Date of Submission
6-2025
Document Type
Thesis
Degree Name
Master of Science in Cellular and Molecular Biology
Department
Biology and Environmental Sciences
Advisor
Rasmani Hazra, Ph.D.
Committee Member
Eva Sapi, Ph.D.
Committee Member
Haresha Samaranayake, Ph.D.
Keywords
Glioblastoma (GBM), MGMT promoter methylation, Temozolomide (TMZ), Glioblastoma Stem-like Cells (GSCs), Transcriptional Subtype, Therapeutic Resistance
MeSH
Glioblastoma, O6-methylguanine-DNA methyltransferase, Temozolomide, Drug Resistance, Neoplasm
LCSH
Glioblastoma multiforme, Drug resistance in cancer cells
Abstract
Glioblastoma (GBM), the most aggressive primary brain tumor, is characterized by profound molecular heterogeneity, which contributes to its resistance to standard therapies. This study investigated the interplay between O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status, transcriptional subtype, and response to temozolomide (TMZ), an alkylating chemotherapeutic agent, in patient-derived glioblastoma stem-like cells (GSCs). We analyzed three well annotated GSC lines derived from patient-derived xenograft (PDX) models, assessing MGMT promoter methylation, measuring TMZ sensitivity through IC₅₀ assays, and inferring transcriptional subtypes using existing RNA sequencing data from the originating PDX tumors. Our findings demonstrated that MGMT methylation status alone did not reliably predict TMZ response. Two GSC lines exhibited MGMT promoter methylation yet showed differing TMZ sensitivities, while the one unmethylated line unexpectedly demonstrated the highest sensitivity to TMZ. Further analysis of transcriptional subtypes revealed that the TMZ resistant GSC belonged to the Classical subtype a molecular class often associated with poor response to therapy while another methylated, moderately resistant line showed a hybrid Mesenchymal/Classical profile. The TMZ sensitive, unmethylated line exhibited mixed features of the Proneural and Classical subtypes. These findings emphasize that transcriptional subtype context may significantly modulate TMZ sensitivity, potentially overriding the predictive value of MGMT methylation alone. The observed variability among GSC lines underscores the complexity of therapeutic resistance in GBM and highlights the need for integrated molecular profiling approaches to improve biomarker-based treatment stratification and guide personalized therapeutic strategies targeting resistant tumor-initiating cell populations.
Recommended Citation
Tuppad, Arati, "Transcriptional Subtype and MGMT Methylation Status of Patient-Derived Glioblastoma Stem-Like Cells: Implications for Temozolomide Response" (2025). Master's Theses. 251.
https://digitalcommons.newhaven.edu/masterstheses/251