C-ERB B-2 AMPLIFICATION IN CYSTIC RENAL-DISEASE

Gene amplification (overexpression) of c-erb B-2 was tested in a variety of cystic renal diseases, renal cell neoplasms (adenomas and carcinomas) and end stage kidneys without cysts. C-erb B-2 encodes a receptor-like protein that shares homology with, but is distinct from the epidermal growth factor (EGF) receptor. A monoclonal antibody that immunoprecipitates a protein of approximately 185 kD from a lysate of NIH/3T3 cells transfected with the c-erb B-2 gene was utilized for testing. Simple renal cysts, cystic renal dysplasia. autosomal recessive polycystic kidney disease (ARPKD), and non-cystic, essentially normal kidneys failed to show c-erb B-2 overexpression. In contrast, autosomal-dominant polycystic kidney disease (ADPKD), acquired (dialysis-associated) cystic disease (ACD), non-cystic end stage kidneys and renal cell neoplasms revealed overexpression of c-erb B-2 with some frequency (40% or more of cases tested). Three cystic disorders revealing c-erb B-2 overexpression also showed platelet-derived growth factors (PDGFs) expression in similar locations (cyst lining and adjacent tubules). Other growth factors [insulin-like growth factor (IGF-1), fibroblast growth factor (FGF) and beta transforming growth factor (TGF-beta)] were not noted to be overexpressed in either c-erb B-2 positive or negative cystic diseases. C-erb B-2 may be a marker related to the proliferative/growth capabilities of selected cystic diseases, including potential for associated genesis of benign and malignant renal cell tumors.