Blockade of Asparagine Endopeptidase Inhibits Cancer Metastasis

Abstract

Asparagine endopeptidase (AEP), also called legumain, is highly expressed in various solid tumors, promoting cancer cell invasion, migration, and metastasis. It has been proposed to be a prognostic marker and therapeutic target for cancer treatment. However, an effective nonpeptide, smallmolecule inhibitor against this protease has not yet been identified. Here we show that a family of xanthine derivatives selectively inhibit AEP and suppress matrix metalloproteinase (MMP) cleavage, leading to the inhibition of cancer metastasis. Through structure–activity relationship (SAR) analysis, we obtained an optimized lead compound (38u) that represses breast cancer invasion and migration. Chronic treatment of nude mice, which had been inoculated with MDA-MB-231 cells, with inhibitor 38u via oral administration robustly inhibits breast cancer lung metastasis in a dose-dependent manner, associated with blockade of MMP-2 by AEP. Therefore, our study supports that 38u might act as a potent and specific AEP inhibitor useful for cancer treatment.

Lansoprazole inhibits the cysteine protease legumain by binding to the active site

“…56,57 Additionally, inhibition of legumain was reported to reduce cancer metastasis. 58 These findings and the results of the present report support the hypothesis that PPIs could halt or slow down cancer development and migration by directly inhibiting cysteine proteases in the tumour or its micro-environment.…”

“…A similar effect on cathepsin B suggests that lansoprazole exerts a class effect on cysteine proteases, proteolytic enzymes with ubiquitous expression and multiple functions. This effect should be taken into consideration not only in relation to off‐target adverse effects by PPIs but also in a drug repositioning strategy where the inhibition of cancer cells by PPIs shows promising results …”

“…This effect should be taken into consideration not only in relation to off-target adverse effects by PPIs but also in a drug repositioning strategy where the inhibition of cancer cells by PPIs shows promising results. 6,58…”

Linear versus Branched Peptide with Same Amino Acid Sequence for Legumain‐Targeting in Macrophages: Targeting Efficiency and Bioimaging Potential

“…The fluorescence from the cells conform to the flow cytometry results: the maximum red fluorescence is observed for RAW 264.7 cells followed by moderate fluorescence from MDA MB 231 cells, and no fluorescence from 4T1 cells (Figure S2). The lower fluorescence observed for MDA MB 231 cells suggests lower legumain activity, in agreement with previous work . The red APC fluorescence is denser in the LLTP treated cells compared to that in the YLTP treated cells.…”

A protease‐responsive fluorescent probe for sensitive imaging of legumain activity in living tumor cells

“…In particular, fluorescent probes have attracted much attention due to their advantages of real‐time imaging and high spatial resolution. It also has extensive applications in molecular imaging (Qiu et al., ; Shi et al., ; Zheng et al., ), disease diagnosis (Chen et al., ; Luo et al., ), and drug development (Liu, Bajjuri, Liu, & Sinha, ; Qi et al., ). Among them, enzyme‐activated fluorescent probes have become the focus of recent research studies, because they can provide accurate information about the enzyme activity and show potential in disease diagnosis (Chen et al., ; Hai et al., ; Luo et al., ; Shaulov‐Rotem et al., ).…”