Synthesis and evaluation of a bimodal CXCR4 antagonistic peptide

Abstract

The antagonistic Ac-TZ14011 peptide, which binds to the chemokine receptor 4, has been labeled with a multifunctional single attachment point reagent that contains a DTPA chelate and a fluorescent dye with Cy5.5 spectral properties. Flow cytometry and confocal microscopy showed that the bimodal labeled peptide gave a specific receptor binding that is similar to monofunctionalized peptide derivatives. Therefore, the newly developed bimodal peptide derivative can be used in multimodal imaging applications.

Figure 1

Conjugation of the MSAP label (2) to Ac-TZ14011 (1) and subsequent indium labeling.

Figure 2

Flow cytometry analysis of the constructs 3 and 4 using (A) MDAMB231 cells or (B) MDAMB231^CXCR4+ cells. Both graphs present untreated cells (trace filled with grey), 1 µM of 3 (black trace) and 1 µM of 4 (grey trace).

Figure 3

(A) Determination of affinity of constructs 3 and 4 with saturation binding experiments. (B) Competition experiments with three other Ac-TZ14011 peptides in the presence of 250 nM of 3. (C) Structures of the peptides used for competition experiments.

Figure 4

Confocal microscopy of peptide 3 using MDAMB231^CXCR4+ cells.