Transferrin functionalization enhances prostate cancer cell uptake and cytotoxicity of cabazitaxel-loaded polymeric nanoparticles.

Abstract

Prostate cancer (PCa) is the second most common cancer in men worldwide, and chemotherapeutic treatment may exhibit limited efficacy owing to side effects and hypersensitivity. Cabazitaxel (CTX) is an antineoplastic agent used to treat prostate cancer; however, it has low selectivity and adverse effects that limit its adherence and efficacy. In this context, transferrin (Tf)-functionalized polymeric nanoparticles have emerged as a potential targeted therapy directed toward the Tf receptor (TfR), which is overexpressed in prostate cancer cells. In this study, cabazitaxel was encapsulated in polycaprolactone (PCL) polymeric nanoparticles functionalized with transferrin (Tf), and its in vitro activity was evaluated in PCa cell lines. Therefore, a study was conducted to determine the optimal preparation conditions in terms of formulation characteristics. The nanoparticles were produced by nanoprecipitation using acetone as the solvent in the presence of the surfactant Poloxamer 188. Transferrin was covalently bound to the PEG-PCL-maleimide moiety on the nanoparticle surface. The transferrin-functionalized nanoparticles had an average particle size of 123.9 nm ± 1.13, a polydispersity index (PDI) of 0.168 ± 0.11, a zeta potential of -11.43 mV ± 1.89, and an encapsulation efficiency (EE%) of 79.6% ± 6.8. In electrophoresis, free transferrin exhibited a band near 80 kDa, with a corresponding band observed in the elution of the functionalized nanoparticles, indicating protein attachment to the nanoparticles. Circular dichroism analysis, together with fluorescence spectroscopy, demonstrated the preservation of protein structural integrity after conjugation. Microscopy techniques (SEM and AFM) revealed the spherical morphology of the nanoparticles, and AFM further confirmed successful conjugation through changes in the surface roughness of the functionalized nanoparticles. The in vitro release study demonstrated that both non-functionalized and transferrin-functionalized PCL-based nanoparticles provided a sustained release of cabazitaxel over 192 h, confirming the potential of these systems for prolonged drug delivery. In cell culture assays, the high cell viability observed in the L929 cell line demonstrated the safety of the developed systems, whereas the marked reduction in viability in DU145 and PC3 cell lines demonstrated the effect of encapsulation on cytotoxicity of the developed systems. Functionalization with transferrin (Tf) significantly increased the in vitro toxicity and cellular internalization. The percentage of cellular internalization was higher in the PC3 cell line than in the DU145 cell line, corroborating the literature reporting higher TfR expression in this lineage. Encapsulation and functionalization demonstrated potential as active drug-targeting vectors, as they increased cytotoxicity compared to free drugs. This finding represents an important advancement in the development of a formulation and approach capable of enhancing therapeutic efficacy while reducing the systemic side effects of the drug.