The activities of hexokinase, phosphofructokinase, aldolase, enolase and pyru-vate kinase were studied in breast cancer metastases occurring at various sites and compared with the enzyme activities in a series of primary breast cancers. The activities of all enzymes studied were significantly higher in the metastases compared to the primary tumors (p ≤ 0.05). However, no changes in the isozyme patterns of enolase and pyruvate kinase were observed when the metastases were compared with primary breast cancers. Differences in location of the metastases did not lead to differences in enzyme activities. Our data suggest an association of an increasing rate of glycolysis with tumor progression.

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.

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A B S T R A C T In the erythrocytes of a patient with hereditary nonspherocytic hemolytic anemia, a homozygous expression of hexokinase deficiency was detected. The mutant enzyme was characterized by normal kinetic parameters with respect to its substrates, glucose and MgATP2-, normal pH optimum, normal heat stability at 40°C, but abnormal behavior with respect to its regulation by glucose-1,6-diphosphate and inorganic phosphate, and an altered electrophoretic pattern. Interpretation of the results revealed the presence of two different hexokinases type I in normal human erythrocytes: one enzyme with a high affinity for glucose-1,6-diphosphate, the inhibition of which is regulated by inorganic phosphate; and another enzyme with a lower affinity for the inhibitor, not regulated by inorganic phosphate. The former enzyme was not detectable in the erythrocytes of the patient, whereas the presence of the latter enzyme could be demonstrated.

In a patient with nonspherocytic hemolytic anemia, a hexokinase deficiency was detected in the red cells (residual activity about 25% of normal) and in blood platelets (20%-35% of normal activity). Although the total hexokinase activity in lymphocytes was normal, the amount of hexokinase type I was decreased to about 50% of normal. However, the deficiency was compensated for by the appearance of type III hexokinase. Compartmentation studies with controlled digitonin- induced cell lysis showed that this type III enzyme was localized in the cytosol, while almost all hexokinase activity in normal lymphocytes is particulate. No abnormal lymphocyte functions could be detected. The patient was homozygous for the defect. The parents and three of five sibs of the patient were apparently heterozygous with residual activities of 50%-67% of normal in their red cells, but did not show any clinical signs of hexokinase deficiency. The variant enzyme had a slightly decreased affinity for MgATP2- and a strongly increased inhibition constant for glucose-1,6-P2. Affinity for glucose, heat stability, and pH optimum were normal. In the electrophoretic pattern of red cell hexokinase, only one subtype of hexokinase I could be detected, while in normal red cells, at least three subtypes are present. In the heterozygous individuals, no enzymatic abnormalities could be detected, except for an aberration in the electropherogram of one sib.