Clinical significance of acidic pI isoenzyme of ribonuclease in human serum.

Employing isoelectric focusing with an Ampholine column, the presence of three major pI isoenzymes (basic, neutral and acidic) of human ribonuclease (RNase) is demonstrated. The acidic pI isoenzyme was observed in pancreatic and hepatic cancer cells and in fetal pancreas and liver tissues, and was frequently detected in the sera of patients with pancreatic and hepatic cancer. This isoenzyme was not, however, detected in the sera of non-cancerous patients. In pancreatic cancer tissues, other pI isoenzymes, except for the acidic one, were markedly suppressed and the isoelectrophoretic patterns of the cancerous tissues closely resembled those obtained from fetal pancreatic tissue. These results suggest that the acidic pI isoenzyme could represent one of the carcinofetal proteins and that the detection of this pI isoenzyme in the patient's serum may be useful for the diagnosis of pancreatic and hepatic cancer.