Extracellular Vesicle-based Delivery of Paclitaxel to Lung Cancer Cells: Uptake, Anticancer Effects, Autophagy and Mitophagy Pathways

Abstract

Background

Due to their unique properties, extracellular vesicles (EVs) are promising nanocarriers for exogenous drug delivery.

Aim

We prepared a drug delivery system based on large EVs (LEVs) containing paclitaxel (PTX) (LEVs-PTX) to investigate anticancer effects on lung cancer cells with a focus on autophagy.

Methods

LEVs-PTX were isolated from lung cancer cells by ultracentrifugation and characterized using different techniques. Rhodamine B dye (Rh B) was used to label LEVs-PTX for cell tracking. MTT assay was performed to investigate the cellular toxicity of PTX and LEVs-PTX for 24 h and 48 h. The uptake of LEVs-PTX was monitored by immunofluorescence microscopy in breast and lung cancer cells. A colorimetric assay was performed to evaluate apoptosis, while Western blotting assays were used to investigate autophagy proteins. Real-time PCR was used to measure mitophagy genes.

Results

Characterization techniques showed that LEVs were isolated and loaded with PTX. Rh B labeled LEVs, which was confirmed by a fluorescence spectrophotometer. Immunofluorescence microscopy showed that the lung and breast cancer cells had captured LEVs. Cell viability was decreased in LEVs-PTX cells which coincided with an increase in caspase-3 activity in LEVs-PTX cells. The Beclin-1 protein level and LC3 II/I ratio decreased, while the P62 protein level was increased in LEVs-PTX cells. The mitophagy genes such as Pink-1 and Parkin were upregulated in LEVs-PTX cells.

Conclusion

The data show that LEVs-PTX induced apoptosis, which inhibited the autophagy pathway and increased mitophagy markers, suggesting damage to cell organelles through intracellular delivery of PTX.