Notch4 intracellular domain binding to Smad3 and inhibition of the TGF-beta signaling.
We present evidence that Notch4ICD attenuates TGF-beta signaling. Cells expressing the activated form of the Notch4 receptor (ICD4) were resistant to the growth-inhibitory effects of TGF-beta. Notch4ICD was found to bind to Smad2, Smad3 and Smad4 but with higher affinity to Smad3. Deletion analysis showed that binding of Smad3 to ICD4 was mediated by its MH2 domain and was not dependent on the presence of the RAM23 region in ICD4. Using two TGF-beta/Activin reporter luciferase assays, RT-PCR and Western blot analysis, we demonstrate that ICD4 and ICD4 deltaRAM23 inhibit Smad-binding element and 3TP luciferase reporter activity and PAI-1 gene expression. MCF-7 human breast cancer cells express Notch4ICD (ICD4) and are resistant to the growth-inhibitory effects of TGF-beta. Blockage of Notch4 processing to ICD4 by gamma-secretase inhibitor renders MCF-7 cells sensitive to growth inhibition by TGF-beta. The interplay between these two signaling pathways may be a significant determinant during mammary tumorigenesis.
Sun
Youping
Y
The Tumor Growth Factor Section, Mammary Biology and Tumorigenesis Laboratory, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA.
Lowther
William
W
Kato
Katsuaki
K
Bianco
Caterina
C
Kenney
Nicholas
N
Strizzi
Luigi
L
Raafat
Dina
D
Hirota
Morihisa
M
Khan
Nadia I
NI
Bargo
Sharon
S
Jones
Brenda
B
Salomon
David
D
Callahan
Robert
R
D020816:Amino Acid Motifs; D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000473:pathology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D051379:Mice; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000502:physiology*; D051880:Receptors, Notch; D015398:Signal Transduction / Q000502:physiology; D051900:Smad3 Protein; D015534:Trans-Activators / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C106075:NOTCH4 protein, human; D011518:Proto-Oncogene Proteins; D000074562:Receptor, Notch4; D011956:Receptors, Cell Surface; D051880:Receptors, Notch; C497790:SMAD3 protein, human; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C073572:Notch4 protein, mouse