Mr 75,000 protein, a tumor marker in renal adenocarcinoma, reacting with antibodies to a synthetic peptide based on a cloned human endogenous retroviral nucleotide sequence.

Using a rabbit antiserum to a synthetic undecapeptide deduced from a cloned human retroviral gag-gene-related DNA sequence, we found a specific immunohistochemical reaction in all of 42 tested renal cell adenocarcinomas (RCC), while none of 17 similarly tested Wilms' tumors and 65 carcinomas at other sites were positive. The RCC included two cases that presented with distant metastases. It had not been possible to establish the origin of these until immunohistochemical staining revealed this typical reaction. Subsequent renal angiography disclosed the primary. In immunoblotting the antiserum detected an Mr 75,000 protein in RCC tissue, and this reaction was blocked by the undecapeptide. The usefulness of this protein as a tumor marker for RCC is discussed.