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

Jannik Paulus, Norbert Sewald

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

An integrin αVβ3-targeting linear RGD mimetic containing a small-molecule drug conjugate (SMDC) was synthesized by combining the antimitotic agent monomethyl auristatin E (MMAE), an enzymatically cleavable Val-Ala-PABC linker with a linear conjugable RGD mimetic. The structure proposal for the conjugable RGD mimetic was suggested upon the DAD mapping analysis of a previously synthesized small-molecule RGD mimetic array based on a tyrosine scaffold. Therefore, a diversifying strategy was developed as well as a novel method for the partial hydrogenation of pyrimidines in the presence of the hydrogenolytically cleavable Cbz group. The small-molecule RGD mimetics were evaluated in an ELISA-like assay, and the structural relationships were analyzed by DAD mapping revealing activity differences induced by structural changes as visualized in dependence on special structural motifs. This provided a lead structure for generation of an SMDC containing the antimitotic drug MMAE. The resulting SMDC containing a linear RGD mimetic was tested in a cell adhesion and an in vitro cell viability assay in comparison to reference SMDCs containing cRGDfK or cRADfK as the homing device. The linear RGD SMDC and the cRGDfK SMDC inhibited adhesion of αVβ3-positive WM115 cells to vitronectin with IC50 values in the low µM range, while no effect was observed for the αVβ3-negative M21-L cell line. The cRADfK SMDC used as a negative control was about 30-fold less active in the cell adhesion assay than the cRGDfK SMDC. Conversely, both the linear RGD SMDC and the cRGDfK SMDC are about 55-fold less cytotoxic than MMAE against the αVβ3-positive WM115 cell line with IC50 values in the nM range, while the cRADfK SMDC is 150-fold less cytotoxic than MMAE. Hence, integrin binding also influences the antiproliferative activity giving a targeting index of 2.8.
Original languageEnglish
Article number869639
JournalFrontiers in Chemistry
Volume10
DOIs
Publication statusPublished - 11 Apr 2022
Externally publishedYes

Funding

The authors thank Beate Nachtigall and Lennard Karsten for their support in the flow cytometry experiments and Carmela Michalek for performing the cell adhesion and cell viability assays. We acknowledge the financial support from the German Research Foundation (DFG) and the Open Access Publication Fund of Bielefeld University for the article processing charge.

FundersFunder number
Deutsche Forschungsgemeinschaft
Universität Bielefeld

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