High-thoughput siRNA screen to mechanistically dissect Vascular Endothelial Growth Factor (VEGF) Internal Ribosomal Entry Site (IRES)-mediated translation in tumorigenesis

• Applicant: Dr. Christian Thoma
• Subject Area: General Genetics and Functional Genome Biology
• Term: from 2008 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 70817203

VEGF is critical for angiogenesis in solid tumors and important for tumor survival under hypoxic conditions1. Although hypoxia leads to global repression of translation by the canonical cap-dependent pathway, the VEGF mRNA remains efficiently translated. This is achieved by IRES-driven translation of the VEGF mRNA2 3. However, the molecular mechanism responsible for VEGF IRES translation is poorly understood. In particular, it has not been addressed whether specific functional modulators are necessary to promote VEGF IRES-mediated translation. We will apply previously established functional genomic, biochemical and cell culture approaches to mechanistically dissect VEGF IRES-driven translation. We have previously developed an in vivo assay based on RNA transfections4 that allows to study the function of cellular IRESs in vivo. Using this system we will perform a highthroughput RNAi screen to identify positive and negative modulators of VEGF IRES translation. Subsequently, we will validate the identified factors in a secondary RNAi screen and functionally characterize these factors using in vivo and in vitro approaches. The proposed research will contribute to our understanding of the molecular and cellular mechanisms that enable selective translation of VEGF mRNA in cancer cells and could ultimately provide novel in vivo-validated targets for therapeutic intervention.

• DFG Programme: Research Grants