Mol Pharm. 2018 Aug 6;15(8):3046-3059. doi: 10.1021/acs.molpharmaceut.8b00163. Epub 2018 Jun 22.
The small GTPase RalA is a known mediator of anchorage-independent growth in cancers and is differentially regulated by adhesion and aurora kinase A (AURKA). Hence, inhibiting AURKA offers a means of specifically targeting RalA (over RalB) in cancer cells. MLN8237 (alisertib) is a known inhibitor of aurora kinases; its specificity for AURKA, however, is compromised by its poor solubility and transport across the cell membrane. A polymer nanovesicle platform is used for the first time to deliver and differentially inhibit AURKA in cancer cells. For this purpose, polysaccharide nanovesicles made from amphiphilic dextran were used as nanocarriers to successfully administer MLN8237 (V) in cancer cells in 2D and 3D microenvironments. These nanovesicles (<200 nm) carry the drug in their intermembrane space with up to 85% of it released by the action of esterase enzyme(s). Lysotracker experiments reveal the polymer nanovesicles localize in the lysosomal compartment of the cell, where they are enzymatically targeted and MLN released in a controlled manner. Rhodamine B fluorophore trapped in the nanovesicles hydrophilic core (V) allows us to visualize its uptake and localization in cells in a 2D and 3D microenvironment. In breast cancer, MCF-7 cells V inhibits AURKA significantly better than the free drug at low concentrations (0.02-0.04 μM). This ensures that the drug in V at these concentrations can specifically inhibit up to 94% of endogenous AURKA without affecting AURKB. This targeting of AURKA causes the downstream differential inhibition of active RalA (but not RalB). Free MLN8237 at similar concentrations and conditions failed to affect RalA activation. V-mediated inhibition of RalA, in turn, disrupts the anchorage-independent growth of MCF-7 cells supporting a role for the AURKA-RalA crosstalk in mediating the same. These studies not only identify the polysaccharide nanovesicle to be an improved way to efficiently deliver low concentrations of MLN8237 to inhibit AURKA but, in doing so, also help reveal a role for AURKA and its crosstalk with RalA in anchorage-independent growth of MCF-7 cells.
小分子 GTPase RalA 是一种已知的癌症锚定非依赖性生长的介质，其表达受到黏附和 Aurora 激酶 A（AURKA）的调控。因此，抑制 AURKA 提供了一种在癌细胞中特异性靶向 RalA（而非 RalB）的方法。MLN8237（alisertib）是 Aurora 激酶的已知抑制剂；然而，其对 AURKA 的特异性受到其较差的溶解性和跨细胞膜转运的限制。聚合物纳米囊泡平台首次用于在癌细胞中递药和差异化抑制 AURKA。为此，采用两亲性葡聚糖制备的多糖纳米囊泡作为纳米载体，在 2D 和 3D 微环境中成功地将 MLN8237（V）递送至癌细胞中。这些纳米囊泡（<200nm）将药物携带在其膜间空间内，其中 85%的药物可通过酯酶的作用释放。溶酶体追踪实验表明，聚合物纳米囊泡定位于细胞的溶酶体区室中，在那里它们被酶靶向并以受控的方式释放 MLN。纳米囊泡亲水性核内的罗丹明 B 荧光团（V）可用于可视化其在 2D 和 3D 微环境中细胞内的摄取和定位。在乳腺癌中，MCF-7 细胞中 V 在低浓度（0.02-0.04μM）下比游离药物更能显著抑制 AURKA。这确保了在这些浓度下 V 中的药物能够特异性抑制高达 94%的内源性 AURKA，而不会影响 AURKB。这种对 AURKA 的靶向作用导致下游活性 RalA 的差异化抑制（但不是 RalB）。在类似的浓度和条件下，游离的 MLN8237 未能影响 RalA 的激活。V 介导的 RalA 抑制继而破坏 MCF-7 细胞的锚定非依赖性生长，支持 AURKA-RalA 串扰在介导相同作用中的作用。这些研究不仅确定了多糖纳米囊泡是一种有效传递低浓度 MLN8237 以抑制 AURKA 的改进方法，而且还揭示了 AURKA 及其与 RalA 的串扰在 MCF-7 细胞锚定非依赖性生长中的作用。
