Fig. 1

Measurement of DNA interstrand cross-linking using the single cell gel electrophoresis (comet) assay. a. Typical comet images obtained from CMeC-1 canine melanoma cells stained with propidium iodide following gel electrophoresis. a and b are untreated cells and c and d cells treated with SG2000 for 1 h at 53 nM. Cells were either unirradiated (a,c) or irradiated with 15 Gy (b,d) prior to analysis. b. Dose-dependent formation of DNA interstrand cross-linking in the CMeC-1 canine melanoma cell line immediately following a 1 h exposure to SG2000. Results are expressed as the mean percentage decrease in the tail moment ± SEM of three independent experiments. c. Persistence of SG2000-induced DNA ICLs in the canine melanoma cell line CMeC-1 following a 1 h treatment with SG2000 at 53 nM during 48 h of post-incubation in drug-free medium. Results show the mean percentage decrease of the tail moment ± SEM from three independent experiments. d. Relationship between SG2000-induced DNA ICL formation (XL₅₀ - dose of SG2000 which gives 50 % decrease in tail moment) versus cytotoxicity (GI₅₀ - measured using the SRB assay (Table 1)) of six canine tumour cell lines (C2, ARCE, KMeC, LMeC, CMeC-1 and CMeC-2) and one human melanoma cell line (LOXIMVI). Values represent the mean ± SEM from three independent experiments