Increase in the amount of nuclear RNA in liver of ascites tumour-bearing mice.

The effect of tumour growth on the liver of the host was studied in the Ehrlich ascites tumour system. During the experimental period there was no infiltration of tumour cells in the liver, and the increase in the proliferation rate of Kupffer cells and parenchymal cells was only small. An increasing stability of the liver cell nuclei towards disruption during the isolation procedure was found to accompany the ascites tumour growth. In parallel, there was an increase in the amount of nuclear RNA and in the cellular speridine concentration. The major cause of these changes is probably an increasing demand on the liver by the growing tumour, illustrated by the fact that an amount of protein exceeding that of the whole liver accumulates in the ascites fluid during tumour growth. A hypothesis according to which the cellular accumulation of spermidine may be involved in the stabilization of cell nuclei and in the accumulation of nuclear RNA is advanced.