title: Cell differentiation and cell-cycle alterations by tyrosine kinase inhibitors in human melanoma cells.
abstract: Differentiation therapy is an attractive option for malignant melanoma, as traditional forms of chemotherapy seem to have little effect on this type of tumour. Among the several pathways for the experimental induction of differentiation of melanoma, we have focused on signal transduction mediated by protein kinases. We have examined the effects of calphostin C (a protein kinase C inhibitor), genistein and methyl 2,5-dihydroxycinnamate (tyrosine kinase inhibitors), and exogenous phosphotyrosine (an activator of protein tyrosine phosphatases) on the growth, morphology and differentiation of malignant melanomas in vitro. All four compounds tested were able to inhibit cell proliferation, but only genistein and methyl 2,5-dihydroxycinnamate were able to induce morphological changes, yielding a more dendritic or a rounder phenotype, respectively. The latter two drugs were also able to induce specific cell-cycle alterations, in contrast to calphostin C and phosphotyrosine. Melanin content was increased greatly in phophotyrosine treated cells and, to a smaller extent, in cells treated with genistein. RNA expression of specific genes encoding cytolytic T-cell antigens was not altered by the two tyrosine kinase inhibitors, in spite of the phenotypic changes observed. Together, these results suggest that tyrosine kinases are involved in cell cycle, growth, and differentiation pathways in malignant melanomas; however, these pathways may not be co-dependent. The results also suggest that these pathways may be sensitive to specific tyrosine kinase inhibitors or activators of protein tyrosine phosphatases.
authors.affiliation: Centre Pluridisciplinaire d'Oncologie, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
authors.forename: R R
authors.initials: RR
authors.lastname: Hartmann
authors.forename: D
authors.initials: D
authors.lastname: Rimoldi
authors.forename: F J
authors.initials: FJ
authors.lastname: Lejeune
authors.forename: S
authors.initials: S
authors.lastname: Carrel
mesh_terms: D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002934:Cinnamates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005134:Eye Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D008545:Melanoma / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology*; D009281:Naphthalenes / Q000494:pharmacology; D019000:Phosphotyrosine / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D012878:Skin Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D002934:Cinnamates; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D019000:Phosphotyrosine; C067472:methyl 2,5-dihydroxycinnamate; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; C058819:calphostin C