Exosome miR-134-5p restrains breast cancer progression via regulating PI3K/AKT pathway by targeting ARHGAP1

Aim: Exosomes has been shown to be involved in the regulation of cancer progression. However, the role of exosome miR-134-5p in breast cancer (BC) progression is unclear.

Methods: Exosomes were extracted from BC cells (MCF-7 and MDA-MB-231) using differential centrifugation and were observed by transmission electron microscope (TEM). The protein levels of exosome markers, apoptosis markers, Rho GTPase activating protein 1 (ARHGAP1, an important oncogene in BC) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) markers were detected by western blot (WB) assay. Quantitative real-time PCR was used to measure the expression levels of miR-134-5p and ARHGAP1. Cell cycle and apoptosis, colony number, viability, migration, and invasion were determined by flow cytometry, colony formation assay, MTT assay, and transwell assay, respectively. The interaction between miR-134-5p and ARHGAP1 was confirmed using a dual-luciferase reporter assay. Xenograft models were constructed to verify the role of exosome miR-134-5p in BC tumor growth in vivo.

Results: MiR-134-5p was lowly expressed in BC cells and in the exosomes of BC cells. Overexpressed exosome miR-134-5p suppressed the proliferation, migration, invasion, and promoted the apoptosis of BC cells. ARHGAP1 was a target of miR-134-5p, and its silencing could inhibit BC progression. In addition, ARHGAP1 overexpression could reverse the negative regulation of miR-134-5p on BC progression. MiR-134-5p could target ARHGAP1 to inhibit the activity of PI3K/AKT pathway. Exosome miR-134-5p overexpression could suppress BC tumor growth via targeting ARHGAP1 in vivo.

Conclusion: Exosome miR-134-5p restrained BC progression through regulating ARHGAP1/PI3K/AKT signaling pathway, suggesting that miR-134-5p might be a therapeutic target for BC.