Abstract 4468: Anticancer activity of novel cucurbitacin analogue in pancreatic cancer
Authors: Sikander Mohammed , Khan Sheema , Chauhan Neeraj , Zaman Mohd Saif , Yallapu Murali Mohan , Halaweish Fathi T. , Chauhan Bhavin , Malik Shabnam , Jaggi Meena , Chauhan Subhash C. 
Published: August 2015

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 were also downregulated. The levels of PTEN and p27 (Kip1) tumor suppressor genes were increased after Cuc D treatment. Additionally, in vivo administration of Cuc D effectively inhibited pancreatic tumor growth in xenograft mouse model.

Conclusion: Overall, this study suggests that Cuc D modulates the expression of key oncogenes and tumor suppressors, thus it can be a promising therapeutic modality for pancreatic cancer prevention and treatment.

Citation Format: Mohammed Sikander, Sheema Khan, Neeraj Chauhan, Mohd Saif Zaman, Murali Mohan Yallapu, Fathi T. Halaweish, Bhavin Chauhan, Shabnam Malik, Meena Jaggi, Subhash C. Chauhan. Anticancer activity of novel cucurbitacin analogue in pancreatic cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4468. doi:10.1158/1538-7445.AM2015-4468