Mechanism of action of G-quadruplex forming oligonucleotide homol | 49101

Oncology & Cancer Case Reports

ISSN - 2471-8556

Mechanism of action of G-quadruplex forming oligonucleotide homologous to the telomere overhang in melanoma


December 05-07, 2016 Philadelphia, USA

Neelu Puri

University of Illinois College of Medicine at Rockford, USA

Posters & Accepted Abstracts: Oncol Cancer Case Rep

Abstract :

T-oligo, a Guanine-Rich Oligonucleotide (GRO) homologous to the 3â??-telomeric overhang of telomeres, elicits potent DNAdamage responses (DDRs) in cancer cells. However, the detailed molecular mechanism of action of T-oligo in cancer cells is largely unknown. Recent studies suggest that GROs can form G-quadruplexes (G4) which are stabilized by the hydrogenbonding of guanine residues. This study aims to examine the G4-forming capabilities of T-oligo in vitro and comparative analysis of anti-proliferative activities of single-stranded (SS) and G4-T-oligo with investigating the molecular mechanism of T-oligo-induced DDRs in melanoma cells. G4-formation by T-oligo was confirmed using non-denaturing PAGE and NMR. Immunofluorescence study conducted with an anti-G-quadruplex antibody (BG4) showed 88.4% co-localization of T-oligo and BG4 in the nuclei of melanoma cells confirming the ability of T-oligo to form G-quadruplex inside the cells. While G4- T-oligo was found more stable in nuclease degradation assay by DNase I, it has decreased anti-proliferative effects then SS-Toligo. However, G4-T-oligo has similar cellular uptake as SS-T-oligo. Further, two shelterin complex proteins TRF2 and POT1 were found to be upregulated by T-oligo suggesting TRF2 and POT1 mediated telomere overhang dissociation. Activity of JNK was also upregulated by T-oligo. SP600125 (JNK inhibitor), inhibited T-oligo-mediated JNK-phosphorylation and partially reversed the anti-proliferative activity of T-oligo in melanoma cells. T-oligo also inhibited mRNA expression of hTERT, a catalytic subunit of telomerase. In conclusion, these studies demonstrate that T-oligo can form G-quadruplex and the antiproliferative mechanism of T-oligo may be mediated through POT1 and TRF2 as well as via JNK-activation inducing hTERTinhibition in melanoma cells.

Biography :


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