In recent years, there has been a notable increase in the incidence and mortality of bladder cancer in China. Despite undergoing treatments such as surgery, chemotherapy, and radiotherapy, patients with bladder cancer still face high recurrence rates and low 5-year survival rates [13, 14]. Given these challenges in treatment and prognosis, it is crucial to explore new biomarkers for bladder cancer while actively seeking new treatment methods. Identifying these biomarkers will enable physicians to accurately detect, identify, and analyze patients’ health conditions, facilitating the development of tailored and effective treatment strategies that can significantly improve cure rates and patient outcomes.

In our previous study, we employed gene chip technology to investigate the expression profiles of circRNAs in four cases of bladder cancer and matched paracancerous tissues. Through this analysis, we identified 127 differentially expressed circRNAs between bladder cancer and paracancerous tissues, including 89 up-regulated circRNAs and 38 down-regulated circRNAs. Our findings suggest that circRNA‑0071196 upregulates CIT levels in BCa by sponging off miRNA-19b-3p, subsequently influencing the proliferation, migration and colony formation capacity of the BCa cells [15]. There is evidence suggesting that the mechanism of action of circRNA involves acting as a “miRNA sponge.” In this process, circRNA competes with miRNA, leading to the inhibition of miRNA transcription and subsequent hindrance of mRNA transcription. Numerous studies have identified circRNAs capable of serving as miRNA sponges, highlighting their significance as important regulators of gene expression [16]. The investigation of urine circRNA represents an emerging research area. Urine circRNA can be stably present in urine and reflect in vivo pathophysiological changes. Increasing studies have demonstrated its potential as a biomarker for various diseases [17, 18]. Urine samples are easily collected non-invasively, making urine circRNA a promising tumor marker. Significant alterations in urine circRNA have been observed in colorectal cancer, prostate cancer, bladder cancer, pancreatic cancer, and other cancer types, suggesting their potential for early cancer diagnosis and prediction of clinical progression. While further validation is necessary, urine circRNA holds great promise as a significant research direction in the field of cancer screening, diagnosis, and treatment in the future [19,20,21,22,23].

Based on previous experimental results, circRNA-0071196 was selected as the focus of this study. The relationship between its relative expression in the urine of 40 BUC patients and the basic clinical characteristics was examined using qRT-PCR. The results (Fig. 2) indicated that there were no statistically significant differences in the relative expression of urine circRNA-0071196 based on gender composition, age, lymph node metastasis, etc. However, a significantly higher relative expression of urine circRNA-0071196 was observed in bladder cancer patients with T2-T4 stage compared to those with Ta + T1 stage. Additionally, the relative expression of urine circRNA-0007905 was significantly higher in high-grade compared to low-grade BUC patients in terms of the G stage. These findings suggest a potential association between circRNA-0071196 expression in urine and the differentiation and invasive growth of BUC.

In this study, the ROC curve was employed to evaluate whether the expression of urine circRNA-0071196 could serve as a potential auxiliary marker for the diagnosis of bladder urothelial cancer patients (Fig. 3). The urinary circRNA-0071196 assay was significantly more sensitive than cytology in detecting bladder cancer, but less specific than cytology (Table 1). The results demonstrated that the urine circRNA-0071196 expression effectively distinguished BUC patients from non-BUC patients, indicating its potential diagnostic value for BUC. In the future, the detection of urine circRNA-0071196 can be included in the diagnosis of BUC to better assess patient condition and monitor treatment effectiveness. In conclusion, this study successfully detected the expression of urine circRNA-0071196 in BUC patients, explored its correlation with clinical pathological features of BUC, and evaluated its potential as a diagnostic marker. These findings provide a novel approach to explore novel candidate tumor markers and therapeutic targets for BUC.