Exosomal Long Noncoding Rna AGAP2-AS1 Regulates Trastuzumab Resistance via Inducing Autophagy in Breast Cancer

Background: Trastuzumab has been widely used for treatment of HER-2-positive breast cancer patients, however, the clinical response has been restricted due to emergence of resistance. Recent studies indicate that long noncoding RNA AGAP2-AS1 (lncRNA AGAP2-AS1) plays an important role in cancer resistance. However, the precise regulatory function and therapeutic potential of AGAP2-AS1 in trastuzumab resistance is still not defined. Methods: : Trastuzumab resistant cells were established. RNA sequencing and qRT-PCR were performed to identify the target gene of AGAP2-AS1. Mass spectrometry, RNA pulldown and RNA immunoprecipitation assays were performed to verify the direct interactions among AGAP2-AS1 and other associated targets, such as embryonic lethal abnormal version like RNA binding protein 1 (ELAVL1) and autophagy related 10 (ATG10). In vitro and in vivo experimental assays were done to clarify the functional role of exosomal AGAP2-AS1 in trastuzumab resistance. Results: : AGAP2-AS1 promotes and disseminates trastuzumab resistance via packaging into exosomes. Exosomal AGAP2-AS1 induces trastuzumab resistance via modulating ATG10 expression and autophagy activity. Mechanically, AGAP2-AS1 is associated with ELAVL1 protein. The AGAP2-AS1-ELAVL1 complex could directly bind to the promoter region of ATG10, inducing H3K27ac and H3K4me3 enrichment, which finally activates ATG10 transcription. AGAP2-AS1-targeting antisenseoligonucleotides (ASO) substantially increased trastuzumab-induced cytotoxicity. Clinically, increased expression of serum exosomal AGAP2-AS1 was associate with poor response to trastuzumab treatment. Conclusion: ExosomalAGAP2-AS1 increased trastuzumab resistance via promoting ATG10 expression and inducing autophagy. Therefore, AGAP2-AS1 may serve aspredictive biomarker and therapeutic target for HER-2+ breast cancer patients.