GLYPICAN-3 (GPC3) MODULATES EPITHELIAL- MESENCHYMAL TRANSITION (EMT) OF HUMAN BREAST CANCER CELLS BY DOWNREGULATING ZEB1

GISELA VANINA NOVACK; LILIAN FEDRA CASTILLO; MARÍA AMPARO LAGO HUVELLE; MARÍA CANDELARIA LLORENS DE LOS RÍOS; ANA MARÍA CABANILLAS; ELISA BAL DE KIER JOFFÉ; MARÍA GISELLE PETERS

Mar del Plata

Simposio; LXI Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC).; 2016

Sociedad Argentina de Investigación Clínica

Glypican 3 (GPC-3) is a heparan sulfate proteoglycan related to cancer. Previously, We overexpressed GPC3 in MDA-MB231 human breast cancer cells (metastatic and GPC3-). We showed that GPC3 inhibits clonogenic and migratory capacities, while increases homotypic adhesion and apoptotic susceptibility. Moreover, GPC3 induced the reexpression of the epithelial marker E-Cadherin. Our results suggest that GPC3 could act as a metastatic suppressor by regulating epithelial-mesenchymal transition (EMT). In this work we observed that GPC3 overexpression induces a change in the MDA-MB231 cell morphology, from a fibroblastic to a more epithelial phenotype, as well as prevents the F-actin stress fibers formation. In vivo assays showed that GPC3 overexpression inhibits tumorigenicity (64% vector vs 20% GPC3 p<0,05), local invasion (75% vector vs 0% GPC3 p<0,05) and spontaneous metastasis incidence (50% vector vs 0% GPC3 p<0,001). To elucidate the molecular mechanisms involved in these effects, we evaluated the canonical wnt pathway activity. Although GPC3 induced an inhibition of this pathway, no changes in the E-Cadherin expression levels were observed when we reverse the effect of GPC3 on wnt signaling. So, we studied the expression of the E-Cadherin transcriptional suppressors: SNAIL, SLUG and ZEB1. GPC3 leaded a decrease in the ZEB1 mRNA and protein levels. When we overexpress ZEB1 in MDA-MB231- GPC3 cells, the increase of E-Cadherin expression induced by GPC3 was reversed. To test this in vivo, we performed IHC for E-Cadherin and ZEB1, in MDA-MB231-GPC3 tumors. ZEB1 staining was detected in 73±15% of vector tumor cells vs 33±3% of GPC3 tumor ones (p<0,001). While the most of control tumor cells was negative for E-Cadherin, this signal was positive in the 95±5% of GPC3 tumor cells (p<0,001). Our results show that GPC3 expression reverted EMT by downregulating ZEB1 expression in human breast cancer cells. This effect would be independent of the canonical wnt pathway.