Abstract 843: CLDN1 mediates tumor invasion in HNSCC by regulation of EMT through AMPK-TGF-β signalling

Abstract

Abstract Background: Claudin-1 (CLDN1), a major component of tight junction complexes in epithelium, maintains cellular polarity and plays critical roles in cell-to-cell communication and epithelial cell homeostasis. Although, the role of CLDN1 in cancer has been generally studied in cancers, the exact regulatory mechanisms and downstream pathways in cancer have been controversial and are not completely understood. Materials and Methods: After, analysed mutational profiling of tumor/non-tumor paired tissue in the patients with head and neck squamous cell carcinoma (HNSCC) by next-generation sequencing (NGS), CLDN1 expression levels were measured in human HNSCC cell lines and tissues from HNSCC patients using next-generation sequencing. For functional in vitro analysis, cell proliferation testing using a WST-1 assay, an invasion assay, and Western blotting was performed after CLDN1 expression regulation. In vivo validations were performed using nude mouse and patient-derived tumor xenograft (PDTX) model. Results: Mutational profiling of tumor/non-tumor paired HNSCC tissue by NGS revealed that HNSCC tumor tissues and cell lines had relatively high levels of CLDN1 expression. Although, CLDN1 regulation did not affect proliferation of HNSCC cell lines, knock down of CLDN1 inhibited invasive characteristics (migration/invasion) with down-regulation of EMT associated proteins (vimentin and slug). We also found that CLDN1 negatively correlated with AMPK phosphorylation and AMPK activator (AICAR) showed the same effect with CLDN1 suppression on HNSCC cells without change in CLDN1 expression which lead to inhibition of TGF-β-induced Smad phosphorylation and their transcriptional activity, suggesting that CLDN1/AMPK/TGF-β cascade. Then, we confirmed antitumorigenic effects of suppression of CLDN1 in HNSCC in a nude mouse and PDTX model. Conclusions: Our findings suggest that CLDN1 acts as oncogenic driver in HNSCC via regulating EMT through AMPK/TGF-β signalling and if validated in further studies, a CLDN1-targeting agent partnered with an existing anti-TGF-β modality could be a novel tactic to overcome HNSCC. Citation Format: Jae Won Chang, Seung-Nam Jung, Lihua Liua, Jin Man Kim, Myung Jin Ban, Yeon Soo Kim, Bok-Soon Lee, Yang Eun Kim, Ho Ryun Won, Chul-Ho Kim, Bon Seok Koo. CLDN1 mediates tumor invasion in HNSCC by regulation of EMT through AMPK-TGF-β signalling [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 843. doi:10.1158/1538-7445.AM2017-843