MicroRNA-200c increases radiosensitivity of human cancer cells with activated EGFR-associated signaling
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Taeryool Koo1,*, Bong Jun Cho2,*, Dan Hyo Kim2, Ji Min Park1,2, Eun Jung Choi2, Hans H. Kim2, David J Lee2 and In Ah Kim1,2,3,4
1Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul, Republic of Korea
2Medical Science Research Institute, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
3Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
4Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea
*These authors contributed equally to this work
In Ah Kim, email: [email protected]
Keywords: microRNA-200c, EGFR-associated signaling network, radiosensitization, human cancer cells
Received: February 13, 2016 Accepted: February 06, 2017 Published: July 03, 2017
MicroRNA-200c (miR-200c) recently was found to have tumor-suppressive properties by inhibiting the epithelial-mesenchymal transition (EMT) in several cancers. miR-200c also interacts with various cellular signaling molecules and regulates many important signaling pathways. In this study, we investigated the radiosensitizing effect of miR-200c and its mechanism in a panel of human cancer cell lines. Malignant glioma (U251, T98G), breast cancer (MDA-MB-468), and lung carcinoma (A549) cells were transfected with control pre-microRNA, pre-miR-200c, or anti-miR-200c. Then, RT-PCR, clonogenic assays, immunoblotting, and immunocytochemisty were performed. To predict the potential targets of miR-200c, microRNA databases were used for bioinformatics analysis. Ectopic overexpression of miR-200c downregulated p-EGFR and p-AKT and increased the radiosensitivity of U251, T98G, A549, and MDA-MB-468 cells. In contrast, miR-200c inhibition upregulated p-EGFR and p-AKT, and decreased radiation-induced cell killing. miR-200c led to persistent γH2AX focus formation and downregulated pDNA-PKc expression. Autophagy and apoptosis were major modes of cell death. Bioinformatics analysis predicted that miR-200c may be associated with EGFR, AKT2, MAPK1, VEGFA, and HIF1AN. We also confirmed that miR-200c downregulated the expression of VEGF, HIF-1α, and MMP2 in U251 and A549 cells. In these cells, overexpressing miR-200c inhibited invasion, migration, and vascular tube formation. These phenotypic changes were associated with E-cadherin and EphA2 downregulation and N-cadherin upregulation. miR-200c showed no observable cytotoxic effect on normal human fibroblasts and astrocytes. Taken together, our data suggest that miR-200c is an attractive target for improving the efficacy of radiotherapy via a unique modulation of the complex regulatory network controlling cancer pro-survival signaling and EMT.
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