Abstract 1241: A preclinical study of the combined treatment of arginase and canavanine in pancreatic cancer

Abstract

Abstract Background: Arginine deprivation is a novel approach for cancer treatment as some cancers were found to be arginine auxotrophic. PEG-BCT-100, a pegylated form of recombinant human arginase, was used to investigate the effect of arginine deprivation on pancreatic cell lines. On the other hand, Canavanine (CAV), a natural toxic analog of arginine isolated from leguminous plant, has also demonstrated its ability in inhibiting cancer cell proliferation. It alters the protein structure and causes critical metabolic defects in the cells by replacing arginine into newly synthesized proteins during translation. In this study, we have also tested the efficacy of combined arginase and CAV treatment on pancreatic cell lines. Methods: Pancreatic cell lines (MIA PaCa-2, CFPAC-1) and normal fibroblast cell line (WI-38), were either incubated in normal or arginine free condition. The corresponding IC50 of CAV was determined by cell viability assay. To evaluate the responsiveness to the combined treatment, cells were monitored by live cell imaging under the conditions of PEG-BCT-100 treatment alone (0.3IU/ml) or in combination with CAV (10μM or 50μM). The apoptotic effect of the combined treatment was examined by Western blotting and Annexin V assay. Results: Either arginase or CAV treatment could inhibit pancreatic cancer cell growth. The cells treated with CAV in arginine free condition demonstrated an inhibition of cell proliferation and its corresponding IC50 was significantly lowered from millimolar to micromolar concentration when arginine was withdrawn. Strong synergism of CAV and PEG-BCT-100 was observed after 48-hour treatment with enhanced apoptosis in pancreatic cell lines, but not in normal fibroblast cells. Both early and late apoptosis were observed in co-treated pancreatic cancer cells as indicated by Annexin V assay and the detection of polyADP ribosyl polymerase (PARP) in Western blot. Conclusion: Arginine deprivation by PEG-BCT-100 combined with CAV treatment showed a strong synergetic effect on inducing cell death in pancreatic cell lines, suggesting that the supplement of CAV could facilitate the treatment outcome of arginine deprivation by arginase. This combined treatment may serve as a treatment strategy for pancreatic cancer. Citation Format: Tsz Tung Kwong, Chi Hang Wong, Herbert Ho Fung Loong, Stephen Lam Chan. A preclinical study of the combined treatment of arginase and canavanine in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1241. doi:10.1158/1538-7445.AM2017-1241