Molecular mechanisms governing melanogenesis in hamster melanomas: relative abundance of tyrosinase and catalase-B (gp 75)

Anticancer Res. 1991 Jan-Feb;11(1):257-62.


Variants of the Bomirski family of hamster melanomas whose proliferative rates differ inversely with the genetically determined degree of melanogenesis were probed for two proteins critical in melanogenesis: tyrosinase and catalase-B (gp 75). The parental black tumor Ma contained both proteins in abundance. The amelanotic variant Ab, inducible in culture with L-tyrosine or L-dopa to form melanosomes and to melanize, had minimal tyrosinase, despite high levels of (tyr)mRNA, and no gp 75. Variant MI, hypomelanotic despite abundant tyrosinase, and synthesizing predominantingly pheo-(red) melanin, expressed barely detectable gp 75. These findings suggest a regulatory control of melanogenesis distal to (tyr)mRNA and strengthen the hypothesis that in vivo tyrosinase without catalase-B favors pheo- over eumelanogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catalase / isolation & purification
  • Catalase / metabolism*
  • Cricetinae
  • Electrophoresis, Polyacrylamide Gel
  • Immunoblotting
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism*
  • Melanins / biosynthesis*
  • Melanoma, Experimental / enzymology
  • Melanoma, Experimental / pathology*
  • Mesocricetus
  • Molecular Weight
  • Monophenol Monooxygenase / genetics
  • Monophenol Monooxygenase / isolation & purification
  • Monophenol Monooxygenase / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / isolation & purification
  • Tyrosine 3-Monooxygenase / metabolism


  • Isoenzymes
  • Melanins
  • RNA, Messenger
  • Catalase
  • Tyrosine 3-Monooxygenase
  • Monophenol Monooxygenase