Recently, the 1H-detected in-cell NMR spectroscopy has emerged as a unique tool allowing the characterization of interactions between nucleic acid-based targets and drug-like molecules in living human cells. Here, we assess the application potential of 1H and 19F-detected in-cell NMR spectroscopy to profile drugs/ligands targeting DNA G-quadruplexes, arguably the most studied class of anti-cancer drugs targeting nucleic acids. We show that the extension of the original in-cell NMR approach is not straightforward. The severe signal broadening and overlap of 1H in-cell NMR spectra of polymorphic G-quadruplexes and their complexes complicate their quantitative interpretation. Nevertheless, the 1H in-cell NMR can be used to identify drugs that, despite strong interaction in vitro, lose their ability to bind G-quadruplexes in the native environment. The in-cell NMR approach is adjusted to a recently developed 3,5-bis(trifluoromethyl)phenyl probe to monitor the intracellular interaction with ligands using 19F-detected in-cell NMR. The probe allows dissecting polymorphic mixture in terms of number and relative populations of individual G-quadruplex species, including ligand-bound and unbound forms in vitro and in cellulo. Despite the probe's discussed limitations, the 19F-detected in-cell NMR appears to be a promising strategy to profile G-quadruplex-ligand interactions in the complex environment of living cells.

• Keywords
• BRACO19, Bcl2, G-quadruplex, KRAS, NMM, PhenDC3, drug, in-cell NMR, ligand, telomeric DNA,
• MeSH
• DNA chemistry   drug effects   MeSH
• G-Quadruplexes drug effects   MeSH
• Nucleic Acid Conformation drug effects   MeSH
• Pharmaceutical Preparations chemistry   MeSH
• Humans MeSH
• Ligands MeSH
• Magnetic Resonance Spectroscopy MeSH
• Models, Molecular MeSH
• Protons MeSH
• Binding Sites drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA MeSH
• Pharmaceutical Preparations MeSH
• Ligands MeSH
• Protons MeSH