Application of polymersomes engineered to target p32 protein for detection of small breast tumors in mice

Abstract

Triple negative breast cancer (TNBC) is the deadliest form of breast cancer and its successful treatment critically depends on early diagnosis and therapy. The multi-compartment protein p32 is overexpressed and present at cell surfaces in a variety of tumors, including TNBC, specifically in the malignant cells and endothelial cells, and in macrophages localized in hypoxic areas of the tumor. Herein we used polyethylene glycol-polycaprolactone polymersomes that were affinity targeted with the p32-binding tumor penetrating peptide LinTT1 (AKRGARSTA) for imaging of TNBC lesions. A tyrosine residue was added to the peptide to allow for 124I labeling and PET imaging. In a TNBC model in mice, systemic LinTT1-targeted polymersomes accumulated in early tumor lesions more than twice as efficiently as untargeted polymersomes with up to 20% ID/cc at 24 h after administration. The PET-imaging was very sensitive, allowing detection of tumors as small as ∼20 mm3. Confocal imaging of tumor tissue sections revealed a high degree of vascular exit and stromal penetration of LinTT1-targeted polymersomes and co-localization with tumor-associated macrophages. Our studies show that systemic LinTT1-targeted polymersomes can be potentially used for precision-guided tumor imaging and treatment of TNBC.

Dual-peptide functionalized acetalated dextran-based nanoparticles for sequential targeting of macrophages during myocardial infarction

“…The assay consisted of coating Ni-NTA magnetic agarose beads with the recombinant hexahistidine-tagged target of the linTT1 peptide, p32. 37 Then, beads were incubated with FAM-labeled nanoparticles conjugated with the linTT1peptide or without it. Beads were finally washed and the nanoparticle-p32 complexes were released using imidazole elution buffer and the eluted fluorescence was measured.…”

Biomolecule–polymer hybrid compartments: combining the best of both worlds

“…Targeting or cell penetrating peptides, less expensive and smaller than antibodies, have been widely exploited to target polymersomes to locations of interest within cells or living organisms. For example, cyclic (RGD and NGQ), [46][47][48][49] pH sensitive fusogenic (GALA) 47 and other targeting (GE11, NLS, LinTT1, ApoE, Tet-1) [50][51][52][53][54] peptides have been mainly used to deliver smart polymer vehicles to specific cells or organelles and/or to improve their tumour penetration for therapeutic or diagnostic applications. Recently, targeting of the nuclear interior has been achieved using polymersomes functionalized with nuclear localization signal (peptide NLS), which position themselves as promising nanocarriers for drug delivery to cell nuclei.…”

“…44,47,49,52,53,56 Beyond that, the peptides can also be coupled to the block copolymers prior to vesicle formation via mixing of the nonfunctionalized polymer with a peptide-functionalized counterpart that self-assemble together to form peptide-functionalized polymersomes. 46,48,50,51,54 Nevertheless, even if this approach enables the simultaneous usage of different types of polymer, e.g. by mixing a triblock co-polymer with a peptide-functionalized diblock copolymer, several features like the use of polymers with matching lengths of hydrophilic and hydrophobic parts is crucial in order to achieve their co-self-assembly into polymersomes.…”

99mTc-Labeled LyP-1 for SPECT Imaging of Triple Negative Breast Cancer

“…LyP-1 is a cyclic nonapeptide with a sequence of CGNKRTRGC, the two cysteines forming a disulfide bond [10]. The potential receptor of LyP-1 is a mitochondrial matrix protein called p32, which is overexpressed and aberrantly localized at the cell surface [11] and in the nucleus [12] of certain tumors [13], such as MDA-MB-231 and 4T1 TNBC cell lines [14, 15]. LyP-1 also belongs to a class of tumor-penetrating peptides with the potential capacities of transvascular transport, cell penetration, and parenchymal penetration.…”