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Ferritin light chain down‐modulation generates depigmentation in human metastatic melanoma cells by influencing tyrosinase maturation
Author(s) -
Maresca Vittoria,
Flori Enrica,
Cardinali Giorgia,
Briganti Stefania,
Lombardi Daniela,
Mileo Anna Maria,
Paggi Marco G.,
Picardo Mauro
Publication year - 2006
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.20543
Subject(s) - tyrosinase , ferritin , melanoma , western blot , microbiology and biotechnology , melanin , cell culture , transfection , gene expression , biology , chemistry , cancer research , gene , biochemistry , enzyme , genetics
Recently, after the identification of ferritin light chain ( L‐ferritin ) gene and protein over‐expression in human metastatic melanoma cells, we engineered, starting from the LM metastatic melanoma cell line, clones in which L‐ferritin gene expression was down‐regulated by the stable expression of a specific antisense construct. The present investigation started from the observation that L‐ferritin down‐regulated LM cells displayed a less pigmented phenotype, confirmed by a major decrease of total melanin, when compared to control LM cells. This finding was accompanied by a dramatic decrease in tyrosinase activity, which was not paralleled by a concomitant reduction of the amount of tyrosinase specific mRNA. Western blot analysis of tyrosinase in control LM cells displayed a pattern, which corresponds to the progressive glycosylation of the native protein up to the 80 kDa form, considered the functional one. Tyrosinase pattern assayed in L‐ferritin down‐regulated LM cells showed the remarkable absence of the 80 kDa form and a prevalence of endoglycosidase H (endo H)‐sensitive immature (70 kDa) tyrosinase, accumulated in the endoplasmic reticulum (ER), as confirmed by confocal microscopy analysis. These results demonstrate that, in a human metastatic melanoma cell line, the stress condition promoted by L‐ferritin down‐modulation, can substantially influence proper maturation of tyrosinase. J. Cell. Physiol. © 2005 Wiley‐Liss, Inc.