Dopamine- -hydroxylase activity in mouse neuroblastoma tumors and in cell cultures.

Dopamine-beta-hydroxylase activity is present in mouse neuroblastoma C-1300 tumors. The activity is proportional to the weight of the tumor. Serum activity is markedly increased in mice that bear the tumors. Treatment of mice with 5-bromodeoxyuridine causes marked inhibition of tumor growth and decrease of dopamine-beta-hydroxylase activity in the serum. The histochemical studies reveal that 1-5% of the cells in mouse C-1300 neuroblastoma tumors contain catecholamines and that catecholamine-containing processes terminate mainly around blood vessels of the tumor. Dopamine-beta-hydroxylase is present in clonal neuroblastoma cell lines. The cell line with the greater tendency to form axon-like processes has a higher activity of this enzyme.