Fig. 1.

ST-401 and NOC kill cancer cells through a different antitumor mechanism: evidence from the NCI-60 cancer cell line panel. a Diagram illustrating ST-401 and NOC binding to the colchicine site of tubulin distinct from the vinca and taxane sites, all of which differentially influence MT dynamics via their binding to distinct sites on tubulin. b The antitumor activity of ST-401 was tested in the NCI-60 cancer cell line panel and results analyzed using COMPARE software. ST-401 exhibited significant antitumor activity in 46 out of 60 cancer cell lines as measured by total growth inhibition (TGI). SF-539 cells are highly sensitive to ST-401, HCT116 cells exhibited an average sensitivity and SNB-19 were much less sensitive to ST-401 (colored arrows). c The top 12 compounds with best correlations in antitumor activity (Pearson correlation) with ST-401. MTAs that target the vinca site (purple) or the taxane site (green) are among the top 12 (7 out of 12). Initial considerations of significance using COMPARE software is normally set at > 0.7 for Pearson correlation values (dotted line) and these values were not reached by these top 12 compounds. d Vector map representation of the direct Pearson correlations between ST-401 (blue) and its closest MTAs acting on the vinca site (purple) and nocodazole (NOC) (red). e Direct comparison of the antitumor activity of ST-401 measured in SF-539, HCT116 and SNB-19 cells within the NCI-60 panel shows differential sensitivities