1. ¹Breast Cancer Program, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL, USA
2. ²Department of Pathology and Skin Cancer Program, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL, USA
3. ³Cancer Immunology Program, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL, USA
4. ⁴Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA
5. ⁵Department of Molecular Biology, Institute for Scientific and Technological Research of San Luis Potosí, San Luis Potosí, Mexico
6. ⁶Department of Pathology, Mexican Institute for Social Security, Mexico City, Mexico
7. ⁷Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
8. ⁸Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
9. ⁹Department of Veterinary and Animal Sciences, University of Massachusetts at Amherst, Amherst, MA, USA

Correspondence: Professor L Miele, Cardinal Bernardin Cancer Center, Loyola University Medical Center, 2160 South First Avenue, Bldg 112, Room 236, Maywood, IL 60153, USA. E-mail: lmiele@lumc.edu

¹⁰These authors contributed equally to this work and should be considered as co-first authors.

Received 1 February 2007; Revised 30 April 2008; Accepted 12 May 2008; Published online 16 June 2008.

Abstract

Notch-1 inhibits apoptosis in some transformed cells through incompletely understood mechanisms. Notch-1 can increase nuclear factor-kappa B (NF-B) activity through a variety of mechanisms. Overexpression of cleaved Notch-1 in T-cell acute lymphoblastic leukemia cells activates NF-B via interaction with the I kappa B kinase (IKK) signalosome. Concomitant activation of the Notch and NF-B pathways has been described in a large series of cervical cancer specimens. Here, we show that wild-type, spontaneously expressed Notch-1 stimulates NF-B activity in CaSki cervical cancer cells by associating with the IKK signalosome through IKK. A significant fraction of tumor necrosis factor (TNF)--stimulated IB kinase activity in CaSki cells is Notch-1-dependent. In addition, Notch-1 is found in the nucleus in association with IKK at IKK-stimulated promoters and is required for association of IKK with these promoters under basal and TNF--stimulated conditions. Notch-1–IKK complexes are found in normal human keratinocytes as well, suggesting that IKK regulation is a physiological function of Notch-1. Both Notch-1 and IKK knockdown sensitize CaSki cells to cisplatin-induced apoptosis to equivalent extents. Our data indicate that Notch-1 regulates NF-B in cervical cancer cells at least in part via cytoplasmic and nuclear IKK-mediated pathways.