Characterization of seven human melanoma cell lines: Melanogenesis and secretion of plasminogen activators

Abstract

Summary Permanent cell lines (UCT-Mel 1 through 7) were established from biopsies of metastatic tissue taken from seven patients with malignant melanoma. Cells from these lines were all aneuploid and all grew as non-contact-inhibited, adherent monolayers. All of the lines, with the remarkable exception of UCT-Mel 6, formed tumours in nude mice, expressed the melanoma M-18 antigen and synthesized plasminogen activators exclusively of the tissue-type. UCT-Mel 6 cells were non tumourigenic, they lacked the M-18 antigen and they synthesized plasminogen activators exclusively of the urokinase type. UCT-Mel I and UCT-Mel 2 formed pigment in vitro and both of these lines showed an increase in pigment content and tyrosinase synthesis with increasing cell density. The rate of plasminogen activator released by UCT-Mel 1 and UCT-Mel 3 declined strikingly as the cells became confluent.Assuming (a) that proteolytic activity is required for cell migration in vivo; (b) that tyrosinase synthesis reflects expression of the differentiated phenotype and (c) that melanoma cells retain some of the characteristics of neural crest cells, we suggest that the effects of confluence and close cell-cell contact provide a useful experimental counterpart for the study of normal neural crest all behaviour that is characterized by an inverse relationship between migration and a protease secretion on the one hand and pigmentation on the other.Human melanoma cells cultured in vitro provide a useful system for examining processes that are relevant both to this particular class of tumours and, at the same time, to cellular biological phenomena of a more general nature.Melanogenesis, for example, is an obvious and readily quantifiable marker of cellular differentiation that can be used to study factors that govern expression of the differentiated phenotype in pigmenting cell lines. Furthermore, as derivatives of the embryonic neural crest, melanoma cells share a common origin with a variety of ectomesenchymal structures, cells of the autonomic nervous system, calcitonin-producing cells, cells of the carotid body and sensory neurones in spinal ganglia and cranial nerves. It is now clear that, in choosing one of these diverse alternative destinies, pluripotential neural crest 'stem-cells' are influenced by environmental cues that come from neighbouring embryonic structures (Le Douarin, 1982 serum (State Vaccine Laboratories, Cape Town), 300 g penicillin ml-1, 200, g streptomycin sulphate ml-1 and 10 yg tylocine ml-1. Cultures were maintained at 37°C in a humid atmosphere containing 5% CO2 in air.Culture media were changed twice weekly. Confluent adherent cultures were passaged by detachment with 0.25% trypsin and 0.02% EDTA in Tris-buffered saline (TBS: 0.137 M NaCl, 5 mM KCl, 0.7 mM Na Phosphate, 25 mM TrisHCl; pH7.4) and re-seeding at -2x 105 cells/ 35 mm dish.Cell lines were tested for mycoplasma contamination (Chen, 1977) and found to be negative.Growth curves were constructed by seeding cells at a low density (usually 105 cells/35mm dish) and fe...

Plasminogen activation in melanocytic neoplasia

“…A large body of experimental evidence supports the participation of the PA/plasmin system in the biology of melanomas. Melanoma cell lines have been shown to produce uPA and/or tPA (22)(23)(24)(25) as membrane bound (24,25) and/or as secreted enzymes (22,23). Additional studies have documented that both enzymes can catalyze degradation of ECM constituents (26,27), and correlations between uPA production and metastatic properties have been drawn for animal and human mela noma cell lines (28,29).…”

Accurate molecular detection of melanoma nodal metastases: an assessment of multimarker assay specificity, sensitivity, and detection rate

“…32 The cells were maintained in RPMI 1640 medium supplemented with 5% fetal calf serum, 50 IU/ml penicillin and 20 µg/ml streptomycin at 37°C under 5% CO 2 /95% air and 90% humidity. UCT-Mel-1 and UCT-Mel-2 were classified as pigmented and UCT-Mel-3 to UCT-Mel-8 as non-pigmented adherent cell lines, according to the visual presence of pigment.…”

Proteolytic mechanisms involved in the metastasis of human melanoma cells

“…A notable exception however, is melanoma, since the majority of melanoma cell lines produce only tPA and not uPA (36,37,38). A melanoma tPA receptor would be of interest as it could provide an alternative mechanism for plasminogen activation at the cell surface.…”

“…However, the case of human melanoma cells appears to be different since many highly metastatic melanoma cells produce only tPA and not uPA (36)(37)(38).…”