hnRNPA2B1 facilitates ovarian carcinoma metastasis by sorting cargoes into small extracellular vesicles driving myofibroblasts activation.

Background: Ovarian carcinoma (OvCa) metastasis is initiated and boosted by tumor-stroma interactions mediated by small extracellular vesicles (sEVs) containing microRNAs (miRNAs). However, the mechanisms of sorting relevant miRNAs into tumoral sEVs remain elusive.

Results: In this study, among the RNA-binding proteins, hnRNPA2B1 was identified as the most significant factor associated with survival in OvCa patients, and its expression was higher in omental metastases compared to paired ovarian lesions. Based on the CRISPR-Cas9 technique, orthotopic xenograft mice revealed a remarkable metastasis-inhibiting effect of hnRNPA2B1-knockdown, accompanied by diminished myofibroblast signals in the omentum. Meanwhile, after hnRNPA2B1-knockdown, OvCa-sEVs largely lost the ability to promote omental metastasis and myofibroblast activation in vivo and in vitro. High-throughput miRNA sequencing of sEV cargoes revealed that UAG motif-containing miRNAs were significantly affected by hnRNPA2B1, and RNA immunoprecipitation (RIP) verified their direct binding to hnRNPA2B1. In pull down assays, the miRNAs with mutated UAG motif exhibited decreased binding capacity to hnRNPA2B1. The myofibroblasts activated by OvCa-sEVs could promote tumor metastasis, and this effect was notably impacted by manipulating hnRNPA2B1, related sEV-miRNAs, and PI3K/AKT signaling.

Conclusions: These findings highlight the miRNA sorting to sEVs mediated by hnRNPA2B1 as an important mechanism involved in OvCa metastasis, which may illuminate new therapeutic strategies.