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Endogenous Oxidative Stress Induces Distinct Redox Forms of Tumor Necrosis Factor Receptor‐1 in Melanoma Cells
Author(s) -
DOMINICI S,
PIERI L,
PAOLICCHI A,
TATA V,
ZUNINO F,
POMPELLA A
Publication year - 2004
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1329.008
Subject(s) - extracellular , receptor , oxidative stress , chemistry , glutathione , biochemistry , clone (java method) , tumor necrosis factor alpha , reactive oxygen species , cell surface receptor , melanoma , microbiology and biotechnology , redox , stimulation , biology , enzyme , cancer research , immunology , endocrinology , dna , organic chemistry
A bstract : Receptors of the TNFR superfamily possess abundant thiols in their extracellular domains, which makes them susceptible to redox modulation by prooxidant agents and processes. Previous studies from our laboratory have documented that membrane γ‐glutamyltransferase (GGT) activity can originate reactive oxygen species in the extracellular milieu, during the GGT‐mediated metabolism of extracellular glutathione. The present study was aimed thus to verify a possible redox‐modulating effect of GGT activity on TNFR1 receptors. The thiol‐specific probe maleimide‐polyethylene glycol was used to selectively label the reduced thiol groups in proteins of cell lysates; fractions corresponding to TNFR1 were then identified by immunoblot. In human melanoma Me665/2 cells, expressing varying GGT levels, at least five distinct forms of TNFR1 have been thus identified. The more oxidized forms appear to be prevalent in the 2/60 clone, expressing higher GGT levels, as compared to clone 2/21. Stimulation of GGT activity in the latter induced an increase of the oxidized TNFR1 forms. It is conceivable that different redox states of TNFR1 may correspond to different binding affinity and/or changes in the transducing function of the receptor. As GGT is frequently expressed by malignant tumors, the described phenomena might concur to alter the sensitivity of cancer cells to agents targeted on activation of TNF‐α‐dependent signaling pathways.