Exosome-based delivery of microRNAs to confer adriamycin-resistance to sensitive cells through modulating the immune- and metabolism-related gene PTEN in HER2-negative breast cancer.

Abstract

e12518 Background: Anthracycline-based chemotherapy is frequently used to treat breast cancer. However, acquired drug-resistance remains a challenge for successful treatment. Recent evidence suggests that in addition to increased tumor cell resistance, modifications in the tumor immune microenvironment (TIME) consistently contribute to the development of chemo-resistance. Methods: TIME scores and tumor-infiltrating immune cells (TICs) scores were used to investigate clinicopathological characteristics and gene transcriptome profiling of 142 HER2-negative breast cancer patients who received anthracycline-based chemotherapy. Exosomes isolated from MCF/7-ADR (ADR-exos) and MCF/7-S (S-exos) cell lines were characterized. MiRNA microarray and TMT mass spectrometry analysis were used to identify differentially expressed miRNA and its target genes. The ability of ADR-exos to transfer drug-resistance mediated by miR-222 was assessed by immunofluorescence assay, flow cytometry and qRT-PCR. We optimized the conditions to load miR-222 mimic (or inhibitor) into exosomes produced by HBL-100 cells (H-exos). The influence of miR-222 inhibitor-containing exosomes on the downstream pathway of miR-222 and the potential therapeutic effects both in vitro and in vivo were evaluated. Results: Firstly, we discovered the complicated and heterogenous TICs subtypes and their unique biological behaviors in HER2-negative breast cancer. Gene set variation analysis (GSVA) was used to quantify 85 differentially expressed immunologic signature gene sets and 7202 corresponding immune-related genes. Using miRNA microarray analysis and TMT mass spectrometry, 45 differentially expressed immune-related proteins affected by the miR-222 level were identified, particularly PTEN, a well-known tumor suppressor factor. Furthermore, we successfully established miRNA mimic/inhibitor-containing exosomes to explore the individual function of exosomal miR-222 in promoting adriamycin-resistance both in vitro and in vivo. Conclusions: HER2-negative breast cancer patients own unique TIME subtypes, leading to different outcomes of chemotherapy. We exhibit the potential applications of miR-222-mimic/inhibitor-containing exosomes for reversing chemo-resistance. Adriamycin-resistant cells can transmit drug-resistance to sensitive cells via delivering miR-222 by modulating the immune- and metabolism-related target gene PTEN both in vitro and in vivo without interference from other relevant drug-resistance factors in exosomes. Therefore, miR-222-containing exosomes as well as the target gene PTEN may be a promising biomarker to predict the chemo-resistance and tumor immunomodulatory effects of Anthracycline-based chemotherapy in HER2-negative breast cancer patients.