Stabilization of G-quadruplexes in Intronic Hematopoietic-specific Enhancer of WT1 gene with G-quadruplex targeting ligands: in silico and in vitro techniques

Abstract

Wilms’ tumor 1 (WT1) gene was identified as a tumor-suppressor gene in childhood renal neoplasm, Wilms' tumor, and has an important impact on cell growth and differentiation. So, mutations in WT1 and its over-expression related to not only Wilms’ tumor but also other tumors and leukemias. WT1’s intronic hematopoietic-specific enhancer is GC-rich and could form G-quadruplex structures. Herein, we study the effect of three G-quadruplex stabilizing ligands on the formation and stability of G-quadruplex structures in WT1 intronic hematopoietic-specific enhancer. We designed a truncated sequence of WT1 intronic enhancer (named WT1-I33) with the highest likelihood score of G-quadruplex formation and study the effect of different concentrations of TMPyP4, daunorubicin, and mitoxantrone on G-quadruplex formation in WT1-I33 oligonucleotide using in silico and cell-free assays. The results revealed that WT1-I33 has the potential to form G-quadruplex structures and these structures in WT1 hematopoietic-specific enhancer could be stabilized by the ligands. According to the role of enhancers in transcription, stabilizing of G-quadruplex structures could make the enhancer inaccessible for the transcription factors and transcription of the WT1 gene might be downregulated. These data could help emerge novel gene-specific therapeutic strategies and selective targeting of G-quadruplex structures.