LACTIC DEHYDROGENASE IN HUMAN NEOPLASTIC TISSUES.

Abstract

Summary A definite and consistent shift in the pattern of molecular forms of lactic dehydrogenase (LDH) has been found in a large series of malignant human neoplasms as compared with benign tumors and normal controls. This has been associated in most cases with an absolute increase in the muscle-type LDH (migrating negatively on electrophoresis). No correlation was found between the degree of these changes and the histologic grading of the tumors. Suggestive but not conclusive evidence was found for an increase in total LDH activity in malignant tumors. In contrast, metastatic nodules were shown to have lower enzyme activity levels and different LDH compositions when compared with their associated primary tumors. The benign tumors were essentially indistinguishable from their normal tissue of origin. The significance of these findings in relation to the known characteristic increase of glycolytic activity in malignant neoplasms is discussed. Consideration is also given to the possible implications of these results for carcinogenesis and cancer chemotherapy.