ABSTRACT
The c-MYC oncogene is overactivated during Burkitt's lymphoma pathogenesis. Targeting c-MYC to inhibit its transcriptional activity has emerged as an effective anticancer strategy. We synthesized four series of disubstituted quindoline derivatives by introducing the second cationic amino side chain and 5-N-methyl group based on a previous study of SYUIQ-5 (1) as c-MYC promoter G-quadruplex ligands. The in vitro evaluations showed that all new compounds exhibited higher stabilities and binding affinities, and most of them had better selectivity (over duplex DNA) for the c-MYC G-quadruplex compared to 1. Moreover, the new ligands prevented NM23-H2, a transcription factor, from effectively binding to the c-MYC G-quadruplex. Further studies showed that the selected ligand, 7a4, down-regulated c-MYC transcription by targeting promoter G-quadruplex and disrupting the NM23-H2/c-MYC interaction in RAJI cells. 7a4 could inhibit Burkitt's lymphoma cell proliferation through cell cycle arrest and apoptosis and suppress tumor growth in a human Burkitt's lymphoma xenograft.
Subject(s)
Alkaloids/pharmacology , Antineoplastic Agents/pharmacology , Burkitt Lymphoma/drug therapy , Indoles/pharmacology , Proto-Oncogene Proteins c-myc/antagonists & inhibitors , Quinolines/pharmacology , Alkaloids/chemical synthesis , Alkaloids/chemistry , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Apoptosis/drug effects , Burkitt Lymphoma/genetics , Burkitt Lymphoma/pathology , Cell Cycle Checkpoints/drug effects , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , G-Quadruplexes/drug effects , Humans , Indoles/chemical synthesis , Indoles/chemistry , Mice, Inbred NOD , Mice, SCID , Molecular Structure , Neoplasms, Experimental/drug therapy , Neoplasms, Experimental/genetics , Neoplasms, Experimental/pathology , Proto-Oncogene Proteins c-myc/genetics , Quinolines/chemical synthesis , Quinolines/chemistry , Structure-Activity Relationship , Transcription, Genetic/drug effectsABSTRACT
G-quadruplexes are specialized secondary structures in nucleic acids that possess significant conformational polymorphisms. The precise G-quadruplex conformations in vivo and their relevance to biological functions remain controversial and unclear, especially for telomeric G-quadruplexes. Here, we report a novel single-chain variable fragment (scFv) antibody, D1, with high binding selectivity for parallel G-quadruplexes in vitro and in vivo. Genome-wide chromatin immunoprecipitation using D1 and deep-sequencing revealed the consensus sequence for parallel G-quadruplex formation, which is characterized by G-rich sequence with a short loop size (<3 nt). By using D1, telomeric parallel G-quadruplex was identified and its formation was regulated by small molecular ligands targeting and telomere replication. Together, parallel G-quadruplex specific antibody D1 was found to be a valuable tool for determination of G-quadruplex and its conformation, which will prompt further studies on the structure of G-quadruplex and its biological implication in vivo.
Subject(s)
G-Quadruplexes , Single-Chain Antibodies/chemistry , Telomere/chemistry , Base Sequence , Cell Line , Consensus Sequence , Genome, Human , HeLa Cells , Humans , Ligands , Models, Molecular , Single-Chain Antibodies/immunology , Telomere/genetics , Telomere/immunologyABSTRACT
To improve the selectivity of indoloquinoline or benzofuroquinoline derivatives, we previously reported several quinazoline derivatives [17]. These compounds could mimic a tetracyclic aromatic system through intramolecular hydrogen bond. Studies showed that these quinazoline derivatives were effective and selective telomeric G-quadruplex ligands. With this encouragement, here we synthesized a series of N-(2-(quinazolin-2-yl)phenyl)benzamide (QPB) compounds as modified quinazoline derivatives. In this modification, a phenyl group was introduced to the aromatic core. The evaluation results showed that part of QPB derivatives had stronger binding ability and better selectivity for telomeric G-quadruplex DNA than LZ-11, the most potential compound of reported quinazoline derivatives. Furthermore, telomerase inhibition of QPB derivatives and their cellular effects were studied.
Subject(s)
DNA/chemistry , G-Quadruplexes , Quinazolines/chemistry , Telomere/chemistry , Binding, Competitive , Cell Survival/drug effects , Cellular Senescence/drug effects , Circular Dichroism , DNA/metabolism , HL-60 Cells , Humans , Kinetics , Ligands , Molecular Structure , Phenol/chemistry , Phenol/metabolism , Quinazolines/metabolism , Quinazolines/pharmacology , Surface Plasmon Resonance , Telomerase/antagonists & inhibitors , Telomerase/metabolism , Telomere/genetics , Telomere/metabolism , Telomere Shortening/drug effectsABSTRACT
A series of 2,4-disubstituted quinazoline derivatives found to be a new type of highly selective ligand to bind with telomeric G-quadruplex DNA, and their biological properties were reported for the first time.Their interactions with telomeric G-quadruplex DNA were evaluated by using fluorescence resonance energy transfer (FRET) melting assay, circular dichroism (CD) spectroscopy, surface plasmon resonance (SPR), nuclear magnetic resonance (NMR), and molecular modeling. Our results showed that these derivatives could well recognize G-quadruplex and have high selectivity toward G-quadruplex over duplex DNA. The structure-activity relationships (SARs) study revealed that the disubstitution of quinazoline and the length of the amide side chain were important for its interaction with the G-quadruplex. Furthermore, telomerase inhibition of the quinazoline derivatives and their cellular effects were studied.
