Implication of the novel microtubule targeting agent, AUS_001, in pancreatic cancer cellular signaling.

748 Background: Pancreatic cancer (PanCa) is considered a major therapeutic challenge due to its poor prognosis, high mortality rate and resistance to most therapies, underlining the need for new treatment approaches. Our previous investigations revealed that the prenylated hydroxy-stilbene, AUS_001, inhibits β-tubulin polymerization via its unique binding to the colchicine site of tubulin. A cell-based profiling platform identified sensitivity of 12 out of 13 PanCa lines to AUS_001 with a median concentration causing 50% growth inhibition of 0.227µM. The goal of the current study was to elucidate the signaling activity and cellular responses following treatment with AUS_001 and explore the prospect of the latter in PanCa treatment. Methods: A series of functional and biochemical assays were performed to delineate the effect of AUS_001 on the growth, colony formation ability, invasive capacity and oxidative status of PanCa cells. Tumor growth was evaluated in PANC-1 implanted CB.17 SCID mice and MIA PaCa-2 implanted nude mice upon intraperitoneal administration of AUS_001 once weekly. Metabolic profiling was carried out using the Seahorse XF Analyzer. RNA silencing and adenovirus-mediated overexpression of the Dominant-Negative Mutant of c-Jun were employed to explore the link of c-Jun activation and AUS_001-induced cytotoxicity. Results: The potential of AUS_001 to disrupt PanCa cell functions was established in vitro and in vivo . Viability and compromised membrane integrity were multiplexed and resulted in half maximal effective concentration agreement indicating drug-induced cytotoxicity. AUS_001-treated cells underwent apoptosis followed by secondary necrosis, exerted diminished anchorage-independent growth and metastatic potential in vitro . Importantly, tumor growth was significantly reduced in PanCa murine xenograft models by AUS_001 as a monotherapy. Pretreatment with N-acetyl-l-cysteine did not alter cellular sensitivity to AUS_001, suggesting that the time-dependent induction of reactive oxygen species upon AUS_001 exposure is not the primary cause of cytotoxicity. Notably, the oxygen consumption rate, extracellular acidification rate and function of all mitochondrial complexes (I-IV) of live MIA PaCa_2 cells were significantly impaired in both glucose- and galactose-containing media 48h after AUS_001 administration. Integration of transcriptomic and proteomic data originating from AUS_001-challenged cells uncovered the dramatic induction of c-Jun and FosB stress responders. Further studies demonstrated that c-Jun transcriptional activation acts as a partial mediator of AUS_001-induced cytotoxicity. Conclusions: Collectively, our findings provide critical insights into the molecular events triggered by AUS_001 in PanCa cells and serve as supporting data for future exploration of AUS_001 as a novel PanCa therapeutic agent.