Disruption of the Pdcd4 tumor suppressor gene in chicken DT40 cells reveals its role in the DNA-damage response

Singh, Priyanka; Marikkannu, Rajeshwari; Bitomsky, Nadja; Klempnauer, Karl‐Heinz

doi:10.1038/onc.2009.239

Cited by 23 publications

(18 citation statements)

References 32 publications

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“…To assess the effect of Pdcd4 on c-Myb expression under more physiological conditions we made use of a Pdcd4-deficient clone of the chicken DT40 cell line that we had established previously (Singh et al, 2009). Consistent with the results of Figure 1, the steady-state level of c-Myb was increased in the Pdcd4 knockout cells (Figure 2a).…”

Section: C-myb Mrna Is a Translational Target Of Pdcd4supporting

confidence: 71%

“…To monitor and normalize transfection efficiencies, the b-galactosidase expression plasmid CMVb (Invitrogen, Karlsruhe, Germany) was included in each transfection. DT40 Pdcd4 (À/À) cells and Pdcd4 (À/À) cells re-expressing hemagglutinin-tagged versions of Pdcd4 have been described (Singh et al, 2009).…”

Section: Cells and Transfectionsmentioning

confidence: 99%

“…On the protein level, p70(S6K) kinase-mediated phosphorylation of Pdcd4 triggers its ubiquitinylation by the E3 ubiquitin ligase complex SCF(betaTRCP) and its subsequent degradation (Dorello et al, 2006). Recent work has suggested that downregulation of Pdcd4 expression contributes to tumor development by stimulating the mobility and metastatic potential of tumor cells Asangani et al, 2008), and by deregulating the cellular DNA damage response (Bitomsky et al, 2008;Singh et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

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Pdcd4 directly binds the coding region of c-myb mRNA and suppresses its translation

et al. 2011

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Pdcd4 is a novel tumor suppressor protein that functions in the nucleus and the cytoplasm, and appears to be involved in the regulation of transcription and translation. In the cytoplasm, Pdcd4 has been implicated in the suppression of translation of mRNAs containing structured 5 0 -untranslated regions; however, the mechanisms that recruit Pdcd4 to specific target mRNAs and the identities of these mRNAs are mostly unknown. In this study, we have identified c-myb mRNA as the first natural translational target mRNA of Pdcd4. We have found that translational suppression of c-myb mRNA by Pdcd4 is dependent on sequences located within the c-myb-coding region. Furthermore, we have found that the N-terminal domain of Pdcd4 has an important role in targeting Pdcd4 to c-myb RNA by mediating preferential RNA binding to the Pdcd4-responsive region of c-myb mRNA. Overall, our work demonstrates for the first time that Pdcd4 is directly involved in translational suppression of a natural mRNA and provides the first evidence for a key role of the RNA-binding domain in targeting Pdcd4 to a specific mRNA.

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Section: C-myb Mrna Is a Translational Target Of Pdcd4supporting

confidence: 71%

Section: Cells and Transfectionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pdcd4 directly binds the coding region of c-myb mRNA and suppresses its translation

et al. 2011

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“…In fact recent studies have demonstrated not only a direct relation between PDCD4 expression and tumor progression (Wei et al , 2009 [36]) but also the key role of PDCD4 and mir-21 in apoptotic inflammatory response (Sheedy et al , 2009 [37]). Moreover, recent cell model studies support suggest a role for loss of PDCD4 expression in increased sensitivity of cells to agents that cause DNA damage (Singh et al , 2009 [38]), all of which would be expected to provide favourable conditions for tumor growth. Mice expressing high levels of PDCD4 are also more resistant to tumor growth in comparison to normal controls.…”

Section: Discussionmentioning

confidence: 99%

Expression of Mir-21 and Mir-143 in Cervical Specimens Ranging from Histologically Normal through to Invasive Cervical Cancer

et al. 2011

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BackgroundMicroRNA expression is severely disrupted in carcinogenesis, however limited evidence is available validating results from cell-line models in human clinical cancer specimens. MicroRNA-21 (mir-21) and microRNA-143 (mir-143) have previously been identified as significantly deregulated in a range of cancers including cervical cancer. Our goal was to investigate the expression patterns of several well-studied microRNA species in cervical samples and compare the results to cell line samples.Methodology/Principal FindingsWe measured the expression of mir-21 and mir-143 in 142 formalin-fixed, paraffin embedded (FFPE) cervical biopsy tissue blocks, collected from Dantec Oncology Clinic, Dakar, Senegal. MicroRNA expression analysis was performed using Taqman-based real-time PCR assays. Protein immunohistochemical staining was also performed to investigate target protein expression on 72 samples. We found that mir-21 expression increased with worsening clinical diagnosis but that mir-143 was not correlated with histology. These observations were in stark contrast to previous reports involving cervical cancer cell lines in which mir-143 was consistently down-regulated but mir-21 largely unaffected. We also identified, for the first time, that cytoplasmic expression of Programmed Cell Death Protein 4 PDCD4; a known target of mir-21) was significantly lower in women with invasive cervical carcinoma (ICC) in comparison to those with cervical intraepithelial neoplasia (2–3) or carcinoma in situ (CIN2-3/CIS), although there was no significant correlation between mir-21 and PDCD4 expression, despite previous studies identifying PDCD4 transcript as a known mir-21 target.ConclusionsWhilst microRNA biomarkers have a number of promising features, more studies on expression levels in histologically defined clinical specimens are required to investigate clinical relevance of discovery-based studies. Mir-21 may be of some utility in predictive screening, given that we observed a significant correlation between mir-21 expression level and worsening histological diagnosis of cervical cancer.

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“…8,11,14,15 In addition, decreased Pdcd4 expression has been shown to deregulate the cellular DNA damage response. 16,17 Pdcd4 encodes a highly conserved, predominantly nuclear protein that is able to shuttle between nucleus and cytoplasm 18 and whose subcellular localization is controlled by protein kinase Akt-mediated phosphorylation. 19 So far, two main activities have been attributed to Pdcd4.…”

Section: Introductionmentioning

confidence: 99%

Association of Tumor Suppressor Protein Pdcd4 With Ribosomes Is Mediated by Protein-Protein and Protein-RNA Interactions

et al. 2010

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The Pdcd4 (programmed cell death gene 4) gene has been implicated as a novel tumor suppressor gene in the development of several types of human cancer. The Pdcd4 protein is believed to act as a translation suppressor of mRNAs containing structured 5′ UTRs. Pdcd4 contains 2 copies of so-called MA3 domains that mediate tight interactions with the translation initiation factor eIF4A, resulting in the inhibition of the eIF4A helicase activity. The N-terminal part of Pdcd4, which has been less well characterized, binds RNA in vitro, but as yet, it has not been clear whether RNA binding by Pdcd4 plays a role in vivo. Here, the authors have identified 2 highly conserved clusters of basic amino acid residues that are essential for the RNA binding activity of Pdcd4. They also show that a substantial fraction of Pdcd4 is present, together with small ribosomal subunits, in translation preinitiation complexes. Using mutants that disrupt RNA binding or the Pdcd4-eIF4A interaction, they demonstrate that the ribosomal association of Pdcd4 is dependent on its RNA binding activity as well as on its ability to interact with eIF4A. Their work provides the first direct evidence for an essential role of the Pdcd4 RNA binding activity in vivo and suggests that RNA binding is required for recruiting Pdcd4 to the translation machinery.

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Disruption of the Pdcd4 tumor suppressor gene in chicken DT40 cells reveals its role in the DNA-damage response

Cited by 23 publications

References 32 publications

Pdcd4 directly binds the coding region of c-myb mRNA and suppresses its translation

Pdcd4 directly binds the coding region of c-myb mRNA and suppresses its translation

Expression of Mir-21 and Mir-143 in Cervical Specimens Ranging from Histologically Normal through to Invasive Cervical Cancer

Association of Tumor Suppressor Protein Pdcd4 With Ribosomes Is Mediated by Protein-Protein and Protein-RNA Interactions

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