Increased expression of LGI1 gene triggers growth inhibition and apoptosis of neuroblastoma cells.
The LGI1 gene has been implicated in the malignant progression of glioblastoma and it has also been genetically linked to a form of partial epilepsy (ADLTE). In this study, we investigated the relevance of LGI1 expression for neuroblastoma cells. The analysis of two cell lines (SH-SY5Y and SK-N-BE) revealed unpredictably low levels of LGI1 and stable cell transfection with LGI1 cDNA yielded moderate increases of LGI1 expression. Neuroblastoma cell clones exhibited impaired cell growth and survival ability in relation to LGI1 levels. The process of growth inhibition could be discerned under experimental conditions of low cell density, since conditions of elevated cell density, which enhance the requirement for survival stimuli, resulted in massive cellular death. At high cell density, spontaneous apoptosis of LGI1 cells was clearly shown by the release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria and by phosphatydil serine exposure and nuclear fragmentation. Activation of apoptotic effectors caspase-3/7 also occurred, however, the broad caspase inhibitor Z-VAD-FMK substantially failed to block cell death. Thus the possibility that LGI1-triggered apoptosis may involve initiator caspases linked to activation of death receptors, appears unlikely. The decreased ratio of Bcl-2 to Bax suggests that apoptosis is initiated by the intrinsic mitochondrial pathway through the release of caspase-dependent and -independent apoptogenic molecules. This study provides the first evidence that LGI1 controls neuronal cell survival, suggesting its role in the development of the nervous system in relation to the pathogenesis of neuroblastoma and ADLTE.
Gabellini
Nadia
N
Department of Biological Chemistry, University of Padua, Padua, Italy. nadia.gabellini@unipd.it
Masola
V
V
Quartesan
S
S
Oselladore
B
B
Nobile
C
C
Michelucci
R
R
Curtarello
M
M
Parolin
C
C
Palù
G
G
D021581:Active Transport, Cell Nucleus; D017209:Apoptosis; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D010768:Phosphoserine / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000235:genetics
C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D003580:Cytochromes; D047908:Intracellular Signaling Peptides and Proteins; C116499:LGI1 protein, human; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D051028:bcl-2-Associated X Protein; D010768:Phosphoserine; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases