Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10738383 | Free Radical Biology and Medicine | 2011 | 11 Pages |
Abstract
Melanoma cell lines and cells corresponding to premalignant melanocytes were established by our group after subjecting a nontumorigenic murine melanocyte lineage, melan-a, to sequential cycles of anchorage blockade. Previous results showed that in melan-a cells the superoxide level increases after such procedure. Superoxide production during melanocyte de-adhesion was inhibited by L-sepiapterin, the precursor of eNOS cofactor BH4, and increased by the inhibitor of BH4 synthesis, DAHP, hence indicating a partial uncoupling state of eNOS. The eNOS uncoupling seems to be maintained in cells derived from melan-a, because they present decreased nitric oxide and increased superoxide levels. The inhibition of superoxide production in Tm5 melanoma cells with L-sepiapterin reinforces their eNOS-uncoupled state. The maintenance of oxidative stress seems to be important in melanoma apoptosis resistance because Mn(III)TBAP, a superoxide scavenger, or L-sepiapterin renders Tm5 cells more sensitive to anoikis and chemotherapy. More importantly, eNOS uncoupling seems to play a pivotal role in melanocyte malignant transformation induced by sustained anchorage impediment, because no malignant transformation was observed when L-NAME-treated melanocytes were subjected to sequential cycles of de-adhesion. Our results show that uncoupled eNOS contributes to superoxide production during melanocyte anchorage impediment, contributing to anoikis resistance and malignant transformation.
Keywords
phorbol 12-myristate 13-acetateDAHPDAF-2DAGTP cyclohydrolase ItetrahydrobiopterinDnmtBH4flavin adenine dinucleotideFMNBH2MnSODNOS2,4-diamino-6-hydroxypyrimidineDNA methyltransferasel-NAMEl-NG-Nitroarginine methyl esterPMAPTIOROSAnoikissuperoxide anioneNOS uncouplingFADMalignant transformationdihydrobiopterindihydroethidiumFree radicalsmanganese superoxide dismutaseVascular endothelial growth factorVascular Endothelial Growth Factor (VEGF)flavin mononucleotidemelanocytesnitric oxide synthaseDHEReactive oxygen species
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Authors
Fabiana H.M. Melo, Fernanda Molognoni, Alice S. Morais, Mariana Toricelli, Margareth G. Mouro, Elisa M.S. Higa, José D. Lopes, Miriam G. Jasiulionis,