Switching off cancer - An overview of G-quadruplex and i-motif functional role in oncogene expression

DNA can self-assemble into G-quadruplexes and i-motifs non-canonical secondary structures that are formed by guanine-rich sequences and the cytosine-rich sequences, respectively. G-quadruplexes and i-motifs have been closely linked to cancer development since they can regulate genes expression in various promoter regions. Moreover, these structures have gained attention as viable targets for anticancer treatments because of their physicochemical properties and gene-regulatory functions. As a result, they are attractive molecular targets for innovative cancer therapies. Herein, we review the G-quadruplex and i-motif structures, their dynamic relationship in biological systems, as well as their significance in cancer biology and the potential therapeutic approaches. Furthermore, we also address the simultaneous and mutually exclusive formation of G-quadruplex and i-motif structures in cellular environment.