title: Blockade of CCN6 (WISP3) activates growth factor-independent survival and resistance to anoikis in human mammary epithelial cells.
abstract: CCN6 is a secreted cysteine-rich matricellular protein (36.9 kDa) that exerts growth-inhibitory functions in breast cancer. Reduction or loss of CCN6 protein has been reported in invasive carcinomas of the breast with lymph node metastasis and in inflammatory breast cancer. However, the mechanism by which CCN6 loss promotes breast cancer growth remains to be defined. In the present study, we developed lentiviral-mediated short hairpin RNA CCN6 knockdown (KD) in nontumorigenic mammary epithelial cells MCF10A and HME. We discovered that CCN6 KD protects mammary epithelial cells from apoptosis and activates growth factor-independent survival. In the absence of exogenous growth factors, CCN6 KD was able to promote growth under anchorage-independent conditions and triggered resistance to detachment-induced cell death (anoikis). On serum starvation, CCN6 KD was sufficient for activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. Growth factor-independent cell survival was stunted in CCN6 KD cells when treated with either human recombinant CCN6 protein or the PI3K inhibitor LY294002. Targeted inhibition of Akt isoforms revealed that the survival advantage rendered by CCN6 KD requires specific activation of Akt-1. The relevance of our studies to human breast cancer is highlighted by the finding that low CCN6 protein levels are associated with upregulated expression of phospho-Akt-1 (Ser(473)) in 21% of invasive breast carcinomas. These results enable us to pinpoint one mechanism by which CCN6 controls survival of breast cells mediated by the PI3K/Akt-1 pathway.
authors.affiliation: Department of Pathology, Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Maria E
authors.initials: ME
authors.lastname: Gonzalez
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Toy
authors.forename: Mousumi
authors.initials: M
authors.lastname: Banerjee
authors.forename: Celina G
authors.initials: CG
authors.lastname: Kleer
mesh_terms: D023102:Anoikis; D017209:Apoptosis; D001940:Breast / Q000378:metabolism*; D055511:CCN Intercellular Signaling Proteins; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D055511:CCN Intercellular Signaling Proteins; C400081:CCN6 protein, human; D002867:Chromones; D004791:Enzyme Inhibitors; D018969:Insulin-Like Growth Factor Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D009025:Morpholines; D011994:Recombinant Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019869:Phosphatidylinositol 3-Kinases
references.citation: Oncogene. 2002 May 9;21(20):3172-80
references.pmid: 12082632
references.citation: Mol Cancer Res. 2009 Jul;7(7):1045-55
references.pmid: 19584265
references.citation: J Biol Chem. 2008 Jun 6;283(23):15807-15
references.pmid: 18381294
references.citation: Nature. 2004 Aug 26;430(7003):1034-9
references.pmid: 15329723
references.citation: Neoplasia. 2004 Mar-Apr;6(2):179-85
references.pmid: 15140407
references.citation: Mol Cell Biol. 1999 Aug;19(8):5800-10
references.pmid: 10409766
references.citation: Breast Cancer Res. 2003;5(2):R37-44
references.pmid: 12631397
references.citation: Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):10983-5
references.pmid: 11572954
references.citation: Science. 1997 Jan 31;275(5300):661-5
references.pmid: 9005851
references.citation: Cell. 1974 Dec;3(4):355-9
references.pmid: 4442124
references.citation: Cell Adh Migr. 2009 Jan-Mar;3(1):7-10
references.pmid: 19372759
references.citation: Cancer Res. 2004 May 1;64(9):3171-8
references.pmid: 15126356
references.citation: Proc Natl Acad Sci U S A. 2007 May 1;104(18):7438-43
references.pmid: 17460049
references.citation: Curr Opin Cell Biol. 2001 Oct;13(5):555-62
references.pmid: 11544023
references.citation: Proc Natl Acad Sci U S A. 2003 Sep 30;100(20):11606-11
references.pmid: 14500907
references.citation: J Biol Chem. 2000 Sep 29;275(39):30597-604
references.pmid: 10899173
references.citation: EMBO J. 1997 May 15;16(10):2783-93
references.pmid: 9184223
references.citation: Breast Cancer Res. 2005;7(6):R1080-9
references.pmid: 16457688
references.citation: Cell Death Differ. 2009 Apr;16(4):571-83
references.pmid: 19079138
references.citation: Oncogene. 1999 Nov 25;18(50):7034-45
references.pmid: 10597304
references.citation: Clin Cancer Res. 1999 Sep;5(9):2511-9
references.pmid: 10499627
references.citation: Mol Cell Biol. 2001 Mar;21(6):2203-12
references.pmid: 11238953
references.citation: Am J Pathol. 2008 Apr;172(4):893-904
references.pmid: 18321996
references.citation: Cancer Res. 2009 Jun 15;69(12):5057-64
references.pmid: 19491266
references.citation: Nat Rev Cancer. 2006 Mar;6(3):184-92
references.pmid: 16453012
references.citation: Front Biosci. 2005 May 01;10:998-1009
references.pmid: 15769600
references.citation: Adv Exp Med Biol. 2006;587:23-40
references.pmid: 17163153
references.citation: Oncogene. 2007 Feb 26;26(9):1338-45
references.pmid: 17322919
references.citation: Cells Tissues Organs. 2007;185(1-3):95-9
references.pmid: 17587813
references.citation: Cell. 2000 Jan 7;100(1):57-70
references.pmid: 10647931
references.citation: Genes Dev. 1999 Nov 15;13(22):2905-27
references.pmid: 10579998
references.citation: Mol Pathol. 2001 Apr;54(2):57-79
references.pmid: 11322167
references.citation: Oncogene. 2002 Feb 14;21(8):1299-303
references.pmid: 11850850
references.citation: Trends Biochem Sci. 2008 Oct;33(10):461-73
references.pmid: 18789696