RBIO-05. DOWNREGULATION OF H-FERRITIN EXPRESSION USING MULTIVALENT CATIONIC LIPOSOMES RESULTS IN INCREASED RADIATION SENSITIVITY IN PATIENT DERIVED GLIOMA INITIATING CELLS

Abstract

AbstractGlioblastoma multiforme (GBM) is the most prevalent, lethal, malignant and refractory primary brain tumor with a very dismal survival rate. The glioma initiating cell (GIC) population within GBMs has been associated with treatment resistance and subsequently been implicated in tumor recurrence. Studies from our lab had previously shown that expression of the heavy chain subunit of the iron storage protein ferritin, H-ferritin, is essential for the survival and therapeutic resistance of non-stem glioma cells. Since H-ferritin is overexpressed in GICs, we hypothesized that downregulating its expression in these cells would lead to increased radiosensitivity. We therefore developed a novel strategy to sensitize these recalcitrant GICs to radiation therapy using a multivalent cationic liposome formulation that could efficiently transfect and deliver H-ferritin siRNA to GICs in vitro. Using patient derived T3691 CD133+ GICs we showed that downregulating H-ferritin led to a reduction in cell viability compared to controls upon being radiated at 4Gy and 8Gy dosage. Additionally these cells also showed an increased expression of the DNA damage response protein phospho-ϒH2AX upon radiation over controls. Thus, we have demonstrated that loss of H-ferritin in GICs leads to increased radiation sensitivity. Ongoing studies are focused on delineating the mechanisms through which H-ferritin loss mediates this effect in GICs.