CircRNA_0044556 regulates paclitaxel resistance in triple-negative breast cancer by targeting miR-665

Background: CircRNAs have been significantly implicated in the development and resistance of triple-negative breast cancer (TNBC). However, the association between circRNA_0044556 and TNBC paclitaxel (PTX) resistance is still limited. Therefore, the purpose of this study was to investigate the effect of circRNA_0044556 on the biological function and PTX resistance of TNBC cells. Methods PTX-resistant TNBC cells (MDA-MB-231/PTX) were obtained by continuously exposing MDA-MB-231 cells to increased paclitaxel levels. First, the expression levels of circRNA_0044556 and miR-665 were measured by qRT‒PCR. Then, the regulatory relationship between miR-665 and circRNA_0044556 was verified by biological information website analysis and double luciferase reporter gene detection experiments. Finally, MTT assay, clonogenesis assay, flow cytometry and Western blot analysis were used to evaluate the influence of cell biological function. Results Elevated circRNA_0044556 was present in TNBC, and paclitaxel increased the expression of circRNA_0044556 in TNBC cells. In TNBC, circRNA_0044556 acts as a ceRNA for miR-665. In addition, low expression of circRNA_0044556 combined with miR-665 inhibited the proliferation of TNBC cells and paclitaxel-resistant TNBC cells while inducing cell death. Conclusions Our study demonstrated that downregulation of circRNA_0044556 inhibited the malignant progression of TNBC cells and paclitaxel resistance via miR-665. Thus, circRNA_0044556 may be a potential therapeutic target for TNBC paclitaxel resistance.