232 A SYMPOSIUM ON RESPIRATORY ENZYMES 



expressed the view that, even as the histology of cancer is suflBciently 

 characteristic to enable a pathologist to recognize the tissue as cancer 

 usually, but not always, so also the experienced student of tissue 

 metabolism could almost always state correctly what is or is not 

 cancer tissue from results of metabolic measurements on tissue sHces. 



Impaired Respiration Mechanisms.— Warburg's idea that the res- 

 piration of cancer tissue is in some manner deranged may still be 

 true, and the idea has inspired a number of studies of individual 

 respiration mechanisms in cancer tissue. Dr. Benoy, Dr. Baker, and I 

 (10) found the succinic oxidase system inactive in sHces of certain 

 tumors, and Dr. Greig and 1(11) showed that most tumor suspensions 

 tested were low in succinic dehydrogenase and the cytochrome- 

 cytochrome oxidase systems. I (12) found that tumor breis added to 

 liver or other tissue breis (except heart) rapidly destroyed the suc- 

 cinic oxidase system of the liver or other tissues. Stotz (13) and 

 Potter and DuBois (14) found low cytochrome c content in a number 

 of cancer tissues. Banga (15) found that certain tumors are scarcely 

 able to reduce added oxalacetate; this and the lack of succinic 

 dehydrogenase would indicate impaired catalysis by the mechanism 

 postulated by Szent-Gyorgyi. 



However, Dr. Greig and I found some tumors with a fair amount 

 of succinic dehydrogenase and some normal tissues with little. Some 

 normal tissues, especially pancreas, and also commercial trypsin, 

 would inhibit liver succinoxidase; the inhibition might be a purely 

 in vitro effect and auto-digestion might partly account for low suc- 

 cinoxidase values found for tumor tissues. Potter and DuBois found 

 at least one normal tissue (lung) with as low a cytochrome c content 

 as tumor tissue, and Breusch (16) found that the rate of oxalacetate 

 reduction was negligible also with some normal tissues, namely 

 spleen, lung, placenta, and peripheral nerves. 



Dr. Baker and I (17) found that the effects of a number of dyes on 

 the metabolism of tumor tissue were different from their effects on 

 any of the normal tissues tested. Nothing further has come of these 

 observations. 



Altogether the various results suggest that cancer tissue tends to 

 differ from normal tissues in its respiratory mechanisms, but no 

 very well-defined difference has yet been disclosed. 



REFERENCES 



1. Warburg, O., The Metabolism of Tumors, translated by F. Dickens ( Richard 

 Smith, Inc., New York, 1930). 



2. Gyorgy, p., Keller, W., and Brehme, T., Biochem. Z., 200, 356 (1928). 



