Studies on the Mechanism of the Erythrocyte Enzyme Abnormalities Induced by Chemotherapy

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Abstract
To determine the possible mecahnisms of the red cell enzyme deficiencies induced by cancer chemotherapy, deficient red cell glucose-6-phosphate dehydrogenase (G-6-PD), pyruvate kinase (PK) and phosphofructokinase (PFK) from 17 patients were purified and characterized. In all cases G-6-PD showed normal kinetics, electrophoretic mobility and thermostability; a decreased enzyme synthesis was possible for the deficient enzyme activity. In each case studied, at least 1 PK property was modified in affinity for phosphoenol pyruvate, thermal stability or electrophoretic mobility, indicating a primary or secondary molecular abnormality. In some patients PFK had significantly increased affinity for citrate inhibitor; the quantity and quality of the M subunits apparently were not altered. Chemotherapy apparently can induce qualitative and quantitative red cell enzyme abnormalities by different mechanisms. These are similar to those observed in spontaneous leukemia and preleukemic states. Such a similarity poses the question of whether or not the red cell enzyme abnormalities induced by chemotherapy could be considered as the 1st sign of secondary leukemia due to treatment by oncostatic drugs.