CONICET | Buscador de Institutos y Recursos Humanos

Cancerprogression can be activated by cytokine signals which regulate transcriptionfactors such as ZEB1 or Snail. We intended to uncoverthe role of PKC signaling in ZEB1 regulation. PKCisoforms andEMT markers were determined by immunoblotting in 9 breast cancer cell lines. PKCα and ZEB1 had a significant positive correlation (p≤0.05). Theinterference of PKCa expression by 2 siRNAssignificantly reduced ZEB1 expression at 72hs in MDA-MB-231 cells (siPKCα1,2: 0.64±0.06 and 0.67±0.06 vs siNonTarget siNT:1)(p≤0,05) as well as in MDA-MB-453 and BT549 (72/96hs) and in MDA-MB-231(96hs). EMT markers changed their expression at no time. However, ZEB1 mRNA (qPCR)did not differ from control in siPKCα/MDA-MB231 cells which suggests that PKCα could regulate ZEB1 expression by diminishing its protein stability.In addition, motility and invasive abilities (Matrigel®invasion assay) of MDA-MB-231cells silenced by 6 siPKCα or 4 siZEB1 lowered significantly againstsiNT cells (siPKCα1,2,3,4,5,6: 40.3±3.5; 52.6±4.2; 53.4±2.6; 52.0±2.8; 42.7±2.4; 59.6±3.1 vs siNT: 83.1±2.9) (p≤0.0001) (siZEB1 1,2,3,4: 25.2±2.3; 31.0±2.49; 80.3±3.0; 39.7±2.7 vs siNT: 150.6±3.9) (p≤0.0001). We also tested the capacity ofactin cytoskeleton to respond to a 10 minute stimulus of 10% Fetal Bovine Serumby Phalloidin-rhodamine stainining on siPKCa or siZEB1MDA-MB-231 cells. Controland siZEB1 cells showed ruffles and lamellipodia structures as a response to10%FBS while siPKCa MDA-MB231 cells were unable to have a normal response. Results were expressed as mean ± SEM. The results suggestthat PKCα could regulate ZEB1 expression in breast cancer cell lines bymodifying its protein stability at short term. The poor ruffle formation only in siPKCa cells compared to a normalresponse in siZEB1 cells suggest that PKCa is able to regulate cell invasion by two mechanisms: ZEB1 dependent and ZEB1 independent. Conclusion: PKCα is novel regulator of ZEB1 and therefore thecell invasion in breast cancer.