Abstract 4468: Anticancer activity of novel cucurbitacin analogue in pancreatic cancer

Background: Human pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths in the United States. Accumulating studies have witnessed the malfunction of many chemotherapeutic regimens and the current standard-of-care therapy, gemcitabine (GEM), enhances patient survival by only few months. Cucurbitacins, naturally occurring dietary tetracyclic triterpenoid compounds, have shown promising anti-cancer activities. Herein, we investigated the potency and anti-cancer efficacy of a novel analogue of cucurbitacin (Cuc D) in pancreatic cancer cell lines and in a xenograft mouse model. Additionally, we determined efficacy of this analogue on MicroRNAs (miRNAs) which are important regulators of genes that have crucial roles in pancreatic tumorigenesis. Methods: The effect of Cuc D on the growth of pancreatic cancer cells was determined by cell proliferation assay using six pancreatic cancer (MiaPaCa-2, CaPan-1, HPAF-II, Panc-1, BxPC-3 and AsPc-1) cells. Cell growth kinetic assay was carried out at 24, 48, 72 and 96 h. The clonogenic potential of cancer cells was also studied using the colony formation assay. Tumor suppressor miR-145, which is downregulated in pancreatic cancer, directly target MUC13. Thus the effect of Cuc D was also investigated on the expression of miR-145 through qPCR analysis. Immunoblotting techniques were performed to study the known direct targets of miRNA-145 and its associated proteins. The anti-cancer potential of Cuc D in pancreatic cancer was also evaluated in vivo using a xenograft mouse model. Results: Our results demonstrate potent anticancer effects of Cuc D on pancreatic cancer cells. Cuc D induces dose and time dependent inhibition of cell proliferation in a panel of gemcitabine sensitive/resistant pancreatic cancer cell line models at nanomolar concentrations (100-500 nM). It also inhibits colony formation and invasiveness of pancreatic cancer cells. Furthermore, Cuc D blocks the cell cycle progression in G2/M phase and decreases the mitochondrial membrane potential in pancreatic cancer cells. Notably, Cuc D significantly increases the expression of tumor suppressor miR-145 in HPAF-II cells as observed by qPCR. Furthermore, Cuc D decreases the expression of MUC13 and its associated proteins including pAKT and HER2. In addition, it restores the expression of p53 level as studied by immunofluorescence technique. The expression of key oncogenic proteins including NF-κB, STAT3 (Tyr-705) and Mcl-1 wer