Phosphorylated intermediates in tumor glycolysis; glycolysis in tumor homogenates.

That slices of tumor tissue will produce large amounts of lactic acid has been well known since the early studies in Warburg's laboratory in 192430 (10, 20). That tumor glycolysis involves the same intermediate pathway as found in normal tissues has, however, been frequently questioned, perhaps most recently by Salter who re-emphasized at the Hershey Conference on Intracellular Enzymes in Normal and Malignant Tissues in 1945 his earlier views that "glycolysis in muscle and tumor extracts follows different pathways" (4). The latter paper called attention to the series of papers by Boyland and his co-workers during 193538 in which the opposite conclusion was reached, but reported that "tumor extracts fail to catalyse the reaction between triosephosphate and pyruvic acid which plays an important part in the accepted scheme for muscle glycolysis." I t is significant, however, that the text stated "whether or not this difference is due to the absence of the specific coenzyme which is necessary for this reaction in muscle remains to be answered experimentally," although they cited the experiments by Boyland's group in which yeast cozymase (DPN) stimulated glycolysis in tumor extracts. Other discrepancies in cancer metabolism were also noted. That part of the lack of agreement might be due to the preparation of extracts was recognized by Salter in the comment that Boyland's aqueous extracts contained coenzyme-destroying enzymes that were absent from the saline extracts used by Salter and his associates. I t was pointed out that tumor adenylic acid deaminase could be extracted by water but not by saline solution. I t is the opinion of the present authors that the technics employed in the manipulation of these systems is probably the chief cause of such lack of agreement as may exist. All of the published work * This work was done in part under a grant to the University of Wisconsin from the American Cancer Society on the recommendation of the Committee on Growth of the National Research Council. ** Fellow in Cancer Research of the American Cancer Society, sponsored by the Committee on Growth of the National Research Council. Present address: Department of Pathology, College of Medicine, University of Vermont, Burlington, Vermont. on tumors has been done with extracts of one kind or another, and thus an ill-defined portion of the original tissue activity has been measured. Since the publication of these reports, considerable advance has been made in the preparation of tissues for the study of enzyme systems, as well as in the reconstruction of these systems. So far as we are aware, no one has attempted to study glycolysis in tumor homogenates. However, some excellent work has been done in the case of brain homogenates, and the conditions for the study of glycolysis in homogenates of this tissue have received considerable attention (1, 13, 14, 17, 18). The present study has been greatly facilitated by the studies cited. The second source of the lack of agreement seems to be more theoretical than technical. In its simplest terms it may be stated as a questionmhow much does the glycolysis of tumor have to differ from that of muscle to have it constitute a "different" pathway? Potter emphasized in 1944 (11) that the metabolism of any given tissue is the resultant of the balance between the individual enzymes that it contains, and more recently (12) developed the generalization that "the Junction of a tissue is the resultant of the organized action of its enzymatic components." The studies in tumor glycolysis reported below show that by every test that we have applied, the phosphorylating pathway of glycolysis occurs in tumor tissue, as in muscle, brain, embryo, and other normal tissues that have been studied. But again and again it has been our experience that small deviations in individual enzyme components of the over-all system occur. The glycolytic enzyme systems are no exception; the behavior of the total glycolytic system varies significantly from tissue to tissue. I t is these differences in detail, now incompletely understood, that further the conclusion that the overall pathway is "different" and it is this conclusion with which we differ. The chief importance of the present work is considered to be the advance it represents in methodology, which may eventually make possible the definition of those differences in detail that exist between the various tissues. The report also brings out the fact that the glycolytic system in tumor