Oxidative stress modulates DNA methylation during melanocyte anchorage blockade associated with malignant transformation.
Both oxidative/nitrosative stress and alterations in DNA methylation are observed during carcinogenesis of different tumor types, but no clear correlation between these events has been demonstrated until now. Melanoma cell lines were previously established after submitting the nontumorigenicmelanocyte lineage, melan-a, to cycles of anchorage blockade. In this work, increased intracellular oxidative species and nitric oxide levels, as well as alterations in the DNA methylation, were observed after melan-a detachment, which were also associated with a decrease in intracellular homocysteine (Hcy), an element in the methionine (universal methyl donor) cycle. This alteration was accompanied by increase in glutathione (GSH) levels and methylated DNA content. Furthermore, a significant increase in dnmt1 and 3b expression was identified along melan-a anchorage blockade. L(G)-Nitro-L-arginine methyl esther (L-NAME), known as a nitric oxide synthase (NOS) inhibitor, and N-acetyl-L-cysteine (NAC) prevented the increase in global DNA methylation, as well as the increase in dnmt1 and 3b expression, observed during melan-a detachment. Interestingly, both L-NAME and NAC did not inhibit nitric oxide (NO) production in these cells, but abrogated superoxide anion production during anchorage blockade. In conclusion, oxidative stress observed during melanocyte anchorage blockade seems to modulate DNA methylation levels and may directly contribute to the acquisition of an anoikis-resistant phenotype through an epigenetic mechanism.
Campos
Ana C E
AC
Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo - UNIFESP, São Paulo, SP, Brazil.
Molognoni
Fernanda
F
Melo
Fabiana H M
FH
Galdieri
Luciano C
LC
Carneiro
Célia R W
CR
D'Almeida
Vânia
V
Correa
Mariangela
M
Jasiulionis
Miriam G
MG
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D023102:Anoikis / Q000235:genetics; D002448:Cell Adhesion / Q000187:drug effects; D018929:Cell Culture Techniques / Q000379:methods; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism; D006710:Homocysteine / Q000378:metabolism; D015227:Lipid Peroxidation; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D012685:Sepharose / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
D006710:Homocysteine; D013481:Superoxides; D009569:Nitric Oxide; D012685:Sepharose; D014357:Trypsin; D005978:Glutathione; D003545:Cysteine; D019331:NG-Nitroarginine Methyl Ester; D000111:Acetylcysteine