ECT2 (epithelial cell transforming sequence 2 oncogene)

2012-06-01   Verline Justilien , Alan P Fields 

Department of Cancer Biology, Mayo Clinic College of Medicine, Jacksonville, Florida, 32224 USA


Atlas Image
Location sequence of ECT2 on Chromosome 3. ECT2 gene is indicated by red arrow.


Atlas Image
Exon-intron structure of the ECT2 gene. Blue vertical bars correspond to exons, orange represents 3UTR.


The ECT2 gene is composed of 23 exons and spans 70793 bases on plus strand.


The ECT2 transcript (NCBI Reference Sequence: NM_018098.4) contains 3916 bases and the open reading frame spans from 29 to 2680. 17 transcript variants have been reported for ECT2.


A pseudogene for ECT2 has not been reported.


Atlas Image
Schematic diagram of the domain structure of the Ect2 protein. N, Amino-terminal region; XRCC1, X-ray repair complementing defective repair in Chinese hamster cells 1 domain; Cyclin B6, cyclin B6-like domain; BRCT, BRAC1 C-terminal domain; S, small central region; NLS, nuclear localization sequence; DH, Dbl homology domain; PH, pleckstrin homology domain; C, Carboxyl-terminal region. Phosphorylation on T341 and T412 activate Ect2 during G2/M phase. T328 is phosphorylated by PKCι and required for Ect2 mediated transformation in NSCLC cells.


Human ECT2 consist of 883 amino acids, with a predicted molecular weight of approximately 104kDa. The N-terminus of Ect2 serves regulatory functions and contains sequences that exhibit high homology to cell cycle control and repair proteins. The XRCC1 domain shows sequence homology to human XRCC1, a protein that repairs defective DNA strand breaks and functions in sister chromatid exchange. The Clb6 domain shows homology to yeast B-cyclin that promotes transition from the G1 to S phase of cell cycle. The Clb6 domain is followed by sequences that exhibit homology to yeast Rad4/Cut5, a protein required for entry into S phase and inhibition of M phase entry prior to completion of DNA synthesis Rad4/Cut5 also plays a critical role in replication checkpoint control in yeast. The Cut5 homology domain contains tandem repeats of the BRCT (Breast Cancer gene 1 Carboxyl-terminal) motif that is conserved in proteins involved in DNA repair and cell cycle checkpoint responses. A small central (S) domain contains two nuclear localization sequences that appear to be involved in the control of the intracellular localization of Ect2. The catalytic core of Ect2 is found within the C-terminus, and consists of a Dbl-homology (DH) and a pleckstrin homology (PH) domain which confer guanine nucleotide exchange activity toward Rho-GTPases. The extreme C-terminal (C) region of Ect2 does not exhibit significant homology to any known protein domains or motifs.


Northern blot analysis reveals that Ect2 is expressed in a broad range of adult tissues including kidney, liver, spleen, testis, lung, bladder, ovary and brain (Miki et al., 1993; Saito et al., 2003). In situ hybridization of fetal tissues shows Ect2 expression in the liver, thymus, proliferating epithelial cells of the nasal cavity and gut, tooth primordial, costal cartilage, heart, lung and pancreas (Saito et al., 2003).


Ect2 expression is cell cycle dependent. During interphase, Ect2 is sequestered within the nucleus. Upon breakdown of the nuclear envelope during mitosis, Ect2 is dispersed throughout the cytoplasm. Ect2 becomes localized to the mitotic spindles during metaphase, the cleavage furrow at telophase, and then the mid-body at the end of cytokinesis (Tatsumoto et al., 1999). In MDCK cells, small amounts of Ect2 can be detected at cell-cell contacts where it is reported to directly interact with the Par6/Par3/PKCζ polarity complex (Liu et al., 2004).


Ect2 is a guanine nucleotide exchange factor and is reported to catalyze GTP exchange on several members of the Rho GTPase family including, RhoA, RhoB, RhoC, RhoG, Rac1 and Cdc42 (Miki et al., 1993; Saito et al., 2004; Solski et al., 2004; Tatsumoto et al., 1999; Wennerberg et al., 2002). ECT2 regulates cytokinesis in mammalian cells through RhoA-mediated pathways (Burkard et al., 2007; Kamijo et al., 2006; Kimura et al., 2000; Nishimura and Yonemura, 2006; Yuce et al., 2005). ECT2 associates with GTPase activating protein, MgcRacGAP to regulate the activity of RhoA which controls contraction of the actomyosin ring and ingression of the cleavage furrow required for cytokinesis. Ect2 has also been implicated in the control of mitotic spindle assembly through activation of Cdc42 (Tatsumoto et al., 2003), and an Ect2→Cdc42→mDia3 signaling pathway has been implicated in facilitating attachment and stabilization of spindle fibers to kinetochores (Oceguera-Yanez et al., 2005). Ect2 may also play a role in cell polarity. In MDCK cells, small amounts of Ect2 can be detected at cell-cell contacts where ECT2 is reported to directly interact with the polarity complex Par6/Par3/PKCζ and to modulate PKCζ activity (Liu et al., 2004). In addition, Ect2 was found in the tight junction-containing detergent-insoluble fraction of Caco2 cells (Chen et al., 2012). Recently, it has been proposed that ECT2 may contribute to neuronal morphological differentiation through regulation of growth cone dynamics perhaps by directly participating in reorganization of the actin cytoskeleton at the tips of neurites (Tsuji et al., 2012).


ECT2 is highly evolutionarily conserved. Homologs of ECT2 are present in other mammals as well as aves, flies, worms and yeast.



Mutations have not been reported for ECT2.

Implicated in

Entity name
Human cancer
The ECT2 gene was initially identified as a proto-oncogene capable of transforming NIH/3T3 fibroblasts (Miki et al., 1993). Subsequent analysis revealed that the originally characterized oncogenic Ect2 clone actually consisted of a carboxyl-terminal truncation of the full-length ECT2 gene. This truncated clone encoded a protein consisting of the DH-PH-C domains of Ect2. This mutant localized to the cytoplasm, possessed constitutive GEF activity and could transform fibroblasts in vitro (Saito et al., 2004). Expression analysis revealed that established human cancer cell lines express only full-length Ect2, indicating that the transforming C-terminal Ect2 fragment originally cloned is not directly relevant to cancer biology (Saito et al., 2003). Interestingly, full length Ect2 is overexpressed in several human tumor types, suggesting a role for elevated Ect2 expression in these tumors (Hirata et al., 2009; Salhia et al., 2008; Sano et al., 2006; Zhang et al., 2008).
Ect2 overexpression is associated with poor prognosis in patients with non-small cell lung cancer (NSCLC), esophageal squamous cell carcinomas (ESCC) (Hirata et al., 2009), glioblastoma multiforme (GBM) (Salhia et al., 2008; Sano et al., 2006) and oral squamous cell carcinomas (OSCC) (Iyoda et al., 2010).
ECT2 is amplified as part of the 3q26 amplicon a region frequently targeted for chromosomal alterations in human tumors (Eder et al., 2005; Han et al., 2002; Lin et al., 2006; Zhang et al., 2006). ECT2 amplification frequently occurs in lung squamous cell carcinomas (LSCC) (Justilien and Fields, 2009), ESCC (Yang et al., 2008; Yen et al., 2005) and cervical cancer (Vazquez-Mena et al., 2012).
Ect2 is overexpressed and mislocalized in human tumors
Ect2 is highly expressed in a variety of human tumors including brain (Salhia et al., 2008; Sano et al., 2006), lung (Hirata et al., 2009; Justilien and Fields, 2009), bladder (Saito et al., 2004), esophageal (Hirata et al., 2009), pancreatic (Zhang et al., 2008), cervical (Vazquez-Mena et al., 2012), colorectal (Jung et al., 2011), oral (Iyoda et al., 2010) and ovarian tumors (Saito et al., 2004). Tumor specific ECT2 gene amplification drives Ect2 overexpression in lung (Hirata et al., 2009; Justilien and Fields, 2009), esophageal (Hirata et al., 2009) and cervical cancers (Vazquez-Mena et al., 2012). Ect2 transforming activity requires both Ect2 GEF activity and mis-localization of Ect2 to the cytoplasm (Saito et al., 2004; Solski et al., 2004). Immunohistochemical analysis demonstrate that Ect2 is predominantly expressed in the nucleus of normal lung epithelial cells (Justilien and Fields, 2009), but that primary NSCLC tumors display increased Ect2 staining in both the nucleus and cytoplasm with little or no staining in the tumor-associated stroma (Hirata et al., 2009; Justilien and Fields, 2009). Similarly, Ect2 stains primarily nuclear in the low-grade astrocytomas (LGA) whereas glioblastoma multiforme (GBMs) display prominent staining of Ect2 in both the cytoplasm and nucleus (Salhia et al., 2008). OSCCs exhibit strong nuclear and cytoplasmic staining of ECT2 staining whereas normal oral tissues showed little to no ECT2 staining (Iyoda et al., 2010).
Ect2 is important for transformation in human cancer cells
Ect2 plays a promotive role in transformation in all tumor model systems examined to date. Inhibition of Ect2 expression by RNAi decreases the proliferation of NSCLC (Hirata et al., 2009), ESCC (Hirata et al., 2009) and OSCC (Iyoda et al., 2010) cells in vitro. In addition, stable knockdown (KD) of Ect2 by short hairpin RNAs (shRNAs) inhibits anchorage-independent growth and cellular invasion of multiple NSCLC cell lines (Justilien and Fields, 2009) Ect2 KD impairs tumor growth of NSCLC cells injected into the flanks of athymic nude mice, demonstrating that Ect2 also plays a role in NSCLC tumorigenicity in vivo (Justilien and Fields, 2009). RNAi-mediated suppression of Ect2 expression in glioblastoma cells caused a significant decrease in cell proliferation and migration in vitro and invasion in an ex vivo rat brain slice assay (Salhia et al., 2008; Sano et al., 2006).
Cellular mechanisms in Ect2 mediated transformation
Ect2 function in NSCLC transformation is distinct from its well established role in cytokinesis. NSCLC cells stably transduced with Ect2 shRNAs do not show significant changes in population doubling time (PDT) or accumulation of multinucleated cells in vitro or in vivo (Justilien and Fields, 2009). NSCLC cells may employ an Ect2-independent cytokinesis mechanism such as previously described in HT1080 fibrosarcoma (Kanada et al., 2008). Whereas Ect2 mediates RhoA activity in cytokinesis, Rac1 appears to be the critical Ect2 effector in NSCLC. Ect2 KD in NSCLC cells leads to a significant decrease in Rac1 activity but no apparent changes in Cdc42 or RhoA activity (Justilien and Fields, 2009; Justilien et al., 2011). Furthermore, expression of a constitutively active Rac1 allele (RacV12) restores anchorage independent growth and invasion in Ect2 KD cells.
Co-immunoprecipitation experiments and mass spectrometry analysis show that Ect2 associates with the PKCι-Par6α complex (Justilien and Fields, 2009; Justilien et al., 2011). Ect2 is largely mis-localized to the cytoplasm of cultured NSCLC cells and the PKCι-Par6α complex regulates Ect2 cytoplasmic mislocalization (Justilien and Fields, 2009). Ect2 isolated from NSCLC cells is highly phosphorylated at a novel, previously uncharacterized site T328. PKCι directly phosphorylates T328 in vitro and the PKCι/Par6 complex regulates T328 phosphorylation in intact NSCLC cells. T328 phosphorylation is required for ECT2 binding to the PKCι-Par6 complex, Rac1 activation and transformation in NSCLC cells (Justilien et al., 2011).


Pubmed IDLast YearTitleAuthors
173605332007Chemical genetics reveals the requirement for Polo-like kinase 1 activity in positioning RhoA and triggering cytokinesis in human cells.Burkard ME et al
222715472012AMP-18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier.Chen P et al
161160792005Atypical PKCiota contributes to poor prognosis through loss of apical-basal polarity and cyclin E overexpression in ovarian cancer.Eder AM et al
124764132002[Establishment and comparative genomic hybridization analysis of human esophageal carcinomas cell line EC9706].Han Y et al
191180532009Involvement of epithelial cell transforming sequence-2 oncoantigen in lung and esophageal cancer progression.Hirata D et al
211247662010Epithelial cell transforming sequence 2 in human oral cancer.Iyoda M et al
213040022011Clinical validation of colorectal cancer biomarkers identified from bioinformatics analysis of public expression data.Jung Y et al
211892482011Oncogenic activity of Ect2 is regulated through protein kinase C iota-mediated phosphorylation.Justilien V et al
162367942006Dissecting the role of Rho-mediated signaling in contractile ring formation.Kamijo K et al
108374912000Accumulation of GTP-bound RhoA during cytokinesis and a critical role of ECT2 in this accumulation.Kimura K et al
162474532006DNA copy number gains in head and neck squamous cell carcinoma.Lin M et al
152542342004Nucleotide exchange factor ECT2 interacts with the polarity protein complex Par6/Par3/protein kinase Czeta (PKCzeta) and regulates PKCzeta activity.Liu XF et al
84644781993Oncogene ect2 is related to regulators of small GTP-binding proteins.Miki T et al
163526582006Centralspindlin regulates ECT2 and RhoA accumulation at the equatorial cortex during cytokinesis.Nishimura Y et al
156427492005Ect2 and MgcRacGAP regulate the activation and function of Cdc42 in mitosis.Oceguera-Yanez F et al
146452602004Deregulation and mislocalization of the cytokinesis regulator ECT2 activate the Rho signaling pathways leading to malignant transformation.Saito S et al
145870372003Rho exchange factor ECT2 is induced by growth factors and regulates cytokinesis through the N-terminal cell cycle regulator-related domains.Saito S et al
190083762008The guanine nucleotide exchange factors trio, Ect2, and Vav3 mediate the invasive behavior of glioblastoma.Salhia B et al
170165982006Expression level of ECT2 proto-oncogene correlates with prognosis in glioma patients.Sano M et al
150731842004Requirement for C-terminal sequences in regulation of Ect2 guanine nucleotide exchange specificity and transformation.Solski PA et al
146244492003Potential roles of the nucleotide exchange factor ECT2 and Cdc42 GTPase in spindle assembly in Xenopus egg cell-free extracts.Tatsumoto T et al
223666512012Ect2, an ortholog of Drosophila Pebble, regulates formation of growth cones in primary cortical neurons.Tsuji T et al
224129032012Amplified genes may be overexpressed, unchanged, or downregulated in cervical cancer cell lines.Vazquez-Mena O et al
123765512002RhoG signals in parallel with Rac1 and Cdc42.Wennerberg K et al
179903282008Amplification of PRKCI, located in 3q26, is associated with lymph node metastasis in esophageal squamous cell carcinoma.Yang YL et al
157619622005Copy number changes of target genes in chromosome 3q25.3-qter of esophageal squamous cell carcinoma: TP63 is amplified in early carcinogenesis but down-regulated as disease progressed.Yen CC et al
161032262005An ECT2-centralspindlin complex regulates the localization and function of RhoA.Yüce O et al
166514132006Integrative genomic analysis of protein kinase C (PKC) family identifies PKCiota as a biomarker and potential oncogene in ovarian carcinoma.Zhang L et al
188425032008Correlation between ECT2 gene expression and methylation change of ECT2 promoter region in pancreatic cancer.Zhang ML et al

Other Information

Locus ID:

NCBI: 1894
MIM: 600586
HGNC: 3155
Ensembl: ENSG00000114346


dbSNP: 1894
ClinVar: 1894
TCGA: ENSG00000114346


Gene IDTranscript IDUniprot

Expression (GTEx)



PathwaySourceExternal ID
Signal TransductionREACTOMER-HSA-162582
Signalling by NGFREACTOMER-HSA-166520
p75 NTR receptor-mediated signallingREACTOMER-HSA-193704
Cell death signalling via NRAGE, NRIF and NADEREACTOMER-HSA-204998
NRAGE signals death through JNKREACTOMER-HSA-193648
Signaling by Rho GTPasesREACTOMER-HSA-194315
Rho GTPase cycleREACTOMER-HSA-194840
Signaling by GPCRREACTOMER-HSA-372790
GPCR downstream signalingREACTOMER-HSA-388396
G alpha (12/13) signalling eventsREACTOMER-HSA-416482


Pubmed IDYearTitleCitations
161032262005An ECT2-centralspindlin complex regulates the localization and function of RhoA.186
174886232007Polo-like kinase 1 triggers the initiation of cytokinesis in human cells by promoting recruitment of the RhoGEF Ect2 to the central spindle.118
194683002009Polo-like kinase 1 directs assembly of the HsCyk-4 RhoGAP/Ect2 RhoGEF complex to initiate cleavage furrow formation.104
163526582006Centralspindlin regulates ECT2 and RhoA accumulation at the equatorial cortex during cytokinesis.95
194683022009Plk1 self-organization and priming phosphorylation of HsCYK-4 at the spindle midzone regulate the onset of division in human cells.88
161298292005MgcRacGAP controls the assembly of the contractile ring and the initiation of cytokinesis.78
190083762008The guanine nucleotide exchange factors trio, Ect2, and Vav3 mediate the invasive behavior of glioblastoma.70
221726732011Targeting of the RhoGEF Ect2 to the equatorial membrane controls cleavage furrow formation during cytokinesis.70
196178972009Ect2 links the PKCiota-Par6alpha complex to Rac1 activation and cellular transformation.60
168038692006Influence of human Ect2 depletion and overexpression on cleavage furrow formation and abscission.57


Verline Justilien ; Alan P Fields

ECT2 (epithelial cell transforming sequence 2 oncogene)

Atlas Genet Cytogenet Oncol Haematol. 2012-06-01

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