Correlation of deoxycytidylate deaminase activity with cell proliferation during hepatocarcinogenesis and tumour growth in transplantable rat hepatomas.

Determination of activity of deoxycytidylate deaminase stabilized by etylene glycol was used to evaluate the rate of DNA synthesis in precancerous liver tissue and in transplantable rat hepatomas. Increased activity of the enzyme in macroscopically unchanged liver tissue occurred during hepatocarcinogenesis induced by 3'-Me-DAB in the period between weeks 1 and 10. The slow growing transplantable tumours derived from primary hepatomas induced by DAB and AF showed slightly increased activity, while the fast growing lines derived from primary tumours induced by 3'-Me-DAB were characterized by markedly increased activity. Thus the enzyme appeared to be a good marker of tumour growth rate. Correlation between increased DNA synthesis during carcinogenesis and the occurrence of alpha-fetoprotein is briefly discussed.