Activation of Nuclear Factor-κB in Human Metastatic Melanoma Cells and the Effect of Oxidative Stress
The biological basis for the general pharmacological resistance of human melanoma is unknown. A unique biochemical feature of the melanocyte is the synthesis of melanin, which leads to the generation of hydrogen peroxide and the consumption of reduced glutathione. This activity produces a state of c...
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Published in | Clinical cancer research Vol. 5; no. 5; p. 1197 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
American Association for Cancer Research
01.05.1999
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Online Access | Get full text |
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Summary: | The biological basis for the general pharmacological resistance of human melanoma is unknown. A unique biochemical feature
of the melanocyte is the synthesis of melanin, which leads to the generation of hydrogen peroxide and the consumption of reduced
glutathione. This activity produces a state of chronic oxidative stress in these cells. We demonstrated previously that the
expression of the c- jun family was dysregulated in metastatic melanoma cells compared with normal human melanocytes (D. T. Yamanishi et al. , J. Invest. Dermatol., 97: 349â353, l991). In the current investigation, we measured the levels of two major redox response transcription factors, nuclear
factor-κB (NF-κB) and activator protein-1, in metastatic melanoma cells and normal melanocytes and their response to oxidative
stress. The basal DNA-binding activity of NF-κB as measured by the electrophoretic mobility shift assay in metastatic melanoma
cells was increased 4-fold compared with that of normal melanocytes. This level of binding was paralleled by a 1.5- to 4-fold
increase in the expression of p50 (NF-κB1), p65 (Rel-A), and IκB-α as measured by Northern blot analysis. In contrast, the
expression of p75 (c- rel ) was markedly decreased (60%) in melanoma cells compared with normal melanocytes. Following oxidative stress produced by
enzyme-generated H 2 O 2 , free H 2 O 2 , or incubation with buthionine sulfoximine, NF-κB binding activity increased 1.5- to 2.5-fold in melanoma cells (buthionine
sulfoximine > H 2 O 2 ), but only slightly in normal melanocytes. In contrast, activator protein-1 binding activity was unaffected or increased
in normal melanocytes in response to oxidative stress, but was either unaffected or decreased in melanoma cells. These results
suggest that the redox regulation of melanoma cells at the molecular level is fundamentally different from normal melanocytes
and may offer a unique avenue for preventive or therapeutic intervention as well as new insights into the pathogenesis of
melanocyte transformation. |
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ISSN: | 1078-0432 1557-3265 |