Stress-relief function of migrasomal autophagosomeformed by inhibition of autophagosome/lysosome fusion

Glioblastoma (GBM) is more difficult to treat than other intractable adult tumors. Here, we describe the composition and function of migrasomes generated along with GBM cell migration. Proteomic analysis revealed that LC3B-positive autophagosomes were abundant in the migrasomes of GBM cells. An increased number of migrasomes was observed following treatment with chloroquine (CQ) or inhibition of the expression of STX17 and SNAP29, which are involved in autophagosome/lysosome fusion. Although ATG7 ablation, which is involved in LC3B lipidation, did not suppress migrasome formation, it was confirmed that migrasome formation could be diminished by blocking the alternative autophagy pathway through double knockout of ATG7/BECN1. Furthermore, depletion of ITGA5 or TSPAN4 did not relieve endoplasmic reticulum (ER) stress in cells, resulting in cell death. Taken together, our study suggests that increasing the number of autophagosomes, through inhibition of autophagosome/lysosome fusion, generates migrasomes that have the capacity to alleviate cellular stress. Summary statementThis study demonstrates that glioblastoma cells contain autophagosomes within their migrasomes. Under stress conditions, the formation of migrasomes serves as a stress-relief mechanism to alleviate cell death.