the upstream regulator of KCC3-dependent MMP2 activation. We conclude that SPAK may promote KCC3-mediated tumor aggressiveness via the NF-κB/p38 MAPK/MMP2 axis.

Structured digital abstract

KCC3 physically interacts with SPAK by anti-bait co-immunoprecipitation (view interaction)

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