Synthesis, Radiosynthesis And Metabolism Of I-131-Y-C(Cgrraggsc)

Background: The formation of the complex interleukin-11(IL-11) and IL-11 receptor (IL-11R) is closely related with tumor progression. Binding of IL-11 to the IL-11 receptor alpha-chain (IL-11R alpha) has been suggested as a target for human cancer. The cyclic peptide c(CGRRAGGSC) is a mimic of IL-11.Objective: To explore I-131-Y-c(CGRRAGGSC) synthesis and radiosynthesis, and metabolism in SKOV3 tumor-bearing mice.Method: In this study, I-131 labeled c(CGRRAGGSC) was designed and characterized. For radiolabeling, tyrosine was used as a linker to connect c(CGRRAGGSC) and I-131. Balb/c nude mice bearing SKOV3 human ovarian carcinoma were used for in vivo studies. Uptake of I-131-cyclic nonapeptide by the tumor was visualized by single photon emission computerized tomography (SPECT).Results: The entire labeling process, which took 15 min by chloramine-T method, resulted in a high labeling yield (93.03 +/- 6.78%), and high radiochemical purity (RCP) (>95%). SPECT imaging showed that accumulation of the probe in the tumor was close to background levels. In addition, biodistribution studies showed that the accumulation of I-131-Y-c(CGRRAGGSC) in normal mice was similar to that of (NaI)-I-131.Conclusion: Tyrosine is a suitable chelating agent for the use of radioiodine labeling, however the bioactivity of the conjugate needs further investigation.