Interfering with microtubule dynamics is a well-established strategy in
cancer treatment; however, many microtubule-targeting agents are associated with drug resistance and adverse effects. Substantial evidence points to
ATP-binding cassette (
ABC) transporters as critical players in the development of resistance. Herein, we demonstrate the efficacy of DJ95 (2-(1H-indol-6-yl)-4-(3,4,5-trimethoxyphenyl)-1H-imidazo[4,5-c]
pyridine), a novel
tubulin inhibitor, in a variety of
cancer cell lines, including
malignant melanomas, drug-selected resistant cell lines, specific
ABC transporter-overexpressing cell lines, and the National Cancer Institute 60 cell line panel. DJ95 treatment inhibited
cancer cell migration, caused morphologic changes to the microtubule network foundation, and severely disrupted mitotic spindle formation of mitotic cells. The high-resolution crystal structure of DJ95 in complex with
tubulin protein and the detailed molecular interactions confirmed its direct binding to the
colchicine site. In vitro pharmacological screening of DJ95 using SafetyScreen44 (Eurofins Cerep-Panlabs) revealed no significant off-target interactions, and pharmacokinetic analysis showed that DJ95 was maintained at therapeutically relevant plasma concentrations for up to 24 hours in mice. In an A375 xenograft model in nude mice, DJ95 inhibited
tumor growth and disrupted
tumor vasculature in xenograft
tumors. These results demonstrate that DJ95 is potent against a variety of cell lines, demonstrated greater potency to
ABC transporter-overexpressing cell lines than existing
tubulin inhibitors, directly targets the
colchicine binding domain, exhibits significant antitumor efficacy, and demonstrates vascular-disrupting properties. Collectively, these data suggest that DJ95 has great potential as a
cancer therapeutic, particularly for multidrug resistance phenotypes, and warrants further development. SIGNIFICANCE STATEMENT:
Paclitaxel is a widely used
tubulin inhibitor for
cancer therapy, but its clinical efficacy is often limited by the development of multidrug resistance. In this study, we reported the preclinical characterization of a new
tubulin inhibitor DJ95, and demonstrated its abilities to overcome
paclitaxel resistance, disrupt
tumor vasculature, and exhibit significant antitumor efficacy.