Gene expression of erythropoietin in renal cell carcinoma

A 57-year-old man with renal cell carcinoma and erythrocytosis showed a high serum level of erythropoietin (EPO). High EPO signal was observed on Northern blot analysis and RT-PCR in the total RNA extracted from the renal tumor. Immunohistochemical staining also demonstrated tumor tissue with high immunostaining of EPO. Nucleotide sequences of EPO cDNA in the tumor were normal. To date, only one report has discussed the nucleotide sequences of a tumor's EPO gene; it showed mutant EPO cDNA in hepatocellular carcinoma tissue. This is the first demonstration of normal EPO cDNA in renal cell carcinoma.