RRC ID 12706
Author Membrino A, Cogoi S, Pedersen EB, Xodo LE.
Title G4-DNA formation in the HRAS promoter and rational design of decoy oligonucleotides for cancer therapy.
Journal PLoS One
Abstract HRAS is a proto-oncogene involved in the tumorigenesis of urinary bladder cancer. In the HRAS promoter we identified two G-rich elements, hras-1 and hras-2, that fold, respectively, into an antiparallel and a parallel quadruplex (qhras-1, qhras-2). When we introduced in sequence hras-1 or hras-2 two point mutations that block quadruplex formation, transcription increased 5-fold, but when we stabilized the G-quadruplexes by guanidinium phthalocyanines, transcription decreased to 20% of control. By ChIP we found that sequence hras-1 is bound only by MAZ, while hras-2 is bound by MAZ and Sp1: two transcription factors recognizing guanine boxes. We also discovered by EMSA that recombinant MAZ-GST binds to both HRAS quadruplexes, while Sp1-GST only binds to qhras-1. The over-expression of MAZ and Sp1 synergistically activates HRAS transcription, while silencing each gene by RNAi results in a strong down-regulation of transcription. All these data indicate that the HRAS G-quadruplexes behave as transcription repressors. Finally, we designed decoy oligonucleotides mimicking the HRAS quadruplexes, bearing (R)-1-O-[4-(1-Pyrenylethynyl) phenylmethyl] glycerol and LNA modifications to increase their stability and nuclease resistance (G4-decoys). The G4-decoys repressed HRAS transcription and caused a strong antiproliferative effect, mediated by apoptosis, in T24 bladder cancer cells where HRAS is mutated.
Volume 6(9)
Pages e24421
Published 2011-1-1
DOI 10.1371/journal.pone.0024421
PII PONE-D-11-09728
PMID 21931711
PMC PMC3169596
MeSH Base Sequence Cell Proliferation DNA-Binding Proteins / metabolism Drug Design* G-Quadruplexes* HeLa Cells Humans Indoles / metabolism Molecular Sequence Data Oligonucleotides / therapeutic use* Point Mutation / genetics Polymorphism, Genetic Promoter Regions, Genetic* Protein Binding Proto-Oncogene Proteins p21(ras) / genetics* Sp1 Transcription Factor / metabolism Transcription Factors / metabolism Transcription Initiation Site Transcription, Genetic Up-Regulation / genetics Urinary Bladder Neoplasms / drug therapy* Urinary Bladder Neoplasms / genetics Urinary Bladder Neoplasms / pathology
IF 2.74
Times Cited 67
DNA material pCMV-SP1 (RDB04267) pGEX-SP1 (RDB05699) pGEX-hMAZ (RDB05701) pCMV-MAZ (RDB03219).