Abstract 2099: Tid1 regulates galectin-7 mediated tumorigenesis of oral squamous cell carcinoma

Abstract Background: We previously identified Tid1, a DnaJ cochaperon protein, functions as a tumour suppressor in oral squamous cell carcinoma (OSCC) tumourigenesis (J Pathol 2009;219:347-55). To further understand the molecular mechanisms mediated by Tid1 on oral tumorigenesis, we applied affinity chromatography and systemic proteomics analysis to identify galectin-7, which specifically interacted with Tid1. Others have shown that Galectin-7 plays a number of important roles in tumor development. However, the role of Galectin-7 in OSCC tumourigenesis remains unclear. Herein, we elucidated the mechanism mediated by Tid1 on regulating galectin-7 mediated cellular signaling and tumorigenesis in OSCC. Methods: First, through HA-tag affinity chromatography and mass spectrometry we identified substrate proteins that specifically interact with Tid1. Secondly, co-immunoprecipitation analysis and confocal microscope was performed to confirm the protein-protein interaction between galectin-7 and Tid1. In vitro tumorigenic properties of OSCC overexpressing galectin-7 were determined. Subsequently, the tumorigenic properties of OSCC after co-overexpression of galectin-7 and Tid1 were investigated. Finally, immunoprecipitation analysis was performed to recognize the Tid1 induced deregulation of galectin-7 by enhancing ubiquitination. Results: We found out that Tid1 interacted with galectin-7. Furthermore, overexpression galectin-7 expression resulted in up-regulation migration, invasion and soft agar colony formation abilities in OSCC. Importantly, co-overexpression of Tid1 decreased the galectin-7 expression and impaired galectin-7-mediated migration, invasion and soft agar colony formation ability of OSCC. Finally, we found galectin-7 ubiquitination as revealed by antiubiquitin immunoblot analysis in immunoprecipitates. Conclusion: Our studies first pointed out that galectin-7 played pivotal roles in OSCC tumorigenesis. Notably, we identified galectin-7 that specifically interacted with Tid1. We hypothesized that Tid1/ Hsp70 may regulate galectin-7 stability by ubiquitinylation. The molecular mechanism by which Tid1 negatively modulates the galectin-7 warrants further investigation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2099. doi:10.1158/1538-7445.AM2011-2099