High throughput kinase inhibitor screens reveal TRB3 and MAPK-ERK/TGFβ pathways as fundamental Notch regulators in breast cancer

Izrailit, Julia; Berman, Hal K.; Datti, Alessandro; Wrana, Jeffrey L.; Reedijk, Michael

doi:10.1073/pnas.1214014110

Cited by 111 publications

(101 citation statements)

References 49 publications

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“…33,37 In addition, previous observations by other laboratories indicate that TRIB3 can enhance proliferation and invasiveness of cancer cells in vitro, [31][32][33] and a recent study has shown that knockdown of TRIB3 produces a moderate increase in the growth of orthotopic xenografts generated with MDA-231 breast cancer cells. 38 A plausible explanation for the apparently contradictory results obtained here and in those studies could be the existence of differences in the genetic alterations, the degree of differentiation or other relevant phenotypic characteristics in the cell lines used in the various studies. In support of this idea, and as shown in the present study, silencing of TRIB3 produces heterogeneous effects on the tumorigenic properties of different cancer cell lines as it enhances the growth rate of tumors generated with U87MG cells (data not shown), accelerates the onset of HepG2 cell-derived tumors and hastens both processes in tumors generated with BT474 cells.…”

Section: Discussionmentioning

confidence: 54%

Loss of Tribbles pseudokinase-3 promotes Akt-driven tumorigenesis via FOXO inactivation

et al. 2014

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Tribbles pseudokinase-3 (TRIB3) has been proposed to act as an inhibitor of AKT although the precise molecular basis of this activity and whether the loss of TRIB3 contributes to cancer initiation and progression remain to be clarified. In this study, by using a wide array of in vitro and in vivo approaches, including a Trib3 knockout mouse, we demonstrate that TRIB3 has a tumorsuppressing role. We also find that the mechanism by which TRIB3 loss enhances tumorigenesis relies on the dysregulation of the phosphorylation of AKT by the mTORC2 complex, which leads to an enhanced phosphorylation of AKT on Ser473 and the subsequent hyperphosphorylation and inactivation of the transcription factor FOXO3. These observations support the notion that loss of TRIB3 is associated with a more aggressive phenotype in various types of tumors by enhancing the activity of the mTORC2/AKT/FOXO axis. Pseudokinases constitute a group of proteins that have a kinase-like domain that lacks at least one of the conserved catalytic residues. 1,2 Different studies have shown that some pseudokinases can exhibit low levels of kinase activity, while others have critical roles as activators of their specific targets. 1,2 Moreover, aberrant regulation of pseudokinases has been implicated in the etiology and progression of a variety of diseases, including cancer. 3 The Tribbles family of pseudokinases was first described in Drosophila as a negative regulator of cell division in early embryogenesis. [4][5][6][7] There are three mammalian Tribbles isoforms (Trib1, Trib2 and Trib3), homologs to the Drosophila tribbles proteins, and they all share a highly conserved central kinase-like domain, which lacks catalytic residues, and a 'tribbles specific' C-terminal domain, which has been proposed to participate in the binding to different Tribbles partners. 8 Tribbles pseudokinase-3 (TRIB3; also named TRB3, NIPK and SKIP3) has been proposed to interact with several proteins, including the transcription factors activating transcription factor 4 (ATF-4) and CHOP 9 as well as with several MAPKs. 10 TRIB3 has also been shown to interact and inhibit AKT, 11 which has been suggested to suppress insulin signaling. 11,12 In addition, administration of different anticancer agents promotes cancer cell death via TRIB3 upregulation and the subsequent inhibition of Akt. [13][14][15][16][17][18][19] However, the precise molecular basis of the regulation of Akt by TRIB3 and whether loss of this pseudokinase may contribute to cancer initiation and progression remains to be clarified.In this study, we investigated the effect of the genetic inactivation of TRIB3 in several cellular and animal models of cancer. Our findings indicate that genetic inhibition of TRIB3 enhances tumorigenesis and that this effect is due -at least primarily -to a selective inactivation of the transcription factor FOXO by the mammalian target of rapamycin complex 2 (mTORC2)/AKT axis. ResultsGenetic inhibition of TRIB3 facilitates oncogene transformation and enhances the tumorigenicity of cancer c...

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Section: Discussionmentioning

confidence: 54%

Loss of Tribbles pseudokinase-3 promotes Akt-driven tumorigenesis via FOXO inactivation

et al. 2014

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“…For example, TRB3 has been demonstrated to inhibit insulin-induced S6 kinase activation (31). Furthermore, it has been revealed that TRB3 binds to ATF4 and regulates its transcriptional activity (32). The expression of TRBs is regulated by inflammatory stimulation and is cell type specific (33).…”

Section: Discussionmentioning

confidence: 99%

“…TRB3 was also demonstrated to be a key factor in complementary kinome small interfering-RNA (siRNA) function, as a regulator of mitogen-activated protein kinase (MAPK) signaling (2). Previous studies have demonstrated that this occurs through the control of the MAPK-extracellular signal-related kinase (MAPK-ERK) and transforming growth factor β (TGFβ) pathways.…”

Section: Introductionmentioning

confidence: 99%

“…TRB3 is also upregulated in cancer as a response to hypoxia (4,6) and is associated with a poor outcome (7) as it promotes the activation of key cancer signaling pathways (such as MAPK-ERK, TGFβ and jagged 1 protein (JAG1)/Notch). TRB3 expression and molecular function has rarely been demonstrated in cancer cell lines, with the exception of breast cancer cell lines (2).…”

Section: Introductionmentioning

confidence: 99%

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Knockdown of TRB3 induces apoptosis in human lung adenocarcinoma cells through regulation of Notch 1 expression

Zhou

Luo

Chen

et al. 2013

Molecular Medicine Reports

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Abstract. The upregulation of tribbles homolog 3 (TRB3), a pseudokinase in mammals, has been observed in several types of malignant cancer, including thyroid, ovarian, liver and colorectal cancer. However, the pathological role and the regulatory mechanism of TRB3 in cancer remain unknown. In the current study, we demonstrated that the expression of TRB3 was upregulated in non-small cell lung cancer (NSCLC), correlating with tumor metastasis, disease recurrence and poor survival in patients. Knocking down TRB3 in aggressive lung cancer cell lines was demonstrated to significantly inhibit their malignant behaviors, including in vitro invasion and cell proliferation, as well as in vivo metastasis and tumor growth. The correlation between TRB3 and Notch 1 expression revealed that Notch 1 was downregulated by the knockdown of TRB3 in the lung adenocarcinoma cell lines. These results have provided insights into the correlation between TRB3 expression and lung cancer progression, and thus may have potential for the prognosis and therapy of lung cancer. IntroductionTribbles homolog 3 (TRB3), a pseudokinase, is essential for the catalytic activity that is performed by 10% of the kinase superfamily members (1). TRB3 was also demonstrated to be a key factor in complementary kinome small interfering-RNA (siRNA) function, as a regulator of mitogen-activated protein kinase (MAPK) signaling (2). Previous studies have demonstrated that this occurs through the control of the MAPK-extracellular signal-related kinase (MAPK-ERK) and transforming growth factor β (TGFβ) pathways.Furthermore, TRB3 regulates JAG1 expression and is required for the proliferation of breast cancer cells (3). In addition, TRB3 is required in normal tissues during conditions of hypoxic/endoplasmic reticulum stress or nutrient deprivation, as it is upregulated and counteracts the effects of stress (4,5). TRB3 is also upregulated in cancer as a response to hypoxia (4,6) and is associated with a poor outcome (7) as it promotes the activation of key cancer signaling pathways (such as MAPK-ERK, TGFβ and jagged 1 protein (JAG1)/Notch). TRB3 expression and molecular function has rarely been demonstrated in cancer cell lines, with the exception of breast cancer cell lines (2).The most understood function of the Notch family is cell fate regulation. This function has been regarded to be linked to the homeostasis of stem cell compartments (8-11) and thus, Notch signaling has been implicated in human cancer (10). Cell-autonomous oncogenic activation of Notch was identified in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL). Notch 1 may be activated through chromosomal translocations and/or mutations (10,12). Downregulated expression of Notch-related factors, including Notch receptors, ligands and targets, has also been observed in solid tumors (10,13), including breast (13) and lung (14) cancer. To the best of our knowledge, no studies with regard to the correlation between cell-autonomous activation of Notch and TRB3 expression in lung cancer have been publishe...

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“…Under conditions of endoplasmic reticulum (ER) stress, TRIB3 promotes apoptosis by negatively regulating the Akt signaling pathway (8,9). In contrast, TRIB3 expression is highly upregulated in some cancer cells and promotes cell proliferation by positively regulating the mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK) pathway (10). To date, the functional involvement of TRIB3 in virus-infected cells has never been demonstrated.…”

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confidence: 99%

Nonstructural 3 Protein of Hepatitis C Virus Modulates the Tribbles Homolog 3/Akt Signaling Pathway for Persistent Viral Infection

Tran

Pham

Nguyen

et al. 2016

J Virol

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Hepatitis C virus (HCV) infection often causes chronic hepatitis, liver cirrhosis, and ultimately hepatocellular carcinoma. However, the mechanisms underlying HCV-induced liver pathogenesis are still not fully understood. By transcriptome sequencing (RNA-Seq) analysis, we recently identified host genes that were significantly differentially expressed in cell culture-grown HCV (HCVcc)-infected cells. Of these, tribbles homolog 3 (TRIB3) was selected for further characterization. TRIB3 was initially identified as a binding partner of protein kinase B (also known as Akt). TRIB3 blocks the phosphorylation of Akt and induces apoptosis under endoplasmic reticulum (ER) stress conditions. HCV has been shown to enhance Akt phosphorylation for its own propagation. In the present study, we demonstrated that both mRNA and protein levels of TRIB3 were increased in the context of HCV replication. We further showed that promoter activity of TRIB3 was increased by HCV-induced ER stress. Silencing of TRIB3 resulted in increased RNA and protein levels of HCV, whereas overexpression of TRIB3 decreased HCV replication. By employing an HCV pseudoparticle entry assay, we further showed that TRIB3 was a negative host factor involved in HCV entry. Both in vitro binding and immunoprecipitation assays demonstrated that HCV NS3 specifically interacted with TRIB3. Consequently, the association of TRIB3 and Akt was disrupted by HCV NS3, and thus, TRIB3-Akt signaling was impaired in HCVinfected cells. Moreover, HCV modulated TRIB3 to promote extracellular signal-regulated kinase (ERK) phosphorylation, activator protein 1 (AP-1) activity, and cell migration. Collectively, these data indicate that HCV exploits the TRIB3-Akt signaling pathway to promote persistent viral infection and may contribute to HCV-mediated pathogenesis. IMPORTANCETRIB3 is a pseudokinase protein that acts as an adaptor in signaling pathways for important cellular processes. So far, the functional involvement of TRIB3 in virus-infected cells has not yet been demonstrated. We showed that both mRNA and protein expression levels of TRIB3 were increased in the context of HCV RNA replication. Gene silencing of TRIB3 increased HCV RNA and protein levels, and thus, overexpression of TRIB3 decreased HCV replication. TRIB3 is known to promote apoptosis by negatively regulating the Akt signaling pathway under ER stress conditions. Most importantly, we demonstrated that the TRIB3-Akt signaling pathway was disrupted by NS3 in HCV-infected cells. These data provide evidence that HCV modulates the TRIB3-Akt signaling pathway to establish persistent viral infection.

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High throughput kinase inhibitor screens reveal TRB3 and MAPK-ERK/TGFβ pathways as fundamental Notch regulators in breast cancer

Cited by 111 publications

References 49 publications

Loss of Tribbles pseudokinase-3 promotes Akt-driven tumorigenesis via FOXO inactivation

Loss of Tribbles pseudokinase-3 promotes Akt-driven tumorigenesis via FOXO inactivation

Knockdown of TRB3 induces apoptosis in human lung adenocarcinoma cells through regulation of Notch 1 expression

Nonstructural 3 Protein of Hepatitis C Virus Modulates the Tribbles Homolog 3/Akt Signaling Pathway for Persistent Viral Infection

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