A nucleoside mixture and its sparing effect on de novo purine nucleotide synthesis

Dietary nucleosides and nucleotides do not affect tumor incidence but reduce amyloidosis incidence in B6C3F1 mice irradiated with californium-252

OBJECTIVE

We investigated the effects of a dietary mixture of nucleosides and nucleotides (NS) on the systemic incidence rates of postirradiation carcinogenesis and non-neoplastic lesions in mice.

METHODS

Five-week-old male B6C3F1 mice were fed AIN-76B Purified Diet supplemented with NS for 1 wk and 13 mo before and after irradiation of neutron with californium-252 ((252)Cf); specifically NS was added to the AIN-76B Purified Diet (without nucleotide) to obtain a final concentration of 0%, 0.5%, or 2.5% NS. A commercial stock diet was also given to mice, and half of the mice were irradiated. Both irradiated and non-irradiated mice were used for reference controls.

RESULTS

The incidence of liver tumors in each NS group was lower than that in the reference control group (P < 0.01), but there were no differences between the 0%, 0.5%, and 2.5% NS groups. In contrast, the incidence rate of mice with non-neoplastic lesions in the 0% NS group was significantly higher than the reference control group (P < 0.05). This higher incidence of mice with non-neoplastic lesions was significantly decreased upon supplementation of the nucleotide-free diet with 0.5% or 2.5% NS (P < 0.01 and P < 0.05, respectively). Of the non-neoplastic lesions observed, the incidence of amyloidosis was decreased significantly upon supplementation of the nucleotide-free diet with 0.5% NS (P < 0.05).

CONCLUSION

Supplementation of a nucleotide-free diet with NS inhibits the development of non-neoplastic lesions, such as those associated with amyloidosis, without promoting the carcinogenesis induced by (252)Cf irradiation.