Enolase isozymes in seminoma

Summary We determined concentrations of and -enolases in normal testis and in seminoma tissues by enzyme immunoassay. Concentrations of -enolase were 4,170±2,040 ng/mg protein in normal testis (n = 8) and 8,140±4,480 ng/mg protein in seminoma (n = 8). Concentrations of -enolase in seminoma (460±571 ng/mg protein) were significantly higher than those of normal testis (59±15 ng/mg protein). Immunohistochemistry showed positive tumor cells for -enolase in 6 of 8 seminoma cases (75%). Serum -enolase levels were elevated (> 6.0 ng/ml) in 9 of 12 patients (75%) with seminoma: 60% of stage I, and 100% of stages II and III. In 10 patients treated by surgical excision and chemotherapy, serum -enolase was significantly reduced after the treatment. These findings indicate that elevated serum -enolase is derived from enhanced -enolase in seminoma tissues, and that serum -enolase could be a useful biomarker for staging and monitoring clinical course in patients with seminoma.