Effects of partial hepatectomy in rats on two transplantable hepatomas. Changes in weight and in synthesis of DNA and ferritin.

Partial hepatectomy in rats carrying Reuber H-139 and H-35 hepatomas is followed by rapid growth of these tumors. At comparable times after implantation, average wet weights of H-139 or H-35 hepatomas in partially hepatectomized rats were significantly higher than average wet weights of these tumors in control rats. In H-35 hepatomas growing subcutaneously, synthesis of DNA, as shown by incorporation of tritiated thymidine, was depressed 18 hours after a two-thirds hepatectomy in the host. Between 18 and 36 hours after partial hepatectomy, DNA synthesis rose steadily, with a maximum at about 36 hours. Incorporation of (14)C-leucine into ferritin (apoferritin) reached a maximum in liver and, to less extent, also in subcutaneous H-35 hepatomas, 48 hours after partial hepatectomy and returned to normal levels at 72 hours. The increase in wet weight of the tumors is most likely the result of an increase in rate of growth concomitant with the restoration of liver mass. The rise in synthesis of DNA and of ferritin in hepatoma cells after partial hepatectomy suggests that these hepatomas were affected by the same humoral factor or mechanism that stimulates cell division and protein synthesis in the liver immediately after partial hepatectomy.