NGR-poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate enhances the antitumor effect of quercetin liposomes in triple-negative breast cancer

In this paper, the pH-sensitive targeting functional material NGR-poly(2-ethyl-2-oxazoline)-cholesteryl methyl carbonate (NGR-PEtOz-CHMC, NPC) modified quercetin (QUE) liposomes (NPC-QUE-L) was constructed. The structure of NPC was confirmed by infrared spectroscopy (IR) and nuclear magnetic resonance hydrogen spectrum (¹H-NMR). Pharmacokinetic results showed that the accumulation of QUE in plasma of the NPC-QUE-L group was 1.28 times and 2.43 times that of the QUE Solution and QUE-L groups, respectively. The release amount of NPC-QUE-L in an acidic environment was significantly higher than in physiological pH value. The order of the tumor cell inhibition rate in different pH environments was NPC-QUE-L > PC-QUE-L > QUE-L. In addition, the cellular uptake of NPC-modified liposomes was higher than that of PC-modified and unmodified liposomes, indicating that NPC had good pH-sensitivity and targeting. In the triple-negative breast cancer (TNBC) model, the relative tumor proliferation rate of NPC-QUE-L is about 73%, which is better than that of the QUE solution group. Western blot results show that NPC-QUE-L can effectively reduce the expression of α-smooth actin and transforming growth factor-β1 in tumor tissues, and improve the degree of tumor fibrosis. In this study, NPC could endow QUE liposomes with good stability, pH-sensitivity, and targeting, which provides a reference for improving the solubility and targeting of poorly soluble natural drug components.