Catecholamine effects on human melanoma cells evoked by alpha1-adrenoceptors.
The biological effects of catecholamines in mammalian pigment cells are poorly understood. Our previous results showed the presence of alpha(1)-adrenoceptors in SK-Mel 23 human melanoma cells. The aims of this work were to (1) characterize catecholamine effects on proliferation, tyrosinase activity and expression, (2) identify the alpha(1)-adrenoceptor subtypes, and (3) verify whether chronic norepinephrine (NE) treatment modified the types and/or pharmacological characteristics of adrenoceptors present in SK-Mel 23 human melanoma cells. Cells treated with the alpha(1)-adrenergic agonist, phenylephrine (PHE, 10(-5) or 10(-4) M), for 24-72 h, exhibited decreased cell proliferation and enhanced tyrosinase activity, but unaltered tyrosinase expression as compared with the control. The proliferation and tyrosinase activity responses were inhibited by the alpha(1)-adrenergic antagonist prazosin, suggesting they were evoked by alpha(1)-adrenoceptors. The presence of actinomycin D, a transcription inhibitor, did not diminish PHE-induced effects. RT-PCR assays, followed by cloning and sequencing, demonstrated the presence of alpha(1A)- and alpha(1B)-adrenoceptor subtypes. NE-treated cells (24 or 72 h) were used in competition assays, and showed no significant change in the competition curves of alpha(1)-adrenoceptors as compared with control curves. Other adrenoceptor subtypes were not identified in these cells, and NE pretreatment did not induce their expression. In conclusion, the activation of SK-Mel 23 human melanoma alpha(1)-adrenoceptors elicit biological effects, such as proliferation decrease and tyrosinase activity increase. Desensitization or expression of other adrenoceptor subtypes after chronic NE treatment were not observed.
Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, R. do Matão, trav. 14, 321, CEP 05508-900 São Paulo, Brazil.
Ana Cristina
AC
Scarparo
Dóris Hissako
DH
Sumida
Marília T C C
MT
Patrão
Maria Christina W
MC
Avellar
Maria Aparecida
MA
Visconti
Ana
A
Maria de Lauro Castrucci
D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000378:metabolism / Q000494:pharmacology*; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D015870:Gene Expression; D006801:Humans; D008545:Melanoma; D014442:Monophenol Monooxygenase / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D010656:Phenylephrine / Q000378:metabolism / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D012878:Skin Neoplasms
D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D014442:Monophenol Monooxygenase; D009638:Norepinephrine