Woo Hyoung Kim

Novel Tc-99m labeled ELR-containing 6-mer peptides for tumor imaging in epidermoid carcinoma xenografts model: a pilot study

ObjectiveELR-containing peptides targeting CXCR2 could be the excellent candidate for targeting ligand of molecular tumor imaging. In this study, we had developed two ELR-containing 6-mer peptides and evaluated the diagnostic performance of Tc-99m labeled 6-mer peptides as a molecular imaging agent in murine models bearing KB epidermoid carcinoma.MethodsPeptides were synthesized using Fmoc solid phase peptide synthesis. Radiolabeling efficiency with Tc-99m was evaluated using instant thin-layer chromatography. In KB epidermoid cancer-bearing mice, gamma images had acquired and tumor-to-muscle uptake ratio was calculated. Competition and biodistribution studies had performed.ResultsTwo 6-mer peptides, ELR-ECG and ECG-ELR were successfully synthesized. After radiolabeling procedures with Tc-99m, the complex Tc-99m ELR-ECG and Tc-99m ECG-ELR were prepared in high yield. In the gamma camera imaging of murine model, Tc-99m ELR-ECG was substantially accumulated in the subcutaneously engrafted tumor and tumor uptake had been suppressed by the free ELR co-injection. However, Tc-99m ECG-ELR was minimally accumulated in the tumor.ConclusionsTwo ELR-containing 6-mer peptides, ELR-ECG and ECG-ELR, were developed as a molecular imaging agent to target CXCR2 of epidermoid carcinoma. Tc-99m ELR-ECG had showed significant uptake in tumor and it was good candidate for a tumor imaging.

Synthesis and evaluation of Tc-99m-labeled RRL-containing peptide as a non-invasive tumor imaging agent in a mouse fibrosarcoma model.

ObjectiveArginine–arginine–leucine (RRL) is considered a tumor endothelial cell-specific binding sequence. RRL-containing peptide targeting tumor vessels is an excellent candidate for tumor imaging. In this study, we developed RRL-containing hexapeptides and evaluated their feasibility as a tumor imaging agent in a HT-1080 fibrosarcoma-bearing murine model.MethodsThe hexapeptide, glutamic acid–cysteine–glycine (ECG)–RRL was synthesized using Fmoc solid-phase peptide synthesis. Radiolabeling efficiency was evaluated using instant thin-layer chromatography. Uptake of Tc-99m ECG–RRL within HT-1080 cells was evaluated in vitro by confocal microscopy and cellular binding affinity was calculated. Gamma images were acquired In HT-1080 fibrosarcoma tumor-bearing mice, and the tumor-to-muscle uptake ratio was calculated. The inflammatory-to-normal muscle uptake ratio was also calculated in an inflammation mouse model. A biodistribution study was performed to calculate %ID/g.ResultsA high yield of Tc-99m ECG–RRL complexes was prepared after Tc-99m radiolabeling. Binding of Tc-99m ECG–RRL to tumor cells had was confirmed by in vitro studies. Gamma camera imaging in the murine model showed that Tc-99m ECG–RRL accumulated substantially in the subcutaneously engrafted tumor and that tumoral uptake was blocked by co-injecting excess RRL. Moreover, Tc-99m ECG–RRL accumulated minimally in inflammatory lesions.ConclusionsWe successfully developed Tc-99m ECG–RRL as a new tumor imaging candidate. Specific tumoral uptake of Tc-99m ECG–RRL was evaluated both in vitro and in vivo, and it was determined to be a good tumor imaging candidate. Additionally, Tc-99m ECG–RRL effectively distinguished between cancerous tissue and inflammatory lesions.

Effect of 18F-FDG Administration on Measurements of Bone Mineral Density and Body Composition by Dual-Energy X-ray Absorptiometry

The purpose of this study was to determine whether antecedent administration of ¹⁸F-fluorodeoxyglucose (FDG) used in positron emission tomography (PET) scanning results in corruption of bone mineral density (BMD) and body composition measured by dual-energy X-ray absorptiometry (DXA) system. DXA measurements of BMD and body composition had been performed twice, before and after ¹⁸F-FDG PET scan in 30 patients. The comparison of pre-values and post-values of all BMD values showed a decrease after the injection. However, only the decrease of whole-body BMD (WB-BMD) was statistically significant (p < 0.05). Whole-body fat mass had increased and whole-body lean body mass had decreased after the injection of ¹⁸F-FDG, and these were statistically significant (p < 0.05). There is statistically significant correlation between the injected ¹⁸F-FDG dose and a decrease of WB-BMD (r = -0.405; p < 0.05). The findings of this study suggest that when both ¹⁸F-FDG PET and DXA measurements for whole-body composition are performed in close-time proximity, ¹⁸F-FDG PET scans should follow the DXA measurement. Otherwise, BMD measurements of total femur or lumbar spine could be followed by ¹⁸F-FDG PET in close-time proximity.