Projects / Programmes source: ARIS

Cathepsin X inhibitors impair the resistence of tumor cells to antiprotease therapy

Research activity

Code Science Field Subfield
4.06.01  Biotechnical sciences  Biotechnology  Recombinant DNA technology 

Code Science Field
B000  Biomedical sciences   

Code Science Field
3.04  Medical and Health Sciences  Medical biotechnology 
Cathepsin, Inhibitor, Cancer, Therapy, Tumor resistance, Invasion, Migration, Signaling
Evaluation (rules)
source: COBISS
Researchers (24)
no. Code Name and surname Research area Role Period No. of publicationsNo. of publications
1.  53738  PhD Krištof Bozovičar  Pharmacy  Researcher  2019 - 2020  30 
2.  35354  PhD Andreja Brožič  Oncology  Researcher  2017 - 2020  40 
3.  33315  PhD Miha Butinar  Biology  Researcher  2017 - 2019  60 
4.  14575  PhD Maja Čemažar  Oncology  Researcher  2017 - 2020  1,410 
5.  53393  Eva Erzar  Medical sciences  Researcher  2019 - 2020 
6.  15284  PhD Stanislav Gobec  Pharmacy  Researcher  2017 - 2020  827 
7.  39198  PhD Tanja Jakoš  Biotechnology  Junior researcher  2017 - 2020  29 
8.  36438  PhD Damijan Knez  Pharmacy  Researcher  2017 - 2019  194 
9.  04648  PhD Janko Kos  Biotechnical sciences  Head  2017 - 2020  1,154 
10.  53777  Mateja Matjaž    Technical associate  2020 
11.  36440  PhD Ana Mitrović  Pharmacy  Researcher  2017 - 2018  106 
12.  38774  Maša Močnik Roner    Technical associate  2017 - 2019 
13.  19170  PhD Urša Pečar Fonović  Pharmacy  Researcher  2017 - 2020  144 
14.  29966  Dejan Pelko    Technical associate  2017 - 2020 
15.  36596  PhD Milica Perišić Nanut  Biotechnical sciences  Researcher  2017 - 2020  141 
16.  32035  PhD Anja Pišlar  Biotechnology  Researcher  2017 - 2020  162 
17.  51651  PhD Tina Vida Plavec  Biotechnology  Junior researcher  2018 - 2020  51 
18.  37481  PhD Mateja Prunk  Biotechnology  Researcher  2017 - 2020  53 
19.  23576  PhD Jerica Sabotič  Biochemistry and molecular biology  Researcher  2017 - 2020  315 
20.  51713  PhD Emanuela Senjor  Biotechnology  Junior researcher  2018 - 2020  49 
21.  08800  PhD Gregor Serša  Oncology  Researcher  2017 - 2020  1,495 
22.  15600  Maja Šimaga    Technical associate  2017 - 2020 
23.  21619  PhD Olga Vasiljeva  Oncology  Researcher  2017 - 2020  183 
24.  52419  PhD Abida Zahirović  Biotechnology  Researcher  2018 - 2020  36 
Organisations (3)
no. Code Research organisation City Registration number No. of publicationsNo. of publications
1.  0106  Jožef Stefan Institute  Ljubljana  5051606000  90,038 
2.  0302  Institute of Oncology Ljubljana  Ljubljana  5055733000  15,390 
3.  0787  University of Ljubljana, Faculty of Pharmacy  Ljubljana  1626973  17,536 
The progression of malignant diseases is associated with excessive activity of the proteolytic enzymes involved in tumor growth, angiogenesis, migration, invasion and metastasis. Among them is a group of cysteine cathepsins that are present in normal cells in endosomes and lysosomes and are responsible for intracellular protein catabolism. In tumor cells these enzymes undergo various changes regarding their expression, activity and localization. Cathepsin B has appeared as the most important tumor promoter. In lysosomes it acts predominantly as an exopeptidase (carboxypeptidase) involved in protein catabolism and autophagy, whereas in tumors, with increased endopeptidase activity, it is responsible for degrading proteins of the extracellular matrix (ECM). Cathepsin B is overexpressed in practically all tumor types and inhibition of its endopeptidase activity has frequently been reported to reduce tumor growth and metastasis in animal cancer models. In recent years, several specific inhibitors of cathepsin B with favorable pharmacological properties have been developed and become candidates for clinical testing. They provide very potent antitumor effects although, after a time, their effectiveness is reduced. We and others have recently found that the main factor of this resistance is delayed over-expression of a similar proteolytic enzyme, cathepsin X. Like cathepsin B, cathepsin X also acts as a carboxypeptidase. However, in tumors it does not switch to endopeptidase activity to degrade the ECM but enhances tumor cell migration and invasion by alternative mechanisms, predominantly through the regulation of integrin receptors and tumor suppressor protein profilin 1. Its higher expression and activity is therefore associated with the renewed ability of tumor cells to migrate and invade, although in this case without degradation of the ECM. Our hypothesis is that inhibitors of cathepsin X may decrease the resistance of tumor cells to anti-peptidase therapy, in particular to therapy with inhibitors of cathepsin B. In the proposed research project we will obtain inhibitors of cathepsin X that will be: i) small molecules that bind reversibly and tightly to cathepsin X, ii) specific for cathepsin X and iii) water-soluble and non-toxic for mammalian cells. The signaling pathways leading to induced overexpression of Cat X as a resistance factor in anti-protease therapy will also be determined, in this way identifying additional targets whose regulation could impair the resistance. New inhibitors will be evaluated in in vitro and in vivo models of tumor migration, invasion, angiogenesis and metastasis, in combination with known inhibitors of cathepsin B and other peptidase inhibitors. The new compounds will be prepared using advanced methods of structure based drug design and synthesis, virtual screening of compound libraries and enzyme kinetics. The structures with the best binding score will be synthesized, purified, and characterized. Formulations that will enable further in vitro and in vivo testing will be developed. Selected compounds will be evaluated in in vitro models of tumor adhesion, migration, invasion and angiogenesis that resemble pathological processes of tumor progression. Moreover, new inhibitors of cathepsin X will be tested in vivo in the mouse models of tumor growth and metastasis that we developed earlier for evaluation of the efficacy of the inhibitors of cathepsin B and other cysteine proteases. They include C57Bl/6 mice and LPB-1 tumor cells in the model of mouse fibrosarcoma, and FVB/N mice tumor cells and their transgenic cell line FVB/PyMT in the model of breast cancer. Our work will constitute an innovative approach to the prevention of drug resistance, enable faster translation of existing anti-peptidase tumor therapy into clinical testing, and promise more effective treatment of cancer patients.
Significance for science
Cancer is the second leading cause of death in the developed world. It affects in general the older population and, due to its prolonged lifetime, its incidence is greatly increasing. Today, cancer represents not only a health problem but also a big social and financial burden for society. To control the disease, new approaches are needed, such as the development and application of targeted drugs and therapy regimens tailored for individual patients. Peptidase inhibitors enable specific drug targeting  and cause fewer off-target effects than classical cytostatic drugs. Moreover, compared to other groups of targeted drugs, for example monoclonal antibodies, the inhibitors can be small molecules with significantly better bioavailability for tumor cells and tissues. They are not immunogenic and their production is less expensive. The use of inhibitors of cathepsin X in parallel with those of cathepsin B or other proteolytic enzymes, or the application of dual inhibitors, could improve the effectiveness of anti-protease therapy by decreasing tumor cell resistance. The use of two specific peptidase inhibitors is safer than that of non-specific general ones, since the latter are more likely to affect proteolytic activity which is not associated with malignant processes, causing in this way severe side effects. Besides improving anti-peptidase therapy our results may have an impact on other studies discovering mechanisms leading to drug resistance. They will also add a new insight into the proteolytic redundancy in cancer and into the interconnection of signaling pathways controlling the expression of proteolytic enzymes. Also, the new inhibitors of cathepsin X can be useful in studies of other pathological processes associated with increased cathepsin X activity, such as neurodegeneration.
Significance for the country
In Slovenia and the European Union, biomedicine, pharmacy and biotechnology constitute a leading scientific and economic priority. Despite economic and financial crises, this industrial sector has achieved substantial growth in recent years and the implementation of new products is vital to maintain such growth in the future. The results of the proposed project make possible the development of new products and technologies, which are economically interesting for pharmaceutical companies developing anticancer drugs. They can also serve as a basis for establishing new start-up companies. The results will be important for Slovenian pharmaceutical industry which already produces and sells drugs that are potential inhibitors of cathepsin B. For example, our industry is a leading producer of the antibiotic nitroxoline, recently identified as a powerful cathepsin B inhibitor. Due toits approved safety, its repositioning for cancer treatment could be faster and cheaper, compared to original drugs, in particular if tumor resistance is minimalized by new inhibitors of cathepsin X. The results of this project may therefore add additional value to cathepsin B targeted anti-tumor drugs, foster their registration and increase the economic impact. Furthermore, they are relevant for the international business recognition and integration of Slovenia into worldwide pharmaceutical and biotech market.
Most important scientific results Interim report, final report
Most important socioeconomically and culturally relevant results Interim report, final report
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