STMC-26. MULTIVALENT CATIONIC LIPOSOMES FOR siRNA TRANSFECTION OF PATIENT DERIVED GLIOMA INITIATING CELLS

Abstract

Glioma initiating cells (GICs) have been implicated as the root cause of treatment failure and tumor recurrence in glioblastoma multiforme (GBM). Therapeutic targeting of GICs is therefore essential to ensure effective treatment without relapse. A novel approach to modulate protein expression in cancer cells is the delivery of siRNAs using liposomes. However, past attempts to transfect cells using neutral liposomes have proven challenging and inefficient owing to the highly refractory nature of these cells. We therefore sought to develop a multivalent cationic liposome (MVCL) formulation for efficient and reproducible transfection of cancer initiating cells. The high valency and cationic charge on these liposomes allows binding to more siRNA molecules while increasing endocytosis into the cell due interactions with the negatively charged cell membrane. To test the ability of these liposomes to transfect GICs in vitro, we transfected CD133+ patient derived GICs with siRNA against the iron storage protein H-ferritin (Hft). Using this method of siRNA delivery, we were able to knockdown the expression of Hft in GICs compared to controls. The most effective Hft knockdown was observed at 48 and 72hours post transfection and was accompanied by a compensatory increase in the expression of light chain subunit of ferritin, L-ferritin. Past studies using Hft shRNA show reduced cell proliferation in GICs upon Hft downregulation. Consistent with this finding, we observed increased release of LDH in Hft siRNA treated GICs versus control and vehicle treated cells. These data suggest that Hft downregulation by itself might be lethal to GICs; a finding that is different from our previous report using astrocytoma cell lines. Thus, we show that MVCL liposomes possess the ability to efficiently transfect and deliver siRNA to patient derived cancer initiating cells providing a new means to modulate protein expression in GICs and a potential new target in H-ferritin.