Hsa_circ_0003645 Promotes Breast Cancer Progression by Regulating miR-139-3p/HMGB1 Axis

Background: The aim of the present study was to investigate the effect of over-expressing circular RNA (circ_0003645) on cell functions and its molecular mechanism in breast cancer. Methods: The expression profile of circ_0003645, breast cancer cell lines, and the transcription levels of circular RNA, miRNA and HMGB1 gene were detected by qRT-PCR. Flow cytometry analysis was manipulated to evaluate cancer cell proliferation and cell apoptosis. The correlation between miR-139p-3p and circular_0003645 or HMGB1 was predicted by GEO, and TCGA was confirmed using the dual-luciferase reporter assay. Results: Circ_0003645 expression was conspicuously increased in both the breast cancer tissues and cell lines. Circ_0003645 knockdown inhibited cell proliferation and induced the apoptosis of breast cancer cells in vitro and in vivo. By sponging miR-139-3p, circ_0003645 promoted the breast cancer cells progression and positively regulated HMGB1 gene. Conclusion: Circ_0003645 functions as a ceRNA for miR-139-3p, which could upregulate HMGB1 and further promote cell proliferation in breast cancer.