TAT-PEG-Asp₈-Doxorubicin Polymeric Nanoassembly For Overcoming Drug-resisant Colon Cancer

ObjectiveThe TAT-PEG-Asp8-Dox nanoparticles were prepared for improving the treatment of multidrug-resistant (MDR) colon cancer. The anti-tumor activity and anti-MDR effect were evaluated both in vitro and in vivo.MethodsThe poly(aspartic acid) with a terminal cysteine was synthesized by using solid-phase synthesis, and then conjugatedwith the cell penetrating peptide TAT-polyethylene glycol (TAT-PEG) through a disulfide bond, thus forming the triblock material TAT-PEG-Asp8. Doxorubicin molecules were further coupled to the Asps segments, which can self-assemble as a hydrophobic body whereas the hydrophilic TAT-PEG chains extend outwards, thereby forming a nanostructured system. The critical micelle concentration (CMC) of TAT-PEG-Asp8-Dox was determined with fluorescence spectrometer using pyrene as a hydrophobic fluorescent probe. The particle size and zeta potential were measured by a Zeta Sizer Nanoparticle analyzer. The morphology imaging of TAT-PEG-Asps-Dox NPs was conducted by Transmission electron microscopy (TEM). The Dox content in the conjugates was measured by fluorescence spectrophotometer. The cytotoxicity and cellular uptake of the nanoparticles were determined and cell apoptosis was observed. The treatment efficacy and toxicity were evaluated on the nu/nu mice bearing drug-resistant colon tumor.ResultsThe TAT-PEG-Asp8-Dox materials were synthesized, and they could self-assemble into nanoparticles in aqueous solutions. The thus-formed TAT-PEG-Asps-Dox NPs were around 150 nm at size and the zeta potential was around+15 mV. The TEM showed uniform spherical morphology. The doxorubicin-loading efficiency was 8.6%. It demonstrated that the TAT-PEG-Asp8-Dox NPs were able to overcome drug efflux in the multidrug resistance cell line (HCT8/ADR) and enhance intracellular accumulation of Dox. The MTT results indicated effective antitumor activity in the HCT8/ADR cells, indicating the ability to reverse MDR in the cancer cells. The subcutaneously transplanted HCT8/ADR tumor model was employed for treatment studies, and the tumor growth was effectively arrested by using the TAT-PEG-Asps-Dox NPs.ConclusionIn this work, a TAT-PEG-Asps-Dox nanoparticle system was developed for sensitizing the drug-resistant colon cancer to chemotherapy. It was demonstrated that the system can significantly enhance the cytotoxicity in the drug-resistant cancer cells and induce apoptosis, offering a promising method for the efficient delivery of anticancer drugs into drug-resistant cells and reversal of MDR.