School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo 192-0982, Japan.
Eur J Pharm Sci. 2023 Dec 1;191:106591. doi: 10.1016/j.ejps.2023.106591. Epub 2023 Sep 23.
Albumin fusion or conjugation is a well-established technique for tumor delivery and is mainly mediated by albumin-induced caveolae-dependent endocytosis. We report that caveolae-dependent endocytic signaling activated by human serum albumin (HSA) is not sufficiently strong to induce cellular uptake, mainly due to its electrostatic repulsion from the negatively charged cell surface sulfated glycosaminoglycans (GAGs), and fusion of the cell-surface-retained protein with HSA is an effective strategy to activate the HSA-induced endocytic signal, thereby improving its intracellular uptake. In this study, human lactoferrin (hLF), a protein that accumulates on the cell surface along with GAGs, was selected for delivery into human lung adenocarcinoma PC-14 cells. When added exogenously, hLF-fused HSA (hLF-HSA) was successfully endocytosed, whereas the simultaneous addition of HSA and hLF did not result in endocytosis, indicating less efficient activation of endocytic signaling by HSA alone and the importance of its fusion. Importantly, the treatment of cells with chlorate, a known inhibitor of GAG sulfation, dramatically suppressed the endocytosis of hLF-HSA owing to the loss of the hLF-GAG interaction. Therefore, the cell-surface localization of HSA imposed by fusion with the cell-surface-retained protein enhances its binding to the relevant receptor, which improves intracellular delivery as an albumin-fusion platform.
白蛋白融合或缀合是一种成熟的肿瘤递药技术，主要通过白蛋白诱导的小窝依赖内吞作用介导。我们报告称，人血清白蛋白（HSA）激活的小窝依赖内吞信号不够强，无法诱导细胞摄取，主要是由于其与带负电荷的细胞表面硫酸化糖胺聚糖（GAGs）的静电排斥，以及将细胞表面保留的蛋白与 HSA 融合是激活 HSA 诱导的内吞信号的有效策略，从而提高其细胞内摄取。在这项研究中，选择人乳铁蛋白（hLF）作为递药载体，hLF 与 GAGs 一起在细胞表面积累。当外源性添加时，hLF 融合的 HSA（hLF-HSA）被成功内化，而同时添加 HSA 和 hLF 则不会导致内吞，这表明 HSA 单独激活内吞信号的效率较低，融合的重要性。重要的是，用氯酸盐处理细胞，一种已知的 GAG 磺化抑制剂，由于 hLF-GAG 相互作用的丧失，显著抑制了 hLF-HSA 的内吞。因此，通过与细胞表面保留蛋白的融合而导致的 HSA 在细胞表面的定位增强了其与相关受体的结合，从而提高了作为白蛋白融合平台的细胞内递药。
