Mechanistic routes of taurine in human fibroblast cells as compared with human melanoma cells

Taurine or 2-aminoethanesulfonic acid is a non-protein amino acid found in high concentrations in a variety of cell types and in many cases represents the most abundant free amino acid present. Taurine is synthesized in the cell by the oxidation of hypotaurine and by the decarboxylation of cysteic acid. Taurine could be produced from several amino acid precursors: cysteine, cysteamine, serine and methionine. This study explored and compared the formation of taurine from radiolabeled precursors, ($\sp3$H) -serine, ($\sp{35}$S) -cysteine and ($\sp{35}$S) -methionine in human fibroblast and human melanoma fibroblast-like cells. Taurine was formed by de novo synthesis from all the labeled precursors tested. The predominant precursor for taurine formation was ($\sp{35}$S) -methionine, similarly it was also the predominant amino acid metabolized by both cell lines. The melanoma cells were found to synthesize taurine more readily than the normal fibroblasts, thereby suggesting that taurine plays an equally important role in the melanoma cells.