The study aims to investigate the in vivo distribution, antitumor effect, and safety of cell membrane-penetrating
peptide-modified
disulfide bond copolymer nanoparticles loaded with
small-interfering RNA (
siRNA) targeting
epidermal growth factor receptor (EGFR) and bromodomain-containing
protein 4 (BRD4) in
triple-negative breast cancer (TNBC).
Polyethylene glycol disulfide bond-linked
polyethylenimine (
PEG-SS-PEI) was modified with
peptides GALA and CREKA and used as vectors to prepare
siRNA nanoparticles. The GALA- and CREKA-modified
PEG-SS-PEI nanoparticles (GC-NPs) were prepared by mixing siEGFR and siBRD4 (1:1) with GALA-
PEG-SS-PEI and CREKA-
PEG-SS-PEI (1:1) in an aqueous
solution at an N/P ratio of 30:1. Nanoparticles loaded with scrambled
siRNA were prepared with the same method. The gene silencing effect on EGFR and BRD4 in vitro was evaluated by Western blotting analysis. TNBC xenograft models were established by
subcutaneous injection of MDA-MB-231 cells into female nude mice. At 1, 3, 6, 12, and 24 h after administration of five formulations of Cy5-siRNA (133 μg/10 g) via the tail vein, the mice were observed and imaged for a biodistribution study using an in vivo imaging system. In the pharmacodynamics experiment,
tumor-bearing mice were treated with respective
siRNA preparations at a dose of 133 μg/10 g for 18 days, and the
body weight and
tumor size were recorded every other day. The
protein expression levels of EGFR, p-EGFR, PI3K, p-PI3K, Akt, p-Akt, BRD4, and c-Myc were determined using Western blotting analysis. Hematological and serum biochemical parameters, organ indices, and HE staining results for the heart, liver, spleen, lung, and kidney were analyzed to evaluate the safety of the nanoparticles. GC-NPs loaded with siEGFR and siBRD4 significantly inhibited the expression of EGFR and BRD4 in vitro. The strongest fluorescence signals were observed in the GC-NP group, especially in
tumors, indicating the excellent
tumor-targeted delivery of GC-NPs we constructed.
Tumor growth was significantly inhibited in the GC-NP-treated group, and the expression of EGFR, p-EGFR, PI3K, p-PI3K, Akt, p-Akt, BRD4, and c-Myc in the
tumors decreased by 71%, 68%, 61%, 68%, 48%, 58%, 59%, and 74% compared to the control group, respectively. There was no significant change in hematological parameters, biochemical indices, or tissue morphology in GC-NP-treated mice.
SiRNA cotargeting EGFR and BRD4 delivered by GALA- and CREKA-modified
PEG-SS-PEI had favorable antitumor effects in vivo toward TNBC with
tumor-targeting efficacy and good biocompatibility.