In recent years, targeting tumor angiogenesis has emerged as a prominent research focus in the treatment and prevention of tumor expansion. A7R (ATWLPPR) exhibits high affinity and specificity for VEGFR-2, which is overexpressed in various tumors. To enhance the tumor tissue and cell penetration capabilities of A7R, we substituted its non-critical amino acid with Arginine (R) and Glutamic acid (E), cyclized the mutant peptide, and linked it to the membrane permeation sequence using coordination principles. We designed and synthesized fifteen novel penetrating peptides that target tumor blood vessels and cells, followed by conducting various biological evaluations and cell imaging experiments. The results demonstrated that Cyclo-A7R-RRR and A7R-RLLRLLR exhibited excellent permeability towards tumor cells, with Cyclo-A7R-RRR showing superior serum stability compared to A7R. Furthermore, the modified peptides showed no toxicity towards HeLa cells, U251 cells, HuH-7 cells, and HEK293 cells under 10 μmol/L. Utilizing Cyclo-A7R-RRR or A7R-RLLRLLR for transmembrane delivery of drug molecules could significantly improve their efficacy. Our findings broaden the potential application scenarios of A7R in targeted tumor angiogenesis.
Triple-negative breast cancer (TNBC) is an extremely aggressive subtype associated with a poor prognosis. At present, the treatment for TNBC mainly relies on surgery and traditional chemotherapy. As a key component in the standard treatment of TNBC, paclitaxel (PTX) effectively inhibits the growth and proliferation of tumor cells. However, the application of PTX in clinical treatment is limited due to its inherent hydrophobicity, weak penetrability, nonspecific accumulation, and side effects. To counter these problems, we constructed a novel PTX conjugate based on the peptide-drug conjugates (PDCs) strategy. In this PTX conjugate, a novel fused peptide TAR consisting of a tumor-targeting peptide, A7R, and a cell-penetrating peptide, TAT, is used to modify PTX. After modification, this conjugate is named PTX-SM-TAR, which is expected to improve the specificity and penetrability of PTX at the tumor site. Depending on hydrophilic TAR peptide and hydrophobic PTX, PTX-SM-TAR can self-assemble into nanoparticles and improve the water solubility of PTX. In terms of linkage, the acid- and esterase-sensitive ester bond was used as the linking bond, with which PTX-SM-TAR NPs could remain stable in the physiological environment, whereas PTX-SM-TAR NPs could be broken and PTX be released at the tumor site. A cell uptake assay showed that PTX-SM-TAR NPs were receptor-targeting and could mediate endocytosis by binding to NRP-1. The vascular barrier, transcellular migration, and tumor spheroids experiments showed that PTX-SM-TAR NPs exhibit great transvascular transport and tumor penetration ability. In vivo experiments, PTX-SM-TAR NPs showed higher antitumor effects than PTX. As a result, PTX-SM-TAR NPs may overcome the shortcomings of PTX and present a new transcytosable and targeted delivery system for PTX in TNBC treatment.Keywords:paclitaxel;peptide-drug conjugate;TAT peptide;A7R peptide;targeted delivery;anticancer therapy;transcytosis
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