Exosomal mir-625-3p derived from hypoxic lung cancer cells facilitates metastasis by targeting SCAI

Background: Tumor hypoxia is a feature of tumor micro-environment (TME), which provides a suitable environment for tumor cells migration and invasion. However, up to now, the function of exosomes derived from hypoxic tumor cells is still not fully understood. The present study is aimed to explore the underlying mechanisms of lung cancer-secreted exosomes-mediated tumor metastasis under hypoxia.

Methods & results: Exosomes were isolated from normoxic or hypoxic NCI-H446 cells. Some characteristic proteins were detected by western blots. Levels of CD63, CD 9 and CD 81 proteins were up-regulated on the membrane of exosomes secreted by hypoxic NCI-H446 cells. Basing on the results from miRNA sequencing, qRT-PCR and wound healing assay, hsa-miR-625-3p was discovered to be accumulated inside hypoxic exosomes and responsible for the metastasis of lung cancer cell. Further experiments from luciferase reporter gene assay demonstrated hsa-miR-625-3p could directly inhibit SCAI expression through binding with its 3'UTR, which suggested the mechanisms by which exosomal hsa-miR-625-3p suppressed tumor cells migration.

Conclusions: Exosomal miR-625-3p derived from hypoxic small lung cancer cells accelerated tumor cells migration through inhibiting SCAI directly.