WRN-targeted therapy using inhibitors NSC 19630 and NSC 617145 induce apoptosis in HTLV-1-transformed adult T-cell leukemia cells

Abstract

BackgroundHuman T-cell leukemia virus type 1 (HTLV-1) infection is associated with adult T-cell leukemia/lymphoma (ATLL), a lymphoproliferative malignancy with a dismal prognosis and limited therapeutic options. Recent evidence shows that HTLV-1-transformed cells present defects in both DNA replication and DNA repair, suggesting that these cells might be particularly sensitive to treatment with a small helicase inhibitor. Because the “Werner syndrome ATP-dependent helicase” encoded by the WRN gene plays important roles in both cellular proliferation and DNA repair, we hypothesized that inhibition of WRN activity could be used as a new strategy to target ATLL cells.MethodsOur analysis demonstrates an apoptotic effect induced by the WRN helicase inhibitor in HTLV-1-transformed cells in vitro and ATL-derived cell lines. Inhibition of cellular proliferation and induction of apoptosis were demonstrated with cell cycle analysis, XTT proliferation assay, clonogenic assay, annexin V staining, and measurement of mitochondrial transmembrane potential.ResultsTargeted inhibition of the WRN helicase induced cell cycle arrest and apoptosis in HTLV-1-transformed leukemia cells. Treatment with NSC 19630 (WRN inhibitor) induces S-phase cell cycle arrest, disruption of the mitochondrial membrane potential, and decreased expression of anti-apoptotic factor Bcl-2. These events were associated with activation of caspase-3-dependent apoptosis in ATL cells. We identified some ATL cells, ATL-55T and LMY1, less sensitive to NSC 19630 but sensitive to another WRN inhibitor, NSC 617145.ConclusionsWRN is essential for survival of ATL cells. Our studies suggest that targeting the WRN helicase with small inhibitors is a novel promising strategy to target HTLV-1-transformed ATL cells.

RecQ helicases in DNA repair and cancer targets

“…Whilst there are no currently approved or ongoing clinical trials for drugs specifically targeting RecQ helicases, there has been considerable effort to identify chemical classes and candidate small molecule inhibitors from academic labs. A high-throughput screen using a radiometric strand displacement assay was used to identify NSC19630 IC 50 = 20 μM [ 83 ], which were also found to induce apoptosis in cells in a WRN-dependent manner [ 83 , 84 ]. Subsequent work identified a structural analogue NSC617145 [ 85 ] that induced sensitization to mitomycin C in cells carrying mutations in the Fanconi Anemia pathway.…”

p30 protein: a critical regulator of HTLV-1 viral latency and host immunity

“…In conclusion, p30 impairs the DNA damage response in HTLV-1 infected cells. Further, treatment with inhibitors that target the DNA repair pathway (PJ45, Olaparib, NSC 19630, and NSC 617145) were found to induce apoptosis not only in HTLV-1 infected cells, but also in ATL-derived cell lines [119,120], suggesting that DNA repair machinery is impaired in ATL transformed cells and that those drugs might represent a promising therapy for HTLV-1-associated diseases.…”

Clinically Applicable Inhibitors Impacting Genome Stability

“…Inhibition of WRN activity by NSC 617145 in Fanconi Anemia (FANCA and FANCD2) or DNA-PKcs deficient cells sensitised them to mitomycin C (MMC) [ 219 ]. The WRN specific inhibitor, NSC 19630, sensitised cells to topotecan, and has shown promise against leukaemia cells [ 220 , 221 ]. Targeted inhibition of WRN has potential as an anticancer strategy for inducing synthetic lethality, when used in combination with other pathway specific inhibitors (such as inhibitors affecting the NHEJ pathway).…”