title: SPAK mediates KCC3-enhanced cervical cancer tumorigenesis.
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.
authors.affiliation: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Min-Hsi
authors.initials: MH
authors.lastname: Chiu
authors.forename: Hsiao-Sheng
authors.initials: HS
authors.lastname: Liu
authors.forename: Yi-Hui
authors.initials: YH
authors.lastname: Wu
authors.forename: Meng-Ru
authors.initials: MR
authors.lastname: Shen
authors.forename: Cheng-Yang
authors.initials: CY
authors.lastname: Chou
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D005260:Female; D057809:HEK293 Cells; D006367:HeLa Cells; D064593:Heterografts; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D016328:NF-kappa B / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000209:etiology* / Q000235:genetics / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000096922:K Cl- Cotransporters
chemical_list: D000199:Actins; D020778:Matrix Metalloproteinase 2; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D027981:Symporters; D048051:p38 Mitogen-Activated Protein Kinases; C119650:SLC12A6 protein, human; D000096922:K Cl- Cotransporters; C486409:STK39 protein, human; C522361:MMP2 protein, human
keywords: KCC3; NF-κB; Ste20-related proline/alanine-rich kinase; matrix metalloproteinase; tumor aggressiveness