Anti-tumor selectivity of a novel tubulin and HSP90 dual-targeting inhibitor in non-small cell lung cancer models.

Dose-limiting toxicity is a main road blocker for successful cancer chemotherapy. By phenotype screening, a novel chemical agent 2-(2-Chlorophenylimino)-5-(4-dimethylamino-benzylidene) thiazolidin-4-one (CDBT) was found to strongly inhibit the proliferation of non-small cell lung cancer (NSCLC) cells H460 and H322 while displaying no obvious toxicity to normal fast-dividing fibroblast cells NHFB and WI-38 at a concentration 100-fold higher than its EC50 to NSCLC cells. CDBT targets microtubule and heat shock protein 90 (HSP90) simultaneously with moderate affinities compared to microtubule targeting Colchicine and HSP90 inhibitor 17-dimethylaminoethylamino-17-demethoxygaldanamcyin (17-DMAG). CDBT blocks microtubule formation, decreases cancer-essential proteins CRAF-1, ERBB2 and phosphorylated AKT, and causes G2/M arrest and apoptosis. The moderate inhibitory effects of CDBT on targets require a higher cellular concentration of targets, a situation only exist in cancer cells. This accounts for its good cancer selectivity. Furthermore, CDBT effectively inhibits tumor growth by 62.4% relative to the vehicle control after i.p. administration at 30 mg/kg for 11 days while showing no toxicity to normal tissues in NSCLC H460 xenograft mouse model.