Figure 7: CX-5461 effectively kills tumour cells deficient for a number of DNA damage repair pathways.

(a) PRKDC^−/− HCT116 cells are more sensitive to CX-5461 compared with PRKDC wild type HCT116 cells. The dose sensitivity of CX-5461 (6 days in drug) was measured by WST-1 assay with representative experiment #2 shown (see Supplementary Fig. 7a for all three experiments). Vertical dashed lines indicate the estimated IC50 values. (b) LIG4^−/− HCT116 cells are more sensitive to CX-5461 and PDS compared with LIG4 wild type HCT116 cells. The drug sensitivity (4 days in drug) was measured by a WST-1 assay. n≥4. IC50 difference for CX-5461 between LIG4^+/+ and LIG4^−/− cells is 5.73 (P<10⁻¹⁰, t-test). Sigmoid fits were unavailable for PDS treated cells so no IC50 estimates or fold change was available. Assessment via a two-way ANOVA test showed that Lig4 deficient cells were more sensitive to PDS than Lig4 proficient cells (F-test P<10⁻¹⁰). Results of drug sensitivity to BMH-21 and cisplatin for LIG4^+/+ and LIG4^−/− cells are shown in Supplementary Fig. 7b. (c) Genotype specific sensitivity to CX-5461 in C. elegans. The percentage of viable embryos observed in the progeny of animals treated for∼20 h with 100 μM CX-5461 or carrier (50 μM NaH₂PO₄). Error bars depict the s.e.m. of at least three experiments. Statistically significant difference by t-test was discovered for all mutants shown in this figure (P<0.05) comparing carrier-treated to CX-5461-treated animals. (d) CX-5461/CX-3543 exhibits antiproliferative potency against a panel of breast cancer cell lines by SRB cytotoxicity assay. Heatmap represents IC50 values for 50 breast cancer cell lines treated with Olaparib, BMH-21, CX-3543 and CX-5461 for 5 days. The ward-linkage method of ‘hclust’ (R function) was used to compute the dendrogram. The panel on the left is ordered by intrinsic subtype of cell lines, the panel on the right is ordered by ranked value of CX-5461 sensitivity. The legends indicate the categorical values for intrinsic subtype, BRCA mutation status, DNA repair mutation status, and cisplatin sensitivity (data from Sanger cell line project).