The proximal promoter region of the human vascular endothelial growth factor gene has a G-quadruplex structure that can be targeted by G-quadruplex–interactive agents

• Published in: Molecular cancer therapeutics 2008-04, Vol.7 (4), p.880-889
• Main Authors: Sun, Daekyu, Liu, Wei-Jun, Guo, Kexiao, Rusche, Jadrian J, Ebbinghaus, Scot, Gokhale, Vijay, Hurley, Laurence H
• Format: Article
• Language: English
• Subjects: angiogenesis; Base Sequence; Breast Neoplasms - drug therapy; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Cell Hypoxia; Circular Dichroism; DNA Footprinting; Drug design; Electrophoretic Mobility Shift Assay; Endometrial Neoplasms - drug therapy; Endometrial Neoplasms - genetics; Endometrial Neoplasms - pathology; Female; G-quadruplex; G-Quadruplexes - drug effects; G-quadruplex–interactive agents; Humans; Kidney Neoplasms - drug therapy; Kidney Neoplasms - genetics; Kidney Neoplasms - pathology; Models, Molecular; Molecular Sequence Data; Nucleic Acid Conformation; Porphyrins - pharmacology; Potassium Chloride - pharmacology; Promoter Regions, Genetic - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Selenium Compounds - pharmacology; Sequence Homology, Nucleic Acid; Sulfuric Acid Esters - metabolism; Transcription; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A - chemistry; Vascular Endothelial Growth Factor A - genetics; VEGF
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-07-2119

Previous studies on the functional analysis of the human vascular endothelial growth factor ( VEGF ) promoter using the full-length VEGF promoter reporter revealed that the proximal 36-bp region (−85 to −50 relative to transcription initiation site) is essential for basal or inducible VEGF promoter activity in several human cancer cells. This region consists of a polypurine (guanine) tract that contains four runs of at least three contiguous guanines separated by one or more bases, thus conforming to a general motif capable of forming an intramolecular G-quadruplex. Here, we show that the G-rich strand in this region is able to form an intramolecular propeller-type parallel-stranded G-quadruplex structure in vitro by using the electrophoretic mobility shift assay, dimethyl sulfate footprinting technique, the DNA polymerase stop assay, circular dichroism spectroscopy, and computer-aided molecular modeling. Two well-known G-quadruplex–interactive agents, TMPyP4 and Se2SAP, stabilize G-quadruplex structures formed by this sequence in the presence of a potassium ion, although Se2SAP is at least 10-fold more effective in binding to the G-quadruplex than TMPyP4. Between these two agents, Se2SAP better suppresses VEGF transcription in different cancer cell lines, including HEC1A and MDA-MB-231. Collectively, our results provide evidence that specific G-quadruplex structures can be formed in the VEGF promoter region, and that the transcription of this gene can be controlled by ligand-mediated G-quadruplex stabilization. Our results also provide further support for the idea that G-quadruplex structures may play structural roles in vivo and therefore might provide insight into novel methodologies for rational drug design. [Mol Cancer Ther 2008;7(4):880–9]