Targeting Human Telomeric G-Quadruplex DNA and Inhibition of Telomerase Activity With [(dmb)2Ru(obip)Ru(dmb)2]4+
et al. (2013) Targeting Human Telomeric G-Quadruplex DNA and Inhibition of Telomerase Activity With
[(dmb)2Ru(obip)Ru(dmb)2]4+. PLoS ONE 8(12): e84419. doi:10.1371/journal.pone.0084419
Targeting Human Telomeric G-Quadruplex DNA and Inhibition of Telomerase Activity With [(dmb) Ru(obip)Ru(dmb) ]4+ 2 2
Shuo Shi 0
Shane Gao 0
Tongcheng Cao 0
Jie Liu 0
Xing Gao 0
Jian Hao 0
Chunyan Lv 0
Hailiang 0
Huang 0
Jun Xu 0
Tianming Yao 0
Andrea Cavalli, University of Bologna & Italian Institute of Technology, Italy
0 1 Department of Chemistry, Tongji University , Shanghai, China, 2 East Hospital , Tongji University School of Medicine , Shanghai , China , 3 Department of Chemistry, Jinan University , Guangzhou , China
Inhibition of telomerase by inducing/stabilizing G-quadruplex formation is a promising strategy to design new anticancer drugs. We synthesized and characterized a new dinuclear complex [(dmb)2Ru(obip)Ru(dmb)2]4+ (dmb = 4,4'-dimethyl-2,2'-bipyridine, obip = (2-(2-pyridyl)imidazo[4,5-f][1,10]phenanthroline) with high affinity for both antiparallel and mixed parallel / antiparallel G-quadruplex DNA. This complex can promote the formation and stabilize G-quadruplex DNA. Dialysis and TRAP experiments indicated that [(dmb)2Ru(obip)Ru(dmb)2]4+ acted as an excellent telomerase inhibitor due to its obvious selectivity for G-quadruplex DNA rather than double stranded DNA. In vitro coculture experiments implied that [(dmb)2Ru(obip)Ru(dmb)2]4+ inhibited telomerase activity and hindered cancer cell proliferation without side effects to normal fibroblast cells. TUNEL assay indicated that inhibition of telomerase activity induced DNA cleavage further apoptosis in cancer cells. Therefore, RuII complex represents an exciting opportunity for anticancer drug design by specifically targeting cancer cell G-quadruplexes DNA.
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Funding: This work was supported by National Programme on Key Basic Research Project (973 Program) (2010CB945200, 2011CB966200); the National
Natural Science Foundation of China (20901060, 31170776, 20871094, 81171646, 20707015, 81070910); New Century Excellent Talents in University
(NCET-10-0606); Shanghai Rising-Star program (11QA1407100); Projects of International Cooperation and Exchanges NSFC (81261130318) and the
Fundamental Research Funds for the Central Universities. The funders had no role in study design, data collection and analysis, decision to publish, or
preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
These authors contributed equally to this work.
Telomeres are believed to play a vital role in genome
integrity by protecting the genomic DNA from degradation and
deleterious recombination events such as end-to-end fusion,
rearrangements, chromosomal translocations, and
chromosomal loss [1,2]. Human telomeric DNA consists of
tandem repeats of double-stranded DNA sequence
(5TTAGGG): (5-CCCTAA) with the 3-end capped with a 100 to
200 nucleotides single-stranded overhang [3,4]. In suitable
conditions, the overhang can readily fold into a four-stranded
structure known as G-quadruplex through Hoogsteen hydrogen
bonds (Figure 1A). Significantly, G-quadruplex has been
suggested to act as a negative regulator of telomere elongation
by inhibiting telomerase activity in vivo thus considered as a
potential cancer therapy target [5-10]. Meanwhile,
Gquadruplex structures in gene promoter regions were also
investigated as a potential new class of therapeutic targets,
since the promoter regions with their diverse sequences may
provide unique scaffolds ideally for designing selective ligands
[11,12]. Successful forming and stabilizing in vivo
Gquadruplex may be an ideal strategy to inhibit telomere
elongation and telomerase activity. Besides, some important
Gquadruplexes formed by human telomeric RNA sequences
were also proved to be attractive therapeutic targets [13-15]. In
contrast to duplex structures, G-quadruplexes show a high
degree of polymorphism in terms of topological features
including individual strand orientation and loop connectivity. For
example, the NMR structure of 5-AG3[T2AG3]3-3 (denoted
22AG) in the presence of Na+ was an antiparallel basket
quadruplex (Figure 1B) [16], but the X-ray structure for the
same sequence in the presence of K+ revealed a parallel
propeller quadruplex [17]. Furthermore, circular dichroism
Figure 1. DNA and complex structures. A) structure of G-quartet with cyclic array of four guanines linked by Hoogsteen
Hbonds, B) Anti-paralled G-quadruplex, C) Mixed-hybrid G-quadruplex, D)An ORTEP drawing of [(dmb)2Ru(obip)Ru(dmb)2]4+.
doi: 10.1371/journal.pone.0084419.g001
studies indicated that it favored a mixed parallel / antiparallel
structure in the presence of K+ solution (Figure 1C) [18,19].
Hitherto, a steady growth of molecules has been reported to
selectively promote the formation and / or stabilization of
Gquadruplex structures for targeting telomere or telomerase.
Compared with many reported (...truncated)