SPOT-004 Nedd9 is crucial for tumour progression in renal cell carcinoma mouse models

Introduction Renal cell carcinoma (RCC) is characterised by high lethality in advanced stages. Vastly resistant to radio- and chemotherapy, RCCs respond to targeted therapies such as tyrosine kinase inhibitors, mTOR antagonists and immune checkpoint inhibitors. However, limited response rates and emerging resistance mechanisms demand new treatment strategies. Scaffolding protein NEDD9 (neural precursor cell expressed, developmentally down regulated 9) is frequently overexpressed in various cancer types and associated with tumour aggressiveness. In vivo ,high NEDD9 expression is associated with adverse clinical outcome and in vitro , NEDD9 promotes aggressiveness in RCC cells. Thus, we systematically characterised the role of NEDD9 in RCC both in vitro and in vivo with the goal to establish basis for new treatment strategies. Material and methods Using RNAi, we generated NEDD9-proficient and -deficient syngeneic (RENCA) and xenograft (786-O) tumour models via subcutaneous and orthotopic transplantations as well as tail vein injections. Tumour growth was monitored dynamically using calliper and MRI imaging. Extensive in vitro studies were performed to analyse NEDD9 and its associated oncogenic signalling cascades including Western blot, proliferation, migration and gene expression analyses. Tissue microarrays (TMAs) of 92 RCC patients were stained for NEDD9 and analysed using automated quantitative analysis (AQUA) technology to associate NEDD9 protein expression with clinical outcome. Results and discussions NEDD9 is highly expressed in RCC cells and NEDD9 depletion significantly impairs migration and proliferation in both human and murine RCC cells. This is accompanied by reduced signalling of oncogenic pathways, particularly activation of ERK1/2. NEDD9 tumour promoting role was confirmed in vivo where NEDD9-deficient murine RCC cells exhibited significantly reduced tumour growth after subcutaneous and orthotopic syngeneic transplantation as well as inhibited lung metastatic seeding capacity after tail vein injection. In human RCC cells, only NEDD9 down-regulation was sufficient to completely abolish tumour growth in subcutaneous, orthotopic and lung seeding xenograft models. In line with our in vitro and in vivo results, we found high NEDD9 expression in human RCC tissue to be significantly associated with shorter overall survival. Conclusion We show for the first time a crucial role for NEDD9 in RCC tumour progression in vivo , which potentially offers new therapeutic approaches.