Dietary nucleotides and intestinal cell lines: I. modulation of growth

Abstract 

Emerging evidence suggests that nucleotide-free diets induce immune suppression and may seriously influence intestinal growth, maturation, and function. Thus, DNA-Na+ salt from fish soft roe, used as a nucleotide source, was investigated in regard to its effect on intestinal growth under optimal and nutrition–depleted conditions. The effect of another dietary additive, RNA from bakers yeast (S. cerevisiae) and various deoxy-mononucleotides have also been clarified. DNA-Na+, RNA, dAMP, dCMP, dGMP, and TMP were added to a human malignant intestinal cell line, CaCo-2 and a rat intestinal cell line of normal origin, IEC-6. Growth effects were ascertained by measuring the amount of tritium-labeled thymidine incorporated into the cell DNA. Our results show that DNA-Na+, RNA, and deoxy-mononucleotides have beneficial effects on growth, trying to compensate for the glutamine- and partially serum-deprived culture condition, depending on the intestinal cell line investigated. Especially the “normal” IEC-6 cell line seemed to benefit from the exogenous nucleotide supply. dAMP increased mostly CaCo-2 growth under optimal conditions. Both dCMP and dGMP supported growth of both cell lines under most culture conditions. In contrast, TMP acted as a general growth inhibitor. Of interest also was the growth-suppressing ability of DNA-Na+ in particular, but also RNA, on vigorously proliferating CaCo-2 cells cultured under optimal nutrition supply. This activity should be investigated in regard to other hyperproliferating and malignant cell types.

Keywords: Deoxy-mononucleotides, DNA from fish soft roe, RNA from baker's yeast, Intestinal cell line growth, Nutrition depletion