Metabolic characteristics of a naturally occurring preneoplastic tissue. I. Glycolytic enzyme activities of hyperplastic alveolar nodule outgrowth and adenocarcinomas of mouse mammary gland.

Enzyme activities involved in glucose utilization via the Embden-Meyerhof and the pentole phosphate pathways were compared in subcellular fractions prepared from: (a) normal mammary glands excised from virgin, pregnant, lactating, and postlactating C3H mice; (6) HAN* outgrowths from virgin mice; (c) spontaneous mammary adenocarcinomas from virgin, pregnant, and lactating mice; and (d) mammary adenocarcinomas that arose in HAN outgrowths in virgin mice. The activities of the following enzymes increased when the normal gland progressed from the pregnant to the lactating state: HK, POI, AL, a-GPDH, LDH, GPDH, 6-PGDH, RP-GP, and RP. Their activities attained maximum values during lactation and declined when the gland involuted. No evidence was found that the carcinogenic state involved a change in intracellular location of the enzymes. A large portion of HK activity in the normal lactating gland and in the adenocarcinoma was associated with mitochondria. All other enzymes were found exclusively in cell sap. Neither normal lactating glands nor adenocarcinomas con tained glucokinase (the adaptable enzyme with a high Km for