Study of SPG7 and SPRED2 genes functional role in human breast cells using 2D and 3D cell cultures

Abstract

The development and maintenance of the normal mammary gland are regulated by complex interactions between different pathways of signal transduction orchestrated by steroid hormones, growth factors and components of the extracellular matrix (ECM). Recently, using cDNA microarrays we have identified the SPG7 and SPRED2 genes as differentially expressed in primary breast tumors with different status of estrogen and progesterone receptors. The SPG7 gene (also named CAR or CMAR) encodes for the paraplegin, a mitochondrial metalloprotease that contain an ATPase domain responsible for an autosomal recessive hereditary spastic paraplegia (HSP). By alternative splicing the SPG7 gene encodes two distinct isoforms, which are associated with several biological processes including membrane trafficking, organelle biogenesis and proteolysis. The SPRED2 gene is a member of the Sprouty/SPRED family and encodes a protein located in the cellular membrane that acts as a negative regulator of the MAPK pathway mediated by growth factors. We identified estrogen response elements (EREs) in the promoter region of both, SPG7 and SPRED2 genes, indicating that they are potentially regulated by the estrogen receptor. The main goal of the present study is to investigate the functional role played by SPG7 and SPRED2 genes, in the morfogenesis of human mammary cell lines using 2D (monolayer of laminin) and 3D (matrigel) cell culture systems and suppression of gene expression by small interfering RNA (siRNA).