Heterogeneity of glycolytic enzyme activity and isozyme composition of pyruvate kinase in breast cancer.

In 6 patients with breast cancer - of whom specimens of the primary tumor as well as one of its metastases were available for examination - we demonstrated intratumoral and intertumoral heterogeneity in expression of activity of the glycolytic enzymes hexokinase, phosphofructokinase, aldolase, enolase and pyruvate kinase. Heterogeneity also existed in isozyme composition of pyruvate kinase. The transition of the tumors towards normal surrounding breast tissue showed either a sharp drop in activity, or a gradual decrease in activity, corresponding to pushing margins or infiltrative growth of the tumor as was demonstrated by histologic examination of these specimens. Likewise, the shift towards expression of K isozyme of pyruvate kinase in breast cancer compared to normal breast tissue could be demonstrated.