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. Our studies showed that DNA2 nuclease is an evolutionarily conserved essential component of HR repair machinery. Here we demonstrate that DNA2 is indeed The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/107383 doi: bioRxiv preprint first posted online Feb. 9, 2017; 3 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 undruggable oncoprotein itself such as KRAS.

FANCD2 and RAD51 recombinase directly inhibit DNA2 nuclease at stalled replication forks and FANCD2 acts as a novel RAD51 mediator in strand exchange to promote genome stability

“…We observed no inhibition of yeast DNA2 by FANCD2, even at great molar excess FANCD2, on either the forked substrate or the reversed fork substrate (Figure S2D and S2E). Note that yDNA2 is more active than hDNA2, as also reported by others (Kumar et al, 2017), accounting for the concentrations used. The lack of inhibition of yeast DNA2 by FANCD2 supports, though it does not prove, that inhibition of hDNA2 by FANCD2 involves a species-specific and therefore likely a physiologically significant protein/protein interaction.…”

Nej1 interacts with Sae2 at DNA double-stranded breaks to inhibit DNA resection

“…Regulation of Dna2-dependent resection seems to be more complex than Exo1, which appears to only require DNA ends not protected by Ku. Furthermore, understanding the function of Dna2 at DSBs has been challenging because DNA2 is an essential gene involved in Okazaki fragment processing and cannot be deleted (21)(22)(23)(24)(25). Earlier work showed that the lethality of dna2Δ can be suppressed by disruption of PIF1 helicase and that the frequency of 5 0 resection decreased at a DSB in dna2Δ pif1-m2 mutants (19,26).…”

Targeting DNA2 Overcomes Metabolic Reprogramming in Multiple Myeloma

“…To test this hypothesis, we used the specific DNA2 activity inhibitor NSC105808 (NSC) 16 . We confirmed that targeting DNA2 activity overcame resistance to ILF2 ASOs and induced MM cell death in vitro (Supplementary Fig.…”