A comparison has been made of the formate-C¹⁴ incorporation into the nucleic acid purines and thymine of regenerating rat liver and Novikoff hepatoma in vivo. The effects of these tissues on one another, and on the host tissues has been studied. The utilization of formate by the nucleic acids of Novikoff hepatoma and regenerating rat liver was not significantly altered in animals containing both of these rapidly dividing tissues. The results indicated that the demand for formate by one of the rapidly growing tissues did not lower the uptake of formate by the nucleic acids of the other tissue. Furthermore it was indicated that nucleic acid synthesis in regenerating liver did not alter the synthesis of nucleic acids in other tissues. Regenerating liver and Novikoff hepatoma had no effect on the nucleic acid metabolism of the host tissues of animals bearing one or both of these tissues. These results are not completely in agreement with those reported in the literature. In a preliminary experiment a radioactive suspension of Novikoff hepatoma was transplanted into rats. Twenty percent of the injected radioactivity was recovered in the urine during the first 24 hours of tumor growth. The specific activities of the nucleic acid bases of the tumor, obtained after 24 hours of growth, were negligible. These findings indicated that the nucleic acids of the donor tumor suspension were not utilized in the synthesis of the nucleic acids of the growing tumor. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. Current therapeutic approaches for HCC including surgical resection and trans-arterial embolization (TAE) remain largely ineffective, underscoring the need for development of novel therapeutic strategies. Because HCC is high vascularized, continuous administration angiogenesis inhibitor using gene therapy approach may facilitate long-term blockade tumor vasculature, thereby perturbing the growth of HCC. Vasostatin 112 (VS112) encodes an alternatively spliced fragment of angiogenesis inhibitor vasostatin, which encompasses residues 1-64 and 133-180 of calreticulin. In this study, recombinant adenovirus encoding VS112 (Ad-VS112) was generated to evaluate its potential for suppression of orthotopic Novikoff hepatoma in syngenic Sprague-Dawley (SD) rats. Adenovirus-mediated VS112 overexpression significantly inhibited the migration and tube formation of endothelial cells, indicating the anti-angiogenic potency of VS112 gene delivery. However, VS112 overexpression had no influence on the viability of N1-S1 Novikoff hepatoma cells. To investigate the prophylactic effect of VS112 expression on hepatoma growth, N1-S1 cells were infected with Ad-VS112 or adenovirus encoding green fluorescent protein (Ad-GFP) then implanted into the liver of SD rats. After 14 days, rats implanted with VS112-expressing showed significantly reduced incidence and size of hepatoma compared with those implanted with Ad-GFP-infected cells. To investigate the therapeutic efficacy of VS112 gene delivery, the SD rats were implanted with N1-S1 cells on day 0, treated with adenovirus vectors (2 x 1010 plaques forming units) via intravenous route on day 1, then sacrificed on day 14 to monitor hepatoma growth. By measuring tumor weight, it was found that Ad-VS112-treated rats exhibited significantly decreased tumor burden compared with control groups, which was in accordance with their lower serum GOT level. Histological analysis revealed a significant reduction of vWF-positive blood vessels in Ad-VS112-treated tumors, which was accompanied with a decrease in Ki-67-positive proliferating cells and an increase in TUNEL-positive apoptotic cells. Moreover, the expression of pro-inflammatory nuclear factor kappa B (NF£eB) and cyclooxgenase II (COXII) was also effectively attenuated in Ad-VS112-treated hepatoma. In conclusion, prior or post VS112 gene delivery potently suppresses the growth of orthotopic hepatoma,thereby holding promises for future treatment of HCC.