Influence of L-tyrosine phenol-lyase on the growth and metabolism of B16 melanoma.

Administration of L-tyrosine phenol-lyase inhibited growth of established B16 melanomas in BDF1 mice. Under the conditions used, the enzyme exerted a cytostatic effect on the tumors. The addition of L-tyrosine phenol-lyase to growing melanoma cultures blocked cell division and caused an accumulation of cells in the G1 (G0) pultures was suppressed, the most pronounced effect of L-tyrosine phenol-lyase was a rapid and near-complete cessation of uridine uptake and incorporation. This block in RNA synthesis was also observed in human fibroblasts treated with L-tyrosine phenol-lyase.