Date of Award

Fall 10-1-2021

Document Type


Degree Name

Doctor of Philosophy (PhD)


Molecular Biophysics and Biochemistry

First Advisor

Bindra, Ranjit


In many solid tumors, methylation status of the O6-methylguanine methyltransferase (MGMT) gene promoter is a prognostic biomarker for treatment with the alkylator, temozolomide (TMZ). In the absence of promoter methylation, the MGMT enzyme removes O6-methylguanine (O6-meG) lesions. However, in the setting of MGMT-promoter methylation (MGMT-), the O6-meG lesion activates the mismatch repair (MMR) pathway which functions to remove the damage. Our group previously reported that MGMT- promoter methylation affects activation of the ataxia telangiectasia and RAD3 related protein (ATR) in response to TMZ treatment. Whether or not MMR proteins are involved in ATR activation in the context of MGMT-promoter methylation upon alkylation damage remains poorly understood. To investigate the function of mismatch repair in ATR activation, I created isogenic cell lines with knockdowns of the individual mismatch repair proteins MSH2, MSH6, MSH3, MLH1, and PMS2 in both the MGMT- and MGMT+ backgrounds. Here, I demonstrate that MSH2, MSH6, MLH1 and PMS2 mismatch repair proteins, specifically, are involved in the ATR-CHK1 axis, whereas MSH3 is likely not. This study elucidates a potential mechanistic understanding of how the MMR system is involved in ATR activation by TMZ in glioblastoma cells, which can ultimately be exploited for therapeutic gain in a wide-variety of MMR-mutated cancers.