Potent Inhibition of Human Telomerase by Nitrostyrene Derivatives

Abstract

Telomerase activity is expressed in most types of cancer cells but not in normal somatic cells, suggesting that telomerase may be an important target for cancer chemotherapy. Inhibition of telomerase results in telomere erosion, leading to the subsequent growth arrest of cancer cells followed by senescence or cell death. In this study, we screened a chemical library for the inhibition of human telomerase, identifying three inhibitors. All compounds contained a common nitrostyrene moiety conjugated to different side chains. One of these compounds, 3-(3,5-dichlorophenoxy)-nitrostyrene (DPNS), showed the most potent inhibitory effect, with 50% inhibition at ϳ0.4 M and did not inhibit DNA and RNA polymerases, including retroviral reverse transcriptase. A series of enzyme kinetic experiments suggests that DPNS is a mixed-type noncompetitive inhibitor, with an inhibitor-binding site distinct from the binding sites for the telomeric substrate primer and the deoxynucleoside-5Ј-triphosphates. Extensive propagation of cancer cell line in the presence of DPNS resulted in progressive telomere erosion followed by the induction of senescence phenotype. The results presented here demonstrate that DPNS is a highly selective, small-molecule telomerase inhibitor in vitro and could be useful as a lead molecule for the further development of inhibitors with an improved potential for efficacy in vivo.

3,4-Methylenedioxy-β-nitrostyrene Inhibits NLRP3 Inflammasome Activation by Blocking Assembly of the Inflammasome

“…Here, we have identified MNS as a novel inhibitor of NLRP3 inflammasome activation. Previously MNS was reported to inhibit platelet aggregation, tumor cell growth, and apoptosis (45)(46)(47). Effects of nitrostyrene on tyrosine kinases, protein phosphatases, and telomerase activity have been suggested to account for those inhibitions.…”

Ubiquitin ligase MKRN1 modulates telomere length homeostasis through a proteolysis of hTERT

“…1D). To more clearly determine the effects of GA on telomerase activity, N-terminal Flag-tagged hTERT and C-terminal HA-tagged hTERT constructs were transfected to Saos-2 cells (these cells lack detectable telomerase activity) (Kim et al 2003). The forced expression of exogenous hTERT produced detectable telomerase activity in these cells (Fig.…”

“…The telomeric repeat amplification protocol (TRAP) was used as previously described (Kim et al 2003). Cell extracts (200 ng of protein) were added to telomerase extension reactions and incubated for 20 min at 37°C.…”

Telomerase activates transcription of cyclin D1 gene through an interaction with NOL1

“…The telomeric repeat amplification protocol (TRAP) was used as previously described (Kim et al, 2003).…”