S100A1

S100 protein is a 21,000-Da component first isolated from brain by Moore (1965). It has 2 subunits, alpha and beta. The S100 molecule is a dimer; thus there are 3 forms of S100: alpha-alpha, known as S-100a(0); alpha-beta, known as S-100a; and beta-beta, known as S-100b.

S100A1 is a calcium-binding protein, which has been recently found expressed in renal cell neoplasms.

Immunocytochemical studies demonstrated that S100 protein is produced by a wide variety of normal and neoplastic cells of mesodermal, neuroectodermal, and epithelial origin.

S100A1 protein expression is constantly detected in the normal parenchyma of the adult and fetal kidney.

Immunochemistry

 S100A1 protein is expressed in oncocytomas, clear cell and papillary renal cell carcinomas but not in chromophobe renal cell carcinomas. Its immunodetection is potentially useful for the differential diagnosis between chromophobe renal cell carcinoma and oncocytoma. (17483815)

 S-100A1 is a reliable marker in distinguishing nephrogenic adenoma from prostatic adenocarcinoma. (19384190)

References

 S-100A1 Is a Reliable Marker in Distinguishing Nephrogenic Adenoma From Prostatic Adenocarcinoma. Cossu-Rocca P, Contini M, Brunelli M, Festa A, Pili F, Gobbo S, Eccher A, Mura A, Massarelli G, Martignoni G. Am J Surg Pathol. 2009 Apr 18. PMID: 19384190

 Diagnostic utility of S100A1 expression in renal cell neoplasms: an immunohistochemical and quantitative RT-PCR study. Rocca PC, Brunelli M, Gobbo S, Eccher A, Bragantini E, Mina MM, Ficarra V, Zattoni F, Zamò A, Pea M, Scarpa A, Chilosi M, Menestrina F, Bonetti F, Eble JN, Martignoni G. Mod Pathol. 2007 Jul;20(7):722-8. PMID: 17483815