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G-Quadruplex Binders Induce Immunogenic Cell Death Markers in Aggressive Breast Cancer Cells
Sarah Di Somma1, Jussara Amato2, Nunzia Iaccarino2
1Department of Translational Medical Sciences, University of Naples Federico II, 80131 Naples, Italy.
Background:
DNA G-quadruplex (G4) structures represent potential anti-cancer targets. In this study, we compared the effect of two G4-targeting compounds, C066-3108 and the gold standard BRACO-19.
Methods:
In breast and prostate cancer cells, cytotoxicity induced by both molecules was measured by a sulforhodamine B assay. In breast cancer cells, cycle, apoptosis, the formation of G4 structures, calreticulin and high mobility group box 1 (HMGB1), as well as T cell activation, were analyzed by flow cytometry and adenosine triphosphate (ATP) by luminescence.
Results:
Both ligands inhibited cell survival and induced DNA damage. In MCF-7 cells, G4 ligands increased the subG0/G1 phase of the cell cycle inducing apoptosis and reduced intracellular ATP. In untreated MCF-7 cells, we observed a slight presence of G4 structures associated with the G2/M phase. In MDA-MB231 cells, G4 ligands decreased the G1 and enhanced the G2/M phase. We observed a decrease of intracellular ATP, calreticulin cell surface exposure and an increase of HMGB1, accompanied by T cell activation. Both compounds induced G4 structure formation in the subG0/G1 phase.
Conclusions:
Our data report similar effects for both compounds and the first evidence that G4 ligands induce the release of danger signals associated with immunogenic cell death and induction of T cell activation.
Insights
Two DNA G-quadruplex (G4) ligands, C066-3108 and BRACO-19, showed similar anti-cancer effects. They induced cell death and DNA damage, releasing danger signals that activate T cells, suggesting potential in cancer immunotherapy.
Area of Science:
- Oncology
- Molecular Biology
- Immunology
Background:
- DNA G-quadruplex (G4) structures are promising anti-cancer targets.
- This study compares two G4-targeting compounds: C066-3108 and BRACO-19.
Purpose of the Study:
- To compare the cytotoxic effects and molecular mechanisms of C066-3108 and BRACO-19 in cancer cells.
- To investigate the induction of DNA damage, cell cycle alterations, apoptosis, and immune signaling pathways by G4 ligands.
Main Methods:
- Cytotoxicity assessed using sulforhodamine B assay in breast and prostate cancer cells.
- Cell cycle, apoptosis, G4 structure formation, calreticulin, high mobility group box 1 (HMGB1), and T cell activation analyzed by flow cytometry.
- Intracellular adenosine triphosphate (ATP) levels measured by luminescence.
Main Results:
- Both G4 ligands inhibited cell survival and induced DNA damage across different cancer cell lines.
- G4 ligands induced apoptosis and altered cell cycle phases (subG0/G1 or G2/M depending on cell type).
- Ligands decreased intracellular ATP, affected calreticulin and HMGB1 levels, and activated T cells, indicating immunogenic cell death.
Conclusions:
- C066-3108 and BRACO-19 exhibit comparable anti-cancer activities.
- G4 ligands promote the release of danger signals, leading to immunogenic cell death and T cell activation, a novel finding for G4-targeting agents.
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