Novel Application of Cell Penetrating R11 Peptide for Diagnosis of Bladder Cancer

OBJECTIVE: As a novel cell-permeable peptide, polyarginine (R11) showed great potential as contrast agent to target bladder cancer (BCa) for therapeutic applications. However, its diagnostic ability and uptake efficiency between BCa and normal bladder tissues is unknown. In this study, we investigated the feasibility of R11 conjugated with fluorescein isothiocyanate (FITC-R11) for detecting BCa in clinical practice. METHOD: FITC-R11 was synthesized and incubated with BCa cell lines (T24, 5637, RT4), normal immortalized human bladder epithelial cell line (SVHUC) and clinical specimens from BCa and benign prostate hyperplasia patients. The uptake efficiency was determined by the mean values of relative FITC intensity. Furthermore, FITC-R11 was intravesically injected into the athymic nude mice bearing orthotopic T24-t tumors and pulmonary metastasis of bladder tumor mice models, the fluorescence intensity of bladder tumors and normal bladder tissues was examined, as well as lung tissues. RESULT: After incubation with FITC-R11, the fluorescence intensity of T24, 5637, RT4 and SVHUC cell line was 64678.56 ± 9699.27, 46456.22 ± 2588.06, 33802.02 ± 429.72 and 17785.01 ± 1704.36, respectively (P < 0.05). In the athymic nude mice bearing orthotopic T24-t tumors, FITC-R11 showed elevated accumulation in the bladder tumors compared with normal bladder tissues, FITC-R11 was also accumulated in the lung of pulmonary metastasis mice. Moreover, the uptake efficiency of FITC-R11 in patients' BCa tissues was much higher than in normal bladder tissues (6441.95 vs. 1196.92, P < 0.05), as well as the urine samples of BCa patients and benign prostate hyperplasia patients (30250.37 vs. 4948.42, P < 0.05). CONCLUSION: As compared with normal bladder tissue, FITC-R11 is a more specific molecular probe for BCa, and has the potential application in clinical practice.