Superiority of an Asymmetric Perylene Diimide in Terms of Hydrosolubility, G-Quadruplex Binding, Cellular Uptake, and Telomerase Inhibition in Prostate Cancer Cells

Abstract

Perylene diimide (PDI) derivatives have been studied as G-quadruplex ligands that suppress telomerase activity by facilitating G-quadruplex formation of telomeric DNA and the hTERT promoter. PIPER, the prototypical PDI, reduces telomerase activity in lung and prostate cancer cells, leading to telomere shortening and cellular senescence of these cells. However, PIPER suffers from poor hydrosolubility and the propensity to aggregate at neutral pH. In this report, we synthesized a new asymmetric PDI, aPDI-PHis, which maintains one N-ethyl piperidine side chain of PIPER and has histidine as another side chain. The results show that aPDI-PHis is superior to its symmetric counterparts, PIPER and PDI-His, in terms of hydrosolubility, G-quadruplex binding, cellular uptake, and telomerase inhibition in prostate cancer cells. These results suggest that one N-ethyl piperidine side chain of PDI is sufficient for G-quadruplex binding, while another side chain can be tuned to elicit desirable properties. These findings might lead to better PDIs for use as anticancer drugs.

Hydrosoluble Perylene Monoimide-Based Telomerase Inhibitors with Diminished Cytotoxicity

“…As demonstrated in our previous publication, aPDI−PHis, an asymmetric perylene diimide derivative with a 2-aminoethylpiperidine side chain and a histidine side chain, is superior to its symmetric counterparts in terms of hydrosolubility, G4 binding, cellular uptake, and telomerase inhibition in prostate cancer cells. 28 Hydrosolubility of PMIs and PIPER. Perylene diimide derivatives (PDIs) with basic side chains often aggregate at neutral to basic pH.…”

“…We previously found that PM2 and aPDI−PHis suppressed telomerase activity and hTERT expression at lower concentrations than PIPER, despite the comparable cellular uptake. 23,28 Therefore, we opted to modify our perylene G4 DNA Binding Study by Spectrophotometry. Telomerase activity in cancer cells can be suppressed through G-quadruplex formations at the hTERT promoter and the 3′overhang of the telomere.…”

“…Oligonucleotides and FAM-tagged oligonucleotides were supplied by Bio Basic (Canada). PIPER, which was synthesized and reported in our previous publication, 28 was used in this study as a control.…”

“…We assessed the telomerase inhibitory effect of PMIs in a cell-free system using our fluorescence-based TRAP assay. 28 A test compound was first incubated in a 90 μL mixture containing 15 pmol TSG4 primer, 200 μM dNTPs, 20 mM Tris–HCl (pH 7.4), 63 mM KCl, 1.5 mM MgCl 2 , 1 mM EGTA, 0.005% Tween 20, and 0.1 mg/mL bovine serum albumin at 37 °C for 2 h. Then, crude telomerase extract (10 μL, 500 ng) was added. The telomerase extension reaction was allowed for 30 min at 30 °C before it was terminated by heating at 95 °C for 5 min.…”

“…Several strategies have been developed to increase the solubility of perylene diimides, including modification of the side chains, 22 , 25 , 26 bay area, 27 and recently, asymmetric PDI. 28 Previously, we found that PM2, a perylene monoimide (PMI) derivative, exhibited better solubility, G4 binding affinity, and telomerase inhibition than PIPER. 20 , 23 Both PM2 and PIPER inhibited telomerase and induced telomere shortening and cellular senescence in lung and prostate cancer cells.…”