BACKGROUND Lipid nanocapsules (LNCs) are promising vehicles for drug delivery. However, since not much was known about cellular toxicity of these nanoparticles in themselves, we have here investigated the mechanisms involved in LNC-induced intoxication of the three breast cancer cell lines MCF-7, MDA-MD-231 and MDA-MB-468. The LNCs used were made of Labrafac™ Lipophile WL1349, Lipoid® S75 and Solutol® HS15. RESULTS High resolution SIM microscopy showed that the DiD-labeled LNCs ended up in lysosomes close to the membrane. Empty LNCs, i.e. without encapsulated drug, induced not only increased lysosomal pH, but also acidification of the cytosol and a rapid inhibition of protein synthesis. The cytotoxicity of the LNCs were measured for up to 72 h of incubation using the MTT assay and ATP measurements in all three cell lines, and revealed that MDA-MB-468 was the most sensitive cell line and MCF-7 the least sensitive cell line to these LNCs. The LNCs induced generation of reactive free oxygen species and lipid peroxidation. Experiments with knock-down of kinases in the near-haploid cell line HAP1 indicated that the kinase HRI is essential for the observed phosphorylation of eIF2α. Nrf2 and ATF4 seem to play a protective role against the LNCs in MDA-MB-231 cells, as knock-down of these factors sensitizes the cells to the LNCs. This is in contrast to MCF-7 cells where the knock-down of these factors had a minor effect on the toxicity of the LNCs. Inhibitors of ferroptosis provided a large protection against LNC toxicity in MDA-MB-231 cells, but not in MCF-7 cells. CONCLUSIONS High doses of LNCs showed a different degree of toxicity on the three cell lines studied, i.e. MCF-7, MDA-MD-231 and MDA-MB-468 and affected signaling factors and the cell fate differently in these cell lines.

中文翻译：

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脂质纳米胶囊诱导的生物反应和细胞毒性。

背景技术脂质纳米胶囊（LNC）是用于药物递送的有前途的载体。但是，由于对这些纳米颗粒本身的细胞毒性了解不多，因此我们在这里研究了LNC诱导的三种乳腺癌细胞MCF-7，MDA-MD-231和MDA-MB-468的中毒机制。所使用的LNC由Labrafac™Lipophile WL1349，Slipoid®和HS15制成。结果高分辨率SIM显微镜显示DiD标记的LNCs最终位于膜附近的溶酶体中。空的LNC，即没有包封的药物，不仅诱导溶酶体pH升高，而且还引起胞浆酸化和蛋白合成的快速抑制。在所有三种细胞系中，使用MTT测定法和ATP测定法在长达72小时的孵育中测量了LNC的细胞毒性，并发现MDA-MB-468对这些LNC最敏感，而MCF-7对这些LNC最不敏感。LNCs诱导生成反应性游离氧和脂质过氧化。在接近单倍体细胞系HAP1中敲除激酶的实验表明，激酶HRI对于观察到的eIF2α磷酸化至关重要。Nrf2和ATF4似乎在MDA-MB-231细胞中对LNC具有保护作用，因为这些因子的敲低使细胞对LNC敏感。这与MCF-7细胞相反，在这些细胞中，这些因子的敲低对LNC的毒性影响较小。肥大症的抑制剂在MDA-MB-231细胞中提供了对LNC毒性的强大保护，而在MCF-7细胞中则没有。结论高剂量的LNC对所研究的三种细胞系表现出不同程度的毒性，即