Objective To investigate the expression and clinical significance of CircRNA ANKS1B (CircANKS1B) and upstream transcription factor 1 (USF1) in breast cancer tissues.

Methods A total of 90 patients with breast cancer were selected as subjects. USF1 protein expression in tissues was detected by immunohistochemistry. The expression of CircANKS1B and USF1 mRNA in tissues was detected by real-time quantitative polymerase chain reaction. The correlation between CircANKS1B and USF1 mRNA in cancer tissues was analyzed. The relationships of CircANKS1B and USF1 mRNA expression with clinicopathologic features of breast cancer were analyzed. The relationships of CircANKS1B and USF1 mRNA expression with prognosis of breast cancer were analyzed. Univariate and multivariate COX proportional risk models were used to analyze the independent influencing factors of the prognosis of breast cancer.

Results The brownish-yellow expression of USF1 in breast cancer tissues was mainly located in the nucleus. The positive rate of USF1 protein expression in breast cancer tissues was 86.67% (78/90), which was significantly higher than 15.56% (14/90) in adjacent tissue (P < 0.001). The relative expression levels of CircANKS1B and USF1 mRNA in the breast cancer tissues were (4.12±0.68) and (6.35±1.21), respectively, which were significantly higher than (1.23± 0.46) and (1.57±0.59) in the adjacent tissue (P < 0.001). There was a significant positive correlation between CircANKS1B and USF1 mRNA expression in breast cancer tissues (r=0.604, P < 0.001). The expression of CircANKS1B and USF1 mRNA showed statistically significant differences in different tumor stages, lymph node metastasis and triple-negative breast cancer (P < 0.05). The median survival time of patients with high CircANKS1B expression was 52.62 months (95%CI, 49.44 to 56.35), which was significantly shorter than 56.78 months (95%CI: 52.46 to 57.05) in patients with low CircANKS1B expression (P=0.045). The median survival time of patients with low expression of USF1 mRNA was 52.53 months (95%CI, 48.83 to 56.23), which was significantly shorter than 56.75 months (95%CI, 54.07 to 59.43) of patients with low USF1 mRNA expression (P=0.014). CircANKS1B high expression, USF1 mRNA high expression, tumor stage Ⅲ and lymph node metastasis are independent influencing factors of the prognosis of breast cancer.

Conclusion The expressions of CircANKS1B and USF1 are increased in breast cancer tissues, and correlated with TNM stage, lymph node metastasis, and are new breast cancer prognostic tumor markers.