CCN6-dependent regulation of ZEB1 in human mammary epithelial cells

LORENZATTI, GUADALUPE; PAL, A; CABANILLAS, ANA MARIA; KLEER, CELINA

TUCUMAN, ARGENTINA

Congreso; XLV Reunión Anual SAIB; 2009

SOCIEDAD ARGENTINA DE BIOQUIMICA Y BIOLOGIA MOLECULAR

ZEB1 is a crucial transcription factor that mediates the EMT (Epithelial to Mesenchymal Transition) and tumor invasion by inhibition of the epithelial phenotype. It is known that IGF-1 can up-regulate ZEB1 expression in an epithelial prostate cancer cell line. Our lab has reported that CCN6 loss triggers EMT and invasion through up-regulation of ZEB1 and downregulation of E-cadherin in breast cells. We hypothesize that CCN6 may regulate EMT in breast cancer by modulating IGF-1 signaling and thereby regulating ZEB1 expression. WB and RT-qPCR analysis in CCN6 knock-down HME (Human Mammary Epithelial) (CCN6 KD) cells revealed an up-regulation of ZEB1 and IGF-1 in both transcripts and protein levels. CCN6 KD cells and the aggressive malignant breast cancer cells MDA-MB-231(which express low CCN6) secrete high levels of IGF-1 in the media as well as activation of the IGF-1 signaling pathway.  The treatment of CCN6 KD cells with 500 ng/mL rhCCN6 induced down-regulation of ZEB1 and IGF-1 transcripts and proteins levels, with reduced IGF-1R and IRS1expression and activation. Concomitantly, the CCN6 treated cells shown a lower expression of the mesenchymal marker vimentin (WB and IF) and decreased invasive abilities. These results suggest that CCN6 regulates ZEB1- dependent EMT and cancer invasion through IGF-1 signaling in breast epithelial cells.