Upregulation of CircCSPP1, CircNRIP1, and CircSMAD2 in Breast Cancer and Their Potential as Diagnostic Biomarkers

Background: Identifying novel diagnostic biomarkers with stable structures, such as circRNAs can improve the early detection and management of BC.Herein, we conducted this study to analyze the expression profile of four circRNAs, including circCSPP1 (hsa_circ_0001806), circNRIP1 (hsa_circ_0004771), circSMAD2 (hsa_circ_0000847), and circFOXP1 (hsa_circ_0008234) in BC.Methods: Tumor tissues and adjacent normal tissues were obtained from patients with sporadic BC.Divergent primers were designed to amplify the target transcripts using quantitative real-time PCR.The expression profiles of circRNAs were analyzed in tumor and adjacent normal tissues.Sanger sequencing was performed to confirm the back-splicing junctions of circRNAs.ROC curves were generated to assess the potential of the mentioned RNAs as diagnostic biomarkers.Results: We observed a significant upregulation of circCSPP1, circNRIP1, and circSMAD2 in tumor tissue compared to adjacent normal tissues.Among them, circCSPP1 was the most highly upregulated one in tumor samples from 39 patients.Expression of circCSPP1 was significantly higher in ER-negative, PRnegative, HER2-negative, and triple-negatives compared to ER-positive, PRpositive, HER2-positive, and non-triple-negative ones.Expression of circNRIP1 was also significantly elevated in the ER-negative and the triple-negative subgroups.These three circRNAs also displayed a desirable potential as diagnostic biomarkers.Conclusion: This is the first paper that reports the upregulation of circCSPP1 and circSMAD2 in BC and upregulation of circCSPP1 and circNRIP1 in the triplenegative subgroup.Our findings suggest that circCSPP1, circNRIP1, and circSMAD2 may serve as promising diagnostic biomarkers for BC.Identifying the downstream pathways regulated by these circRNAs could lead to the discovery of new therapeutic targets.