The Hairpin Form of r(GC) in c9ALS/FTD Is Repeat-Associated Non-ATG Translated and a Target for Bioactive Small Molecules.

The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is an expanded GC repeat [(GC)] in C9ORF72. ALS/FTD-associated toxicity has been traced to the RNA transcribed from the repeat expansion [r(GC)], which sequesters RNA-binding proteins (RBPs) and undergoes repeat-associated non-ATG (RAN) translation to generate toxic dipeptide repeats. Using in vitro and cell-based assays, we identified a small molecule (4) that selectively bound r(GC), prevented sequestration of an RBP, and inhibited RAN translation.

Macrocyclic pyridyl polyoxazoles: structure-activity studies of the aminoalkyl side-chain on G-quadruplex stabilization and cytotoxic activity.

Pyridyl polyoxazoles are 24-membered macrocyclic lactams comprised of a pyridine, four oxazoles and a phenyl ring. A derivative having a 2-(dimethylamino)ethyl chain attached to the 5-position of the phenyl ring was recently identified as a selective G-quadruplex stabilizer with excellent cytotoxic activity, and good in vivo anticancer activity against a human breast cancer xenograft in mice. Here we detail the synthesis of eight new dimethylamino-substituted pyridyl polyoxazoles in which the point of attachment to the macrocycle, as well as the distance between the amine and the macrocycle are varied.

Macrocyclic biphenyl tetraoxazoles: synthesis, evaluation as G-quadruplex stabilizers and cytotoxic activity.

A series of macrocyclic biphenyl tetraoxazoles was synthesized. The latter stages of the synthetic approach allowed for the addition of varied N-protected α-amino acids, which were subsequently deprotected and condensed to provide the desired macrocycles. Improved yields could be realized in the macrocyclization step of their synthesis relative to other macrocyclic G-quadruplex stabilizers.

Macrocyclic hexaoxazoles: Influence of aminoalkyl substituents on RNA and DNA G-quadruplex stabilization and cytotoxicity.

A series of 24-membered macrocyclic hexaoxazoles containing one or two aminoalkyl substituents was synthesized and evaluated for cytotoxicity and for their ability to selectively stabilize G-quadruplex DNA and RNA. The most cytotoxic analog 4a, with IC(50) values of 25 and 130 nM using KB3-1 and RPMI 8402 cells, is efficacious in vivo in athymic nude mice with a human tumor xenograft from the breast cancer cell line MDA-MB-435.

Macrocyclic pyridyl polyoxazoles: selective RNA and DNA G-quadruplex ligands as antitumor agents.

The synthesis of a series of 24-membered pyridine-containing polyoxazole macrocycles is described. Seventeen new macrocycles were evaluated for cytotoxic activity against RPMI 8402, KB-3, and KB-3 cell lines that overexpress the efflux transporters MDR1 (KBV-1) and BCRP (KBH5.0).

A G-quadruplex stabilizer induces M-phase cell cycle arrest.

G-quadruplex stabilizers such as telomestatin and HXDV bind with exquisite specificity to G-quadruplexes, but not to triplex, duplex, or single-stranded DNAs. Studies have suggested that the antiproliferative and possibly anti-tumor activities of these compounds are linked to their inhibitory effect on telomerase and/or telomere function. In the current studies, we show that HXDV, a synthetic analog of telomestatin, exhibits antiproliferative activity against both telomerase-positive and -negative cells and induces robust apoptosis within 16 h of treatment, suggesting a mode of action independent of telomerase.

Ring-closing metathesis for the synthesis of a highly G-quadruplex selective macrocyclic hexaoxazole having enhanced cytotoxic potency.

The synthesis of a 24-membered macrocyclic hexaoxazole via ring-closing metathesis is described. The target compound selectively stabilizes G-quadruplex DNA with no detectable stabilization of duplex DNA. An MTT cytotoxicity assay indicated that this unsaturated macrocyclic hexaoxazole exhibits significant cytotoxicity toward P388, RPMI 8402, and KB3-1 cell lines with IC50 values of 45, 25, and 38 nM, respectively.

Targeting human telomeric G-quadruplex DNA with oxazole-containing macrocyclic compounds.

Oxazole-containing macrocycles, which include the natural product telomestatin, represent a promising class of anticancer agents that target G-quadruplex DNA. Two synthetic hexaoxazole-containing macrocyclic compounds (HXDV and HXLV-AC) have been characterized with regard to their cytotoxic activities versus human cancer cells, as well as the mode, thermodynamics, and specificity with which they bind to the intramolecular (3+1) G-quadruplex structural motif formed in the presence of K+ ions by human telomeric DNA. Both compounds exhibit cytotoxic activities versus human lymphoblast (RPMI 8402) and oral carcinoma (KB3-1) cells, with associated IC50 values ranging from 0.

Lysinyl macrocyclic hexaoxazoles: synthesis and selective G-quadruplex stabilizing properties.

Macrocyclic hexaoxazoles having one or two lysinyl side chains in which the terminal nitrogen is either a primary amine, N,N-dimethylamine, or an acetamide have been synthesized. Sodium ion has been found to be beneficial to the macrocyclization step by acting as a template around which the linear polyoxazole can organize. Each of the targeted compounds selectivity stabilizes G-quadruplex versus duplex DNA.

Defining the mode, energetics and specificity with which a macrocyclic hexaoxazole binds to human telomeric G-quadruplex DNA.

Oxazole-containing macrocycles represent a promising class of anticancer agents that target G-quadruplex DNA. We report the results of spectroscopic studies aimed at defining the mode, energetics and specificity with which a hexaoxazole-containing macrocycle (HXDV) binds to the intramolecular quadruplex formed by the human telomeric DNA model oligonucleotide d(T2AG3)4 in the presence of potassium ions. HXDV binds solely to the quadruplex nucleic acid form, but not to the duplex or triplex form.

Synthesis and G-quadruplex stabilizing properties of a series of oxazole-containing macrocycles.

The synthesis of 24-membered macrocycles containing four, six, and seven oxazole moieties is described. Selected compounds were evaluated for their ability to specifically bind and stabilize G-quadruplex DNA and for cytotoxic activity. An unexpected oxidative cleavage reaction afforded a macrocyclic imide that was also evaluated for G-quadruplex stabilizing and cytotoxic activity.

Synthesis and biological activity of the tea catechin metabolites, M4 and M6 and their methoxy-derivatives.

Syntheses are reported for metabolites M4 (1) and M6 (2) of the green tea polyphenols epicatechin (EC) and epigallocatechin (EGC) and their gallate derivatives. Several methoxy-derivatives of 1 and 2 were also prepared. Compounds 1 and 2 were evaluated for growth inhibitory activity against a panel of immortalized and malignant human cell lines with 1 being the more active compound.