PSORIASIN (S100A7)

Psoriasin (S100A7) is a relatively new member of the S100 gene family that is located within the S100 gene cluster on chromosome 1q21 and sh ares the typical calcium binding domains that define this family of pr oteins. It was first identified as a 11.4 kDa cytoplasmic and secreted protein isolated from skin involved by psoriasis, which can be induce d in cultured squamous epithelial cells. It is now known to be express ed by both normal cultured and malignant keratinocytes and malignant b reast epithelial cells within ductal carcinoma in situ, suggesting an association with abnormal pathways of differentiation. Current evidenc e supports a role in the pathogenesis of inflammatory skin disease, as a chemotactic factor for hematopoietic cells, and a role in early sta ges of breast tumor progression in association with the development of the invasive phenotype. While therapeutic potential as a target for m odulation of the inflammatory response in psoriasis awaits further stu dies, potential clinical applications already include a role as a dete ction marker for squamous cell carcinoma and a diagnostic marker to di stinguish in situ from invasive breast cancer cells. (C) 1998 Elsevier Science Ltd. All rights reserved.