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Activation of mammalian target of rapamycin complex 1 (mTORC1) and Raf/Pyk2 by growth factor-mediated Eph receptor 2 (EphA2) is required for cholangiocarcinoma growth and metastasis

Authors

  • Xiang-Dan Cui,

    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
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  • Mi-Jin Lee,

    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
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  • Jong-Hyun Kim,

    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
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  • Pei-Pei Hao,

    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
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  • Lan Liu,

    1. Department of Pathology, Yanbian University Hospital, Yanji, Jilin, China
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  • Goung-Ran Yu,

    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
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  • Dae-Ghon Kim

    Corresponding author
    1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Institute for Medical Science, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk, Republic of Korea
    • Division of GI and Hepatology, Research Institute of Clinical Medicine, Department of Internal Medicine, Chonbuk National University Medical School and Hospital, Jeonju, Jeonbuk 561-712, Republic of Korea
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    • fax: +82-63-254-1609


  • Potential conflict of interest: Nothing to report.

  • These authors contributed equally to this work

Abstract

Eph receptor 2 (EphA2) overexpression is frequently accompanied by the loss of its cognate ligand during tumor progression. However, the molecular mechanism of this ligand-independent promotion of tumor by EphA2 remains unclear in highly malignant and fatal cholangiocarcinoma (CC). We examined the biological role of EphA2 in tumor growth and metastasis in CC tissues and cells according to the degree of differentiation and we explored the downstream signaling pathways of EphA2. Growth factor-mediated EphA2 overexpression itself leads to the activation of the mammalian target of rapamycin complex 1 (mTORC1) and extracellular signal-regulated kinase (ERK) pathways through ligand-independent activation of EphA2 (phosphorylation of S897). An in vitro soft agar assay and in vivo orthotopic or subcutaneous tumor model showed that EphA2 enhanced colony formation and accelerated tumor growth, and which seemed to be mainly associated with Akt (T308)/mTORC1 activation. Aberrant expression and activation of EphA2 was also associated with poorer differentiation and higher metastatic ability. Enhanced metastatic ability was also observed in an orthotopic tumor model or lung metastasis model, correlating with Pyk2(Y402)/c-Src/ERK activation in addition to activation of the canonical Raf/MEK/ERK pathway. The mTORC1 and Raf/Pyk2 pathways also appeared to affect each other. These results suggest that growth factor-mediated EphA2 might be involved in tumor growth and metastasis through activation of the mTORC1 and Raf/Pyk2 pathways. Therapeutic strategies that target EphA2 and its downstream effectors may be useful to control CC. (HEPATOLOGY 2013;57:2248–2260)

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