Figure 3. Robust tumor accumulation and tumor gene silencing using si<(EG₁₈L)₂.

a-d, Mice bearing intra-mammary MDA-MB-231.Luc tumors were treated with siRNA-lipid conjugates, or free siRNA, using siRNA sequences against luciferase (si_Luc). a, Schematic showing treatment schedule for i.v. delivery of siRNA-lipid conjugates, or free siRNA, to tumor-bearing mice. b, Cy5 fluorescence tumor:kidney ratio for each mouse as measured on day 7 (18h after injection with fluorescent siRNA). c, Luciferase activity was measured in tumor lysates collected on treatment day 7. Bars show the average (± S.D.) tumor luciferase per group, and points are the values for each tumor (assessed in triplicate). All values shown are relative to the average luciferase activity of saline-treated controls, which was set to a value of 1. d, Tumors were assessed by IHC analysis for firefly luciferase (green). Nuclei were counterstained with DAPI (blue). Representative images are shown, n = 5–8. e-f, Mice bearing intra-mammary MDA-MB-231 tumors were treated one time with si<(EG₁₈L)₂, using siRNA sequences against MCL1 (si_MCL1) at increasing doses (2.5 mg/kg - 20 mg/kg). Tumors were assessed on treatment day 4 and day 8. e, Schematic showing i.v. delivery of siRNA-lipid conjugates, or free siRNA, to tumor-bearing mice. f, Human MCL1 mRNA levels measured in whole tumor RNA collected on treatment day 4 (left panel) and day 8 (right panel). Bars show the average (± S.D.), and points are the values for an individual tumor (assessed in triplicate). All values shown are relative to values measured in non-targeting controls, which was set to a value of 1. * P < 0.05; ** P < 0.01 ; *** P < 0.001; **** P < 0.0001