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1977 (1)
1Author    H. B. Leising, D. 0. SdiadhtsdiabelRequires 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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 TEI-XML for    default:Reihe_C/32/ZNC-1977-32c-0567.pdf 
 Identifier    ZNC-1977-32c-0567 
 Volume    32