Abstract 3713: Targeting β-catenin pathway by nanoparticle-mediated delivery of norcantharidin impairs the stemness of triple negative breast cancer cells

Abstract

Abstract Background Norcantharidin (NCTD) is known as an inhibitor of serine/threonine protein phosphatase types 1 and 2A (PP1/PP2A) and exhibits potent anticancer efficacies. Our preliminary study identified NCTD interfering with the interaction between phospho-β-catenin and PP1/PP2A could downregulate the levels of non-phospho β-catenin in the cytoplasm in Triple Negative Breast Cancer (TNBC) cells. As β-catenin pathway plays an important role in cancer stemness, we hypothesize that NCTD could prevent β-catenin nuclear translocation, impair the stemness and reduce the metastasis of TNBC. However, the inherent features of short half-life and nephrotoxicity hinder NCTD's further in vivo application. The goal of this study was to test the therapeutic effect of targeting β-catenin pathway by nanoparticle-mediated delivery of NCTD against TNBC. Experimental Design NCTD was loaded into an integrin α5 targeting nanoparticle (NP) (RGD-LPH) via complexing with polyethyleneimine. The targeting efficiency of RGD-LPH was tested by the in vivo imaging of RGD-LPH labeled by cyanine 7.5 (cy7.5). The effects of NP-mediated delivery NCTD on TNBC cell malignant behaviors and tumor metastasis were tested in various in vitro and in vivo models. Results We found that RGD-LPH NP-mediated delivery of NCTD significantly reduced the active and total β-catenin levels as evidenced by Western Blot. The self-renewal capacity was remarkably blocked by RGD-LPH, as examined by sphere formation. RGD-LPH also suppressed features of cancer cells related to proliferation, as examined by MTT, clonogenic assay and soft agar colony formation. In particular, compared to free NCTD, RGD-LPH demonstrated extended-release profile and long-last effect in the long-term experiments such as clonogenic assay and soft agar colony formation assay. In vivo, systemic delivery of RGD-LPH(cy7.5) indicated a preferential uptake in primary tumor and lung of the tumor-bearing mice. Efficacy studies indicated reduced metastasis of mice from RGD-LPH treatment. Conclusion: Collectively, our results strongly suggest that NCTD being encapsulated in RGD-LPH, which warrants further development for preclinical and clinical studies as a novel TNBC therapeutic approach, is a robust modulator of Wnt signaling with anti-metastasis activity. Citation Format: Yunfei Li, Zhishan Wang, Yajuan Xiao, Chengfeng Yang. Targeting β-catenin pathway by nanoparticle-mediated delivery of norcantharidin impairs the stemness of triple negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3713.