EGFR phosphorylation of DCBLD2 recruits TRAF6 and stimulates AKT-promoted tumorigenesis
Haizhong Feng, … , Hai Yan, Shi-Yuan Cheng
Haizhong Feng, … , Hai Yan, Shi-Yuan Cheng
Published July 25, 2014
Citation Information: J Clin Invest. 2014;124(9):3741-3756. https://doi.org/10.1172/JCI73093.
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EGFR phosphorylation of DCBLD2 recruits TRAF6 and stimulates AKT-promoted tumorigenesis

Abstract

Aberrant activation of EGFR in human cancers promotes tumorigenesis through stimulation of AKT signaling. Here, we determined that the discoidina neuropilin-like membrane protein DCBLD2 is upregulated in clinical specimens of glioblastomas and head and neck cancers (HNCs) and is required for EGFR-stimulated tumorigenesis. In multiple cancer cell lines, EGFR activated phosphorylation of tyrosine 750 (Y750) of DCBLD2, which is located within a recently identified binding motif for TNF receptor-associated factor 6 (TRAF6). Consequently, phosphorylation of DCBLD2 Y750 recruited TRAF6, leading to increased TRAF6 E3 ubiquitin ligase activity and subsequent activation of AKT, thereby enhancing EGFR-driven tumorigenesis. Moreover, evaluation of patient samples of gliomas and HNCs revealed an association among EGFR activation, DCBLD2 phosphorylation, and poor prognoses. Together, our findings uncover a pathway in which DCBLD2 functions as a signal relay for oncogenic EGFR signaling to promote tumorigenesis and suggest DCBLD2 and TRAF6 as potential therapeutic targets for human cancers that are associated with EGFR activation.

Authors

Haizhong Feng, Giselle Y. Lopez, Chung Kwon Kim, Angel Alvarez, Christopher G. Duncan, Ryo Nishikawa, Motoo Nagane, An-Jey A. Su, Philip E. Auron, Matthew L. Hedberg, Lin Wang, Jeffery J. Raizer, John A. Kessler, Andrew T. Parsa, Wei-Qiang Gao, Sung-Hak Kim, Mutsuko Minata, Ichiro Nakano, Jennifer R. Grandis, Roger E. McLendon, Darell D. Bigner, Hui-Kuan Lin, Frank B. Furnari, Webster K. Cavenee, Bo Hu, Hai Yan, Shi-Yuan Cheng

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Figure 2

DCBLD2 is required for EGFR-driven tumorigenesis.

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DCBLD2 is required for EGFR-driven tumorigenesis. (A) IB analyses of DCB...
(A) IB analyses of DCBLD2 knockdown with 2 different shRNAs (shD2#1 and shD2#2) or a control shRNA in U87 and SNB19 cells. P, parental cells; vIII, U87 or SNB19 cells expressing EGFRvIII. β-Actin was used as a loading control. (B) Effects of knockdown of DCBLD2 by shD2 or shC on cell proliferation in vitro. (C) Effects of knockdown of DCBLD2 by shD2 or shC on cell apoptosis in vitro. (D) Effect of DCBLD2 knockdown by shD2 or shC on glioma cell colony formation in vitro. (E) shRNA knockdown of DCBLD2 inhibits EGFRvIII-promoted U87 glioma growth in the brain. Representative images of H&E, Ki-67, and TUNEL analyses of brain sections, with indicated U87 gliomas (arrows). Nuclei were stained with DAPI (blue). Ki-67 and TUNEL are in red. Scale bars: 1 mm (H&E staining); 50 μm (Ki-67 staining); 100 μm (TUNEL staining). Images represent results of 5 mice per group. (F) Quantification of tumor size, cell proliferation, and cell apoptosis. Data were from stained brain sections of 5 mice per group. (G) IB analyses of DCBLD2 knockdown by shD2 or shC in patient-derived GSCs (GSC83). (H) shRNA knockdown of DCBLD2 inhibits endogenous EGFRvIII-promoted tumorigenesis of gliomas established by patient-derived GSC83 cells in the brain. Quantification of tumor size is also shown. Scale bars: 1 mm. In B, C, D, F, and H, error bars ± SD. *P < 0.05, **P < 0.01, compared with parental or EGFRvIII cells or tumors treated with shC. Data and images are representative of 2 to 3 independent experiments.