Evaluation of novel cathepsin-X inhibitors in vitro and in vivo and their ability to improve cathepsin-B-directed antitumor therapy

Abstract

New therapeutic targets that could improve current antitumor therapy and overcome cancer resistance are urgently needed. Promising candidates are lysosomal cysteine cathepsins, proteolytical enzymes involved in various critical steps during cancer progression. Among them, cathepsin X, which acts solely as a carboxypeptidase, has received much attention. Our results indicate that the triazole-based selective reversible inhibitor of cathepsin X named Z9 (1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-2-((4-isopropyl-4H-1,2,4-triazol-3-yl)thio)ethan-1-one) significantly reduces tumor progression, both in vitro in cell-based functional assays and in vivo in two independent tumor mouse models: the FVB/PyMT transgenic and MMTV-PyMT orthotopic breast cancer mouse models. One of the mechanisms by which cathepsin X contributes to cancer progression is the compensation of cathepsin-B activity loss. Our results confirm that cathepsin-B inhibition is compensated by an increase in cathepsin X activity and protein levels. Furthermore, the simultaneous inhibition of both cathepsins B and X with potent, selective, reversible inhibitors exerted a synergistic effect in impairing processes of tumor progression in in vitro cell-based assays of tumor cell migration and spheroid growth. Taken together, our data demonstrate that Z9 impairs tumor progression both in vitro and in vivo and can be used in combination with other peptidase inhibitors as an innovative approach to overcome resistance to antipeptidase therapy.

Cathepsin X is a conserved cell death protein involved in algal response to environmental stress

“…Cathepsins are a conserved protein family found across eukaryotes, and they are involved in protein cleavage in a wide variety of pathways such as proteolytic activity within lysosomes, signaling pathways, immunity, and in different types of PCD in plants and animals 48–52 . Among the family of cathepsins, CPX was studied mainly in mammalian systems in the context of various diseases 53–55 , while its function and roles in algae and in other protists remain completely unknown. Since other cathepsin types were shown to be involved in PCD in plants and animals 48–52 , we chose to study its role in the response to oxidative stress and PCD induction in C. reinhardtii and P. tricornutum .…”

“…Among the family of cathepsins, CPX was studied mainly in mammalian systems in the context of various diseases [53][54][55] , while its function and roles in algae and in other protists remain completely unknown. Since other cathepsin types were shown to be involved in PCD in plants and animals [48][49][50][51][52] , we chose to study its role in the response to oxidative stress and PCD induction in C. reinhardtii and P. tricornutum.…”

Melatonin alleviates chronic stress-induced hippocampal microglia pyroptosis and subsequent depression-like behaviors by inhibiting Cathepsin B/NLRP3 signaling pathway in rats

“…The CRS procedure in detail was executed as our previously reported [ 28 , 29 ]. The dosage and use of MT [ 30 ], VX-765 [ 31 ], Pazopanib [ 31 ], Nitroxoline [ 32 ], and MCC950 [ 33 ] were determined based on previous studies. The investigators were blinded to the group allocation during the experiment.…”

Cathepsin B in programmed cell death machinery: mechanisms of execution and regulatory pathways

“…However, the ideal inhibitor of CatB with good cell permeability, selectivity, efficacy and safety is yet to be developed. Furthermore, due to the compensatory mechanism between other cysteine cathepsins (such as CatX) and CatB observed in cancer and inflammation, long-term use of CatB inhibitors may not prove to be effective in clinical treatment [ 60 , 109 ].…”