Metastatic triple-negative breast cancer (TNBC) remains difficult to treat because of tumour heterogeneity, widespread dissemination and the emergence of therapeutic resistance. Although many oncogenic pathways can be inhibited using small molecules, several critical intracellular cancer dependencies remain therapeutically inaccessible because they lack suitable binding pockets or catalytic domains. Centrosomal protein 55 (CEP55) represents one such target. CEP55 is overexpressed in multiple aggressive cancers and promotes extracellular-matrix remodelling, integrin–FAK signalling and tumour progression. Genetic ablation of CEP55 across complementary cellular and tumour models suppressed oncogenic phenotypes and markedly prolonged survival in a PTEN-deficient cancer model, identifying CEP55 as a potential therapeutic vulnerability.
We therefore developed an antisense oligonucleotide (ASO) nanomedicine targeting CEP55 mRNA. Second- and third-generation chemically modified ASOs were designed against conserved regions of the human and murine CEP55 transcripts. Candidate ASOs were compared with a non-targeting control and evaluated for CEP55 inhibition, downstream signalling, clonogenic growth and three-dimensional tumour growth. In parallel, non-template control, folate receptor-targeted, hyaluronic acid/CD44-targeted and dual-targeted lipid nanoparticle (LNP) formulations were compared in receptor-defined cell models and assessed through in vivo biodistribution and preliminary safety profiling. The lead CEP55-ASO–LNP formulation was subsequently evaluated following systemic intravenous administration.
CEP55-directed ASO treatment reduced CEP55 protein expression and associated oncogenic signalling. In MDA-MB-231 cells, treatment with 100 nM ASO for 48 hours reduced expression and consequently clonogenic and three-dimensional growth, migration and invasion relative to the non-targeting oligonucleotide. Surface functionalisation produced receptor-dependent differences in LNP uptake, with folate targeting emerging as the lead strategy based on cellular uptake and biodistribution analyses. Systemically administered CEP55-ASO–LNPs reached breast-cancer lesions in the lung, while folate-targeted particles improved functional delivery relative to untargeted LNPs.
These findings demonstrate that chemically stabilised ASOs encapsulated within actively targeted LNPs can convert a previously undruggable intracellular cancer dependency into a systemically deliverable preclinical RNA therapeutic. They further identify efficient and consistent delivery across metastatic sites as the principal barrier to the clinical translation of CEP55-silencing therapeutics.