Biology Contribution
Radiosensitizing the Vasculature of Primary Brainstem Gliomas Fails to Improve Tumor Response to Radiation Therapy

https://doi.org/10.1016/j.ijrobp.2021.09.047Get rights and content

Purpose

Diffuse intrinsic pontine gliomas (DIPGs) arise in the pons and are the leading cause of death from brain tumors in children. DIPGs are routinely treated with radiation therapy, which temporarily improves neurological symptoms but generally fails to achieve local control. Because numerous clinical trials have not improved survival from DIPG over standard radiation therapy alone, there is a pressing need to evaluate new therapeutic strategies for this devastating disease. Vascular damage caused by radiation therapy can increase the permeability of tumor blood vessels and promote tumor cell death.

Methods and Materials

To investigate the impact of endothelial cell death on tumor response to radiation therapy in DIPG, we used dual recombinase (Cre + FlpO) technology to generate primary brainstem gliomas which lack ataxia telangiectasia mutated (Atm) in the vasculature.

Results

Here, we show that Atm–deficient tumor endothelial cells are sensitized to radiation therapy. Furthermore, radiosensitization of the vasculature in primary gliomas triggered an increase in total tumor cell death. Despite the observed increase in cell killing, in mice with autochthonous DIPGs treated with radiation therapy, deletion of Atm specifically in tumor endothelial cells failed to improve survival.

Conclusions

These results suggest that targeting the tumor cells, rather than endothelial cells, during radiation therapy will be necessary to improve survival among children with DIPG.

Section snippets

Mouse strains

The Institutional Animal Care and Use Committee (IACUC) at Duke University approved all animal studies. The mouse strains used were previously described, including NestinTVA, p53FRT, VE-Cadherin-Cre, ATMFL, and Rosa26-loxP-STOP-loxP-tdTomato or LSL-Tomato.11, 12, 13, 14, 15 NestinTVA mice were provided by Oren Becher (Northwestern), and ATMFL mice were provided by Frederick Alt (Boston Children's Hospital). VE-Cadherin-Cre and LSL-Tomato mice were purchased from the Jackson Laboratory. The p53

Generating primary brainstem gliomas with radiosensitive vasculature

To evaluate the impact of endothelial cell death on tumor response to radiation therapy, we used RCAS-TVA technology to initiate primary tumor development in the neonatal brainstem.17 NestinTVA mice, which express the RCAS cognate tumor virus A (TVA) receptor in stem and progenitor cells of the brain, were injected in the brainstem with avian cells expressing RCAS retroviruses. Although RCAS-Cre has commonly been used to recombine and inactivate tumor suppressor alleles in the brain,18,19 we

Discussion

In order to evaluate the role of vascular damage in regulating brain tumor response to radiation therapy, we used RCAS-TVA and dual recombinase technology to generate primary brainstem gliomas in mice with radiosensitive vasculature. To enhance the cell death of endothelial cells, we used transgenic mice that specifically deleted Atm in endothelial cells. In this system, endothelial cell death increased approximately 3-fold. Moreover, we observed a doubling of total cell death within the tumors

Conclusions

Using a primary brainstem glioma model with enhanced vascular radiosensitivity, we observed increased radiation-induced endothelial cell death and indirect tumor cell death after radiation therapy. However, this did not translate into improved survival. These results support strategies to radiosensitize the tumor cells rather than the vasculature to try to improve survival in DIPG.

References (27)

  • D Hargrave et al.

    Diffuse brainstem glioma in children: Critical review of clinical trials

    Lancet Oncol

    (2006)
  • M Gallitto et al.

    Role of radiation therapy in the management of diffuse intrinsic pontine glioma: A systematic review

    Adv Radiat Oncol

    (2019)
  • C Barlow et al.

    ATM-deficient mice: A paradigm of ataxia telangiectasia

    Cell

    (1996)
  • CW Song et al.

    Biological principles of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS): Indirect cell death

    Int J Radiat Oncol Biol Phys

    (2019)
  • W Budach et al.

    Impact of stromal sensitivity on radiation response of tumors

    J Natl Cancer Inst

    (1993)
  • EJ Moding et al.

    Atm deletion with dual recombinase technology preferentially radiosensitizes tumor endothelium

    J Clin Invest

    (2014)
  • EJ Moding et al.

    Tumor cells, but not endothelial cells, mediate eradication of primary sarcomas by stereotactic body radiation therapy

    Sci Transl Med

    (2015)
  • Y Shiloh et al.

    The ATM protein kinase: Regulating the cellular response to genotoxic stress, and more

    Nature Rev Molecular Cell Biol

    (2013)
  • MD Rainey et al.

    Transient inhibition of ATM kinase is sufficient to enhance cellular sensitivity to ionizing radiation

    Cancer Res

    (2008)
  • I Hickson et al.

    Identification and characterization of a novel and specific inhibitor of the ataxia-telangiectasia mutated kinase ATM

    Cancer Res

    (2004)
  • S Zha et al.

    Ataxia telangiectasia-mutated protein and DNA-dependent protein kinase have complementary V(D)J recombination functions

    Proc Natl Acad Sci U S A

    (2011)
  • EC Holland et al.

    Modeling mutations in the G1 arrest pathway in human gliomas: Overexpression of CDK4 but not loss of INK4a-ARF induces hyperploidy in cultured mouse astrocytes

    Genes Dev

    (1998)
  • JA Alva et al.

    VE-Cadherin-Cre-recombinase transgenic mouse: A tool for lineage analysis and gene deletion in endothelial cells

    Dev Dyn

    (2006)

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    This work was supported by grants (to D.G.K.) from the National Cancer Institute (R35 CA197616), the Pediatric Brain Tumor Foundation, Hannah's Heroes St. Baldrick's Research Grant, and The Leon Levine Foundation. D.G.K. and K.D. were supported by the National Cancer Institute (Duke Brain SPORE P50-CA19099). O.J.B. was supported by Madox's Warriors, the Fly A Kite Foundation, Cristian Rivera Foundation, and the Rory David Deutsch Foundation. Z.J.R. was supported by the Pediatric Brain Tumor Foundation, an Emily Beazley's Kures for Kids St. Baldrick's Research Fellowship, and a New Investigator Award from the Michael Mosier Defeat DIPG and ChadTough and SoSo Strong Foundations.

    Disclosures: D.G.K. is a cofounder of and received research support from XRad Therapeutics, which is developing radiosensitizers; is on the scientific advisory board of and owns stock in Lumicell, Inc, which is developing intraoperative imaging technology; and receives research support from Merck, Bristol-Myers Squibb, and Varian Medical Systems.

    All data analyzed during this study are included in this published article (and its supplementary information files), and the raw data used to generate each figure are stored on a laboratory server.

    Acknowledgments—The authors dedicate this work to the memory of Rose Sugarman, who died of a DIPG. The authors thank John Nouls from the Duke Center for In Vivo Microscopy for assistance in obtaining magnetic resonance images.

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