Drug resistance‑related sunitinib sequestration in autophagolysosomes of endothelial cells

Abstract

Our previous study demonstrated that the tyrosine kinase receptor inhibitor sunitinib induces acquired drug resistance in endothelial cells. The present study explored the role of lysosomal sequestration of sunitinib in the acquisition of drug resistance in human microcapillary endothelial HMEC-1 cells. Resistance was induced by escalating concentrations of sunitinib and a shift in IC50 from 12.8 to >20 µM was detected. The results of time-lapse fluorescence microscopy illustrated an instantaneous emergence of fluorescent vesicles in living cells once sunitinib was added. Most of these vesicles emerged in the juxtanuclear area, and exhibited the characteristics of growing autophagosomes and lysosomes. The vesicles were identified as autophagosomes and lysosomes because they co-located with the lysosomal tracers Lyso-ER and Lyso-NIR, and the protein markers lysosomal-associated membrane protein 1 (LAMP-1) and microtubule-associated protein 1A/1B-light chain 3 (LC3). The results of western blotting demonstrated that sunitinib induced upregulation of LAMP-1 and LC3-II, and downregulation of sequestosome 1/p62, indicating the activation of autophagy. Bafilomycin A1, which suppresses lysosomal acidification, completely blocked sunitinib sequestration; however, chloroquine, which blocks lysosomal fusion with autophagosomes, exhibited no effect. Notably, bafilomycin A1 and chloroquine significantly counterbalanced HMEC-1 drug-resistance. These results provided evidence for autophagy-flux-associated sunitinib lysosomal sequestration in endothelial cells, leading to isolation of the drug from the cytoplasm; a key process involved in the development of drug resistance during antiangiogenic therapy. These data supported the notion that inhibiting autophagy may be a potential strategy to prevent drug sequestration and resistance to antiangiogenic therapy.

Molecular Mechanisms of Resistance to Immunotherapy and Antiangiogenic Treatments in Clear Cell Renal Cell Carcinoma

“…Lysosomal sequestration is a reversible resistance mechanism. A study conducted in sunitinib resistant RCC cells revealed that lysosomal function was suppressed when sunitinib was withdrawn from the cell cultures and drug sensitivity was retrieved [ 150 ]. Furthermore, alkalinizing lysosomes with an H+-ATPase inhibitor like bafilomycin has been also studied for reversing sunitinib resistance since pH gradient plays a key role in its sequestration.…”

Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

“…Interestingly, lysosomal sequestration is a reversible process [169,170]. Studies on sunitinib-resistant RCC tumour cell lines have shown that sensitivity to the drug was regained and the lysosome capacity reversed after the cells were cultured without sunitinib [171].…”

Autophagy-targeted therapy to modulate age-related diseases: Success, pitfalls, and new directions

“…Some mechanisms of tumor resistance to drugs are mediated by lysosome; as is the case with the lysosomal sequestration of multiple weak-base hydrophobic drugs, including tyrosine kinase inhibitors (e.g., sunitinib) ( Gotink et al., 2011 ). Such organelle-mediated drug sequestration keeps these drugs away from their intracellular sites, hence resulting in tumor resistance ( Wu et al., 2020 ). The approved drug pantoprazole used for the management of gastroesophageal reflux disease significantly increases the sensitivity of tumor xenografts to paclitaxel by inhibiting autophagy ( Tan et al., 2017 ).…”