Human translesion DNA polymerases ι and κ mediate tolerance to temozolomide in MGMT-deficient glioblastoma cells

Glioblastoma (GBM) is a highly aggressive brain tumor associated with poor patient survival. The current standard treatment involves invasive surgery, radiotherapy, and chemotherapy employing temozolomide (TMZ). Resistance to TMZ is, however, a major challenge. Previous work from our group has ident...

Full description

Saved in:
Bibliographic Details
Published in:DNA repair 2024-09, Vol.141, p.103715, Article 103715
Main Authors: Latancia, Marcela Teatin, Leandro, Giovana da Silva, Bastos, André Uchimura, Moreno, Natália Cestari, Ariwoola, Abu-Bakr Adetayo, Martins, Davi Jardim, Ashton, Nicholas William, Ribeiro, Victória Chaves, Hoch, Nicolas Carlos, Rocha, Clarissa Ribeiro Reily, Woodgate, Roger, Menck, Carlos Frederico Martins
Format: Article
Language:English
Subjects:
Cancer
Chemotherapy resistance
DNA polymerase
Glioma
Temozolomide
Translesion synthesis
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Glioblastoma (GBM) is a highly aggressive brain tumor associated with poor patient survival. The current standard treatment involves invasive surgery, radiotherapy, and chemotherapy employing temozolomide (TMZ). Resistance to TMZ is, however, a major challenge. Previous work from our group has identified candidate genes linked to TMZ resistance, including genes encoding translesion synthesis (TLS) DNA polymerases iota (Polɩ) and kappa (Polκ). These specialized enzymes are known for bypassing lesions and tolerating DNA damage. Here, we investigated the roles of Polɩ and Polκ in TMZ resistance, employing MGMT-deficient U251-MG glioblastoma cells, with knockout of either POLI or POLK genes encoding Polɩ and Polκ, respectively, and assess their viability and genotoxic stress responses upon subsequent TMZ treatment. Cells lacking either of these polymerases exhibited a significant decrease in viability following TMZ treatment compared to parental counterparts. The restoration of the missing polymerase led to a recovery of cell viability. Furthermore, knockout cells displayed increased cell cycle arrest, mainly in late S-phase, and lower levels of genotoxic stress after TMZ treatment, as assessed by a reduction of γH2AX foci and flow cytometry data. This implies that TMZ treatment does not trigger a significant H2AX phosphorylation response in the absence of these proteins. Interestingly, combining TMZ with Mirin (double-strand break repair pathway inhibitor) further reduced the cell viability and increased DNA damage and γH2AX positive cells in TLS KO cells, but not in parental cells. These findings underscore the crucial roles of Polɩ and Polκ in conferring TMZ resistance and the potential backup role of homologous recombination in the absence of these TLS polymerases. Targeting these TLS enzymes, along with double-strand break DNA repair inhibition, could, therefore, provide a promising strategy to enhance TMZ's effectiveness in treating GBM. [Display omitted] •TLS KO cells are more sensitive to TMZ treatment compared to parental cells.•TLS KO cells show late-S phase arrest compared to parental cells upon TMZ treatment.•Mre11 inhibitor, Mirin, synergizes with TMZ reducing cell viability in TLS KO cells.•TMZ and Mre11 inhibitor treatment increases DNA damage and γH2AX in TLS KO cells.
ISSN:1568-7864
1568-7856
1568-7856
DOI:10.1016/j.dnarep.2024.103715