O005 Evaluation of occludin, a tight junction transmembrane protein in human lung cancer and its potential role in metastatic disease

Abstract

Abstract Introduction Tight junctions (TJs) maintain cell adhesion. Modulation can promote cell dissociation/motility/ metastasis. Occludin is a transmembrane protein within TJs and may play a role in TJ modulation. The aim of this research was to identify the expression of Occludin in human lung cancer and its effect in cell motility/dissociation. Methods qPCR was used to quantify Occludin transcripts in a human lung cancer cohort (n=80) (Peking University Cancer Hospital Research Ethics Committee). In vitro experiments on A549/COR-L23 lung cancer cell lines included immunofluorescence staining, cell attachment/migration using ECIS Z-Theta. Cells were treated with Hepatocyte Growth Factor (HGF, 50ng/μl) and/or cell migration inhibitors N-WASPi (Wiskostatin) and ROCKi (Y-27632). Results qPCR analysis revealed reduced expression of Occludin in patients with metastasis (no bone mets 21.7+/- 12 v bone mets 3.23+/- 3 (p=0.42) v boneActv 0.263+/-0.096 (p=0.077). A549 cells showed a similar cell migration pattern with HGF, ROCKi/HGF+ROCKi. In COR-L23, HGF increased cell migration; ROCKi/HGF+ROCKi showed suppression. N-WASPi/HGF+N-WASPi prevented all cell migration. Immunofluorescence demonstrated that HGF caused loss of Occludin from cell-to-cell membranes with single cells and increased pseudopodia in COR-L23 and A549. Conclusion This preliminary study suggests an association between Occludin and bone metastasis in lung cancer. HGF promoted Occludin loss from cell membranes, cell dissociation and increased pseudopodia/increased cell motility. This suggests that loss of Occludin from cell membranes is linked to reduced TJ function leading to cell dissociation/increased motility. NWASPi may provide pharmacological value in future lung carcinoma treatment.