Inhibition of DNA2 nuclease as a therapeutic strategy targeting replication stress in cancer cells

Abstract

Replication stress is a characteristic feature of cancer cells, which is resulted from sustained proliferative signaling induced by activation of oncogenes or loss of tumor suppressors. In cancer cells, oncogene-induced replication stress manifests as replication-associated lesions, predominantly double-strand DNA breaks (DSBs). An essential mechanism utilized by cells to repair replication-associated DSBs is homologous recombination (HR). In order to overcome replication stress and survive, cancer cells often require enhanced HR repair capacity. Therefore, the key link between HR repair and cellular tolerance to replication-associated DSBs provides us with a mechanistic rationale for exploiting synthetic lethality between HR repair inhibition and replication stress. DNA2 nuclease is an evolutionarily conserved essential enzyme in replication and HR repair. Here we demonstrate that DNA2 is overexpressed in pancreatic cancers, one of the deadliest and more aggressive forms of human cancers, where mutations in the KRAS are present in 90–95% of cases. In addition, depletion of DNA2 significantly reduces pancreatic cancer cell survival and xenograft tumor growth, suggesting the therapeutic potential of DNA2 inhibition. Finally, we develop a robust high-throughput biochemistry assay to screen for inhibitors of the DNA2 nuclease activity. The top inhibitors were shown to be efficacious against both yeast Dna2 and human DNA2. Treatment of cancer cells with DNA2 inhibitors recapitulates phenotypes observed upon DNA2 depletion, including decreased DNA double strand break end resection and attenuation of HR repair. Similar to genetic ablation of DNA2, chemical inhibition of DNA2 selectively attenuates the growth of various cancer cells with oncogene-induced replication stress. Taken together, our findings open a new avenue to develop a new class of anticancer drugs by targeting druggable nuclease DNA2. We propose DNA2 inhibition as new strategy in cancer therapy by targeting replication stress, a molecular property of cancer cells that is acquired as a result of oncogene activation instead of targeting currently undruggable oncoprotein itself such as KRAS.

Natural product β-thujaplicin inhibits homologous recombination repair and sensitizes cancer cells to radiation therapy

“…Thus we propose to use β-thujaplicin target cancer cells with replication stress, which may cause a synthetic lethality. In our recent publication, we specifically reported that HR repair inhibitors targeting a key DNA resection enzyme DNA2 nuclease activity can potentially be used to target cells with replication stress, which requires HR repair capacity to overcome replication-associated DSBs [54]. It is our future interest to test whether the natural product such as β-thujaplicin containing HR repair inhibitory effect can have a similar therapeutic function targeting cancer cells with replication stress.…”

<p>Nematicidal activity of silver nanoparticles from the fungus <em>Duddingtonia flagrans</em></p>

“…Nanotechnology is a field of science that is constantly developing, as its applications both in medical sciences and biological sciences are broad: medical diagnosis, biosensors, health care, drug delivery, and water purification. 3 Within the field of nanotechnology, silver nanoparticles (AgNPs) have been widely studied due to their exclusive physical, chemical, and optical properties. 4 Several studies have investigated a wide variety of chemical, physical, and biological synthesis methods with the objective of establishing a technique that makes morphological regulation of the AgNPs possible.…”

“…analysis of the nematicidal action of the biosynthesized agNPs on l3 of A. caninumInitially, 50 µL of the solution of L 3 s of A. caninum (13 L 3 /µL) was added to each of the 27 microtubes. Then these microtubes were divided into nine groups:GroupI (negative control): solution of L 3 larvae +1 mL of ultrapure water; Group II (positive control): solution of L 3 larvae +1 mL of levamisole 22.3%; Group III (positive control): solution of L 3 larvae +1 mL of ivermectin 1%; International Journal of Nanomedicine downloaded from https://www.dovepress.com/ by 44.224.250.200 on 01-Aug-2020 For personal use only.…”

A universal fluorescence-based toolkit for real-time quantification of DNA and RNA nuclease activity

“…Nucleases may also represent anticancer targets, and this assay could offer an alternative method for studying the effect of future anticancer drugs on the activity of their target nuclease (76). In a similar instance, a discontinuous assay using PG was successfully performed to study the inhibitory role of actin on DNase I (77).…”