title: G-quadruplex-binding benzo[a]phenoxazines down-regulate c-KIT expression in human gastric carcinoma cells.
abstract: There is considerable interest in the structure and function of G-quadruplex nucleic acid secondary structures, their cellular functions, and their potential as therapeutic targets. G-Quadruplex sequence motifs are prevalent in gene promoter regions and it has been hypothesized that G-quadruplex structure formation is associated with the transcriptional status of the downstream gene. Using a functional cell-based assay, we have identified two novel G-quadruplex ligands that reduce the transcription of a luciferase reporter driven from the G-quadruplex-containing c-KIT promoter. We have further shown that endogenous c-KIT expression in a human gastric carcinoma cell line is also reduced on treatment with these molecules. Biophysical analysis using surface plasmon resonance has shown that these molecules preferentially bind with high affinity to one of the two G-quadruplex sequences in the c-KIT promoter over double-stranded DNA. This work highlights the utility of cell-based reporter assays to identify new G-quadruplex binding molecules that modulate transcription and identifies benzo[a]phenoxazine derivatives as potential antitumor agents.
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge, UK.
authors.forename: Keith I E
authors.initials: KI
authors.lastname: McLuckie
authors.forename: Zoë A E
authors.initials: ZA
authors.lastname: Waller
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Sanders
authors.forename: David
authors.initials: D
authors.lastname: Alves
authors.forename: Raphaël
authors.initials: R
authors.lastname: Rodriguez
authors.forename: Jyotirmayee
authors.initials: J
authors.lastname: Dash
authors.forename: Grahame J
authors.initials: GJ
authors.lastname: McKenzie
authors.forename: Ashok R
authors.initials: AR
authors.lastname: Venkitaraman
authors.forename: Shankar
authors.initials: S
authors.lastname: Balasubramanian
mesh_terms: D001665:Binding Sites; D015536:Down-Regulation / Q000187:drug effects*; D054856:G-Quadruplexes; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D015394:Molecular Structure; D010078:Oxazines / Q000737:chemistry / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology*; D020349:Surface Plasmon Resonance; D014407:Tumor Cells, Cultured
chemical_list: D010078:Oxazines; D012333:RNA, Messenger; D019009:Proto-Oncogene Proteins c-kit