De novo purine biosynthesis is a major driver of chemoresistance in glioblastoma

Jack M. Shireman, Fatemeh Atashi, Gina Lee, Eunus S. Ali, Miranda R. Saathoff, Cheol H. Park, Sol Savchuk, Shivani Baisiwala, Jason Miska, MacIej S. Lesniak, C. David James, Roger Stupp, Priya Kumthekar, Craig M. Horbinski, Issam Ben-Sahra, Atique U. Ahmed

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Glioblastoma is a primary brain cancer with a near 100% recurrence rate. Upon recurrence, the tumour is resistant to all conventional therapies, and because of this, 5-year survival is dismal. One of the major drivers of this high recurrence rate is the ability of glioblastoma cells to adapt to complex changes within the tumour microenvironment. To elucidate this adaptation's molecular mechanisms, specifically during temozolomide chemotherapy, we used chromatin immunoprecipitation followed by sequencing and gene expression analysis. We identified a molecular circuit in which the expression of ciliary protein ADP-ribosylation factor-like protein 13B (ARL13B) is epigenetically regulated to promote adaptation to chemotherapy. Immuno-precipitation combined with liquid chromatography-mass spectrometry binding partner analysis revealed that that ARL13B interacts with the purine biosynthetic enzyme inosine-5′-monophosphate dehydrogenase 2 (IMPDH2). Further, radioisotope tracing revealed that this interaction functions as a negative regulator for purine salvaging. Inhibition of the ARL13B-IMPDH2 interaction enhances temozolomide-induced DNA damage by forcing glioblastoma cells to rely on the purine salvage pathway. Targeting the ARLI3B-IMPDH2 circuit can be achieved using the Food and Drug Administration-approved drug, mycophenolate mofetil, which can block IMPDH2 activity and enhance the therapeutic efficacy of temozolomide. Our results suggest and support clinical evaluation of MMF in combination with temozolomide treatment in glioma patients.

Original languageEnglish
Pages (from-to)1230-1246
Number of pages17
Issue number4
StatePublished - Apr 1 2021

Bibliographical note

Publisher Copyright:
© 2021 The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For permissions, please email:


  • cellular plasticity
  • chemoresistance
  • glioblastoma
  • purine biosynthesis

ASJC Scopus subject areas

  • Clinical Neurology


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