cysteinyldopa and Neuroblastoma

Recent work has highlighted the involvement of a dopamine derivative, 5-S-cysteinyl-dopamine (CysDA), in neurodegeneration and apoptotic cell death. In this paper we study in further detail the apoptotic process activated by this catechol-thioether derivative of dopamine in SH-SY5Y neuroblastoma cells. CysDA activates a cascade of events by an initial perturbation of Calcium homeostasis in the cell. Cell treatment with the catechol-thioether induces an immediate rise in intracellular Ca(2+) concentration, as demonstrated by a shift in the indo-1 dye emission spectrum, and a sustained high calcium concentration at long times of incubation. Fluorescence microscopy data show that the treatment of cells induces mitochondrial transmembrane potential depolarization, a clear evidence of the onset of apoptotic process. Programmed cell death activation is also demonstrated by cytochrome c release from the mitochondria, by an increased activity of both caspase-8 and -9 and by the poly(ADP-ribose)polymerase (PARP-1) cleavage, yielding the typical 86 kDa fragment due to caspase-3 activity. Overall, our data support the hypothesis that CysDA may induce apoptotic death in neuronal cells, via an initial perturbation of calcium homeostasis in the cytosol.

Topics: Apoptosis; Blotting, Western; Calcium; Catechols; Cell Line, Tumor; Cysteinyldopa; Cytochromes c; Humans; Membrane Potentials; Microscopy, Fluorescence; Mitochondria; Neuroblastoma; Neurons; Poly(ADP-ribose) Polymerases; Signal Transduction

5-S-Cysteinyldopa, a melanin precursor, has been shown to possess selective toxicity to tumour cells in vitro and in vivo. The mechanism of cytotoxicity of the catechol was studied in comparison with L-dopa and 5-S-cysteaminyldopamine. Growth inhibition of human neuroblastoma cell line of YT-nu by 5-S-cysteinyldopa was completely depressed by addition of catalase. Superoxide dismutase and five drugs thought to scavenge hydroxyl radicals or quench singlet oxygen had little effect on the cytotoxicity. Hydrogen peroxide itself was also cytotoxic at low concns. These results indicated that hydrogen peroxide was a mediator of the cytotoxicity of 5-S-cysteinyldopa. It is suggested that reaction of the catechol with cellular superoxide radicals contributes to the production of hydrogen peroxide in addition to autoxidation. Catalase reduced the cytotoxicity of L-dopa by half, while it had no inhibitory effect on the strong cytotoxicity of 5-S-cysteaminyldopamine.

Topics: Animals; Antineoplastic Agents; Cell Line; Cell Survival; Cysteinyldopa; Dihydroxyphenylalanine; Dopamine; Humans; Hydrogen Peroxide; Levodopa; Male; Mice; Neoplasms, Experimental; Neuroblastoma; Oxidation-Reduction

The natural catecholic amino acid 5-S-cysteinyl-3,4-dihydroxyphenylalanine (1) was selectively toxic to a variety of human tumor cell lines in culture and exhibited antitumor activity against L1210 leukemia and B-16 melanoma in mice at doses which were not toxic to the host. Structural analogues of 5-S-cysteinyl-3,4-dihydroxyphenylalanine including several new compounds, were synthesized and tested for growth inhibition of cultured cells of human neuroblastoma YT-nu and Chinese hamster fibroblasts Don-6. Some were also examined for antitumor activity against L1210 and B-16 in vivo. 4-S-Cysteinylcatechols and 2- and 4-S-cyteinylphenols, which cannot be prepared by conventional methods, were synthesized by the reaction of catechols and phenols with cystine and boiling aqueous HBr. 5-S-Cysteinyl- and 2-S-Cysteinyl-3,4-dihyroxyphenylalanine (1 and 2), L-3,4-dihydroxyphenylalanine (L-Dopa), and 2- and 4-S-cysteinylphenol (14 and 15) were toxic to the YT-nu cell line only, while 4-S-cysteinylcatechol (6), 3-S-cysteinyl-5-methylcatechol (8), 5-S-cysteaminyldopamine (9), and 4-methylcatechol were strongly toxic to both cell lines. Compound I (1000 mg/kg), 6 (500 mg/kg), and 8 (400 mg/kg) increased the life span of L1210-bearing mice by 50, 50, and 43%, respectively, and compounds 1 and 8 were marginally effective against B-16 melanoma as well. Compound 9 was too toxic to show any activity. There was a good correlation between the cytotoxicity and the in vivo activity.

Topics: Animals; Antineoplastic Agents; Cell Division; Cell Line; Cricetinae; Cysteinyldopa; Dihydroxyphenylalanine; Humans; Leukemia L1210; Male; Melanoma; Mice; Neoplasms, Experimental; Neuroblastoma

The catecholic amino acids, dopa and 5-S-cysteinyldopa, and the dopamine metabolite, homovanillic acid, were determined in 8 neuroblastomas. 5-S-Cysteinyldopa and/or dopa were detected in all cases and homovanillic acid was present in 5. Dopa was also found in two tumours in which no definite histological diagnosis could be made. Neuroblastoma cells were cultured from 7 patients. The ageing of human sympathoblasts in culture was accompanied by modifications in the ability to synthetize dopa, which is a precursor of catecholamines as well as of melanins, and the metabolite homovanillic acid. An increase in the levels of 5-S-cysteinyldopa, a metabolite of the melanocytes, has been observed. Concurrent modifications of ultrastructural morphology with the disappearance of granular vesicles and appearance of melanosomes were noticed. This modulation of the original phenotypic expression commonly resulted in cell death, but in one case of metastatic adenopathy of a neuroblastoma we have been able to establish a permanent pigmented cell line.

Topics: Animals; Cell Line; Cysteinyldopa; Dihydroxyphenylalanine; Female; Homovanillic Acid; Humans; Male; Melanins; Mice; Neuroblastoma