Effects of 3-aminobenzamide on induction of multiorgan carcinogenesis by N-nitrosobis(2-hydroxypropyl)amine in hamsters

Characterization of three cloned cell lines from a N-nitrosobis(2-hydroxypropyl)amine-induced transplantable hamster pancreatic ductal adenocarcinoma

To investigate characteristics of pancreatic carcinoma growth behavior, the cloned cell lines, HPD1NR, HPD2NR, and HPD3NR, were established from a transplantable hamster ductal adenocarcinoma induced by N-nitrosobis(2-hydroxypropyl)amine (BHP). All three clones showed similar epithelial cell morphology and grew as sheets in culture with no differences in doubling times, ranging from 23-28 h. Mutation in the c-Ki-ras exon 1 was detected in common. The modal chromosome numbers were also found to be similar at 60, 62, and 60-62 in the less than tetraploid cells in the three clones. In contrast, a clear difference in frequencies of tetraploid or polyploid cells at 24.7, 22.5, and 75.5% in HPD1NR, HPD2NR, and HPD3NR, respectively, was evident. Tumorigenic potency evaluated by transplanting individual clones revealed HPD3NR to display pronouncedly less growth in syngeneic hamsters. The results suggest that increase in frequency of tetraploid or polyploid cells might be associated with a decreased in vivo growth potential of hamster pancreatic ductal adenocarcinomas, and suggest that these clones might become a valuable tool for understanding in vivo growth mechanisms of cancer cells.

Effects of novobiocin on the induction of gamma-glutamyltranspeptidase positive foci in the liver of rats treated with diethylnitrosamine

Effects of novobiocin on the induction of gamma-glutamyltranspeptidase(GGT)-positive foci, an early lesion occurring during hepatocarcinogenesis, after diethylnitrosamine(DEN) initiation were investigated in Fischer 344 rats. Animals were given DEN at a dose of 20 mg/kg b. w. followed by novobiocin at doses of 50, 100 and 200 mg/kg b. w. The latter two doses, but not 50 mg/kg b. w., significantly inhibited the development of GGT-positive foci, providing evidence of the possible involvement of mono(ADP-ribosyl)ation in the initiation phase of hepatocarcinogenesis in rats.

Delayed DNA synthesis induced by 3-aminobenzamide in partially hepatectomized liver of rats

The possibility of poly(ADP-ribosyl)ation playing a role during liver regeneration induced by partial hepatectomy (PH) in vivo was examined. When rats were given an i.p. injection of 3-aminobenzamide (ABA) at a dose of 600 mg/kg body weight 12 h after PH, the levels of DNA synthesis at 20 h after PH were significantly reduced. The time course of DNA synthesis in regenerating liver was significantly delayed in the ABA-treated group. Enzymatic assay revealed the activity of poly-(ADP-ribose)polymerase (PADPRP) in controls to be increased in parallel with the increase of DNA synthesis induced by PH. This increase in PADPRP activity was delayed and very much weaker after ABA treatment. The results thus suggested that poly(ADP-ribosyl)ation might play an important role in DNA synthesis during liver regeneration in vivo.

Effects of 3-aminobenzamide on the post-initiation phase of N-nitrosobis(2-oxopropyl)amine induced pancreatic carcinogenesis in Syrian hamsters

Effects of 3-aminobenzamide (ABA) on pancreatic carcinogenesis after initiation by N-nitrosobis(2-oxopropyl)amine (BOP) were investigated in Syrian hamsters. Animals were given BOP at a dose of 70 mg/kg body weight by subcutaneous injection and following a 2-week recovery period, were administered basal diet or basal diet containing 0.5, 0.75 and 1.5% ABA for 30 weeks. While the incidences of resultant pancreatic lesions, including hyperplasia, atypical hyperplasia and carcinoma, induced by BOP were not significantly influenced by ABA treatment, the mean numbers of those pancreatic lesions were significantly decreased in a dose-dependent way. The results therefore suggested the possible involvement of poly(ADP-ribosyl)ation in the post-initiation phase of pancreatic carcinogenesis in hamsters.