Inhibition of CCN6 (Wnt-1-induced signaling protein 3) down-regulates E-cadherin in the breast epithelium through induction of snail and ZEB1.
The cysteine-rich protein CCN6 [or Wnt-1-induced signaling protein 3 (WISP3)] exerts tumor-suppressive effects in aggressive inflammatory breast cancer. Loss of CCN6 is associated with poorly differentiated phenotypes and increased invasion. Here, we show that reduction of CCN6 expression occurs in 60% of invasive breast carcinomas and is associated with axillary lymph node metastases. Furthermore, low CCN6 expression in invasive carcinoma tissue samples correlates with reduced expression of E-cadherin. In vitro, RNA interference knockdown of CCN6 in two benign human mammary epithelial cell lines (HME and MCF10A) decreased expression of E-cadherin protein and mRNA and reduced activity of the E-cadherin promoter; this reduction was dependent on intact E-box elements. CCN6 knockdown in HME cells resulted in up-regulation of the E-cadherin transcriptional repressors Snail and ZEB1 and enhanced their recruitment and binding to the E-cadherin promoter as analyzed by chromatin immunoprecipitation assays. Small interfering RNA-mediated knockdown of ZEB1 or Snail blocked the down-regulation of E-cadherin caused by CCN6 inhibition. These data show, for the first time, that CCN6 expression is reduced or lost in a substantial number of invasive breast carcinomas and that CCN6 modulates transcriptional repressors of E-cadherin. Together, our results lead to a new hypothesis that Snail and ZEB1 are downstream of CCN6 and play a critical role in CCN6-mediated regulation of E-cadherin in breast cancer.
Huang
Wei
W
Department of Pathology, University of Michigan Medical School, 1150 W. Medical Center Drive, Ann Arbor, MI 48109-0605, USA.
Zhang
Yanhong
Y
Varambally
Sooryanarayana
S
Chinnaiyan
Arul M
AM
Banerjee
Mousumi
M
Merajver
Sofia D
SD
Kleer
Celina G
CG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology; D055511:CCN Intercellular Signaling Proteins; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000235:genetics*; D024721:E-Box Elements / Q000235:genetics; D004848:Epithelium / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D008207:Lymphatic Metastasis; D042361:Mammary Glands, Human / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000235:genetics; D000071799:Zinc Finger E-box-Binding Homeobox 1
D055511:CCN Intercellular Signaling Proteins; C400081:CCN6 protein, human; D015820:Cadherins; D018398:Homeodomain Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; C486307:ZEB1 protein, human; D000071799:Zinc Finger E-box-Binding Homeobox 1