Research shows blocking SET enhances glioblastoma cells' sensitivity to radiation — Evidence Review

Researchers at The Ohio State University Comprehensive Cancer Center have identified the protein SET as a potential target to make glioblastoma cells more susceptible to standard treatments. Related studies broadly support these findings, highlighting SET and PP2A pathways as key modulators of glioblastoma resistance and vulnerability (1, 2).

• Multiple studies have shown that inhibiting SET or related proteins disrupts survival mechanisms in glioblastoma cells, increasing their sensitivity to radiation and reducing tumor formation; this aligns with the new findings (1, 2).
• Research on PP2A regulation and its inhibition by proteins such as SET, ANP32A, and CIP2A supports the therapeutic potential of restoring PP2A activity to impair oncogenic signaling and DNA repair, thereby sensitizing tumors to treatment (2).
• Broader literature on glioblastoma radioresistance identifies DNA repair pathways and cell signaling as critical contributors; targeting mechanisms like SET/PP2A may address key gaps where conventional therapies have failed (3, 6).

Study Overview and Key Findings

Glioblastoma remains one of the most aggressive and treatment-resistant cancers, with current therapies frequently failing to produce durable responses. The study from The Ohio State University Comprehensive Cancer Center focuses on the role of SET, a protein that inhibits the tumor suppressor enzyme PP2A, in contributing to this resistance. By targeting SET and related proteins, the researchers aim to enhance the efficacy of radiation and chemotherapy, potentially providing a new avenue for overcoming glioblastoma’s robust defenses. Notably, their work explores the potential of repurposing existing drugs that modulate these pathways, although clinical application is still in early stages.

Property	Value
Study Year	2026
Organization	The Ohio State University Comprehensive Cancer Center - Arthur G. James Cancer Hospital and Richard J. Solove Research Institute
Journal Name	Cancer Letters
Authors	Arnab Chakravarti, MD
Population	Glioblastoma cells in laboratory and animal models
Methods	Animal Study
Outcome	Tumor formation, sensitivity to radiation
Results	Blocking SET increased glioblastoma cells' vulnerability to radiation.

Literature Review: Related Studies

To place these findings in context, we searched the Consensus database, which indexes over 200 million research papers. The following search queries were used to identify relevant literature:

1. SET inhibition glioblastoma radiation sensitivity
2. glioblastoma treatment radiation response mechanisms
3. brain cancer vulnerabilities targeted therapy

Literature Review Table

Topic	Key Findings
How do SET and related proteins contribute to glioblastoma resistance and recurrence?	- Inhibiting SETMAR (a SET family protein) or the SETMAR-NHEJ axis in glioblastoma residual cells impairs DNA repair, induces senescence, and prevents recurrence (1). - Overexpression of SET and related proteins (ANP32A, CIP2A) inhibits PP2A activity, promoting oncogenic signaling and radioresistance; blocking these proteins restores vulnerability (2).
Can targeting PP2A or its endogenous inhibitors sensitize glioblastoma to therapy?	- Restoring PP2A activity by inhibiting its endogenous inhibitors (ANP32A, CIP2A, SET) disrupts oncogenic kinase signaling, reduces tumor formation, and sensitizes tumors to radiation through impaired DNA repair (2). - Activation of PP2A can also impair DNA damage response kinases (ATR, ATM), enhancing radiosensitivity (2).
What are the mechanisms underlying glioblastoma radioresistance and how can they be targeted?	- Resistance is driven by enhanced DNA repair pathways, cell cycle arrest, apoptosis escape, and microenvironmental factors (3, 4, 5, 6). - Targeting radiation-tolerant persister cells and their regulatory axes (e.g., NF-κB-YY1-miR-103a) improves radiosensitivity and inhibits recurrence (7).
Are there promising new targeted or repurposed therapies for glioblastoma?	- Repurposable neuroactive drugs have demonstrated anti-glioblastoma activity, with some agents synergizing with standard therapies in preclinical models (12). - Candidate radiosensitizers and molecularly targeted agents are being investigated, but clinical validation remains limited (6, 10).

How do SET and related proteins contribute to glioblastoma resistance and recurrence?

Several studies have demonstrated that SET and related proteins play a key role in glioblastoma's resistance to treatment by promoting DNA repair and survival pathways. The new study's focus on SET inhibition aligns with previous findings that disrupting SET-mediated mechanisms can prevent tumor recurrence and sensitize cancer cells to therapy.

• SETMAR, a SET-domain protein, is upregulated in therapy-resistant glioblastoma cells and enables efficient DNA repair, driving recurrence (1).
• Knockdown or inhibition of SETMAR induces senescence and apoptosis in residual disease cells, impairing their survival post-radiation (1).
• Overexpression of SET, ANP32A, and CIP2A suppresses PP2A activity, thus maintaining oncogenic signaling and resistance (2).
• Inhibition of these proteins restores PP2A tumor suppressor function and increases the vulnerability of glioblastoma cells to radiation (2).

Can targeting PP2A or its endogenous inhibitors sensitize glioblastoma to therapy?

Research has increasingly highlighted the therapeutic potential of activating or restoring PP2A activity in glioblastoma. The new study’s findings that blocking SET (an endogenous PP2A inhibitor) sensitizes tumor cells to radiation are consistent with this broader body of work.

• Inhibiting endogenous PP2A inhibitors like SET, ANP32A, and CIP2A leads to decreased oncogenic signaling and increased DNA damage in tumor cells (2).
• CRISPR-Cas9 silencing of these inhibitors impairs the DNA damage response, particularly through ATR and ATM kinases, enhancing radiosensitivity (2).
• Restoration of PP2A activity is a promising strategy for combination with radiation or chemotherapy (2).
• The potential of repurposing existing drugs that activate PP2A is under investigation, though clinical translation remains early (2).

What are the mechanisms underlying glioblastoma radioresistance and how can they be targeted?

The literature identifies multiple, often redundant, mechanisms that contribute to glioblastoma’s robust radioresistance. Targeting these mechanisms—including DNA repair pathways and survival signaling—is an area of active research, supporting the rationale behind the new study.

• Radioresistance is mediated by enhanced DNA repair (e.g., NHEJ pathway), cell cycle changes, evasion of apoptosis, and the supportive tumor microenvironment (3, 4, 5).
• Mesenchymal-like transitions and activation of specific signaling pathways (e.g., NF-κB, YY1, F3) further promote resistance and recurrence (4, 5, 7).
• Experimental models show that targeting radiation-tolerant persister cells or their regulatory axes improves radiosensitivity and inhibits recurrence (7).
• Understanding these mechanisms provides a foundation for development of radiosensitizers and combination therapies (6).

Are there promising new targeted or repurposed therapies for glioblastoma?

While targeted therapies and radiosensitizers are being actively studied, translating these findings into clinical benefit has proven challenging. Recent efforts focus on exploiting specific vulnerabilities and repurposing existing drugs based on mechanistic insights.

• High-throughput screening has identified neuroactive drugs (e.g., certain antidepressants) with potent anti-glioblastoma efficacy; these agents can synergize with existing therapies in preclinical models (12).
• Clinical trials of radiosensitizers and targeted agents are ongoing, but so far no targeted therapy has been validated for routine clinical use in glioblastoma (6, 10).
• The blood-brain barrier, tumor heterogeneity, and compensatory resistance mechanisms remain significant obstacles to effective targeted therapy (9, 10).
• Novel strategies rooted in tumor biology, such as PP2A activation or microenvironment modulation, offer new avenues for treatment development (2, 8, 12).

Future Research Questions

Although the new findings are promising, several key areas remain to be addressed before translating this approach to clinical care. Further research is needed to determine safety, efficacy, and optimal strategies for targeting SET and related pathways in glioblastoma patients.

Research Question	Relevance
Can selective SET inhibition improve survival in glioblastoma patients?	Clinical trials are needed to determine whether the preclinical benefits of SET inhibition translate to improved patient outcomes 1 2.
What are the potential side effects of targeting PP2A and its inhibitors in the brain?	Safety and tolerability must be assessed, as PP2A is involved in many normal cellular functions, and off-target effects could limit clinical application 2 10.
Can existing FDA-approved drugs that activate PP2A be repurposed for glioblastoma?	Early studies suggest potential, but rigorous evaluation in preclinical and clinical models is required to assess efficacy and safety 2 12.
How does SET inhibition interact with other mechanisms of radioresistance in glioblastoma?	Exploring the interplay between SET, DNA repair pathways, and the tumor microenvironment will help identify combination strategies for overcoming resistance 1 3 4 6.
Are there biomarkers that predict which glioblastoma patients will benefit from SET or PP2A-targeted therapy?	Identifying predictive biomarkers could enable personalized treatment, increasing the likelihood of clinical success and minimizing unnecessary toxicity 9 10.