| | 1 | Author
| H. B. Leising, D. 0. Sdiadhtsdiabel | Requires cookie* | | | Title
| Stimulation of Tyrosinase Activity and Melanin Formation of Cultured Melanoma Cells by Serum Deprivation Alone or in Combination with Dibutyryl Cyclic AMP and Theophylline  | | | | Abstract
| Serum removal from the media of serial monolayer cultures of the Harding-Passey melanoma during an incubation period of 3 days resulted in an exponentially declining DNA synthesis rate (measured by the incorporation of [14C] thymidine) and in an inhibition of cell proliferation. Pro tein synthesis, as measured by the incorporation of radioactive leucine, was less affected than DNA synthesis. Incubation in serum-free culture medium resulted in significant rises of tyrosinase ac tivity and cellular melanin content. Addition of dibutyryl adenosine 3':5' monophosphate (Bu2cAMP, 5 X 1 0 -4 m) and theophylline (5 X 1 0 ~ 4 m) to serum-free cultures caused a further striking increase of tyrosinase activity and melanin formation, while treatment of serum containing cultures with Bu2eAMP and theophylline showed only a slight rise in melanogenesis. It is sug gested that these stimulatory effects are mediated by an increased intracellular cAMP level, since a correlation between the degree of melanogenesis and cellular cAMP content was indicated. Treat ment of serum-free or serum-containing cultures with the phosphodiesterase inhibitor theophylline (5 X 1 0 -4 — 1 X 1 0 -3 m) alone revealed only a slight enhancement (about 20%) of melanogenesis. Because augmentation of melanogenesis by serum-free medium alone or together with Bu,cAMP and theophylline was prevented by cycloheximide (or actinomycin D), de novo protein synthesis seems to be required for these stimulatory effects. | | | |
Reference
| (Z. Naturforsch. 32c, 567 [1977]; received February 24 1977) | | | |
Published
| 1977 | | | |
Keywords
| Melanoma, Cell Culture, Serum Removal, Tyrosinase, Melanin | | | |
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| default:Reihe_C/32/ZNC-1977-32c-0567.pdf | | | | Identifier
| ZNC-1977-32c-0567 | | | | Volume
| 32 | |
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