Abstract 1601: Intensive NTS/NTR1 interaction enhances epithelial-mesenchymal transition and promotes tumor metastasis via activating canonical Wnt/β-catenin signaling pathway in hepatocellular carcinoma

Abstract

Abstract Neurotensin (NTS) is an endogenous 13 amino-acid neuropeptide distributed throughout the central nervous system and in parts of the digestive system. Since its first detection in breast carcinoma over two decades ago, NTS and its high-affinity receptor, neurotensin receptor 1 (NTR1), have been found to affect various pathological processes, including growth, anti-apoptosis, migration, and invasion, during the development and progression of breast, colon, prostate, pancreas, and lung carcinoma. However, limited studies have investigated the intracellular events mediated by NTS/NTR1 in HCC. In our previous study, we found NTS overexpression in certain hepatocellular carcinoma (HCC) samples that displayed stronger inflammatory response in a microenvironment, more severe epithelial-mesenchymal transition (EMT) in cancer, and worse prognosis than NTS− HCC patients. In the present study, the significant correlation between NTS upregulation and tumor metastasis was confirmed in 100 cases of HCC tissue samples, in which high NTS expression was associated with incomplete envelope and portal vein invasion, as well as early relapse and short survival after surgery. Furthermore, distinct EMT features were identified in NTS+ HCC samples via Immunohistochemistry, which expressed decreased E-cadherin, increased β-catenin translocating to the cytoplasm, and increased N-cadherin. To elucidate the molecular mechanisms involved in NTS-mediated EMT and HCC metastasis, two HCC cell lines (i.e., Hep3B and HepG2) were genetically modified by NTR1 gene transfection and NTR1-specific siRNA interference to establish different NTS-responsible HCC models in vitro. These models demonstrated that exogenous NTS stimulation and/or upregulated NTR1 expression exerted an acceleratory effect on cell migration and invasion rather than proliferation and apoptosis in both HCC cell lines. Real-time polymerase chain reaction (RT-PCR) and Western blot indicated that intensive NTS/NTR1 interaction repressed E-cadherin expression but enhanced N-caherin and β-catenin expression in HCC cell lines, accompanied by dramatic increases in the expression of Wnt1, Wnt3, Wnt5, Axin, and p-GSK3β. SR48692 and TSW119, which are specific inhibitors targeting NTR1 and GSK3β phosphorylation, significantly impaired NTS/NTR1 interaction and Wnt/β-catenin pathway activation, thereby blocking NTS-induced EMT and inhibited tumor invasion in vitro. Furthermore, SR48692 inhibited the lung metastases of HCC cells line in vivo. Thus, we proposed that the ectopic expression of NTS in HCC enhanced cell EMT and promoted tumor invasion via activating the canonical Wnt/β-catenin pathway, thereby resulting in poor prognosis after conventional surgery. Citation Format: Jinpu Yu, Yingnan Ye, Xinxin Long, Jieying Chen, Pengpeng Liu, Hui Li, Feng Wei, Xiubao Ren. Intensive NTS/NTR1 interaction enhances epithelial-mesenchymal transition and promotes tumor metastasis via activating canonical Wnt/β-catenin signaling pathway in hepatocellular carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1601.