Both angiogenesis and lncRNAs play crucial roles in the development and progression of breast cancer. Considering the unknown association of angiogenesis and lncRNAs in breast cancer, we aim to identify angiogenesis-related lncRNAs (ARLs) and explore their prognostic value. Here, based on analysis of The Cancer Genome Atlas database, the correlation between ARL and the prognosis and immune infiltration landscape of breast cancer were investigated. Eight ARLs (MAFG−DT, AC097478.1, AL357054.4, AL118556.1, SNHG10, MED14OS, OTUD6B−AS1, and CYTOR) were selected to construct the risk model as a prognostic signature. The survival rate of the patients in the high-risk group was lower than that in the low-risk group. The ARL signature was an independent prognostic predictor, and areas under the curve of 1-, 3-, and 5-year survival were 0.745, 0.695, and 0.699, respectively. The prognostic ARLs were associated with the immune infiltration landscape and could indicate the immune status, immune response, tumor mutational burden, and drug sensitivity of patients with breast cancer. Furthermore, qRT-PCR of clinical samples revealed that OTUD6B−AS1 was correlated with prognostic pathological parameters. OTUD6B−AS1 promoted breast cancer cell proliferation, wound healing, migration, invasion, and human umbilical vein endothelial cells tube formation. Mechanistically, OTUD6B−AS1 regulated EMT- and angiogenesis-related molecules. Taken together, we constructed and verified a robust signature of eight ARLs for the prediction of survival in patients with breast cancer, and the characterization of the immune infiltration landscape. Our findings suggest that OTUD6B−AS1 could be a therapeutic target for patients with breast cancer.

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Background Emerging evidence shows that circular RNAs (circRNAs) play crucial parts in tumorigenesis and progression. In this work, the expression, clinical significance, function and potential mechanism of circ_0075796 in breast cancer were explored. Methods The expression of circ_0075796 in 189 pairs of breast cancer tissues and adjacent normal tissues was detected by quantitative real-time PCR (qRT-PCR). Cell Counting Kit-8 (CCK-8) assay, methyl thiazolyl tetrazolium (MTT) assay and colony formation assay were conducted for cell proliferation. Transwell assay and wound healing assay were used for cell migration and invasion. Flow cytometry analysis was adopted for cell cycle and cell apoptosis. The cellular localization of circ_0075796 was determined by fluorescence in situ hybridization (FISH). The circ_0075796/miR-452-3p/SAMD5 axis was screened out by bioinformatics analysis and verified by qRT-PCR. Methylated RNA Immunoprecipitation (MeRIP) was used to detect the N6-methyladenosine (m6A) modification levels of circ_0075796. QRT-PCR was used to detect the expression of RNA binding protein Quaking (QKI) in breast cancer tissues and adjacent normal tissues. Results circ_0075796 was downregulated in breast cancer tissues compared with adjacent normal tissues. In addition, circ_0075796 showed satisfactory diagnostic value to discriminate breast cancer and normal controls. Downregulated circ_0075796 expression was correlated with lymph node metastasis, HER2 expression, larger tumor size, high Ki-67 expression, advanced histological grade, aggressive molecular subtypes and advanced clinical stages. Overexpression of circ_0075796 inhibited cell proliferation, migration and invasion in vitro. FISH showed that circ_0075796 was localized in the cytoplasm and nucleus of breast cancer cells. Bioinformatics analysis and qRT-PCR revealed the potential circ_0075796/miR-452-3p/SAMD5 axis. Moreover, circ_0075796 showed lower m6A modification levels in breast cancer tissues compared to adjacent normal tissues. QKI was predicted to contain binding sites of circ_0075796 and was downregulated in breast cancer tissues compared to adjacent normal controls. Conclusions circ_0075796 was downregulated in breast cancer compared to normal controls, and showed potential diagnostic value for breast cancer. Downregulation of circ_0075796 was correlated with aggressive clinical features of breast cancer and overexpression of circ_0075796 inhibited the progression of breast cancer in vitro, indicating that circ_0075796 may be related to tumorigenesis and development of breast cancer.