Cellular senescence is a tumor suppressor mechanism. However glioblastoma multiforme (GBM), the most malignant primary brain tumor with a median survival of about one year, is highly resistant to senescence. There is a critical need for new therapeutic modalities and agents that sensitize GBM to senescence to improve patient outcome. A family of PI5P4K phosphorylates phosphatidylinositol 5-phosphate (PI5P) and converts it to phosphatidylinositol 4,5-phosphate (PI[4,5]P2) to regulate phosphoinositide signaling. In the preliminary studies, my laboratory found that PI5P4K?inds directly to guanine nucleotides. Our X-ray structural analyses show that PI5P4K?tilizes GTP as the preferred phospho-donor, as opposed to ATP. Kinetic analyses also predict that physiological GTP levels control the PI5P4K?ctivity. Importantly, we have found that cellular GTP levels play critical rol in suppressing GBM senescence and that PI5P4K?nockdown triggers senescence of GBM cells. We have identified a small chemical compound that inhibits PI5P4K activity in vitro and in vivo. The treatment of the PI5P4K chemical inhibitor induces senescence of GBM cells. These results indicate that inhibitors of PI5P4K?ould be useful in preventing or treating GBM. The goal of this proposal is to determine the significance of a novel type of GTP-dependent kinase, PI5P4K?in regulating GBM senescence, and to determine whether inhibition of PI5P4K?ould induce GBM senescence and reduce its tumorigenic activity in vitro and in vivo. To test the hypothesis, we will determine the role of PI5P4K?n GBM cell growth by shRNA-mediated PI5P4K?nockdown and pharmacological inhibition using in vitro cell culture and a clinically relevant orthotopic implantation model of glioblastoma (Aim 1). We will use biochemical and biological analyses to determine the mechanism of GTP detection by PI5P4K?Aim 2). We will determine how PI5P4K?egulates senescence by characterizing PI5P4K?ownstream effectors (Aim 3). Collectively, these studies will lead to reveal the novel mechanism and opportunity for inducing senescence and growth arrest of glioblastoma cells by targeting PI5P4K?

Public Health Relevance

Glioblastoma multiforme (GBM) is the most prominent and malignant primary brain tumor confers a dismal median survival of about one year. In this proposal we will test the hypothesis that inhibition of PI5P4K?phosphatidylinositol-5-phosphate 4-kinase-?will serve as a new therapeutic strategy against GBM. We will use pharmacological and molecular approaches that target PI5P4K?n GBM cell culture and in GBM animal tumor models.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS089815-03
Application #
9132360
Study Section
Tumor Cell Biology Study Section (TCB)
Program Officer
Fountain, Jane W
Project Start
2014-09-30
Project End
2019-08-31
Budget Start
2016-09-01
Budget End
2017-08-31
Support Year
3
Fiscal Year
2016
Total Cost
$334,827
Indirect Cost
$122,911
Name
University of Cincinnati
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
041064767
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
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