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Publication Abstract from PubMed

EGFR tyrosine kinase inhibitors have made remarkable success in targeted cancer therapy. However, therapeutic resistance inevitably occurred and EGFR-targeting therapy has been demonstrated to have limited efficacy or utility in glioblastoma, colorectal cancer, and hepatocellular carcinoma. Therefore, there is a high demand for the development of new targets to inhibit EGFR signaling. Herein, we found that the EGFR oncogene proximal promoter sequence forms a unique type of snap-back loop containing G-quadruplex (G4), which can be targeted by small molecules. For the first time, we determined the NMR solution structure of this snap-back EGFR-G4, a three-tetrad-core, parallel-stranded G4 with naturally occurring flanking residues at both the 5'-end and 3'-end. The snap-back loop located at the 3'-end region forms a stable capping structure through two stacked G-triads connected by multiple potential hydrogen bonds. Notably, the flanking residues are consistently absent in reported snap-back G4s, raising the question of whether such structures truly exist under in vivo conditions. The resolved EGFR-G4 structure has eliminated the doubt and showed distinct structural features that distinguish it from the previously reported snap-back G4s, which lack the flanking residues. Furthermore, we found that the snap-back EGFR-G4 structure is highly stable and can form on an elongated DNA template to inhibit DNA polymerase. The unprecedented high-resolution EGFR-G4 structure has thus contributed a promising molecular target for developing alternative EGFR signaling inhibitors in cancer therapeutics. Meanwhile, the two stacked triads may provide an attractive site for specific small-molecule targeting.

Structure of the Major G-Quadruplex in the Human EGFR Oncogene Promoter Adopts a Unique Folding Topology with a Distinctive Snap-Back Loop.,Liu Y, Li J, Zhang Y, Wang Y, Chen J, Bian Y, Xia Y, Yang MH, Zheng K, Wang KB, Kong LY J Am Chem Soc. 2023 Jul 26;145(29):16228-16237. doi: 10.1021/jacs.3c05214. Epub , 2023 Jul 17. PMID:37460135^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.