Experimental Study On The Targeting Property Of Bladder Cancer Cell Line BIU-87 Tumor Homing Peptide NYZL1

Objective:To identify the targeting property of NYZL1, a bladder cancer cell line BIU-87 tumor homing peptide which was obtained by using in vivo phage display, through in vivo and in vitro testing technology. Methods:The peptide NYZL1 and its control peptide sv NYZL1 were synthesized by solid-phase peptide synthesis using Fmoc chemistry. Fluorescein-conjugated peptides were also synthesized. Probes were added to the bladder cancer BIU- 87 cell suspensions and incubated for the appropriate times. We detected the fluorescence intensity values using the Flow cytometry(FCM) to identify the affinity of probes. BIU- 87 cells incubating with probes, the image of cells was observed by laser confocal microscope(LSCM) which could illustrate the affinity and specificity by detecting the fluorescent images of probes and cells. We established sixteen bladder cancer BIU- 87 cells xenograft models which were randomly divided into 2 groups( n=8 each) and then injected experimental and control probes intravenously. Probes circulating for 4 h, we excised tumors and control organs, such as heart, liver, spleen, lung, kidney, bladder and cholecyst from 5 models of each group to analyze targeting ability of probes by using optical molecular imaging system. After 24 h, frozen sections of tumors and control organs were prepared and examined for fluorescence by LSCM to explore the targeting ability and specificity of probes by detecting the fluorescent images of tumors and control organs. Results:1. The Fluorescein-conjugated peptides of NYZL1 was FITC-aminocaproic acid-CSSPIGRHC(FITC-NYZL1), and its control probe was FITC-aminocaproic acid-CRIGSPHSC(FITC-sv NYZL1).2. FCM study has shown that the average fluorescence intensity values of probes labeled BIU-87 cells were 50.34±3.63 and 17.72±1.57, respectively. According to LSCM images, the green fluorescence was observed in experimental group, rather than control group. And the average fluorescence intensity values of FITC were 864.41±188.47 and 53.57±17.50, respectively.3. Optical molecular imaging system study has demonstrated that the green fluorescence was obviously observed in tumor tissues, bladder and cholecyst; however, control organs, such as heart, liver, spleen, lung and kidney were not. LSCM study has shown that the green fluorescence was observed in tumor tissues of experimental group; however, other organs of experimental group and organs of control group were not. Conclusions:The bladder cancer tumor homing peptide NYZL1 can specifically bound to bladder cancer BIU-87 cells and its xenografts and label tumors by fluorescein. It might be a useful targeted vector for diagnosis and treatment of bladder cancer.