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- Aripaka, Karthik, et al.
(författare)
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TRAF6 function as a novel co-regulator of Wnt3a target genes in prostate cancer
- 2019
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Ingår i: EBioMedicine. - : Elsevier. - 2352-3964. ; 45, s. 192-207
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tumour necrosis factor receptor associated factor 6 (TRAF6) promotes inflammation in response to various cytokines. Aberrant Wnt3a signals promotes cancer progression through accumulation of β-Catenin. Here we investigated a potential role for TRAF6 in Wnt signaling.Methods: TRAF6 expression was silenced by siRNA in human prostate cancer (PC3U) and human colorectal SW480 cells and by CRISPR/Cas9 in zebrafish. Several biochemical methods and analyses of mutant phenotype in zebrafish were used to analyse the function of TRAF6 in Wnt signaling.Findings: Wnt3a-treatment promoted binding of TRAF6 to the Wnt co-receptors LRP5/LRP6 in PC3U and LNCaP cells in vitro. TRAF6 positively regulated mRNA expression of β-Catenin and subsequent activation of Wnt target genes in PC3U cells. Wnt3a-induced invasion of PC3U and SW480 cells were significantly reduced when TRAF6 was silenced by siRNA. Database analysis revealed a correlation between TRAF6 mRNA and Wnt target genes in patients with prostate cancer, and high expression of LRP5, TRAF6 and c-Myc correlated with poor prognosis. By using CRISPR/Cas9 to silence TRAF6 in zebrafish, we confirm TRAF6 as a key molecule in Wnt3a signaling for expression of Wnt target genes.Interpretation: We identify TRAF6 as an important component in Wnt3a signaling to promote activation of Wnt target genes, a finding important for understanding mechanisms driving prostate cancer progression.
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| 3. |
- Gudey, Shyam Kumar, 1982-, et al.
(författare)
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Regulated intramembrane proteolysis of the TGF beta type I receptor conveys oncogenic signals
- 2014
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Ingår i: Future Oncology. - London, UK : Future Medicine Ltd. - 1479-6694 .- 1744-8301. ; 10:11, s. 1853-1861
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Tidskriftsartikel (refereegranskat)abstract
- Cancer cells produce high levels of TGF beta, a multipotent cytokine. Binding of TGF beta to its cell surface receptors, the transmembrane serine/threonine kinases T beta RII and T beta RI, causes phosphorylation and activation of intracellular latent Smad transcription factors. Nuclear Smads act in concert with specific transcription factors to reprogram epithelial cells to become invasive mesenchymal cells. TGF beta also propagates non-canonical signals, so it is crucial to have a better understanding of the underlying molecular mechanisms which favor this pathway. Here we highlight our recent discovery that TGF beta promotes the proteolytic cleavage of T beta RI in cancer cells, resulting in the liberation and nuclear translocation of its intracellular domain, acting as co-regulator to transcribe pro-invasive genes. This newly identified oncogenic TGF beta pathway resembles the Notch signaling pathway. We discuss our findings in relation to Notch and provide a short overview of other growth factors that transduce signals via nuclear translocation of their cell surface receptors.
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| 4. |
- Gudey, Shyam Kumar, 1982-
(författare)
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TRAF6 stimulates TGFβ-induced oncogenic signal transduction in cancer cells
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prostate cancer is one of the leading causes of cancer-related deaths in men worldwide, with 10,000 new cases/year diagnosed in Sweden. In this context, there is an urgent need to identify new biomarkers to detect prostate cancer at an initial stage for earlier treatment intervention. Although how prostate cancer develops has not been fully established, the male sex hormone testosterone is a known prerequisite for prostate cancer development. High levels of transforming growth factor-β (TGFβ) are prognostically unfavorable in prostate cancer patients.TGFβ is a multifunctional cytokine that regulates a broad range of cellular responses. TGFβ signals through either the canonical Smad or the non-Smad signaling cascade. Cancerous cells develop different strategies to evade defense mechanisms and metastasize to different parts of the body. This thesis unveils one such novel mechanism related to TGFβ signaling.The first two articles provide evidence that TGFβ receptor type I (TβRI) is ubiquitinated by tumor necrosis factor receptor-associated factor 6 (TRAF6) and is cleaved at the ectodomain region by tumor necrosis factor alpha converting enzyme (TACE) in a protein kinase C zeta type-dependent manner. After TβRI is shed from the ectodomain, it undergoes a second cleavage by presenilin 1 (PS1), a γ-secretase catalytic subunit, which liberates the TβRI intracellular domain (TβRI-ICD) from the cell membrane. TRAF6 promotes TGFβ-dependent Lys63-linked polyubiquitination and recruitment of PS1 to the TβRI complex, and facilitates the cleavage of TβRI by PS1 to generate a TβRI-ICD. The TβRI-ICD then translocates to the nucleus, where it binds with the transcriptional co-activator p300 and regulates the transcription of pro-invasive target genes such as Snail1. Moreover, the nuclear translocated TβRI-ICD cooperates with the Notch intracellular domain (NICD), a core component in the Notch signaling pathway, to drive the expression of invasive genes. Interestingly, treatment with g-secretase inhibitors was able to inhibit cleavage of TβRI and inhibit the TGFβ-induced oncogenic pathway in an in vivo prostate cancer xenograft model.In the third article, we identified that Lysine 178 is the acceptor lysine in TβRI that is ubiquitinated by TRAF6. The TβRI K178R mutant was neither ubiquitinated nor translocated to the nucleus, and prevented transcriptional regulation of invasive genes in a dominant negative manner.In the fourth article, we show that TGFβ utilizes the E3-ligase TRAF6 and the p38 mitogen-activated protein kinase to phosphorylate c-Jun. In turn, the phosphorylated c-Jun activates p21 and Snail1 in a non-canonical Smad-independent pathway, and thereby promotes invasion in cancerous cells.In summary, we elucidate a new mechanism of TGFβ-induced oncogenic signal transduction in cancer cells in which TRAF6 plays a fundamental role. This opens a new avenue in the field of TGFβ signaling.
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| 5. |
- Mu, Yabing, et al.
(författare)
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TRAF6 ubiquitinates TGFβ type I receptor to promote its cleavage and nuclear translocation in cancer
- 2011
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Ingår i: Nature Communications. - London : Macmillan Publishers Limited. - 2041-1723. ; 2:330
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor β (TGFβ) is a pluripotent cytokine promoting epithelial cell plasticity during morphogenesis and tumour progression. TGFβ binding to type II and type I serine/threonine kinase receptors (TβRII and TβRI) causes activation of different intracellular signaling pathways. TβRI is associated with the ubiquitin ligase tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6). Here we show that TGFβ, via TRAF6, causes Lys63-linked polyubiquitination of TβRI, promoting cleavage of TβRI by TNF-alpha converting enzyme (TACE), in a PKCζ-dependent manner. The liberated intracellular domain (ICD) of TβRI associates with the transcriptional regulator p300 to activate genes involved in tumour cell invasiveness, such as Snail and MMP2. Moreover, TGFβ-induced invasion of cancer cells is TACE- and PKCζ- dependent and the TβRI ICD is localized in the nuclei of different kinds of tumour cells in tissue sections. Thus, our data reveal a specific role for TβRI in TGFβ mediated tumour invasion.
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