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Down-regulation of TGF-beta receptors in human colorectal cancer: implications for cancer development
M Matsushita1, K Matsuzaki, M Date
1Third Department of Internal Medicine, Kansai Medical University, Moriguchi, Osaka, Japan.
Abstract:
Many colorectal cancer cells are resistant to the anti-proliferative effects of transforming growth factor-beta (TGF-beta). TGF-beta also acts as paracrine factor from cancer cells on their mesenchymal cells. The aim of this study was to examine the expression of TGF-beta and its receptors in human colorectal cancer tissue and determine any relationship with cancer growth. In situ hybridization and Northern blot hybridization detection of TGF-beta1, type I and type II receptor mRNA and immunohistochemical staining of TGF-beta1 were performed using 11 human colorectal adenomas, 22 colorectal cancers and ten normal colorectal mucosas as control. TGF-beta receptor mRNAs were expressed mainly by normal colorectal epithelial cells and adenoma. However, mRNAs for TGF-beta receptors were only faintly, if at all, expressed in eight of 22 human colorectal cancers. In addition, intense signals of TGF-beta1 mRNA and the protein were detected in all colorectal cancers. TGF-beta receptor mRNAs and TGF-beta1 protein were also distributed in fibroblasts and endothelial cells in the interstitium. Moreover, Smad 4 protein was translocated to nucleus in primarily cultured adenoma cells, but not in cancer cells after TGF-beta stimulation. The escape of human colon cancer from TGF-beta-mediated growth inhibition by down-regulation of TGF-beta receptors as well as the effects of TGF-beta on stroma formation and angiogenesis indicate a possible role for TGF-beta in the progression of colon cancer in an intact host.
Insights
Colorectal cancer cells evade growth inhibition by down-regulating transforming growth factor-beta (TGF-beta) receptors. This study reveals TGF-beta
Area of Science:
- Molecular Biology
- Oncology
- Gastroenterology
Background:
- Colorectal cancer (CRC) cells often exhibit resistance to the anti-proliferative signals of transforming growth factor-beta (TGF-beta).
- TGF-beta functions as a paracrine factor, influencing mesenchymal cells surrounding cancer cells.
Purpose of the Study:
- To investigate the expression patterns of TGF-beta and its receptors in human colorectal cancer tissues.
- To ascertain the correlation between TGF-beta signaling components and colorectal cancer progression.
Main Methods:
- Utilized in situ hybridization and Northern blot hybridization to detect TGF-beta1, type I, and type II receptor mRNA.
- Employed immunohistochemical staining for TGF-beta1 protein.
- Analyzed human colorectal adenomas, cancers, and normal mucosas.
Main Results:
- TGF-beta receptor mRNAs were predominantly expressed in normal colorectal epithelial cells and adenomas, but showed significantly reduced expression in most colorectal cancers.
- Intense signals for TGF-beta1 mRNA and protein were observed in all colorectal cancers, also present in stromal fibroblasts and endothelial cells.
- Smad 4 protein translocation to the nucleus upon TGF-beta stimulation occurred in adenoma cells but was absent in cancer cells.
Conclusions:
- Human colon cancers escape TGF-beta-mediated growth inhibition through the downregulation of its receptors.
- TGF-beta influences stroma formation and angiogenesis, suggesting a role in colorectal cancer progression within the host environment.