Over-expressing a Gene Involved in Cholesterol Metabolism Correlates with Increased Radiation Resistance

Abstract

Record ID: 184

Award(s): Excellence in Undergraduate Research Mentorship; Excellence in Research Communication

Program Affiliation: Capstone

Presentation Type: Poster

Abstract: Head and Neck Squamous Cell Carcinoma (HNSCC) has a high incidence of post-radiation therapy relapse. This is a major contributing factor to poor treatment outcomes in almost 50% of patients. The focus of our research is to understand and utilize the radiation resistance mechanisms of HNSCC cells to improve that outcome. By analyzing tumors pre-radiation, relapse was correlated with increased expression of genes involved in cholesterol metabolism. Sterol regulatory element-binding protein 2 (SREBP2) is a protein that activates genes involved in cholesterol metabolism, commonly referred to as cholesterogenic genes. We hypothesized that SREBP2 activation promotes HNSCC radioresistance, so inhibiting SREBP2 will increase cell radiation sensitivity. To test this, we cloned the cDNA sequence corresponding to the activated form of SREBP2 (nSREBP2) and used the virus pLV-Eif1a-IRES-Puro, a lentivirus similar to HIV, as the plasmid backbone. After ensuring the virus contained successfully cloned DNA, it was introduced to tumor cell lines Cal27 (human) and Moc1 (mouse) and treated with the antibiotic puromycin in a process called selection. Selection confirmed nSREBP2 was overexpressed, and that host cells had increased cholesterogenic gene expression. When exposed to radiation, an increased survival rate for cells with over-expressed nSREBP2 was observed in comparison to normal cells. These results confirm that nSREBP2 protects against radiation, and are the basis for ongoing experimentation to test if inhibiting SREBP2 activation in HNSCC tumor cells makes radiation therapy more effective.