Overexpressed circ-CEP128, a potential new circular RNA biomarker, promotes cisplatin resistance of bladder cancer cells by regulating necroptosis
Abstract Background Bladder cancer (BC) is the most common malignancy of urinary system and cisplatin (DDP) remains the only chemotherapy option for treatment of BC at the advanced stage. The critical molecules involved in the regulation of cisplatin resistance are still largely unknown. CircRNAs has been demonstrated to be involved in tumorigenesis and development and drug resistance of various cancer cells. CircCEP128 contributed to BC progression by regulating miR-145-5p/MYD88/MAKP axis. However, functions and molecular mechanisms of circCEP128 in DDP resistance of bladder cancer cells still remain largely unclear. Methods Bladder cancer tissue and the corresponding adjacent normal tissue as well as serum samples were obtained from a total of 60 BC patients who received the same cisplatin-based chemotherapy. The expression level of circCEP128 in tissues and serums was measured using qRT-PCR. WB was utilized to detect expression level of PCNA, Cyclin D1, RIPK3, p-RIPK3, MLKL or p-MLKL. Functionally, BC cell viability and proliferation are measured through relevant experiments, including CCK8 assay and cell colony formation assay. Results In the current study, we demonstrated that circCEP128 expression was distinctly elevated in the BC tissues and serums, especially in the chemoresistant BC tissues or cell lines, correlated with poor prognosis of BC patients. In addition, ROC curve suggested that circCEP128 might serve as an effective diagnostic biomarker for BC and treatment. Furthermore, cell function assays showed that circCEP128 silencing by siRNA could reverse the drug-resistance of BC cells to cisplatin by inducing necroptosis through regulation of RIPK3/MLKL signaling pathway. Conclusions Our findings indicated that circCEP128 may serve as a valuable diagnostic biomarker in BC and contribute to cisplatin resistance of bladder cancer cells by repressing necroptosis through RIPK3/MLKL signaling pathway. These findings provide novel insights into the role of circCEP128 as a biomarker for the diagnosis and treatment target of BC.