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Molecular and functional consequences of Smad4 C-terminal missense mutations in colorectal tumour cells

(2004) BIOCHEMICAL JOURNAL. 379(1). p.209-216
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Abstract
Smad4 is an essential signal transducer of the transforming growth factor beta (TGF-beta) signalling pathway and has been identified as a tumour suppressor, being mutated in approx. 50% of pancreatic cancers and approx. 15% of colorectal cancers. Two missense mutations in the C-terminal domain of Smad4, D351H (Asp351-->His) and D537Y (Asp537-->Tyr), have been described recently in the human colorectal cancer cell lines CACO-2 and SW948 respectively [Woodford-Richens, Rowan, Gorman, Halford, Bicknell, Wasan, Roylance, Bodmer and Tomlinson (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 9719-9723]. Previous work in vitro suggested that only Asp-351 was required for interaction with Smad2 [Wu, Fairman, Penry and Shi (2001) J. Biol. Chem. 276, 20688-20694]. In the present study, we investigate the functional consequences of these point mutations in vivo. We demonstrate that neither of these colorectal cancer cells undergo growth arrest in response to TGF-beta, which can be explained, at least in part, by their inability to up-regulate cyclin-dependent kinase inhibitors p21 (CIP1 ) or p15 ( INK4b) after TGF-beta stimulation. Although the point-mutated Smad4s are expressed at normal levels in these colorectal cancer cells, they cannot interact with either TGF-beta-induced phosphorylated Smad2 or Smad3. As a result, these Smad4 mutants do not accumulate in the nucleus after TGF-beta stimulation, are not recruited to DNA by relevant Smad-binding transcription factors and cannot generate transcriptionally active DNA-bound complexes. Therefore both these colorectal tumour cells completely lack functional Smad4 activity owing to the missense mutations. Given the location of these mutations in the three-dimensional structure of the Smad4 C-terminal domain, the results also give us significant insights into Smad complex formation.
Keywords
Smad complex, colorectal cancer, Smad4, TGF-beta (transforming growth factor) signalling, turriour suppressor, tumorigenesis, GROWTH-FACTOR-BETA, TGF-BETA, INTERACTION MOTIF, CYCLE ARREST, GENE, SUPPRESSOR, COMPLEXES, PROMOTER, CANCER, ELEMENTS

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Citation

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Chicago
De Bosscher, Karolien, Caroline S Hill, and Francisco J Nicolás. 2004. “Molecular and Functional Consequences of Smad4 C-terminal Missense Mutations in Colorectal Tumour Cells.” Biochemical Journal 379 (1): 209–216.
APA
De Bosscher, K., Hill, C. S., & Nicolás, F. J. (2004). Molecular and functional consequences of Smad4 C-terminal missense mutations in colorectal tumour cells. BIOCHEMICAL JOURNAL, 379(1), 209–216.
Vancouver
1.
De Bosscher K, Hill CS, Nicolás FJ. Molecular and functional consequences of Smad4 C-terminal missense mutations in colorectal tumour cells. BIOCHEMICAL JOURNAL. 2004;379(1):209–16.
MLA
De Bosscher, Karolien, Caroline S Hill, and Francisco J Nicolás. “Molecular and Functional Consequences of Smad4 C-terminal Missense Mutations in Colorectal Tumour Cells.” BIOCHEMICAL JOURNAL 379.1 (2004): 209–216. Print.
@article{2955618,
  abstract     = {Smad4 is an essential signal transducer of the transforming growth factor beta (TGF-beta) signalling pathway and has been identified as a tumour suppressor, being mutated in approx. 50% of pancreatic cancers and approx. 15% of colorectal cancers. Two missense mutations in the C-terminal domain of Smad4, D351H (Asp351-->His) and D537Y (Asp537-->Tyr), have been described recently in the human colorectal cancer cell lines CACO-2 and SW948 respectively [Woodford-Richens, Rowan, Gorman, Halford, Bicknell, Wasan, Roylance, Bodmer and Tomlinson (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 9719-9723]. Previous work in vitro suggested that only Asp-351 was required for interaction with Smad2 [Wu, Fairman, Penry and Shi (2001) J. Biol. Chem. 276, 20688-20694]. In the present study, we investigate the functional consequences of these point mutations in vivo. We demonstrate that neither of these colorectal cancer cells undergo growth arrest in response to TGF-beta, which can be explained, at least in part, by their inability to up-regulate cyclin-dependent kinase inhibitors p21 (CIP1 ) or p15 ( INK4b) after TGF-beta stimulation. Although the point-mutated Smad4s are expressed at normal levels in these colorectal cancer cells, they cannot interact with either TGF-beta-induced phosphorylated Smad2 or Smad3. As a result, these Smad4 mutants do not accumulate in the nucleus after TGF-beta stimulation, are not recruited to DNA by relevant Smad-binding transcription factors and cannot generate transcriptionally active DNA-bound complexes. Therefore both these colorectal tumour cells completely lack functional Smad4 activity owing to the missense mutations. Given the location of these mutations in the three-dimensional structure of the Smad4 C-terminal domain, the results also give us significant insights into Smad complex formation.},
  author       = {De Bosscher, Karolien and Hill, Caroline S and Nicolás, Francisco J},
  issn         = {0264-6021},
  journal      = {BIOCHEMICAL JOURNAL},
  keywords     = {Smad complex,colorectal cancer,Smad4,TGF-beta (transforming growth factor) signalling,turriour suppressor,tumorigenesis,GROWTH-FACTOR-BETA,TGF-BETA,INTERACTION MOTIF,CYCLE ARREST,GENE,SUPPRESSOR,COMPLEXES,PROMOTER,CANCER,ELEMENTS},
  language     = {eng},
  number       = {1},
  pages        = {209--216},
  title        = {Molecular and functional consequences of Smad4 C-terminal missense mutations in colorectal tumour cells},
  url          = {http://dx.doi.org/10.1042/BJ20031886},
  volume       = {379},
  year         = {2004},
}

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