RESUMO
A photoreactive molecular dye targeting the G-quadruplex nucleic acid (G4) of the human telomeric sequence Tel22, and several mutated analogues, was activated by green light (λ=532 nm). Highly selective covalent modification of G4 versus single-stranded and double-stranded DNA was achieved with efficiency up to 64%. The phenoxyl radical was generated and detected by laser-flash photolysis as a reactive intermediate that targeted loop thymine residues. These insights may suggest a non-invasive tool for selective nucleic acid tagging and "pull-down" cellular applications.
Assuntos
Quadruplex G/efeitos da radiação , Luz , Alquilação , Dicroísmo Circular , DNA/química , Eletroforese em Gel de Poliacrilamida , Humanos , Ligantes , Fenóis/química , Fotólise , Telômero/químicaRESUMO
Caught in the oxirane: Naphthalene diimides conjugated to a quinone methide and an oxirane have been synthesized and investigated as selective DNA G-quadruplex alkylating agents. The oxirane derivative generates a stable adduct with a G-quadruplex and shows selective alkylation of the loop adenines, as illustrated.
Assuntos
Adenina/análogos & derivados , Adenina/química , DNA/química , Óxido de Etileno/química , Alquilação , Sequência de Bases , Óxido de Etileno/síntese química , Quadruplex G , Espectrometria de Massas em TandemRESUMO
The synthesis, physico-chemical properties and biological effects of a new class of naphthalene diimides (NDIs) capable of reversibly binding telomeric DNA and alkylate it through an electrophilic quinone methide moiety (QM), are reported. FRET and circular dichroism assays showed a marked stabilization and selectivity towards telomeric G4 DNA folded in a hybrid topology. NDI-QMs' alkylating properties revealed a good reactivity on single nucleosides and selectivity towards telomeric G4. A selected NDI was able to significantly impair the growth of melanoma cells by causing telomere dysfunction and down-regulation of telomerase expression. These findings points to our hybrid ligand-alkylating NDIs as possible tools for the development of novel targeted anticancer therapies.
Assuntos
Alquilantes/química , Quadruplex G , Telômero/química , Alquilantes/farmacologia , Alquilação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Ligantes , Modelos Moleculares , Telômero/efeitos dos fármacosRESUMO
Selective recognition and alkylation of G-quadruplex oligonucleotides has been achieved by substituted naphathalene diimides (NDIs) conjugated to engineered phenol moieties by alkyl-amido spacers with tunable length and conformational mobility. FRET-melting assays, circular dichroism titrations and gel electrophoresis analysis have been carried out to evaluate both reversible stabilization and alkylation of the G-quadruplex. The NDIs conjugated to a quinone methide precursor (NDI-QMP) and a phenol moiety by the shortest alkyl-amido spacer exhibited a planar and fairly rigid geometry (modelled by DFT computation). They were the best irreversible and reversible G-quadruplex binders, respectively. The above NDI-QMP was able to alkylate the telomeric G-quadruplex DNA in the nanomolar range and resulted 100-1000 times more selective on G-quadruplex versus single- and double-stranded oligonucleotides. This compound was also the most cytotoxic against a lung carcinoma cell line.