Glucose contribution to nucleic acid base synthesis in proliferating hepatoma cells: a glycine-biosynthesis-mediated pathway

Abstract

The coupling of glycolysis to serine and glycine metabolism was studied in fast-growing Zajdela hepatoma cultured cells. During the exponential phase of growth, occurring between 12 and 72 h, cells exhibited a decreased glycogen content together with a high glycolytic activity. Glycogen labelling, evaluated by 1 h-pulse experiments with [U-14C]glucose (5.5 mM), was minimal during the first 48 h and increased 2.5-fold at 72 h and 8-fold at 96 h, at which times it was also stimulated 2-fold by 10 nM insulin. [U-14C]Glucose carbons were incorporated into nucleic acid bases, with maximal incorporation at 72 h, the rate of nucleotide base labelling exceeding that of glycogen during the first 2 days of culture. Incubation of the cells with [U-14C]glucose resulted in the release into the medium of 14C-labelled glycine, the first intermediate formed on the route from serine to DNA. The rate of release per cell decreased as a function of cell growth, concomitantly with an increased rate of glucose carbon incorporation into nucleotide bases. The latter implied the intermediary formation of amino acids since the transaminase inhibitor cycloserine (10 mM), which totally inhibited [14C]glycine release, decreased by 65% nucleotide labelling from [U-14C]glucose. A dose-dependent inhibition by serine of the rate of [U-14C]glucose carbon incorporation into nucleotide bases was observed, which was maximal at 5 mM serine. These metabolic flux measurements indicate that glucose can be used as a precursor of nucleic acid synthesis. These results strongly suggest that this process is to a large extent mediated by a serine/glycine-biosynthesis-mediated pathway, and reinforce the hypothesis that glycolysis contributes to enhancing the provision of precursors required for cell proliferation.

Metabotyping of human colorectal cancer using two-dimensional gas chromatography mass spectrometry

“…Our findings using human CRC tissue samples corroborated with the findings by Locasale et al and Possemato et al and indicated a possible existence of a similar metabolic perturbation in human CRC. Although this metabolic deregulation had been reported via in vitro cell culture studies [29][30][31], our results confirmed the perturbation of serine biosynthesis in human CRC for the first time. This significant finding underscored the potential of exploring PHGDH suppression as a therapeutic strategy in human CRC.…”

Metabolic sensitivity of pancreatic tumour cell apoptosis to glycogen phosphorylase inhibitor treatment

“…However, further increase (doubling) in drug concentration induces a seven-fold enhancement of apoptosis. Tumour cells heavily rely on all available extra- and intracellular glucose sources for the rapid synthesis of nucleotides, amino acids and fatty acids, which is demonstrated by the depleted glycogen pool of transformed cells ( Hughes, 1976 ; Karnik et al , 1981 ; Bismut et al , 1995 ). It is evident from the metabolic profile reported here that the ability of MIA cells to progress in the cell cycle is severely impeded by limited glycogen breakdown in the presence of CP-320626 and that the cell cycle arrest readily progresses into apoptosis with higher doses of the drug.…”

Comparative proteomic analysis of silkworm fat body after knocking out fibroin heavy chain gene: a novel insight into cross-talk between tissues

“…Glycine-serine biosynthetic pathway meets these requirements of cell growth and proliferation, including proteins, lipids, and nucleic acids (Locasale 2013). Serine-glycine metabolism is linked to the glycolytic pathway, which plays an important role in the biosynthesis of DNA as a major one-carbon donor (Bismut et al 1995). All these evidences suggested that glycine-serine synthetic Table 2 marked with yellow.…”