G4ME 2026 IV edizione meeting italiano su g-quadruplex e strutture non canoniche del DNA

Naphthalene diimides (NDIs) are extremely versatile DNA/RNA G-quadruplex ligands with fluorescent properties, useful for theranostic applications and photodynamic therapy (Doria et al., 2015; Salvati et al 2016). NDIs are known to cause DNA damage at the telomeric level by binding the telomeric G4s eventually leading to the activation of DNA damage response (DDR) signaling (Doria et al 2019). NDI dyads (dNDI) exhibited an extraordinary toxicity in a wide range of cancer cells, despite their relatively low DNA damaging activity, suggesting a major complexity in the mode of interaction of those compounds with intracellular targets (Pirota et al 2025). Fluorescence Lifetime Imaging Microscopy data indicated the localization of the tetra-substituted NDI dyad in the nucleolar compartment in different cell types, with consequent impact on nucleolar structural organization and cellular whole protein synthesis rate. Given their high metabolic rate, cancer cells must rely on an efficient ribosome biogenesis pathway, which targeting could be critical for cancer cell survival. For a deeper characterization of interactions between dNDI and nucleolar DNA/RNA G-quadruplex structures, we generated a biotinylated version of tetra-substituted dNDI, which efficiently enter the cell, inducing cell proliferation inhibition, nucleolar morphology alteration and decrease of protein synthesis rate. The biotinylated compound will enable us to investigate the direct interaction of dNDI with nucleolar G4 targets exploring the complexity of the mechanisms at the basis of the extraordinary cytotoxicity. The outcome of this work could potentially define new strategies of application of G4 binders in anti-cancer therapy, hitting one of the most commonly upregulated pathway in cancer progression.