title: IGF-1 upregulates electroneutral K-Cl cotransporter KCC3 and KCC4 which are differentially required for breast cancer cell proliferation and invasiveness.
abstract: The cellular function of electroneutral K-Cl cotransport (KCC) is to regulate epithelial ion transport and osmotic homeostasis. Here we investigate the mechanisms by which insulin-like growth factor 1 (IGF-1) cooperates with KCC to modulate breast cancer biology. IGF-1 stimulates KCC activity of MCF-7 breast cancer cells in a dose- and time-dependent manner. Increased KCC3 and KCC4 abundances contribute to IGF-1-enhanced KCC activity. Endogenous cellular invasiveness was modestly attenuated by KCC4-specific siRNA and the residual invasiveness was much less sensitive to IGF-1 stimulation. KCC3 knockdown significantly reduced basal growth rate and almost abolished IGF-1-stimulated cell proliferation. Consistently, MCF-7 cells obtained advantage in cell proliferation and invasiveness by overexpression of KCC3 and KCC4, respectively. Blockade of gene transcription by actinomycin D abolished IGF-1-mediated increase in KCC3 and KCC4 mRNA, indicating that IGF-1 increases KCC abundance through the regulation of KCC genes. IGF-1 treatment triggered phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK) cascades which were differentially required for IGF-1-stimulated biosynthesis of KCC3 and KCC4. Loss-of-function mutations in KCC significantly inhibited the development and progression of xenograft tumor in SCID mice. The expression level of IGF-1 and KCC polypeptides in the surgical specimens showed a good linear correlation, suggesting autocrine or paracrine IGF-1 stimulation of KCC production in vivo. Among patients with early-stage node-negative breast cancer, disease-free survival (DFS) and overall survival (OS) curves were significantly different based on IGF-1 and KCC expression. Thus, we conclude that KCC activation by IGF-1 plays an important role in IGF-1 receptor signaling to promote growth and spread of breast cancer cells.
authors.affiliation: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Yueh-Mei
authors.initials: YM
authors.lastname: Hsu
authors.forename: Cheng-Yang
authors.initials: CY
authors.lastname: Chou
authors.forename: Helen H W
authors.initials: HH
authors.lastname: Chen
authors.forename: Wen-Ying
authors.initials: WY
authors.lastname: Lee
authors.forename: Yih-Fung
authors.initials: YF
authors.lastname: Chen
authors.forename: Pin-Wen
authors.initials: PW
authors.lastname: Lin
authors.forename: Seth L
authors.initials: SL
authors.lastname: Alper
authors.forename: J Clive
authors.initials: JC
authors.lastname: Ellory
authors.forename: Meng-Ru
authors.initials: MR
authors.lastname: Shen
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D051379:Mice; D016513:Mice, SCID; D009361:Neoplasm Invasiveness; D011379:Prognosis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D023041:Xenograft Model Antitumor Assays; D000096922:K Cl- Cotransporters
chemical_list: D007334:Insulin-Like Growth Factor I; D012333:RNA, Messenger; D017526:Receptor, IGF Type 1; D027981:Symporters; C119650:SLC12A6 protein, human; D000096922:K Cl- Cotransporters; C119651:SLC12A7 protein, human