Pretreatment effects on the uptake/retention kinetics of L-dopa in Harding-Passey melanoma.
Malignant melanoma cells possess a unique biochemical pathway that converts L-3,4-dihydroxyphenylalanine (L-dopa) to the biopigment melanin. Selective cytotoxic incorporation of exogenous L-dopa into melanoma cells in vivo may provide a means of designing specific chemotherapeutic agents useful in the treatment of this disease. Using the Harding-Passey murine melanotic tumor model, a preferential uptake of [3H]L-dopa by the tumor was characterized. Following pretreatment of the tumor-bearing mice with nonradioactive L-dopa, a significant enhancement (p less than 0.01) of [3H]L-dopa incorporation and retention into melanoma for a period of 24 h was observed, when compared with the concomitant tissue distribution and clearance of radioactivity in the control animals. This finding suggests that by initial pretreatment of melanoma with nonradioactive L-dopa, the subsequent selective accumulation of [3H]L-dopa in tumor may provide a useful tool in testing new modalities of therapy in malignant melanoma.
D000311:Adrenal Glands / Q000378:metabolism; D000818:Animals; D007274:Injections, Intraperitoneal; D007700:Kinetics; D007980:Levodopa / Q000008:administration & dosage / Q000378:metabolism*; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism*; D008657:Metabolic Clearance Rate / Q000187:drug effects; D051379:Mice; D011292:Premedication
D007980:Levodopa