Screening of candidate G-quadruplex ligands for the human <i>c-KIT</i> promotorial region and their effects in multiple <i>in-vitro</i> models

Abstract

// Eleonora Zorzan 1 , Silvia Da Ros 2 , Caterina Musetti 2 , Lara Zorro Shahidian 1 , Nuno Filipe Ramos Coelho 1 , Federico Bonsembiante 1 , S&eacute;bastien L&eacute;tard 3 , Maria Elena Gelain 1 , Manlio Palumbo 2 , Patrice Dubreuil 3 , Mery Giantin 1 , Claudia Sissi 2 , Mauro Dacasto 1 1 Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Padua, Italy 2 Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy 3 Centre de Recherche en Cancerologie de Marseille, INSERM (U1068), CNRS (U7258), Universit&eacute; Aix-Marseille (UM105), Marseille, France Correspondence to: Mauro Dacasto, e-mail: mauro.dacasto@unipd.it Claudia Sissi, e-mail: claudia.sissi@unipd.it Keywords: c-KIT , G-quadruplex, in-vitro models, G4-ligands, anthraquinone Received: September 14, 2015&emsp;&emsp;&emsp;&emsp; Accepted: February 20, 2016&emsp;&emsp;&emsp;&emsp; Published: March 01, 2016 ABSTRACT Stabilization of G-quadruplex (G4) structures in promoters is a novel promising strategy to regulate gene expression at transcriptional and translational levels. c-KIT proto-oncogene encodes for a tyrosine kinase receptor. It is involved in several physiological processes, but it is also dysregulated in many diseases, including cancer. Two G-rich sequences able to fold into G4, have been identified in c-KIT proximal promoter, thus representing suitable targets for anticancer intervention. Herein, we screened an &ldquo;in house&rdquo; library of compounds for the recognition of these G4 elements and we identified three promising ligands. Their G4-binding properties were analyzed and related to their antiproliferative, transcriptional and post-transcriptional effects in MCF7 and HGC27 cell lines. Besides c-KIT , the transcriptional analysis covered a panel of oncogenes known to possess G4 in their promoters. From these studies, an anthraquinone derivative (AQ1) was found to efficiently downregulate c-KIT mRNA and protein in both cell lines. The targeted activity of AQ1 was confirmed using c-KIT &ndash;dependent cell lines that present either c-KIT mutations or promoter engineered (i.e., &alpha;155, HMC1.2 and ROSA cells). Present results indicate AQ1 as a promising compound for the target therapy of c- KIT -dependent tumors, worth of further and in depth molecular investigations.