The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma

  • Authors:
    • Dingyuan Luo
    • Xinke Xu
    • Junliang Li
    • Cheng Chen
    • Wei Chen
    • Fangyu Wang
    • Yanping Xie
    • Fangcheng Li
  • View Affiliations

  • Published online on: August 14, 2018     https://doi.org/10.3892/ijo.2018.4525
  • Pages: 2067-2080
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Abstract

Glioblastoma multiforme (GBM) is the most common primary malignant tumor affecting the human brain. Despite improvements in therapeutic technologies, patients with GBM have a poor clinical result and the molecular mechanisms responsible for the development of GBM have not yet been fully elucidated. 3-phosphoinositide dependent protein kinase 1 (PDK1) is upregulated in various tumors and promotes tumor invasion. In glioma, transforming growth factor-β (TGF‑β) promotes cell invasion; however, whether TGF‑β directly regulates PDK1 protein and promotes proliferation and invasion is not yet clear. In this study, PDK1 levels were measured in glioma tissues using tissue microarray (TMA) by immunohistochemistry (IHC) and RT‑qPCR. Kaplan-Meier analyses were used to calculate the survival rate of patients with glioma. In vitro, U251 and U87 glioma cell lines were used for functional analyses. Cell proliferation and invasion were analyzed using siRNA transfection, MTT assay, RT‑qPCR, western blot analysis, flow cytometry and invasion assay. In vivo, U251 glioma cell xenografts were established. The results revealed that PDK1 protein was significantly upregulated in glioma tissues compared with non-tumorous tissues. Furthermore, the higher PDK1 levels were associated with a large tumor size (>5.0 cm), a higher WHO grade and a shorter survival of patients with GBM. Univariate and multivariate analyses indicated that PDK1 was an independent prognostic factor. In vivo, PDK1 promoted glioma tumor xenograft growth. In vitro, functional analyses confirmed that TGF‑β upregulated PDK1 protein expression and PDK1 promoted cell migration and invasion, and functioned as an oncogene in GBM, by upregulating c‑Jun protein and inducing epithelial-mesenchymal transition (EMT). c‑Jun protein were overexpressed in glioma tissues and positively correlated with PDK1 levels. Moreover, our findings were further validated by the online Oncomine database. On the whole, the findings of this study indicate that in GBM, PDK1 functions as an oncogene, promoting proliferation and invasion.
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November-2018
Volume 53 Issue 5

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Luo D, Xu X, Li J, Chen C, Chen W, Wang F, Xie Y and Li F: The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma. Int J Oncol 53: 2067-2080, 2018
APA
Luo, D., Xu, X., Li, J., Chen, C., Chen, W., Wang, F. ... Li, F. (2018). The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma. International Journal of Oncology, 53, 2067-2080. https://doi.org/10.3892/ijo.2018.4525
MLA
Luo, D., Xu, X., Li, J., Chen, C., Chen, W., Wang, F., Xie, Y., Li, F."The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma". International Journal of Oncology 53.5 (2018): 2067-2080.
Chicago
Luo, D., Xu, X., Li, J., Chen, C., Chen, W., Wang, F., Xie, Y., Li, F."The PDK1/c‑Jun pathway activated by TGF‑β induces EMT and promotes proliferation and invasion in human glioblastoma". International Journal of Oncology 53, no. 5 (2018): 2067-2080. https://doi.org/10.3892/ijo.2018.4525