g02 METABOLISM OF THE CANCER CELL 12 



IV. NUCLEIC ACIDS AND NUCLEOP ROTEINS 



(a) Composition 



A most comprehensive compilation of the purine and pyrimidine content of 

 normal and neoplastic tissues appears in the two volume treatise on Nucleic 

 Acids, edited by Chargaff and Davidson (ChargafT, 1955; Magasanik, 1955; 

 \'endrely, 1955; Leslie, 1955). Greenstein (1954; Chapter VIII), has reviewed 

 many of the studies on the concentration of nucleic acids and nucleoproteins in 

 neoplastic tissues. In general, it would appear that some quantitative differences 

 between normal and cancerous tissues do occur. There is no consistent purine or 

 pyrimidine pattern, however, that would characterize the nucleic acids of malig- 

 nant tissues. 



(?) Purines and pyrimidines. Chargaff and Lipshitz (1953) found that the purine 

 and pyrimidine composition of DNA from normal human liver and carcinomatous 

 human liver were almost identical. These investigators also established that the 

 sugar in each of the DNA fractions was 2-deoxyribose. DNA, prepared from nuclei 

 by salt extraction, was hydrolyzed with formic acid and the bases separated by 

 chromatography (Khouvine, 1954). Certain differences were reported in the 

 purine and pyrimidine composition of the DNA from normal and cancerous tissues. 

 The adenine content of an ovarian epithelioma was low compared to normal 

 tissues. Khouvine and Hirsch (1952) observed that the RNA extracted from 

 cancerous epithelial tissues of rats was high in guanine and cytosine, and relatively 

 low in uracil. 



Woodhouse (1954) prepared DNA from several spontaneous and induced ani- 

 mal tumors and also from human tumors. Following perchloric acid hydrolysis 

 the purines and pyrimidines were separated and determined by ultraviolet spectro- 

 scopy. The findings are shown in Table 5. Ratios of adenine to guanine and thy- 

 mine to cytosine were greater than unity in normal as well as in the cancerous 

 tissues. Certain tumor preparations of DNA exhibited some deviation in the base 

 content i.e., a low value for thymine in mouse sarcoma. In all instances the various 

 normal tissues were remarkably constant. A much wider range of values was noted 



TABLE 5 



MOLAR RATIOS OF BASES IN DNA 



(From Woodhouse 1954) 

 All values expressed on a molar basis relative to adenine = i.o 



Adenine G = Guanine C = Cytosine T = Thymine 



