A G-quadruplex Stabilizer Induces M-phase Cell Cycle Arrest

Abstract

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. HXDV was also shown to inhibit cell cycle progression causing M-phase cell cycle arrest, as evidenced by accumulation of cells with 4 N DNA content, increased mitotic index, separated centrosomes, elevated histone H3 phosphorylation at Ser-10 (an M-phase marker), and defective chromosome alignment and spindle fiber assembly (revealed by time-lapse microscopy). The M-phase arrest caused by HXDV paralleled with reduction in the expression level of the major M-phase checkpoint regulator Aurora A. All these cellular effects appear to depend on the G-quadruplex binding activity of HXDV as its non-G-quadruplex binding analog, TXTLeu, is completely devoid of all these effects. In the aggregate, our results suggest that HXDV, which exhibits anti-proliferative and apoptotic activities, is also a novel M-phase blocker, with a mode of action dependent on its G-quadruplex binding activity.

Macrocyclic Pyridyl Polyoxazoles: Selective RNA and DNA G-Quadruplex Ligands as Antitumor Agents

“…7c HXDV has moderate cytotoxicity towards tumors cells (average IC 50 ~0.5 μM), which is comparable to that reported for telomestatin 8. HXDV induces robust apoptosis in both telomerase positive and telomerase negative cells within 16 h, causes M-phase cell cycle arrest, and reduces the expression of the M-phase checkpoint regulator Aurora A 9. These effects are not observed for the non-G-quadruplex stabilizing 24-membered macrocycle TXTLeu (tetraoxazoletetraleucine, Figure 1).…”

Translational repression of cyclin D3 by a stable G-quadruplex in its 5′ UTR: implications for cell cycle regulation

“…While a previous report suggested that the reduction in the Aurora A protein level during a G-quadruplex stabilizer-induced cell cycle arrest may result from the stabilization of a potential RNA G-quadruplex in its 5' UTR, no direct evidence was provided to support the formation of this RNA G-quadruplex and the role of this sequence in cell cycle regulation. 66 We demonstrated in this study that the CRQ RNA G-quadruplex within the 5' UTR of CCND3 plays a role in the G1/S phase transition of the cell cycle. Mutations that disrupt the formation of the G-quadruplex structure led to the production of more CCND3 protein from the expression vectors, which promoted the phosphorylation and inactivation of the Rb tumor suppressor gene and subsequently resulted in accelerated cell cycle progression and cell proliferation.…”

The ribosome and its role in protein folding: looking through a magnifying glass

“…This is elegantly demonstrated by the recent advances in time-resolved cryo-electron microscopy, based on insights from single-molecule fluorescence measurements. The studies provided a detailed insight into the structure of the ribosome in real time as it transitions through different functional states during protein biosynthesis (Fischer et al, 2010;Tsai et al, 2014;Chen et al, 2015;Belardinelli et al, 2016).…”