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Additive Effects of Cu-ATSM and Radiation on Survival of Diffuse Intrinsic Pontine Glioma Cells
Journal article   Open access   Peer reviewed

Additive Effects of Cu-ATSM and Radiation on Survival of Diffuse Intrinsic Pontine Glioma Cells

Sarah A King, Shane R Solst, Claire H Graham, Lianna Z Fiore, Rana Rheem, Ann Tomanek-Chalkley, Melissa A Fath, Joseph M Caster, Douglas R Spitz and Michelle E Howard
Radiation research, Vol.203(1), pp.10-17
01/2025
DOI: 10.1667/RADE-24-00076.1
PMCID: PMC11815956
PMID: 39492578
url
https://pmc.ncbi.nlm.nih.gov/articles/PMC11815956/pdf/nihms-2048522.pdfView
Open Access

Abstract

Diffuse intrinsic pontine gliomas (DIPG) are highly aggressive and treatment-resistant childhood primary brainstem tumors with a median survival of less than one year after diagnosis. The prevailing standard of care for DIPG, radiation therapy, does not prevent fatal disease progression, with most patients succumbing to this disease 3-8 months after completion of radiation therapy. This underscores the urgent need for novel combined-modality approaches for enhancing therapy responses. This study demonstrates that the cellular redox modulating drug, copper (II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) dose-dependently (1-3 μM) decreased clonogenic cell survival in SU-DIPG50 and SU-DIPG36 cell lines during 6 h of exposure but had no significant effect on survival in normal human astrocytes (NHA). Additional significant (>90%) decreases in DIPG clonogenic survival were observed at 24 h of Cu-ATSM exposure. However, NHAs also began to show dose-dependent 10-70% survival decreases at this point. Notably, 3 μM Cu-ATSM for 6 h resulted in additive clonogenic cell killing of DIPG lines when combined with radiation, which was not seen in NHAs and was partially inhibited by the copper chelator, bathocuproinedisulfonic acid. Cu-ATSM toxicity in DIPG cells was also inhibited by overexpression of mitochondrial-targeted catalase. These results support the hypothesis that Cu-ATSM is selectively cytotoxic to DIPGs by a mechanism involving H2O2 generation and copper and being additively cytotoxic with ionizing radiation.Diffuse intrinsic pontine gliomas (DIPG) are highly aggressive and treatment-resistant childhood primary brainstem tumors with a median survival of less than one year after diagnosis. The prevailing standard of care for DIPG, radiation therapy, does not prevent fatal disease progression, with most patients succumbing to this disease 3-8 months after completion of radiation therapy. This underscores the urgent need for novel combined-modality approaches for enhancing therapy responses. This study demonstrates that the cellular redox modulating drug, copper (II)-diacetyl-bis(N4-methylthiosemicarbazone) (Cu-ATSM) dose-dependently (1-3 μM) decreased clonogenic cell survival in SU-DIPG50 and SU-DIPG36 cell lines during 6 h of exposure but had no significant effect on survival in normal human astrocytes (NHA). Additional significant (>90%) decreases in DIPG clonogenic survival were observed at 24 h of Cu-ATSM exposure. However, NHAs also began to show dose-dependent 10-70% survival decreases at this point. Notably, 3 μM Cu-ATSM for 6 h resulted in additive clonogenic cell killing of DIPG lines when combined with radiation, which was not seen in NHAs and was partially inhibited by the copper chelator, bathocuproinedisulfonic acid. Cu-ATSM toxicity in DIPG cells was also inhibited by overexpression of mitochondrial-targeted catalase. These results support the hypothesis that Cu-ATSM is selectively cytotoxic to DIPGs by a mechanism involving H2O2 generation and copper and being additively cytotoxic with ionizing radiation.

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