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KCa3.1 channel inhibition sensitizes malignant gliomas to temozolomide treatment
Giuseppina D'Alessandro1,2, Alfonso Grimaldi1, Giuseppina Chece1
1Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.
Abstract:
Malignant gliomas are among the most frequent and aggressive cerebral tumors, characterized by high proliferative and invasive indexes. Standard therapy for patients, after surgery and radiotherapy, consists of temozolomide (TMZ), a methylating agent that blocks tumor cell proliferation. Currently, there are no therapies aimed at reducing tumor cell invasion. Ion channels are candidate molecular targets involved in glioma cell migration and infiltration into the brain parenchyma. In this paper we demonstrate that: i) blockade of the calcium-activated potassium channel KCa3.1 with TRAM-34 has co-adjuvant effects with TMZ, reducing GL261 glioma cell migration, invasion and colony forming activity, increasing apoptosis, and forcing cells to pass the G2/M cell cycle phase, likely through cdc2 de-phosphorylation; ii) KCa3.1 silencing potentiates the inhibitory effect of TMZ on glioma cell viability; iii) the combination of TMZ/TRAM-34 attenuates the toxic effects of glioma conditioned medium on neuronal cultures, through a microglia dependent mechanism since the effect is abolished by clodronate-induced microglia killing; iv) TMZ/TRAM-34 co-treatment increases the number of apoptotic tumor cells, and the mean survival time in a syngeneic mouse glioma model (C57BL6 mice implanted with GL261 cells); v) TMZ/TRAM-34 co-treatment reduces cell viability of GBM cells and cancer stem cells (CSC) freshly isolated from patients.Taken together, these data suggest a new therapeutic approach for malignant glioma, targeting both glioma cell proliferating and migration, and demonstrate that TMZ/TRAM-34 co-treatment affects both glioma cells and infiltrating microglia, resulting in an overall reduction of tumor cell progression.
Insights
Combining temozolomide (TMZ) with TRAM-34, a KCa3.1 channel blocker, effectively reduces malignant glioma cell invasion and proliferation. This novel therapeutic strategy enhances apoptosis and survival in preclinical models, offering a promising new avenue for glioma treatment.
Area of Science:
- Neuro-oncology
- Molecular biology
- Pharmacology
Background:
- Malignant gliomas are aggressive brain tumors with limited treatment options.
- Current standard therapy, temozolomide (TMZ), targets proliferation but not invasion.
- Ion channels, specifically KCa3.1, are implicated in glioma cell migration.
Purpose of the Study:
- To investigate the co-adjuvant effects of blocking the KCa3.1 channel with TRAM-34 in combination with TMZ.
- To evaluate the impact of this combination therapy on glioma cell proliferation, invasion, apoptosis, and survival.
Main Methods:
- Utilized GL261 glioma cell lines and patient-derived GBM cells and cancer stem cells (CSCs).
- Assessed the effects of TRAM-34 and TMZ co-treatment on cell migration, invasion, apoptosis, and cell cycle progression.
- Evaluated the in vivo efficacy in a syngeneic mouse glioma model.
- Investigated the role of microglia in the therapeutic response.
Main Results:
- TRAM-34 demonstrated co-adjuvant effects with TMZ, reducing glioma cell migration, invasion, and colony formation.
- KCa3.1 blockade and silencing potentiated TMZ's inhibitory effect on glioma cell viability and increased apoptosis.
- The TMZ/TRAM-34 combination attenuated glioma-conditioned medium toxicity on neurons via a microglia-dependent mechanism.
- In vivo studies showed increased tumor cell apoptosis and prolonged survival in mice treated with TMZ/TRAM-34.
- Co-treatment reduced the viability of patient-derived GBM cells and CSCs.
Conclusions:
- Targeting KCa3.1 channels alongside TMZ offers a novel therapeutic strategy for malignant gliomas.
- This combination therapy effectively inhibits both glioma cell proliferation and invasion.
- The TMZ/TRAM-34 co-treatment impacts glioma cells and microglia, leading to reduced tumor progression.
