NF-kappaB activation is associated with homocysteine-induced injury in Neuro2a cells.
BACKGROUND
Perinatal exposure to hyperhomocysteinemia might disturb neurogenesis during brain development and growth. Also, high levels of homocysteine trigger neurodegeneration in several experimental models. However, the putative mechanisms of homocysteine-induced toxicity in the developing nervous system have poorly been elucidated. This study was aimed to investigate homocysteine effects in undifferentiated neuroblastoma cells, Neuro2a.


RESULTS
A 4 h exposure to homocysteine in a concentration range of 10-100 microM did not affect cell viability and ROS production in Neuro2a cell cultures. Instead, ROS levels were increased by two-three folds in cells treated with 250 microM and 500 microM homocysteine, respectively, in comparison with control cells. Also, the highest homocysteine dose significantly reduced the viable cell number by 40%. Notably, the treatment with homocysteine (250 microM-500 microM) in the presence of antioxidants, such as N-acetylcysteine and IRFI 016, a synthetic alpha-tocopherol analogue, recovered cell viability and significantly reduced homocysteine-evoked increases in ROS production. Moreover, antioxidants, particularly IRFI 016, were able to counteract NF-kappaB activation induced by 250 microM homocysteine. Cell treatment with 250 microM homocysteine also triggered the onset of apoptosis, as demonstrated by the increased expression of early apoptotic markers such as Bax, caspase-3 and p53. In contrast, Bcl2 expression was not affected by homocysteine exposure. Interestingly, the specific inhibition of NF-kappaB nuclear translocation by the synthetic peptide SN50 was able to almost completely suppress the homocysteine-evoked rises in pro-apoptotic protein expression as well as in caspase-3 activity. Further, also IRFI 016 and N-acetylcysteine were able to significantly reduce caspase-3 activation induced by homocysteine treatment.


CONCLUSIONS
These observations suggest an involvement of redox state alterations and activated NF-kappaB in apoptosis onset triggered by homocysteine in neuroblastoma cells Neuro2a. However, further investigations are needed to characterize molecular events involved in the NF-kappaB activation induced by homocysteine.
Ferlazzo
Nadia
N
Department of Biochemical, Physiological and Nutritional Sciences, University of Messina - Messina, Italy. nadiaferlazzo@email.it
Condello
Salvatore
S
Currò
Monica
M
Parisi
Giulia
G
Ientile
Riccardo
R
Caccamo
Daniela
D
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001572:Benzofurans / Q000494:pharmacology; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D016166:Free Radical Scavengers / Q000494:pharmacology; D006710:Homocysteine / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism / Q000473:pathology; D010455:Peptides / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000032:analysis / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014810:Vitamin E / Q000031:analogs & derivatives / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D001572:Benzofurans; D016166:Free Radical Scavengers; D016328:NF-kappa B; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; C118258:SN50 peptide; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D006710:Homocysteine; D014810:Vitamin E; D053148:Caspase 3; D024502:alpha-Tocopherol; C071049:Raxofelast; D000111:Acetylcysteine