Related Experiment Video
Updated: Jan 19, 2026
Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
Published on: December 9, 2015
Mechanisms associated with temozolomide resistance in U87MG cell line: in silico and in vitro approaches
Felipe Umpierre Conter1, Rafael Rodrigues Dihl2, Daniel Simon1
1Laboratory of Cancer Biology, Graduate Program in Cellular and Molecular Biology Applied to Health, Lutheran University of Brazil, Canoas, Brazil.
Abstract:
IDH-wildtype grade diffuse glioma is the most aggressive primary brain tumor in adults, with limited survival despite standard therapy with temozolomide (TMZ). Resistance to TMZ is driven by DNA repair pathways, tumor heterogeneity, and microenvironmental adaptations, indicating the need for novel therapeutic strategies. Using a systems biology approach, a compound-protein and protein-protein interaction networks was constructed with STRING 12.0 and STITCH 5.0 databases, identifying hub-bottleneck proteins associated with TMZ resistance. Topological and gene ontology analyses revealed 5 functional modules enriched in DNA repair and apoptosis, with PARP1, PCNA, TP53, MSH2, and HSPA1a emerging as key regulators. HSPA1a modulated survival by inhibiting TP53 and caspase signaling, while also blocking mismatch repair via MSH2 and MLH1 upregulation. In vitro studies using U87MG cells exhibited greater sensitivity to demethoxycurcumin (DMC) compared to TMZ. Importantly, DMC synergized with TMZ to reduce the concentration required for growth inhibition. Comet assays data confirmed TMZ-induced DNA damage and transient base excision repair (BER) impairment, while DMC enhanced both PCNA expression and caspase-mediated apoptosis. Co-treatment with DMC and TMZ sustained PARP1 downregulation, prolonged DNA damage, and amplified apoptosis. These findings indicated that DMC functions as an effective chemosensitizer, elevating TMZ efficacy. Combining DMC with DNA repair inhibitors may represent a promising therapeutic strategy to overcome resistance and improve IDH-wildtype grade diffuse glioma treatment outcomes.
Insights
Demethoxycurcumin (DMC) enhances temozolomide (TMZ) efficacy against aggressive IDH-wildtype diffuse gliomas by sensitizing cells to DNA damage and apoptosis. This combination therapy offers a promising strategy to overcome treatment resistance in brain tumors.
Area of Science:
- Neuro-oncology
- Molecular Biology
- Systems Biology
Background:
- IDH-wildtype glioblastoma is an aggressive brain tumor with poor outcomes despite temozolomide (TMZ) treatment.
- TMZ resistance is linked to DNA repair mechanisms, tumor heterogeneity, and the tumor microenvironment.
- Novel therapeutic strategies are crucial for improving patient survival.
Purpose of the Study:
- To identify key regulators of TMZ resistance in IDH-wildtype diffuse glioma using a systems biology approach.
- To evaluate the therapeutic potential of demethoxycurcumin (DMC) alone and in combination with TMZ.
- To elucidate the mechanisms by which DMC sensitizes glioma cells to TMZ.
Main Methods:
- Construction of compound-protein and protein-protein interaction networks using STRING and STITCH databases.
- Topological and gene ontology analyses to identify hub proteins and functional modules.
- In vitro studies with U87MG cells, including cell viability assays and comet assays.
- Assessment of DNA damage, apoptosis, and expression of key proteins (PARP1, PCNA, TP53, MSH2, MLH1, caspases).
Main Results:
- Key regulators of TMZ resistance identified include PARP1, PCNA, TP53, MSH2, and HSPA1a.
- HSPA1a was found to inhibit TP53 and caspase signaling, and upregulate MSH2/MLH1, contributing to resistance.
- Demethoxycurcumin (DMC) demonstrated greater sensitivity than TMZ in U87MG cells and synergized with TMZ.
- DMC enhanced TMZ-induced DNA damage, PCNA expression, and apoptosis, while prolonging DNA damage and downregulating PARP1 upon co-treatment.
Conclusions:
- Demethoxycurcumin (DMC) acts as an effective chemosensitizer, significantly enhancing the efficacy of temozolomide (TMZ).
- The combination of DMC and TMZ overcomes resistance by amplifying DNA damage and apoptosis.
- Combining DMC with DNA repair inhibitors presents a promising therapeutic avenue for IDH-wildtype diffuse glioma.
