Detection and cloning of epidermal zinc-α2-glycoprotein cDNA and expression in normal human skin and in tumors

Zinc-α₂-glycoprotein (Znα₂gp) is almost ubiquitous in body fluids, and its antibody labels the corresponding secretory epithelia. We have found that Znα₂gp is also expressed in human epidermis. We cloned the Znα₂gp cDNA by screening our cDNA library, derived from epidermal keratinocytes, with a probe for prostate Znα₂gp. It had complete nucleic acid sequence homology with that from prostate, including the signal peptide. Just as Znα₂gp expression is higher in more differentiated breast tumors, so in skin tumors the highest mRNA levels occurred in the normal controls, the lowest in basal cell carcinomas (the least differentiated epidermal tumor type), and intermediate levels in squamous cell carcinomas and Merkel cell carcinomas. A similar increase in Znα₂gp gene expression with differentiation was observed when epidermal keratinocytes were cultured in media that varied in cellular maturation potential. J. Cell. Biochem. 67:216–222, 1997. © 1997 Wiley-Liss, Inc.