¹⁷⁷Lu-DTPA-BIS-BIOTIN Binding of Octreotide-dextran-avidinated PANC-1 Cell Lines in Vitro

Tyr3-octreotide, dextran-40 and avidin were used to prepare octreotide-dextran-avidin (TOC-Dx⁴⁰-Av). DTPA-BIS-BIOTIN was labelled with ¹⁷⁷Lu. The in vitro somatostatin receptor binding study was carried out by pretargeted method using TOC-Dx⁴⁰-Av and ¹⁷⁷Lu-DTPA-BIS-BIOTIN. The 24 well cell culture plates were prepared with PANC-1 cell monolayer and then incubated with TOC-Dx⁴⁰-Av. After two washed with PBS, the cells were incubated with different concentration of ¹⁷⁷Lu-DTPA-BIS-BIOTIN(48.8～391 pmol).Cells uptake was evaluated with γ counter. The results showed that the chemical purity of TOC-Dx⁴⁰-Av was over 99%. The results also showed that TOC-Dx⁴⁰-Av remained high receptor binding affinity to somatostatin receptor which indicated that TOC-Dx⁴⁰-Av could bind to ¹⁷⁷Lu-DTPA-BIS-BIOTIN with the molar ratio of 1∶1 on the cell surface.