Nanoparticulate delivery of potent microtubule inhibitor for metastatic melanoma treatment

Melanoma is the most aggressive type of skin cancer, which readily metastasizes through lymph nodes to the lungs, liver, and brain. Since the repeated administration of most chemotherapeutic drugs develops chemoresistance and severe systemic toxicities, herein we synthesized 2-(4-hydroxy-1H-indol-3-yl)-1H-imidazol-4-yl)(3,4,5-trimethoxyphenyl) methanone (abbreviated as QW-296), a novel tubulin destabilizing agent with little susceptible to transporter-mediated drug resistance. QW-296 disturbed the microtubule dynamics at the nanomolar concentration in A375 and B16F10 melanoma cells. QW-296 binding to colchicine-binding site on tubulin protein was confirmed by molecular modeling and tubulin polymerization assay. QW-296 significantly inhibited A375 and B16F10 cell proliferation, induced G2/M cell cycle arrest and led to apoptosis and cell death. To improve its aqueous solubility, QW-296 was encapsulated into methoxy poly(ethyleneglycol)-b-poly(carbonate-co-lactide) [mPEG-b-P(CB-co-LA)] polymeric nanoparticles by solvent evaporation, with the mean particle size of 122.0 ± 2.28 nm and drug loading of 3.70% (w/w). Systemic administration of QW-296 loaded nanoparticles into C57/BL6 albino mice bearing lung metastatic melanoma at the dose of 20 mg/kg 4 times a week for 1.5 weeks resulted in significant tumor regression and prolonged mouse median survival without significant change in mouse body weight. In conclusion, QW-296 loaded nanoparticles have the potential to treat metastatic melanoma.