Synthesis and Photothermal Effects of Intracellular Aggregating Nanodrugs Targeting Nasopharyngeal Carcinoma

Abstract

Chemotherapy for the treatment of nasopharyngeal carcinoma (NPC) is usually associated with many side effects; therefore, its treatment options have not yet been completely resolved. Improving distribution to the targeted tumor region and enhancing the cellular uptake of drugs can efficiently alleviate the above adverse medical effects. Near-infrared (NIR) laser light-mediated photothermal therapy (PTT) and photodynamic therapy (PDT) are promising strategies for cancer treatment. In the present study, we developed an efficient multifunctional nanocluster with enhanced targeting and aggregation efficiency for PTT and PDT that is composed of a biocompatible folic acid (FA), indocyanine green (ICG) and 2-cyanobenzothiazole (CBT)-functionalized peptide labeled with an aldehyde sodium alginate-modified magnetic iron oxide nanoparticle (ASA-MNP)-based nanocarrier. FA can bind to folate receptors on cancer cell membranes to enhance nanocluster uptake. CBT-modified peptide can react with glutathione (GSH), which is typically present at higher levels in cancer cells, to form intracellular aggregates and increase the local concentration of the nanodrug. In in vitro studies, these nanodrugs displayed the desired uptake capacity by NPC cells and the ability to suppress the growth of cancer cells under laser irradiation. Animal studies validated that these nanodrugs are safe and nontoxic, efficiently accumulate in NPC tumor sites following injection via the caudal vein, and shows superior inhibition of tumor growth in a tumor-bearing mouse model upon near-infrared laser irradiation. The results indicate the potential application of the multifunctional nanoparticles (NPs), which can be used as a new method for the treatment of folate receptor-positive NPC.

Keywords: folic acid targeting; indocyanine green; intracellular aggregation; nasopharyngeal carcinoma; photothermal effect.

FIGURE 1

Schematic illustration of the construction of FA-PEG/CBT@SPION-ICG and photothermal therapy of nasopharyngeal carcinoma.

FIGURE 2

Characterization of FA-PEG@SPION-ICG. TEM images of FA-PEG/CBT@SPION-ICG (i) and FA-PEG/CBT@SPION-ICG after being treated by GSH (ii). DLS diagram of FA-PEG/CBT@SPION-ICG after being treated by GSH (B). UV absorption spectrum of free ICG and FA-PEG/CBT@SPION-ICG (C). In vitro temperature profile (D).

FIGURE 3

Prussian blue staining (A) and Hoechst staining (B) (C) of different formations under various conditions. #Stands for p < 0.05 ASA@SPION versus FA-PEG@SPION. $ Stands for p < 0.05 ASA@SPION versus FA-PEG/CBT@SPION. * Stands for p < 0.05 FA-PEG@SPION versus FA-PEG/CBT@SPION. & Stands for p < 0.05 ICG versus FA-PEG/CBT@SPION-ICG. TEM results of HNE-1 cells after cellular uptake of FA-PEG@SPION-ICG and FA-PEG/CBT@SPION-ICG (D). Multimodal small animal imaging after injection of different formations at 8 h (E).

FIGURE 4

Calcein-AM/PI live/dead cell staining (10 ×) (A), ROS detected by DCFH-DA staining (B), and western blot analysis (C) of different formations under various conditions. In B, i is PBS, ii is FA-PEG@SPION-ICG, iii is FA-PEG/CBT@SPION-ICG, iv is PBS + Laser, v is ICG + Laser, vi is FA-PEG@SPION-ICG + Laser, and vii is FA-PEG/CBT@SPION-ICG + Laser.

FIGURE 5

Thermal imaging of the mice after treatment with different formulations with NIR or MHT (A). Imaging was performed before and on day 2 after the different treatments (B). Tissues dissected from nude mice, mass histogram of the tumor weight, mass histogram of the tumor growth inhibition rate, and a line graph of tumor tissue volume over time (C) (N = 5) (*) p < 0.05 (**) p < 0.01 (***) p < 0.001. Immunohistochemical analysis of Hsp70 expression in different groups (D). Figure 4D, i is PBS, ii is PBS + Laser, iii is FA-PEG/CBT@SPION-ICG, iv is FA-PEG@SPION-ICG + MHT, v is FA-PEG/CBT@SPION-ICG + MHT, vi is free ICG + Laser, vii is FA-PEG@SPION-ICG + Laser, and viii is FA-PEG/CBT@SPION-ICG + Laser.

FIGURE 6

Cell viability detected by CCK-8 assay (A). H&E staining of the heart, liver, spleen, lung, kidney, and tumor tissues of nude mice (× 20) (B).