BACKGROUND: Neurotensin receptors are overexpressed in several cancer types including pancreatic ductal adenocarcinoma. Three NTR subtypes have been cloned: NTR-1, NTR-2 and NTR-3. The most expressed NTR-1 is not present in normal pancreatic tissue and has a low expression in chronic pancreatitis. OBJECTIVE: Objective of this study was to test in vitro affinity of the new 68Ga labelled neurotensin analogue DOTA-NT-20.3 (fragment 6-13, Ac-Lys(DOTA)-Pro-Arg(N-CH3)-Arg-Pro-Tyr-Tle-Leu) on the human pancreatic ductal adenocarcinoma cell line AsPC-1. METHOD: For the preparation of 68Ga-DOTA-NT-20.3, 68GaCl3 solution (eluted from 68Ge/68Ga generator) and 50 μg of precursor (Iason, Graz, Austria) water dissolved were used in an automatic synthesis module. The labeled compound was added to cell culture flask and incubated at 37°C. At various time points after tracer addition up to 80min, cells were recovered, rinsed and counted for radioactivity. Results were expressed as percent binding normalized to 200000 cells and affinity parameters were calculated. RESULTS: Labeling yield was ≥98 %. The molar ratio between labelled and total peptide was about 1/400. AsPC-1 cell line showed rapid uptake of the tracer including surface and internalized binding, tending to a plateau phase 80 min after tracer addition (11%/200.000 cells). The Kd (7.335 pmol) and Bmax (90.52 kBq) value indicated high tracer affinity for AsPC-1cell line especially if compared with the literature data regarding other malignancies (e.g. colonic cancer cell line). Binding sites were 1.09x106 sites per cell. CONCLUSION: New tracer 68Ga-DOTA-NT-20.3 can be a suitable candidate for the clinical use in patients with pancreatic ductal adenocarcinoma.
- MeSH
- adenokarcinom metabolismus patologie MeSH
- heterocyklické sloučeniny monocyklické chemie metabolismus MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádory slinivky břišní metabolismus patologie MeSH
- neurotensin agonisté chemie metabolismus MeSH
- peptidové fragmenty chemie metabolismus MeSH
- radioizotopy galia chemie metabolismus MeSH
- receptory neurotensinu metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Somatostatin analogues labelled with radiometals or radiohalogens are useful for the imaging and treatment of somatostatin receptor-containing tumours. In this study, the procedures for the radioiodination of glucose-Tyr3-octreotate (gluc-Tyr3-tate) and radiolabelling of DOTA-Tyr3-octreotate (DOTA-Tyr3-tate) with 111In, 177Lu and 125I were compared and their metabolism in rats was analyzed. The usefulness of high performance liquid chromatography (HPLC) analysis and instant thin-layer chromatography on silica gel (ITLC-SG) for both radiochemical purity determination and analysis of metabolism in urine was investigated. MATERIALS AND METHODs: For labelling with radiometals, the formation of a complex with the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) functionality of the peptide was employed. Radioiodination was performed by the chloramime-T method. The radiochemical purity of radiolabelled peptides and the analyses of rat urine were determined by HPLC and/or ITLC-SG methods. Male Wistar rats were used in the elimination studies. RESULTS: DOTA-Tyr3-tate was simply radiolabelled with radiometals with high yield and high radiochemical purity. Stopping of the reaction was a critical step for radioiodination, therefore labelling of gluc-Tyr3-tate and DOTA-Tyr3-tate with 125I was not so simple and the reaction product had to be purified by preparative HPLC analysis. Whereas 111In-DOTA-Tyr3-tate and 177Lu-DOTA-Tyr3-tate were eliminated in rat urine in a practically unchanged form, a significant proportion of metabolites was observed with radioiodinated peptides, particularly at longer time intervals. CONCLUSION: Labelling of DOTA-Tyr3-tate with radiometals is simple and the radiochemical purity of prepared compounds is very high, while iodination of the peptides demands purification of the product by preparative HPLC. The analysis of rat urine showed that excretion of radioiodinated peptides included a significant proportion of metabolites.
- MeSH
- cyklické peptidy chemie metabolismus MeSH
- financování organizované MeSH
- glukosa analogy a deriváty metabolismus MeSH
- heterocyklické sloučeniny monocyklické chemie metabolismus MeSH
- izotopové značení MeSH
- krevní proteiny metabolismus MeSH
- krysa rodu rattus MeSH
- lutecium chemie MeSH
- potkani Wistar MeSH
- radiofarmaka chemická syntéza metabolismus MeSH
- radioizotopy india chemie MeSH
- radioizotopy jodu chemie MeSH
- radionuklidy chemie MeSH
- vazba proteinů MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
