EGF-Induced EMT and Invasiveness in Serous Borderline Ovarian Tumor Cells: A Possible Step in the Transition to Low-Grade Serous Carcinoma Cells?

Department of Obstetrics and Gynecology, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
PLoS ONE (Impact Factor: 3.23). 03/2012; 7(3):e34071. DOI: 10.1371/journal.pone.0034071
Source: PubMed

ABSTRACT In high-grade ovarian cancer cultures, it has been shown that epidermal growth factor (EGF) induces cell invasion by activating an epithelial-mesenchymal transition (EMT). However, the effect of EGF on serous borderline ovarian tumors (SBOT) and low-grade serous carcinomas (LGC) cell invasion remains unknown. Here, we show that EGF receptor (EGFR) was expressed, that EGF treatment increased cell migration and invasion in two cultured SBOT cell lines, SBOT3.1 and SV40 large T antigen-infected SBOT cells (SBOT4-LT), and in two cultured LGC cell lines, MPSC1 and SV40 LT/ST-immortalized LGC cells (ILGC). However, EGF induced down-regulation of E-cadherin and concurrent up-regulation of N-cadherin in SBOT cells but not in LGC cells. In SBOT cells, the expression of the transcriptional repressors of E-cadherin, Snail, Slug and ZEB1 were increased by EGF treatment. Treatment with EGF led to the activation of the downstream ERK1/2 and PI3K/Akt. The MEK1 inhibitor PD98059 diminished the EGF-induced cadherin switch and the up-regulation of Snail, Slug and ZEB1 and the EGF-mediated increase in SBOT cell migration and invasion. The PI3K inhibitor LY294002 had similar effects, but it could not block the EGF-induced up-regulation of N-cadherin and ZEB1. This study demonstrates that EGF induces SBOT cell migration and invasion by activating EMT, which involves the activation of the ERK1/2 and PI3K/Akt pathways and, subsequently, Snail, Slug and ZEB1 expression. Moreover, our results suggest that there are EMT-independent mechanisms that mediate the EGF-induced LGC cell migration and invasion.

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    • "Previous studies showed that EGFR regulates AKT and ERK1/2 activity in ovarian cancer [15], [22]. Because miR-7 can post-transcriptionally inhibit the expression of EGFR, we hypothesized that miR-7 regulates AKT and ERK1/2 pathway activation. "
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    ABSTRACT: Epidermal growth factor receptor (EGFR) overexpression and activation result in increased proliferation and migration of solid tumors including ovarian cancer. In recent years, mounting evidence indicates that EGFR is a direct and functional target of miR-7. In this study, we found that miR-7 expression was significantly downregulated in highly metastatic epithelial ovarian cancer (EOC) cell lines and metastatic tissues, whereas the expression of, EGFR correlated positively with metastasis in both EOC patients and cell lines. Overexpression of miR-7 markedly suppressed the capacities of cell invasion and migration and resulted in morphological changes from a mesenchymal phenotype to an epithelial-like phenotype in EOC. In addition, overexpression of miR-7 upregulated CK-18 and β-catenin expression and downregulated Vimentin expression, accompanied with EGFR inhibition and AKT/ERK1/2 inactivation. Similar to miR-7 transfection, silencing of EGFR with this siRNA in EOC cells also upregulated CK-18 and β-catenin expression and downregulated Vimentin expression, and decreased phosphorylation of both Akt and ERK1/2, confirming that EGFR is a target of miR-7 in reversing EMT. The pharmacological inhibition of PI3K-AKT and ERK1/2 both significantly enhanced CK-18 and β-catenin expression and suppressed vimentin expression, indicating that AKT and ERK1/2 pathways are required for miR-7 mediating EMT. Finally, the expression of miR-7 and EGFR in primary EOC with matched metastasis tissues was explored. It was showed that miR-7 is inversely correlated with EGFR. Taken together, our results suggested that miR-7 inhibited tumor metastasis and reversed EMT through AKT and ERK1/2 pathway inactivation by reducing EGFR expression in EOC cell lines. Thus, miR-7 might be a potential prognostic marker and therapeutic target for ovarian cancer metastasis intervention.
    PLoS ONE 05/2014; 9(5):e96718. DOI:10.1371/journal.pone.0096718 · 3.23 Impact Factor
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    • "The cells were then harvested and lysed with RIPA buffer (10 mM Tris–HCl, pH 8.0, 5 mM EDTA, 150 mM NaCl, 1% Na deoxycholale, 10 mM NaF, 1 mM Na 3 VO 3 , 1% Triton X-100 and 0.1% SDS with complete protease inhibitor cocktail tablet (Roche)) for Western blot analysis. The final concentrations of EGFR-inhibitor III (Shushan et al., 2007), PD98059 (Cheng et al., 2012; Lu et al., 2008), U0126 (Yang et al., 2007) and S3I-201 (Sen et al., 2012) were 2, 25, 10 and 50 lM, respectively . The final concentration of DMSO was controlled to under 0.1%. "
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    ABSTRACT: Embryo implantation requires a precise synchronism between the receptive uterus and activated blastocyst and is regulated by complicated molecular networks. Although many implantation-related genes have been identified, the crosstalk among them is still unknown. Snail, a transcription repressor, plays a central role during epithelial-mesenchymal transition. Our previous study showed that Snail is highly expressed at implantation site in mouse uterus. This study was to examine how Snail is related with other implantation-related genes in mice. Uterine stromal cells were isolated from mouse uteri on day 4 of pregnancy and treated with HB-EGF. Snail was induced significantly by HB-EGF. By using specific inhibitors and siRNA, we demonstrated that HB-EGF induction on Snail expression is dependent on the EGFR-ERK-Stat3 pathway. Cox-2 was regulated by Snail. The current findings demonstrate that Snail can relate with HB-EGF, Stat3 and Cox-2 and may play a role during mouse embryo implantation and decidualization.
    Molecular and Cellular Endocrinology 08/2013; 381(1-2). DOI:10.1016/j.mce.2013.08.011 · 4.41 Impact Factor
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    • "E-cadherin is a well-described cosuppressor that was important in cell adhesion. Decreased production of E-cadherin, one of the central events underlying EMT, has been linked to increased invasiveness in several cancers [9], [44]–[46]. However, there is no consensus on the association between reduced E-cadherin expression detected by IHC and poor survival in patients with CRC at present. "
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    ABSTRACT: Epithelial-mesenchymal transition (EMT) plays a crucial role in the progression and aggressiveness of colorectal carcinoma. E-cadherin is the best-characterized molecular marker of EMT, but its prognostic significance for patients with CRC remains inconclusive. Eligible studies were searched from the PubMed, Embase and Web of Science databases. Correlation between E-cadherin expression and clinicopathological features and prognosis was analyzed. Subgroup analysis was also performed according to study location, number of patients, quality score of studies and cut-off value. A total of 27 studies comprising 4244 cases met the inclusion criteria. Meta-analysis suggested that downregulated E-cadherin expression had an unfavorable impact on overall survival (OS) of CRC (n = 2730 in 14 studies; HR = 2.27, 95%CI: 1.63-3.17; Z = 4.83; P = 0.000). Subgroup analysis indicated that low E-cadherin expression was significantly associated with worse OS in Asian patients (n = 1054 in 9 studies; HR = 2.86, 95%CI: 2.13-3.7, Z = 7.11; P = 0.000) but not in European patients (n = 1552 in 4 studies; HR = 1.14, 95%CI: 0.95-1.35, Z = 1.39; P = 0.165). In addition, reduced E-cadherin expression indicated an unfavorable OS only when the cut off value of low E-cadherin expression was >50% (n = 512 in 4 studies; HR = 2.08, 95%CI 1.45-2.94, Z = 4.05; P = 0.000). Downregulated E-cadherin expression was greatly related with differentiation grade, Dukes' stages, lymphnode status and metastasis. The pooled OR was 0.36(95%CI: 0.19-0.7, Z = 3.03, P = 0.002), 0.34(95%CI: 0.21-0.55, Z = 6.61, P = 0.000), 0.49(95%CI: 0.32-0.74, Z = 3.02, P = 0.002) and 0.45(95%CI: 0.22-0.91, Z = 3.43, P = 0.001), respectively. This study showed that low or absent E-cadherin expression detected by immunohistochemistry served as a valuable prognostic factor of CRC. However, downregulated E-cadherin expression seemed to be associated with worse prognosis in Asian CRC patients but not in European CRC patients. Additionally, this meta-analysis suggested that the negative threshold of E-cadherin should be >50% when we detected its expression in the immunohistochemistry stain.
    PLoS ONE 07/2013; 8(7):e70858. DOI:10.1371/journal.pone.0070858 · 3.23 Impact Factor
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