Variants of phosphohexose isomerase in gastrointestinal and mammary carcinoma: isoelectric focusing patterns of normal and tumor tissues derived from surgical specimens of the same patient.

The occurrence of charge variants of phosphohexose isomerase was elucidated in cancerous and, for comparison, in noncancerous tissues obtained from the same organ. Surgical specimens from 35 patients with gastrointestinal and mammary carcinoma were studied by means of the isoelectric focusing (IEF) technique. Differences in the IEF pattern could be demonstrated in 90% of the patients with gastric cancer. Corresponding values for the patients with colorectal and mammary carcinoma were 50 and 73%, respectively. Almost all normal specimens proved to be monomorphic, revealing only the major basic band with a pI of 9.1. In most of the tumors, additional bands of pI 8.9 and 8.6 were found. This "typical" IEF pattern in tumor tissues was observed in 60% of gastric and 73% of mammary tumors, but in only 36% of colorectal tumors. The results obtained suggest that the IEF pattern of phosphohexose isomerase in tumor tissue might be a useful tool for tumor diagnosis.