Therapeutic potential of anti-miR29a in breast cancer patients with type 2 diabetes: an in vitro and xenograft mouse-model study

BACKGROUND: MicroRNAs (miRNAs) acting as tumour suppressors or oncogenes, known as oncomiRs, are a promising new focus in targeted therapies for cancer. Approximately 16% of breast cancer patients have pre-existing diabetes. Breast cancer with type 2 diabetes mellitus (BDM) is provided with its unique biological characteristics and clinical characteristics. This study primarily investigated the therapeutic potential and regulatory mechanism of miR-29a in patients with BDM. METHODS: The significance of miR-29a in BDM was analyzed by real-time reverse transcriptase polymerase chain reaction (qRT-PCR) in breast tissues. A cell model for BDM was established by using MDA-MB-231 cells cultured in 3T3-L1 adipocytes cultured with high levels of glucose and insulin. A type 2 diabetes mellitus (T2DM) mouse model was induced in female BALB/c mice through a high-fat diet plus low doses of streptozotocin (STZ). The xenograft mouse-model for BDM was established on these T2DM mouse by using MDA-MB-231 cells. Then the biological effects of miR-29a knockdown mediated by lentivirus-shRNAs on cell proliferation, apoptosis, cell cycle, and migration were investigated. RESULTS: Our results indicated that miR-29a was upregulated in patients with BDM, which correlated with a worse prognosis. In human breast cancer cells, miR-29a knockdown reduced cell proliferation and cell migration and invasion in BDM. In the T2DM xenograft, miR-29a knockdown suppressed MDA-MB-231 cells tumorigenesis and metastasis. We also demonstrated that miR-29a promoted BDM cell growth and metastasis by targeting Sirtuin 1 (SIRT1). CONCLUSIONS: Our findings indicated that anti-miR-29a inhibited cell proliferation and invasion in BDM by targeting SIRT1. We believe anti-miR-29a may represent a novel therapeutic approach for the management of patients with BDM.