An anionic phthalocyanine decreases NRAS expression by breaking down its RNA G-quadruplex

Keiko Kawauchi,Kohei Murata,Daisuke Miyoshi,Hisae Tateishi-Karimata,Katsuhiko Itoh,Naoki Sugimoto,Takaaki Tsuruoka,Kensuke Akamatsu,Takatoshi Yasui,Wataru Sugimoto,Kazuki Takagi

doi:10.1038/s41467-018-04771-y

Keiko Kawauchi, Kohei Murata + Show 9 more

Open Access

https://doi.org/10.1038/s41467-018-04771-y

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Journal: Nature Communications	Publication Date: Jun 11, 2018
Citations: 55	License type: open-access

Affiliation: Konan University

Abstract

Aberrant activation of RAS signalling pathways contributes to aggressive phenotypes of cancer cells. The RAS-targeted therapies for cancer, therefore, have been recognised to be effective; however, current developments on targeting RAS have not advanced due to structural features of the RAS protein. Here, we show that expression of NRAS, a major isoform of RAS, can be controlled by photo-irradiation with an anionic phthalocyanine, ZnAPC, targeting NRAS mRNA. In vitro experiments reveal that ZnAPC binds to a G-quadruplex–forming oligonucleotide derived from the 5′-untranslated region of NRAS mRNA even in the presence of excess double-stranded RNA, which is abundant in cells, resulting in selective cleavage of the target RNA’s G-quadruplex upon photo-irradiation. In line with these results, upon photo-irradiation, ZnAPC decreases NRAS mRNA and NRAS expression and thus viability of cancer cells. These results indicate that ZnAPC may be a prominent photosensitiser for a molecularly targeted photodynamic therapy for cancer.

Highlights

Photodynamic therapy (PDT) is being widely recognised as a minimally invasive cancer treatment[1,2,3,4]
ZnAPC binds to the G-quadruplex derived from NRAS mRNA
Because RNA is more abundant than its corresponding DNA in the cell, firstly, we evaluated the binding affinity of anionic phthalocyanines (APCs) for NRAS RNA, which is a parallel G-quadruplex-forming RNA oligonucleotide derived from the 5′ untranslated regions (UTRs) of NRAS mRNA (the nucleotide sequence and circular dichroism (CD) spectrum are shown in Supplementary Table 1 and Supplementary Figure 1, respectively)

Summary

Introduction

Photodynamic therapy (PDT) is being widely recognised as a minimally invasive cancer treatment[1,2,3,4]. The gene expression regulated by formation of G-quadruplexes is assumed to be associated with cancer development and progression[27]. This notion has been supported by a growing body of evidence on G-quadruplex ligands as potential anticancer drugs[31,33,34,35]. The expression of cancer-related proteins regulated by formation of a G-quadruplex, including NRAS, can be effectively controlled if a ligand can bind reversibly and attack irreversibly DNA and RNA G-quadruplexes. The approach in this study holds promise for a molecularly targeted PDT for cancer

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Results

Conclusion