Fig. 10: Carrier-free delivery of MCL1-targeting siRNA diminishes MCL-1 expression, tumor cell survival, and tumor growth in TNBC. | Nature Communications

Fig. 10: Carrier-free delivery of MCL1-targeting siRNA diminishes MCL-1 expression, tumor cell survival, and tumor growth in TNBC.

From: Structural optimization of siRNA conjugates for albumin binding achieves effective MCL1-directed cancer therapy

Fig. 10

a HCC70 cells were treated in serum-free OptiMEM with siRNA-lipid conjugates and assessed 48 h post-treatment for expression of MCL1 transcript levels relative to the housekeeping gene PPIB. Data are shown relative to MCL1 levels seen in siControl-L2 (250 nM)-treated cells (n = 3). b HCC70 cells treated with siRNA-lipid conjugates for 24–96 h at 100 nM were assessed using Caspase 3/7-Glo (n = 4–8). c, d Mice bearing orthotopic HCC70 tumors were treated on day 0 and day 7 with siControl-L2 or siMCL1-L2 (10 mg/kg, delivered i.v.). Tumors were collected on day 8. n = 3–4. c Representative images of HCC70 tumors assessed by IHC for MCL-1. d Quantification of the percentage of HCC70 tumor cells staining positive for Ki67 and cleaved (cl.) caspase 3 (n = 3–4). e, f Mice harboring HCC70 (n = 8–9), HCC1187 (n = 6), and MDA-MB-231 (n = 8–10) orthotopic tumors (50–100 mm3) received once weekly i.v. treatment with siControl-L2, siMCL1-L2, vehicle (used for delivery of MIK665), or MIK665 through day 28 (HCC70 and HCC1187) and through day 49 (MDA-MB-231). Tumors were collected on day 8 (HCC70), day 35 (HCC70), day 42 (HCC1187), and day 56 (MDA-MB-231) or earlier if tumors ulcerated or exceeded humane size limitations. e Tumor volumes were measured throughout treatment. Statistical values were calculated based on area under the curve. f Kaplan–Meier analysis of tumor-bearing mice, defining survival as tumor volume under 1000 mm3 (HCC1187 and MDA-MB-231) or 200 mm3 (HCC70, which exhibited slow tumor growth rate). Average time to exceed the defined tumor volume (T50) for each group is shown above each panel. p values are calculated using the log-rank (Mantel–Cox) test. For (a, b), significance was assigned by two-way ANOVA with Sidak’s multiple comparisons test. For (d), significance was assigned using one-way ANOVA with Tukey’s multiple comparisons test. For (e), significance was determined using an unpaired t-test.

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