Amino acid utilization during cell growth and apoptosis induction.

The amino acid utilization between human promyelocytic leukemia (HL-60), human oral squamous carcinoma (HSC-2, HSC-4, NA), human salivary gland tumor (HSG) and rat neuron cells (PC-12) were compared, using amino acid analyzer. All these cells consumed four essential amino acids (valine, methionine, isoleucine, leucine), glutamine and arginine, whereas they produced glycine, alanine and ammonia, without significantly affecting threonine, tyrosine, phenylalanine, histidine or lysine concentration. Serine and glutamine utilization varied considerably from cell to cell. HL-60 cells consumed serine and arginine at much higher rates than other cells. Serine depletion accumulated the G1 arrested cells, and produced increasing numbers of the apoptotic cells. Supplementation of serine significantly extended the period of logarithmic cell growth. During apoptosis induction of HL-60 cells by dopamine, sodium ascorbate or sodium 5,6-benzylidene-L-ascorbate, the oxidation of methionine to methionine sulfoxide was enhanced, but the consumption of serine, glutamine and arginine was reduced. In the presence of HL-60 cells, the methionine oxidation was significantly inhibited, suggesting the antioxidant action of the cells. These present study suggests the importance of re-evaluation of culture condition for each cell lines.