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TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.

Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Temozolomide (TMZ) is the only drug currently been used for treatment of newly diagnosed GBM patients but the benefit from this agent has been hampered by the primary and secondary resistance. Thus, there is a strong need for...

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Autores principales: Kitange, Gaspar, Sarkaria, Jann
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10616571/
http://dx.doi.org/10.1093/noajnl/vdad121.056
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author Kitange, Gaspar
Sarkaria, Jann
author_facet Kitange, Gaspar
Sarkaria, Jann
author_sort Kitange, Gaspar
collection PubMed
description Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Temozolomide (TMZ) is the only drug currently been used for treatment of newly diagnosed GBM patients but the benefit from this agent has been hampered by the primary and secondary resistance. Thus, there is a strong need for uncovering the mechanisms of TMZ resistance. The DNA repair protein O6-methylguanine-DNA-methyltransferase (MGMT) is the main driver of primary TMZ resistance and lacking MGMT expression due to promoter hypermethylation has been associated with a significant survival prolongation. However, the MGMT-independent resistance mechanisms remain poorly understood. To investigate TMZ resistance mechanisms, we developed in vivo TMZ resistant models using GBM patient derived xenografts (PDXs) by treating animals bearing flank PDXs with clinically relevant 3-cyles of TMZ. The recurrent tumors were all resistant to TMZ through multiple mechanisms, including MGMT re-expression, elevated homologous recombination (HR) and/or non-homologous end joining (NHEJ) repair activities, and loss of mismatch repair (MMR). However, other tumors developed resistance due to unknown mechanisms. To identify novel modulators of TMZ sensitivity, we performed genome wide screening using shRNA library, and we identified over 600 druggable targets. Validation experiments identified RBBP4 gene as one of the candidates involved in TMZ sensitivity. Silencing RBBP4 in GBM cells sensitized both MGMT-methylated and -unmethylated GBM cells to TMZ. Mechanistically, RBBP4 interacts with p300 to form a chromatin remodeling complex that control expression of DNA damage repair genes, and silencing RBBP4 or p300 significantly blocked the recovery of TMZ induced DNA double strand breaks causing cell death. We also found the nuclear pore exporter XPO1 is the modulator of TMZ sensitivity, and the XPO1 inhibitor Selinexor is currently being evaluated for GBM treatment in a clinical trial. Collectively, our work has uncovered multiple mechanisms of TMZ resistance that are potential targets for GBM therapy.
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spelling pubmed-106165712023-11-01 TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY. Kitange, Gaspar Sarkaria, Jann Neurooncol Adv Final Category: Translational Research Glioblastoma (GBM) is the most common and aggressive primary brain tumor. Temozolomide (TMZ) is the only drug currently been used for treatment of newly diagnosed GBM patients but the benefit from this agent has been hampered by the primary and secondary resistance. Thus, there is a strong need for uncovering the mechanisms of TMZ resistance. The DNA repair protein O6-methylguanine-DNA-methyltransferase (MGMT) is the main driver of primary TMZ resistance and lacking MGMT expression due to promoter hypermethylation has been associated with a significant survival prolongation. However, the MGMT-independent resistance mechanisms remain poorly understood. To investigate TMZ resistance mechanisms, we developed in vivo TMZ resistant models using GBM patient derived xenografts (PDXs) by treating animals bearing flank PDXs with clinically relevant 3-cyles of TMZ. The recurrent tumors were all resistant to TMZ through multiple mechanisms, including MGMT re-expression, elevated homologous recombination (HR) and/or non-homologous end joining (NHEJ) repair activities, and loss of mismatch repair (MMR). However, other tumors developed resistance due to unknown mechanisms. To identify novel modulators of TMZ sensitivity, we performed genome wide screening using shRNA library, and we identified over 600 druggable targets. Validation experiments identified RBBP4 gene as one of the candidates involved in TMZ sensitivity. Silencing RBBP4 in GBM cells sensitized both MGMT-methylated and -unmethylated GBM cells to TMZ. Mechanistically, RBBP4 interacts with p300 to form a chromatin remodeling complex that control expression of DNA damage repair genes, and silencing RBBP4 or p300 significantly blocked the recovery of TMZ induced DNA double strand breaks causing cell death. We also found the nuclear pore exporter XPO1 is the modulator of TMZ sensitivity, and the XPO1 inhibitor Selinexor is currently being evaluated for GBM treatment in a clinical trial. Collectively, our work has uncovered multiple mechanisms of TMZ resistance that are potential targets for GBM therapy. Oxford University Press 2023-10-31 /pmc/articles/PMC10616571/ http://dx.doi.org/10.1093/noajnl/vdad121.056 Text en © The Author(s) 2023. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology. https://creativecommons.org/licenses/by-nc/4.0/This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Final Category: Translational Research
Kitange, Gaspar
Sarkaria, Jann
TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title_full TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title_fullStr TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title_full_unstemmed TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title_short TRANSLATIONAL RESEARCH-03 MULTIPLE MECHANISMS MODULATE TEMOZOLOMIDE RESISTANCE AND ARE POTENTIAL TARGETS FOR GLIOBLASTOMA THERAPY.
title_sort translational research-03 multiple mechanisms modulate temozolomide resistance and are potential targets for glioblastoma therapy.
topic Final Category: Translational Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10616571/
http://dx.doi.org/10.1093/noajnl/vdad121.056
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