Size‐Dependent Cellular Uptake of RGD Peptides

Abstract

Monomeric RGD peptides show unspecific fluid‐phase uptake in cells, whereas multimeric RGD peptides are thought to be internalized by integrin‐mediated endocytosis. However, a potential correlation between uptake mechanism and molecular mass has been neglected so far. A dual derivatization of peptide c(RGDw(7Br)K) was performed to investigate this. A fluorescent probe was installed by chemoselective Suzuki–Miyaura cross‐coupling of the 7‐bromotryptophan and a poly(ethylene glycol) (PEG) linker was attached to the lysine residue. Flow cytometry and live cell imaging confirmed unspecific uptake of the small, non‐PEGylated peptide, whereas the PEG5000 peptide conjugate unveiled a selective internalization by M21 cells overexpressing αvβ3 and no uptake in αv‐deficient M21L cells.

Synthesis and Evaluation of a Non-Peptide Small-Molecule Drug Conjugate Targeting Integrin αVβ3

“…Low TI values may also be associated with non-receptor-mediated uptake mechanisms. The size-dependent cellular uptake ( Kemker et al, 2019 ) could be an explanation for this behavior because of the relatively low molecular mass of the conjugates 16-18 . It was also previously reported that a integrin α V β 3 -addressing cRGDfK-carboxyfluorescein conjugate was taken up by integrin-positive and integrin-negative cell lines with the assumption of a fluid-phase uptake ( Borbély et al, 2019a ).…”

Influence of Linker Molecules in Hexavalent RGD Peptides on Their Multivalent Interactions with Integrin αvβ3

“…One possible explanation for this result is the involvement of internalization. 27 Once the radioligand-receptor complex is internalized into cells, the dissociation kinetics of radioactivity from the cells would be completely different. Although we did not investigate the degree of internalization in this study, the influence of linker molecules on the internalization process is worth investigating and the subject of our future study.…”

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

“…Besides addressing the indole C 2 , the regioselective enzymatic halogenation at C5, C6, or C7 using FAD-dependent tryptophan halogenases opens a broad area of Pd-catalysed late-stage diversifications [53][54][55]. It has been proven that Pd-catalysed cross-couplings are very versatile tools for selective and bio-orthogonal modifications of haloindoles, halotryptophans and halotryptophan-containing peptides as well as natural products [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70]. Additionally, halotryptophans were incorporated in pentapeptides as building blocks for macrocyclisation by Suzuki-Miyaura cross-coupling (SMC) aiming at the preparation of bicyclic peptides [71].…”