Yap LF, Jenei V, Robinson CM, Moutasim K, Benn TM, Threadgold SP et al.. Upregulation of Eps8 in oral squamous cell carcinoma promotes cell migration and invasion through integrin-dependent Rac1 activation. Oncogene 28: 2524-2534

Department of Oral and Dental Science, University of Bristol, Bristol, UK.
Oncogene (Impact Factor: 8.46). 06/2009; 28(27):2524-34. DOI: 10.1038/onc.2009.105
Source: PubMed


Oral squamous cell carcinoma (OSCC) is a lethal disease and early death usually occurs as a result of local invasion and regional lymph node metastases. Current treatment regimens are, to a certain degree, inadequate, with a 5-year mortality rate of around 50% and novel therapeutic targets are urgently required. Using expression microarrays, we identified the eps8 gene as being overexpressed in OSCC cell lines relative to normal oral keratinocytes, and confirmed these findings using RT-PCR and western blotting. In human tissues, we found that Eps8 was upregulated in OSCC (32% of primary tumors) compared with normal oral mucosa, and that expression correlated significantly with lymph node metastasis (P=0.032), suggesting a disease-promoting effect. Using OSCC cell lines, we assessed the functional role of Eps8 in tumor cells. Although suppression of Eps8 produced no effect on cell proliferation, both cell spreading and migration were markedly inhibited. The latter cell functions may be modulated through the small GTP-ase, Rac1 and we used pull-down assays to investigate the role of Eps8 in Rac1 signaling. We found that alphavbeta6- and alpha5beta1-integrin-dependent activation of Rac1 was mediated through Eps8. Knockdown of either Eps8 or Rac1, inhibited integrin-dependent cell migration similarly and transient expression of constitutively active Rac1 restored migration of cells in which Eps8 expression had been suppressed. We also showed that knockdown of Eps8 inhibited tumor cell invasion in an organotypic model of OSCC. These data suggest that Eps8 and Rac1 are part of an integrated signaling pathway modulating integrin-dependent tumour cell motility and identify Eps8 as a possible therapeutic target.

Download full-text


Available from: Ian C Paterson, Jul 03, 2014
  • Source
    • "It contributes to cell proliferation, participates in the signaling pathway promoting cell survival, and is known for its central role in the control of cell adhesion and migration (18,19). It has also been reported that Rac1 is overexpressed in colorectal and lung tumors (20,21), and is associated with metastasis and invasion in breast, upper urinary tract and oral squamous cell tumors (22–25). "
    [Show abstract] [Hide abstract]
    ABSTRACT: MicroRNAs (miRNAs) are 22- to 25-nucleotide non-coding RNA molecules that function as negative regulators of gene expression. In previous years, increasing evidence has arisen implicating the involvement of miRNAs in carcinogenesis. In previous studies, the role of miRNA-101 (miR-101) in tumors has been identified as a tumor suppressor and, until now, the role of miR-101 and Rac1 in thyroid cancer has remained undefined. This study revealed that miR-101 is significantly downregulated in papillary thyroid carcinoma (PTC) tissue and thyroid cancer cell lines, and that the downregulated miR-101 is associated with lymph node metastasis. Infection with the miR-101 murine stem cell virus may markedly inhibit cell migration and invasion in TPC-1 and HTH83 thyroid cancer cell lines. Rac1 was demonstrated to be negatively regulated by miR-101 at the post-transcriptional level, via a specific target site within the 3' untranslated region by dual-luciferase reporter assay. The expression of Rac1 was also observed to inversely correlate with miR-101 expression in PTC tissues; knockdown of Rac1 by shRNA inhibited thyroid cancer cell migration and invasion, resembling that of miR-101 overexpression. Thus, these findings suggested that miR-101 acts as a novel suppressor by targeting the Rac1 gene and inhibiting thyroid cancer cell migration and invasion.
    Full-text · Article · Oct 2014 · Oncology letters
  • Source
    • "Eps8 was originally identified as a novel phosphorylation substrate for the epidermal growth factor receptor (EGFR) and is also phosphorylated upon activation of other tyrosine kinases including fibroblast growth factor receptor (FGFR), platelet-derived growth factor (PDGF) and erbB-2 [8]. It has since been identified as a phosphorylation substrate for Src [9] and elevated expression of Eps8 has been observed in v-Src transformed cells [9], [10] and a variety of human cancers [11], [12], [13]. Phosphorylation is an important post-translational modification in the regulation of protein-protein interactions constituting cellular signal transduction, and aberrant regulation of phosphorylation can lead to malignancy. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Eps8 is involved in both cell signalling and receptor trafficking. It is a known phosphorylation substrate for two proteins involved in the fibroblast growth factor receptor (FGFR) signalling pathway: the receptor itself and Src. Here we report a differential proteomic analysis of Eps8 aimed to identify specific FGFR and Src family kinase dependent phosphosites and co-associated phosphodependent binding partners. This study reveals a total of 22 Eps8 pTyr and pSer/Thr phosphorylation sites, including those that are dependent on Src family and FGFR kinase activity. Peptide affinity purification of proteins that bind to a selection of the pTyr phosphosites has identified a range of novel Eps8 binding partners including members of the intracellular vesicle trafficking machinery (clathrin and AP-2), proteins which have been shown to regulate activated receptor trafficking (NBR1 and Vav2), and proteins involved in receptor signalling (IRS4 and Shp2). Collectively this study significantly extends the understanding of Eps8 post-translational modification by regulated phosphorylation, identifies novel Eps8 binding partners implicated in receptor trafficking and signalling, and confirms the functions of Eps8 at the nexus of receptor signalling and vesicular trafficking.
    Full-text · Article · Apr 2013 · PLoS ONE
  • Source
    • "To determine whether elevated levels of endogenous TGF-b1 or TGF-b2 altered the invasive capacity of I-7 cells, we used a three-dimensional organotypic model that has been used previously to study tumour cell invasion in a physiologically relevant manner (Nystrom et al. 2005; Yap et al. 2009). I-7 cells that overexpressed either TGF-b1 or TGF-b2 were markedly more invasive than controls, with islands of cells penetrating deeper into the matrix (Figure 2a) for each isoform , both overexpressing clones behaved in a similar way. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Transforming growth factor-β (TGF-β) is known to act as a tumour suppressor early in carcinogenesis, but then switches to a pro-metastatic factor in some late stage cancers. However, the actions of TGF-β are context dependent, and it is currently unclear how TGF-β influences the progression of human squamous cell carcinoma (SCC). This study examined the effect of overexpression of TGF-β1 or TGF-β2 in Ras-transfected human malignant epidermal keratinocytes that represent the early stages of human SCC. In vitro, the proliferation of cells overexpressing TGF-β1 or TGF-β2 was inhibited by exogenous TGF-β1; cells overexpressing TGF-β1 also grew more slowly than controls, but the growth rate of TGF-β2 overexpressing cells was unaltered. However, cells that overexpressed either TGF-β1 or TGF-β2 were markedly more invasive than controls in an organotypic model of SCC. The proliferation of the invading TGF-β1 overexpressing cells in the organotypic assays was higher than controls. Similarly, tumours formed by the TGF-β1 overexpressing cells following transplantation to athymic mice were larger than tumours formed by control cells and proliferated at a higher rate. Our results demonstrate that elevated expression of either TGF-β1 or TGF-β2 in cells that represent the early stages in the development of human SCC results in a more aggressive phenotype.
    Full-text · Article · Apr 2012 · International Journal of Experimental Pathology
Show more