Notch-1 associates with IKKalpha and regulates IKK activity in cervical cancer cells.
Notch-1 inhibits apoptosis in some transformed cells through incompletely understood mechanisms. Notch-1 can increase nuclear factor-kappa B (NF-kappaB) activity through a variety of mechanisms. Overexpression of cleaved Notch-1 in T-cell acute lymphoblastic leukemia cells activates NF-kappaB via interaction with the I kappa B kinase (IKK) signalosome. Concomitant activation of the Notch and NF-kappaB pathways has been described in a large series of cervical cancer specimens. Here, we show that wild-type, spontaneously expressed Notch-1 stimulates NF-kappaB activity in CaSki cervical cancer cells by associating with the IKK signalosome through IKKalpha. A significant fraction of tumor necrosis factor (TNF)-alpha-stimulated IkappaB kinase activity in CaSki cells is Notch-1-dependent. In addition, Notch-1 is found in the nucleus in association with IKKalpha at IKKalpha-stimulated promoters and is required for association of IKKalpha with these promoters under basal and TNF-alpha-stimulated conditions. Notch-1-IKKalpha complexes are found in normal human keratinocytes as well, suggesting that IKK regulation is a physiological function of Notch-1. Both Notch-1 and IKKalpha knockdown sensitize CaSki cells to cisplatin-induced apoptosis to equivalent extents. Our data indicate that Notch-1 regulates NF-kappaB in cervical cancer cells at least in part via cytoplasmic and nuclear IKK-mediated pathways.
Breast Cancer Program, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL 60153, USA.
L L
LL
Song
Y
Y
Peng
J
J
Yun
P
P
Rizzo
V
V
Chaturvedi
S
S
Weijzen
W M
WM
Kast
P J B
PJ
Stone
L
L
Santos
A
A
Loredo
U
U
Lendahl
G
G
Sonenshein
B
B
Osborne
J-Z
JZ
Qin
A
A
Pannuti
B J
BJ
Nickoloff
L
L
Miele
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D005260:Female; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D051883:Receptor, Notch2 / Q000378:metabolism; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000378:metabolism*
D000970:Antineoplastic Agents; D002843:Chromatin; D016328:NF-kappa B; C497761:NOTCH1 protein, human; C106075:NOTCH4 protein, human; D011518:Proto-Oncogene Proteins; D051881:Receptor, Notch1; D051883:Receptor, Notch2; D000074562:Receptor, Notch4; D051880:Receptors, Notch; C496559:CHUK protein, human; D051550:I-kappa B Kinase; D002945:Cisplatin