Open Access

Myristoylated alanine-rich C-kinase substrate effector domain phosphorylation regulates the growth and radiation sensitization of glioblastoma

  • Authors:
    • Nicholas J. Eustace
    • Joshua C. Anderson
    • Catherine P. Langford
    • Hoa Q. Trummell
    • Patricia H. Hicks
    • John S. Jarboe
    • James A. Mobley
    • Anita B. Hjelmeland
    • James R. Hackney
    • Rune T. Pedersen
    • Kadia Cosby
    • G. Yancey Gillespie
    • James A. Bonner
    • Christopher D. Willey
  • View Affiliations

  • Published online on: March 29, 2019     https://doi.org/10.3892/ijo.2019.4766
  • Pages: 2039-2053
  • Copyright: © Eustace et al. This is an open access article distributed under the terms of Creative Commons Attribution License.

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Abstract

Glioblastoma harbors frequent alterations in receptor tyrosine kinases, phosphatidylinositol‑3 kinase (PI3K) and phosphatase and tensin homolog (PTEN) that dysregulate phospholipid signaling driven tumor proliferation and therapeutic resistance. Myristoylated alanine‑rich C‑kinase substrate (MARCKS) is a 32 kDa intrinsically unstructured protein containing a polybasic (+13) effector domain (ED), which regulates its electrostatic sequestration of phospholipid phosphatidylinositol (4,5)‑bisphosphate (PIP2), and its binding to phosphatidylserine, calcium/calmodulin, filamentous actin, while also serving as a nuclear localization sequence. MARCKS ED is phosphorylated by protein kinase C (PKC) and Rho‑associated protein kinase (ROCK) kinases; however, the impact of MARCKS on glioblastoma growth and radiation sensitivity remains undetermined. In the present study, using a tetracycline‑inducible system in PTEN‑null U87 cells, we demonstrate that MARCKS overexpression suppresses growth and enhances radiation sensitivity in vivo. A new image cytometer, Xcyto10, was utilized to quantify differences in MARCKS ED phosphorylation on localization and its association with filamentous actin. The overexpression of the non‑phosphorylatable ED mutant exerted growth‑suppressive and radiation‑sensitizing effects, while the pseudo‑phosphorylated ED mutant exhibited an enhanced colony formation and clonogenic survival ability. The identification of MARCKS protein‑protein interactions using co‑immunoprecipitation coupled with tandem mass spectrometry revealed novel MARCKS‑associated proteins, including importin‑β and ku70. On the whole, the findings of this study suggest that the determination of the MARCKS ED phosphorylation status is essential to understanding the impact of MARCKS on cancer progression.

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June 2019
Volume 54 Issue 6

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

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APA
Eustace, N.J., Anderson, J.C., Langford, C.P., Trummell, H.Q., Hicks, P.H., Jarboe, J.S. ... Willey, C.D. (2019). Myristoylated alanine-rich C-kinase substrate effector domain phosphorylation regulates the growth and radiation sensitization of glioblastoma. International Journal of Oncology, 54, 2039-2053. https://doi.org/10.3892/ijo.2019.4766
MLA
Eustace, N. J., Anderson, J. C., Langford, C. P., Trummell, H. Q., Hicks, P. H., Jarboe, J. S., Mobley, J. A., Hjelmeland, A. B., Hackney, J. R., Pedersen, R. T., Cosby, K., Gillespie, G. Y., Bonner, J. A., Willey, C. D."Myristoylated alanine-rich C-kinase substrate effector domain phosphorylation regulates the growth and radiation sensitization of glioblastoma". International Journal of Oncology 54.6 (2019): 2039-2053.
Chicago
Eustace, N. J., Anderson, J. C., Langford, C. P., Trummell, H. Q., Hicks, P. H., Jarboe, J. S., Mobley, J. A., Hjelmeland, A. B., Hackney, J. R., Pedersen, R. T., Cosby, K., Gillespie, G. Y., Bonner, J. A., Willey, C. D."Myristoylated alanine-rich C-kinase substrate effector domain phosphorylation regulates the growth and radiation sensitization of glioblastoma". International Journal of Oncology 54, no. 6 (2019): 2039-2053. https://doi.org/10.3892/ijo.2019.4766