A Peptide Derived From D. Melanogaster Hairless Protein Promotes The Negative Regulation Of Notch Aberrant Constitutive Signaling On Human Breast Cancer Cells

The Notch Signaling Pathway (NSP), by a Notch intracellular domain (NICD) constitutive overexpression, has been related to many cancer types. In breast cancer, the constitutively activated NSP plays a principal role in aberrant cell cycle progression, poor cellular differentiation and apoptosis inhibition. It is well known the high conservation of Notch proteins through the metazoarians. Hairless is a negative regulator of NSP in D. melanogaster, but a homologous Hairless protein in mammals is unclear. The design of an expression plasmid, pReNegAID, which encodes a peptide based on the CSL binding domain of the Hairless protein of D. melanogaster will be used for analyzing the ReNegAID peptide participation it the negative regulation of NSP in the mammary gland cancer context. Both the pReNeg-AID plasmid and the mock plasmid were transfected into breast cancer cells in order to analyze cell proliferation (MTT assay) and gene expression pattern related to the NSP common genes between Hedgehog and Wingless pathways and genes related to apoptosis, cell differentiation and cell cycle. Moreover, control expression of Luciferase reported plasmid was performed and data showed that ReNeg-AID peptide induces a switch in the gene expression pattern related to the NSP and induce G1/S cell cycle arrest by the negative regulation of the Notch-1 receptor expression and it suggests cross talking between Hedgehog pathway (Hh) and NSP in mammary cancer cells to avoid the molecular machinery of initial epithelial to mesenchymal transition (EMT).