TGF beta signalling and its role in tumour pathogenesis.
Abstract
Transforming growth factor beta (TGF-beta) is a multifunctional cytokine involved in the regulation of cell proliferation, differentiation and survival/or apoptosis of many cells. Knock-out experiments in mice for the three isoforms of TGF-beta have demonstrated their importance in regulating inflammation and tissue repair. TGF-beta is implicated in the pathogenesis of human diseases, including tissue fibrosis and carcinogenesis. TGF-beta receptors act through multiple intracellular pathways. Upon binding of TGF-beta with its receptor, receptor-regulated Smad2/3 proteins become phosphorylated and associate with Smad4. Such complex translocates to the nucleus, binds to DNA and regulates transcription of specific genes. Negative regulation of TGF-beta/Smad signalling may occur through the inhibitory Smad6/7. Furthermore, TGF-beta-activated kinase-1 (TAK1) is a component of TGF-beta signalling and activates stress-activated kinases: p38 through MKK6 or MKK3 and c-Jun N-terminal kinases (JNKs) via MKK4. In the brain TGF-beta, normally expressed at the very low level, increases dramatically after injury. Increased mRNA levels of the three TGF-beta isoforms correlate with the degree of malignancy of human gliomas. TGF-betas are secreted as latent precursors requiring activation into the mature form. TGF-beta may contribute to tumour pathogenesis by direct support of tumour growth and influence on local microenvironment, resulting in immunosuppression, induction of angiogenesis, and modification of the extracellular matrix. TGF-beta1,2 may stimulate production of vascular endothelial growth factor (VEGF) as well as plasminogen activator inhibitor (PAI-I), that are involved in vascular remodelling occurring during angiogenesis. Blocking of TGF-beta action inhibits tumour viability, migration, metastases in mammary cancer, melanoma and prostate cancer model. Reduction of TGF-beta production and activity may be a promising target of therapeutic strategies to control tumour growth.Acta Biochimica Polonica is an OpenAccess quarterly and publishes four issues a year. All contents are distributed under the Creative Commons Attribution-ShareAlike 4.0 International (CC BY 4.0) license. Everybody may use the content following terms: Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
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