Author(s): Doris Balinsky, Charles E Platz, Jeffrey W Lewis
Isozyme patterns of 23 different enzymes were compared in normal, benign, and malignant breast tissues; in MCF-7 cells; and in organoids of normal human breast tissue. Benign lesions generally showed Â¡sozymepatterns similar to those of normal tissues. LÃ¡clate dehydrogenase isozyme 5 was significantly increased in malignant tumors; MCF-7 cells had only lÃ¡clate dehydrogenase (i_-lactale:NAD oxidoreduclase; EC 18.104.22.168). The mitochondria! form of maiale dehydrogenase was also significanlly increased in human malignanl lumors; Ihis was espe cially evidenl when comparing lumor and apparenlly uninvolved breast tissue from the same patient The Â«4isozyme of pyruvale kinase was Ihe major form in mosl malignanl breast tumors, bul in only 41% of normal lissues, 30% of fibrocyslic disease spec imens, and 46% of fibroadenomas. A more anodal band of pyruvate kinase, probably a K3M or KaK""1hybrid, predominated in most normal and benign tissues, but in only 63% of primary and 56% of secondary lumors. All specimens had predominantly creatine kinase BB, aldolase A4, and hexokinase I. Traces of aldolase A3C and of hexokinase II were observed in some tumors. None of Ihe lumors had Ihe Regan varianl of alkaline phosphalase. The isozymes of lÃ¡clale and maiale dehydrogenases and of pyruvale kinase appear lo be Ihe most promising as putalive lumor markers.