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

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Latancia, Marcela Teatin ; da Silva Leandro, Giovana ; Bastos, Andre Uchimura ; Moreno, Natalia Cestari ; Ariwoola, Abu-Bakr Adetayo ; Martins, Davi Jardim ; Ashton, Nicholas William ; Ribeiro, Victoria Chaves ; Hoch, Nicolas Carlos ; Rocha, Clarissa Ribeiro Reily ; Woodgate, Roger ; Menck, Carlos Frederico Martins

• Document type: Journal article
• Source: DNA Repair; v. 141, p. 13-pg., 2024-07-18.

Abstract

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 (Pol iota) and kappa (Pol kappa). These specialized enzymes are known for bypassing lesions and tolerating DNA damage. Here, we investigated the roles of Pol iota and Pol kappa in TMZ resistance, employing MGMT-deficient U251-MG glioblastoma cells, with knockout of either POLI or POLK genes encoding Pol iota and Pol kappa, 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 gamma H2AX 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 gamma H2AX positive cells in TLS KO cells, but not in parental cells. These findings underscore the crucial roles of Pol kappa and Polx 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. (AU)

• FAPESP's process: 19/19435-3 - The role of DNA damage and mitochondrial function in vascular, immune and neurological ageing (DNA MoVINg)
• Grantee: Carlos Frederico Martins Menck
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/10061-0 - Role of translesion synthesis in cisplatin and temozolomide resistance in Glioma cells
• Grantee: Marcela Teatin Latancia
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 13/08028-1 - CEGH-CEL - Human Genome and Stem Cell Research Center
• Grantee: Mayana Zatz
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC