Professor Chung-Ang University Anseong-si, Kyonggi-do, Republic of Korea
Introduction:: Doxorubicin (DOX), an anthracycline anticancer drug, has been extensively used in chemotherapy to treat cancer by intercalating within the DNA of cancer cells. However, free DOX causes systemic side effects and low therapeutic efficacy due to its poor targetability. Targeted drug delivery systems have been developed to overcome this limitation. Sodium hyaluronate (HA), a ligand of the CD44, has been used as the targeted drug delivery system against CD44-overexpressing cancer cells. However, most of HA-based nanoparticles for the delivery of DOX were synthesized using physically loading or chemically conjugation involve surfactants or crosslinkers that can cause undesired toxicity. Herein, we report the self-associated HA/DOX nanoaggregates (HA/DOX) without surfactants or crosslinkers and evaluate their therapeutic effects on CD44-overexpressing cancer cells.
Materials and Methods:: The self-associated HA/DOX nanoaggregates were prepared by simple mixing of HA and DOX. To optimize the synthesis of HA/DOX, the HA solution (1.56 μmol) was reacted with different molar ratios of DOX (1.56 μmol, 3.12 μmol, 7.8 μmol, and 15.6 μmol) by simple mixing. The formation of the self-associated HA/DOX nanoaggregates was confirmed by monitoring turbidity (at 600 nm by using an UV/Vis spectrophotometer) and photos. Also, the prepared HA/DOX nanoaggregates were characterized by 1H-NMR spectroscopy, particle size analyzer, and TEM analysis. In addition, their intracellular uptake and cytotoxic effects were evaluated on squamous cell carcinoma (SCC7) by using a customized confocal laser scanning microscope (CLSM), CCK-8, and annexin V staining assays.
Results, Conclusions, and Discussions:: The synthesis of HA/DOX nanoaggregates was optimized by confirming turbidity of solutions. At molar ratio of 1:5 (HA to DOX) or more, unclear solution and higher absorption peak were observed, indicating the formation of the self-associated HA/DOX nanoaggregates. The size distribution and TEM analyses showed that the HA/DOX were formed as nano-sized spherical shapes with mono-dispersity. In in vitro studies, HA/DOX nanoaggregates were highly internalized into CD44-overexpressing SCC7 cancer cells, compared to free DOX, and thereby leading to enhanced chemotherapeutic effects. In conclusion, this study showed that HA/DOX nanoaggregates could be fabricated by simple mixing, and they were effective to treat CD44-overexpressing cancer cells.
