Exosomal-mediated transfer of OIP5-AS1 enhanced cell chemoresistance to trastuzumab in breast cancer via up-regulating HMGB3 by sponging miR-381-3p.

Background: Long noncoding RNA OPA-interacting protein 5 antisense transcript 1 (OIP5-AS1) was confirmed to involve in the malignancy of breast cancer. However, whether exosomal OIP5-AS1 is implicated in trastuzumab resistance remains unclear.

Methods: The IC value of cells to trastuzumab, cell proliferation, migration, and apoptosis was analyzed by cell counting kit-8 assay, colony formation assay, transwell assay, or flow cytometry, respectively. The expression of OIP5-AS1 and microRNA (miR)-381-3p was detected using quantitative real-time polymerase chain reaction. Exosomes were isolated by ultracentrifugation and qualified by nanoparticle tracking analysis software. Western blot was used to detect the protein levels of tumor susceptibility gene 101 (TSG101), CD81, CD63, or high-mobility group protein B3 (HMGB3). The interaction between miR-381-3p and OIP5-AS1 or HMGB3 was confirmed by dual-luciferase reporter assay and pull-down assay. experiments were conducted using murine xenograft models.

Results: OIP5-AS1 was elevated in trastuzumab-resistant breast cancer cells, and OIP5-AS1 knockdown rescued trastuzumab sensitivity. Extracellular OIP5-AS1 was packaged into exosomes, which were secreted by trastuzumab-resistant cells, and could be absorbed by trastuzumab-sensitive cells in breast cancer. Importantly, intercellular transfer of OIP5-AS1 via exosomes enhanced trastuzumab resistance OIP5-AS1 was a sponge of miR-381-3p; besides, miR-381-3p targeted HMGB3. Murine xenograft analysis showed exosomal OIP5-AS1 induced trastuzumab resistance Exosomal OIP5-AS1 was dysregulated in the serum of breast cancer patients and might be a promising diagnostic biomarker in trastuzumab resistance.

Conclusion: Intercellular transfer of OIP5-AS1 by exosomes enhanced trastuzumab resistance in breast cancer via miR-381-3p/HMGB3 axis, indicating a potential therapeutic strategy to boost the effectiveness of trastuzumab in resistant breast cancer patients.