Abstract 5104: Extracellular vesicles expressing CEACAM proteins in the urine of bladder cancer patients

Abstract

Abstract Purpose: Early detection and long-term monitoring are important for urothelial carcinoma of the bladder (UCB). Urine cytology and existing markers have insufficient diagnostic performance. Here, we used medium-sized extracellular vesicles (EVs) in urine to find specific markers for UCB and evaluate their usefulness as diagnostic material. Experimental Design: To search for specific markers in urinary EVs derived from UCB, we performed a comparative analysis using shotgun proteomics with urine from four UCB patients and four healthy subjects. Next, we used male 24 healthy specimens, 18 non-cancer specimens, and 29 UCB specimens for analysis of urinary EVs using a flow cytometer to evaluate the diagnostic performance of UCB-specific EVs. Results. NTA analysis showed that the size of EVs extracted from urine by centrifugation was mostly less than 400 nm. By shotgun analysis of EVs, we detected several proteins characteristic of UCB and found that CEACAM proteins was increased in patients. Flow cytometric analysis revealed that the degree of expression of CEACAM1, 5, and 6 antigens on the surface of EVs varied among patients. EVs expressing CEACAM antigens also expressed MUC1, suggesting that they were derived from tumorigenic uroepithelial cells. The number of EVs expressing CEACAM1, 5, and 6 proteins (CEACAMs+EVs) was significantly increased in UCB (Mean9.5%±SD14%), non-bladder cancer (0.69±0.46), and healthy (0.37±0.31) by flow cytometry. The results of ROC analysis showed a good score of AUC=0.929. A provisional CEACAMs+EVs cutoff % was established with a sensitivity of 83% and specificity of 98%. Here, seven out of nine cases of negative urine cytology (class 2) were determined to be positive. Conclusions: The presence of CEA antigen in the urine of patients with bladder cancer is known, but it has not yet been practically used for diagnosis. We have discovered EVs that specifically express these antigens and have obtained useful diagnostic performance. EVs expressing CEACAM proteins in urine are expecting target as a new liquid biopsy for UCB patients. Citation Format: Ko Igami, Takeshi Uchiumi, Masaki Shiota, Saori Ueda, Masatoshi Eto, Dongchon Kang. Extracellular vesicles expressing CEACAM proteins in the urine of bladder cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5104.