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Y. Murata
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P2.01 - Poster Session with Presenters Present (ID 461)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Biology/Pathology
- Presentations: 1
- Moderators:
- Coordinates: 12/06/2016, 14:30 - 15:45, Hall B (Poster Area)
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P2.01-071 - Biological Implication of Cytoplasmic ECT2 in Malignant Progression of Lung Adenocarcinoma (ID 4361)
14:30 - 14:30 | Author(s): Y. Murata
- Abstract
Background:
Epithelial cell transforming 2 (ECT2) is a guanine nucleotide exchange factor (GEF) for Rho family GTPases including RhoA, Rac1, and Cdc42. In normal cells, ECT2 is localized in the nucleus,where it regulates dynamic processes including the cell cycle and cytokinesis. On the other hand, several studies have suggested that ECT2 signaling promotes tumor proliferation, migration, and invasion in non-small cell lung cancer. Recently, Murata et al. demonstrated that ECT2 is amplified in early invasive adenocarcinoma but not in situ adenocarcinoma (Cancer Sci, 105:490, 2014). However, the oncogenic mechanism whereby ECT2 drives cell transformation in lung adenocarcinoma is still unknown
Methods:
Cellular fractionation assay was conducted using nine lung adenocarcinoma cell lines Calu-3, A549, RERF-LC-KJ, NCI-H1650, PC-9, NCI-H23, NCI-H1975, LC-2/ad, and HCC827. Immunoblotting, Immunofluorescence, and Immunohistochemistry assays were used to evaluate the expression and localization of ECT2. For ECT2 amplification, nine lung adenocarcinoma were genetically examined using Quantitative Real-Time PCR. Immunoprecipitation was used to examine the interaction between ECT2 and PKCι. And ECT2 siRNA was confirmed the effect of ECT2 on the downstream singling pathway.
Results:
In this study, we showed that ECT2 was localized predominantly in the nucleus of normal lung epithelial cells, whereas tumor cells in nine lung adenocarcinoma cell lines expressed ECT2 protein to differing degrees in their cytoplasm. Importantly, high expression of cytoplasmic ECT2 in surgically resected materials was significantly associated with poor outcome. Moreover, our data showed that overexpression of ECT2 mRNA was roughly correlated with ECT2 amplification in lung adenocarcinoma cell lines. We then investigated the mechanism underlying the cytoplasmic localization of ECT2 and its oncogenic activity in lung adenocarcinoma using the lung adenocarcinoma cell lines Calu-3, A549, RERF-LC-KJ, NCI-H1650, PC-9, NCI-H23, NCI-H1975, LC-2/ad, and HCC827. We found that the cytoplasmic ECT2 was phosphorylated and bound to protein kinase C iota (PKCι) in the cytoplasm. We also observed that the overexpression of cytoplasmic ECT2 greatly increased its degree of phosphorylation and enhanced its interaction with PKCι, resulting in significant promotion of tumor growth through activation of the Mek1,2/Erk1,2 cytoplasmic downstream signaling pathway.
Conclusion:
These results indicate that aberrant cytoplasmic localization of ECT2 is a specific feature of lung adenocarcinoma and important for its malignant progression. This finding offers new insight into the molecular mechanism responsible for aberrant cytoplasmic localization of ECT2, which is correlated with the progression of malignancy, and highlights cytoplasmic ECT2 expression as a new prognostic biomarker in lung adenocarcinoma.
