Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Original Article
  • Published:

Ect2 links the PKCι–Par6α complex to Rac1 activation and cellular transformation

Oncogene volume 28, pages 3597–3607 (2009)Cite this article

Abstract

Protein kinase Cι (PKCι) promotes non-small cell lung cancer (NSCLC) by binding to Par6α and activating a Rac1-Pak-Mek1,2-Erk1,2 signaling cascade. The mechanism by which the PKCι–Par6α complex regulates Rac1 is unknown. Here we show that epithelial cell transforming sequence 2 (Ect2), a guanine nucleotide exchange factor for Rho family GTPases, is coordinately amplified and overexpressed with PKCι in NSCLC tumors. RNA interference-mediated knockdown of Ect2 inhibits Rac1 activity and blocks transformed growth, invasion and tumorigenicity of NSCLC cells. Expression of constitutively active Rac1 (RacV12) restores transformation to Ect2-deficient cells. Interestingly, the role of Ect2 in transformation is distinct from its well-established role in cytokinesis. In NSCLC cells, Ect2 is mislocalized to the cytoplasm where it binds the PKCι–Par6α complex. RNA interference-mediated knockdown of either PKCι or Par6α causes Ect2 to redistribute to the nucleus, indicating that the PKCι–Par6α complex regulates the cytoplasmic localization of Ect2. Our data indicate that Ect2 and PKCι are genetically and functionally linked in NSCLC, acting to coordinately drive tumor cell proliferation and invasion through formation of an oncogenic PKCι–Par6α-Ect2 complex.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10

Similar content being viewed by others

References

  • Balsara BR, Sonoda G, du Manoir S, Siegfried JM, Gabrielson E, Testa JR . (1997). Comparative genomic hybridization analysis detects frequent, often high-level, overrepresentation of DNA sequences at 3q, 5p, 7p, and 8q in human non-small cell lung carcinomas. Cancer Res 57: 2116–2120.

    CAS  PubMed  Google Scholar 

  • Brass N, Ukena I, Remberger K, Mack U, Sybrecht GW, Meese EU . (1996). DNA amplification on chromosome 3q26.1-q26.3 in squamous cell carcinoma of the lung detected by reverse chromosome painting. Eur J Cancer 32A: 1205–1208.

    Article  CAS  Google Scholar 

  • Frederick LA, Matthews JA, Jamieson L, Justilien V, Thompson EA, Radisky DC et al. (2008). Matrix metalloproteinase-10 is a critical effector of protein kinase Ciota-Par6alpha-mediated lung cancer. Oncogene.

  • Hara T, Abe M, Inoue H, Yu LR, Veenstra TD, Kang YH et al. (2006). Cytokinesis regulator ECT2 changes its conformation through phosphorylation at Thr-341 in G2/M phase. Oncogene 25: 566–578.

    Article  CAS  Google Scholar 

  • Hirata D, Yamabuki T, Miki D, Ito T, Tsuchiya E, Fujita M et al. (2009). Involvement of epithelial cell transforming sequence-2 oncoantigen in lung and esophageal cancer progression. Clin Cancer Res 15: 256–266.

    Article  CAS  Google Scholar 

  • Imoto I, Pimkhaokham A, Fukuda Y, Yang ZQ, Shimada Y, Nomura N et al. (2001). SNO is a probable target for gene amplification at 3q26 in squamous-cell carcinomas of the esophagus. Biochem Biophys Res Commun 286: 559–565.

    Article  CAS  Google Scholar 

  • Kanada M, Nagasaki A, Uyeda TQ . (2008). Novel functions of Ect2 in polar Lamellipodia formation and polarity maintenance during ‘contractile ring-Independent’ cytokinesis in adherent cells. Mol Biol Cell 19: 8–16.

    Article  CAS  Google Scholar 

  • Kim JE, Billadeau DD, Chen J . (2005). The tandem BRCT domains of Ect2 are required for both negative and positive regulation of Ect2 in cytokinesis. J Biol Chem 280: 5733–5739.

    Article  CAS  Google Scholar 

  • Liu XF, Ishida H, Raziuddin R, Miki T . (2004). Nucleotide exchange factor ECT2 interacts with the polarity protein complex Par6/Par3/protein kinase Czeta (PKCzeta) and regulates PKCzeta activity. Mol Cell Biol 24: 6665–6675.

    Article  CAS  Google Scholar 

  • Liu XF, Ohno S, Miki T . (2006). Nucleotide exchange factor ECT2 regulates epithelial cell polarity. Cell Signal 18: 1604–1615.

    Article  CAS  Google Scholar 

  • Miki T, Smith CL, Long JE, Eva A, Fleming TP . (1993). Oncogene ect2 is related to regulators of small GTP-binding proteins. Nature 362: 462–465.

    Article  CAS  Google Scholar 

  • Niiya F, Tatsumoto T, Lee KS, Miki T . (2006). Phosphorylation of the cytokinesis regulator ECT2 at G2/M phase stimulates association of the mitotic kinase Plk1 and accumulation of GTP-bound RhoA. Oncogene 25: 827–837.

    Article  CAS  Google Scholar 

  • Niiya F, Xie X, Lee KS, Inoue H, Miki T . (2005). Inhibition of cyclin-dependent kinase 1 induces cytokinesis without chromosome segregation in an ECT2 and MgcRacGAP-dependent manner. J Biol Chem 280: 36502–36509.

    Article  CAS  Google Scholar 

  • Regala RP, Weems C, Jamieson L, Copland JA, Thompson EA, Fields AP . (2005a). Atypical protein kinase Ciota plays a critical role in human lung cancer cell growth and tumorigenicity. J Biol Chem 280: 31109–31115.

    Article  CAS  Google Scholar 

  • Regala RP, Weems C, Jamieson L, Khoor A, Edell ES, Lohse CM et al. (2005b). Atypical protein kinase C iota is an oncogene in human non-small cell lung cancer. Cancer Res 65: 8905–8911.

    Article  CAS  Google Scholar 

  • Saito S, Liu XF, Kamijo K, Raziuddin R, Tatsumoto T, Okamoto I et al. (2004). Deregulation and mislocalization of the cytokinesis regulator ECT2 activate the Rho signaling pathways leading to malignant transformation. J Biol Chem 279: 7169–7179.

    Article  CAS  Google Scholar 

  • Saito S, Tatsumoto T, Lorenzi MV, Chedid M, Kapoor V, Sakata H et al. (2003). Rho exchange factor ECT2 is induced by growth factors and regulates cytokinesis through the N-terminal cell cycle regulator-related domains. J Cell Biochem 90: 819–836.

    Article  CAS  Google Scholar 

  • Salhia B, Tran NL, Chan A, Wolf A, Nakada M, Rutka F et al. (2008). The guanine nucleotide exchange factors trio, Ect2, and Vav3 mediate the invasive behavior of glioblastoma. Am J Pathol 173: 1828–1838.

    Article  CAS  Google Scholar 

  • Sano M, Genkai N, Yajima N, Tsuchiya N, Homma J, Tanaka R et al. (2006). Expression level of ECT2 proto-oncogene correlates with prognosis in glioma patients. Oncol Rep 16: 1093–1098.

    CAS  PubMed  Google Scholar 

  • Snaddon J, Parkinson EK, Craft JA, Bartholomew C, Fulton R . (2001). Detection of functional PTEN lipid phosphatase protein and enzyme activity in squamous cell carcinomas of the head and neck, despite loss of heterozygosity at this locus. Br J Cancer 84: 1630–1634.

    Article  CAS  Google Scholar 

  • Solski PA, Wilder RS, Rossman KL, Sondek J, Cox AD, Campbell SL et al. (2004). Requirement for C-terminal sequences in regulation of Ect2 guanine nucleotide exchange specificity and transformation. J Biol Chem 279: 25226–25233.

    Article  CAS  Google Scholar 

  • Sonoda G, Palazzo J, du Manoir S, Godwin AK, Feder M, Yakushiji M et al. (1997). Comparative genomic hybridization detects frequent overrepresentation of chromosomal material from 3q26, 8q24, and 20q13 in human ovarian carcinomas. Genes Chromosomes Cancer 20: 320–328.

    Article  CAS  Google Scholar 

  • Sugita M, Tanaka N, Davidson S, Sekiya S, Varella-Garcia M, West J et al. (2000). Molecular definition of a small amplification domain within 3q26 in tumors of cervix, ovary, and lung. Cancer Genet Cytogenet 117: 9–18.

    Article  CAS  Google Scholar 

  • Takai S, Long JE, Yamada K, Miki T . (1995). Chromosomal localization of the human ECT2 proto-oncogene to 3q26.1-->q26.2 by somatic cell analysis and fluorescence in situ hybridization. Genomics 27: 220–222.

    Article  CAS  Google Scholar 

  • Tatsumoto T, Xie X, Blumenthal R, Okamoto I, Miki T . (1999). Human ECT2 is an exchange factor for Rho GTPases, phosphorylated in G2/M phases, and involved in cytokinesis. J Cell Biol 147: 921–928.

    Article  CAS  Google Scholar 

  • Zhang J, Anastasiadis PZ, Liu Y, Thompson EA, Fields AP . (2004). Protein kinase C βII induces cell invasion through a Ras/MEK-, PKCiota/RAC 1-dependent signaling pathway. J Biol Chem 279: 22118–22123.

    Article  CAS  Google Scholar 

  • Zhang ML, Lu S, Zhou L, Zheng SS . (2008). Correlation between ECT2 gene expression and methylation change of ECT2 promoter region in pancreatic cancer. Hepatobiliary Pancreat Dis Int 7: 533–538.

    CAS  PubMed  Google Scholar 

Download references

Acknowledgements

We acknowledge Dr Roderick P Regala for assistance with the ectopic tumor studies, Dr Andras Khoor and Capella Weems for analysis of primary NSCLC tumors, Pam Kreinest and Brandy Edenfield for immunohistochemistry, Dr Lee Jamieson and Alyssa Kunz for technical assistance, and Drs E Aubrey Thompson and Nicole R Murray for critical review of the paper. This work was supported in part by grants from the National Institutes of Health (CA081436), The V Foundation for Cancer Research and The Mayo Foundation to APF.

Author information

Authors and Affiliations

  1. Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, FL, USA

    V Justilien & A P Fields

Authors
  1. V Justilien
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A P Fields
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to A P Fields.

Additional information

Supplementary Information accompanies the paper on the Oncogene website (http://www.nature.com/onc)

Supplementary information

Rights and permissions

Reprints and permissions

About this article

Cite this article

Justilien, V., Fields, A. Ect2 links the PKCι–Par6α complex to Rac1 activation and cellular transformation. Oncogene 28, 3597–3607 (2009). https://doi.org/10.1038/onc.2009.217

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/onc.2009.217

Keywords

This article is cited by

Search

Advanced search

Quick links