Aromatic Core Extension in the Series of N‐Cyclic Bay‐Substituted Perylene G‐Quadruplex Ligands: Increased Telomere Damage, Antitumor Activity, and Strong Selectivity for Neoplastic over Healthy Cells

Abstract

Based on previous work on both perylene and coronene derivatives as G-quadruplex binders, a novel chimeric compound was designed: N,N'-bis[2-(1-piperidino)-ethyl]-1-(1-piperidinyl)-6-[2-(1-piperidino)-ethyl]-benzo[ghi]perylene-3,4:9,10-tetracarboxylic diimide (EMICORON), having one piperidinyl group bound to the perylene bay area (positions 1, 12 and 6, 7 of the aromatic core), sufficient to guarantee good selectivity, and an extended aromatic core able to increase the stacking interactions with the terminal tetrad of the G-quadruplex. The obtained "chimera" molecule, EMICORON, rapidly triggers extensive DNA damage of telomeres, associated with the delocalization of telomeric protein protection of telomeres 1 (POT1), and efficiently limits the growth of both telomerase-positive and -negative tumor cells. Notably, the biological effects of EMICORON are more potent than those of the previously described perylene derivative (PPL3C), and more interestingly, EMICORON appears to be detrimental to transformed and tumor cells, while normal fibroblasts expressing telomerase remain unaffected. These results identify a new promising G-quadruplex ligand, structurally and biologically similar on one side to coronene and on the other side to a bay-monosubstituted perylene, that warrants further studies.

Evidence for G-quadruplex in the promoter of vegfr-2 and its targeting to inhibit tumor angiogenesis

“…Importantly, the effects of RHPS4 on EC function appeared to be principally mediated by a reduced expression of vegfr-2 : they recapitulated those observed by using a specific interference RNA against vegfr-2 (Figure 3D), and they were antagonized by overexpressing the vegfr-2 gene under the control of the CMV viral promoter (Figure 3E). The link between G4 ligand-mediated inhibition of vegfr-2 and impairment of EC functions was reinforced by using other chemically unrelated G4 ligands, Emicoron and PPL3C, two molecules, belonging to the coronene and perilene families of ligands, respectively (41,42). Consistently with the polymerase stop assay data, PPL3C and Emicoron caused a different degree of VEGFR-2 protein reduction and impairment of EC migration (Supplementary Figure S5A–C).…”

“…However, there are several novel aspects in our study, which include not only the discovery of a new G4-containg gene but also the functional relevance of this finding through intervention with small molecules, both in cell cultures and in animal model. Specifically, we found that a number of chemically unrelated G4 ligands (26,39,41,42) are able to bind to and stabilize the G4 structure identified within the promoter of vegfr-2, providing an explanation for their inhibitory effect on VEGFR-2 expression and on EC proliferation, migration, differentiation and in vivo angiogenesis. The effects of G4 ligands have been observed in human- and mouse-derived EC consistently with the presence of the G4 structure in both cell types (54) [as determined by the G4 prediction software QGRS (33)].…”

Targeting G-Quadruplex DNA Structures by EMICORON Has a Strong Antitumor Efficacy against Advanced Models of Human Colon Cancer

“…1A), having one piperidinyl group bound to the perylene bay area, sufficient to guarantee a good selectivity, and an extended aromatic core able to increase the stacking interactions with the ending tetrad of the G4. The subsequent profiling of its biologic properties demonstrated that this compound is outstandingly potent in inducing selective DNA damage to telomeres of cancer cells versus normal cells, endowing with efficient antiproliferative effect on several tumor cell lines at low micromolar concentrations (21). Moreover, in agreement with its ability to target the G4 sequence identified in the promoter of VEGFR-2 (22), EMICORON can bind to G4 structures throughout the genome (Fig.…”

“…perylene-3,4:9,10-tetracarboxylic diimide [EMICORON; molecular formula: C 52 H 59 N 6 O 4 .4HCl; molecular weight ¼ 977, estimated pK a (piperidine) ¼ 11] was synthesized as previously described (21) and used as a salt, specifically hydrochloride, with a good solubility in water. 7-Ethyl-10-hydroxycamptothecin (SN-38, Alexis) and doxorubicin (Ebewe) were also used.…”

From R-Loops to G-Quadruplexes: Emerging New Threats for the Replication Fork

“…In this direction, EMICORON is a very promising compound showing a good efficacy in vivo towards colon cancer models [117]. The compound destabilizes telomeric DNA but also downregulates both BCL2 and MYC by binding their promoters [118,119]. This broader activity may explain its efficacy.…”