Projects / Programmes
Optimization of nitroxoline-based inhibitors of cathepsin B as potential drugs for the treatment of cancer
| Code |
Science |
Field |
Subfield |
| 1.09.00 |
Natural sciences and mathematics |
Pharmacy |
|
| Code |
Science |
Field |
| B740 |
Biomedical sciences |
Pharmacological sciences, pharmacognosy, pharmacy, toxicology |
| Code |
Science |
Field |
| 3.01 |
Medical and Health Sciences |
Basic medicine |
drug discovery, cancer, antitumour drugs, cathepsin B, nitroxoline, structure-based design, innovative approach, reversible covalent inhibitors
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
30816 |
PhD Izidor Sosič |
Pharmacy |
Head |
2016 - 2017 |
251 |
Organisations (1)
Abstract
Human cathepsin B is a lysosomal cysteine protease that has many house-keeping functions, such as intracellular proteolysis. It can act as both an endopeptidase and an exopeptidase, a characteristic that is attributed to a 21-amino-acid insertion above the active site. Dysregulation of cathepsin B activity is associated with many pathological states. The most thoroughly studied is its involvement in cancer, where its essential role in the proteolytic processes that lead to tumour invasion and metastasis has been established. Metastatic progression still remains the biggest challenge in the development of effective therapies for the treatment of cancer. With respect to the important pharmacological relevance of cathepsin B, the discovery of new small-molecule inhibitors that can bind selectively and reversibly into its active site needs to be given substantial emphasis. However, none of the currently identified cathepsin B inhibitors are in clinical use, due to poor bioavailability, off-target effects, and high toxicity. The reasons for this are associated with the chemical nature of these compounds, as they contain a peptide backbone and a highly reactive electrophilic functional group that interacts with the catalytic cysteine and irreversibly inactivates the enzyme.
Recently, we discovered that nitroxoline (5-nitro-8-hydroxyquinoline) is a non-covalent, reversible, low-micromolar inhibitor of cathepsin B. Its applicability was demonstrated in cell-based assays and in in vivo models. The new mechanism of cysteine protease inhibition and the resolved nitroxoline-cathepsin B co-crystal structure represent a template for the rational structure-based improvement of the inhibitory activities of novel cathepsin B inhibitors. It is known that more potent lead compounds in vitro have greater potential to be successfully developed into clinical candidates, and subsequently into drugs that achieve their therapeutic effects at the correct doses.
The ultimate goals of the Project are: (i) to design, develop and synthesise nitroxoline derivatives with optimised pharmacodynamic properties; (ii) to optimise the pharmacokinetic (ADME) properties of new inhibitors; and (iii) to determine the effects of cathepsin B inhibition on the reduction of tumour progression processes in in vitro and in vivo models. To achieve these goals, the PI will initially use computer-aided structure-based design. Using this approach, the essential structural elements required for enhanced biological activity will be predicted (i.e., appropriate side chains, functional groups). Special focus will be addressed to a correctly positioned functional group in the molecule that can form reversible covalent interactions with the catalytic cysteine in the cathepsin B active site. As it is known that the ADME (i.e., absorption, distribution, metabolism, excretion) parameters are equally relevant to potency in lead compound optimisation, the appropriate physico-chemical properties of new compounds will be continually monitored during the design process. Based on all assembled information, the appropriate nitroxoline derivatives will be synthesised.
Selective cathepsin B inhibitors developed within the Project will be optimised in terms of their pharmacodynamic and pharmacokinetic properties. Finally, the influence of efficient cathepsin B inhibition by the prepared compounds on in vitro and in vivo anti-tumour activity will be experimentally established through comprehensive biochemical and biological evaluations. In this way, we will be able to determine the full therapeutic potential of cathepsin B inhibition as a cancer treatment approach. Therefore, these advanced lead compounds or clinical candidates will be of paramount scientific, economical and healthcare importance, as they will serve as a valuable contribution in the permanent battle against cancer.
Significance for science
Cathepsin B still represents an extremely interesting pharmacological target, which is worth taking advantage of in the fight against cancer. Due to a lack of selective and non-peptide molecules that could modulate the activity of cathepsin B, this enzyme remains under-utilized for the time being. There are no clinically relevant inhibitors of cathepsin B, as the vast majority of known inhibitors are of peptide-type. In addition, these compounds possess a highly reactive (electrophilic) functional group in the structure. As a result, these molecules have low bioavailability and many side effects due to non-specific interactions with off-target protein proteins. With the research results obtained during the project, we further confirmed the role of cathepsin B in tumor progression. This represents an important contribution to the identification of new anti-tumor agents that exploit less studied mechanisms of action. In the project, we focused on reversibly acting and non-peptide molecules, which is a more demanding approach in the field of cysteine ??protease inhibitors (this does not apply only for cathepsin B); however, with molecules of this type (i.e., non-peptide), significantly improved pharmacokinetic properties can be achieved, while at the same time avoiding the constraints of currently known peptide-like inhibitors. For derivatives of nitroxoline, we further demonstrated that with the use of structure-based optimization, improved activity on the enzyme can be achieved in comparison with nitroxoline, which has a non-peptide scaffold and represented our starting point. Such research flow is essential in optimizing the hit compound (nitroxoline) to the lead compound. In-depth biochemical tests (cellular level, in vivo testing) have shown very promising results, which represents a clear evidence that we are developing cathepsin B inhibitors in the proper way. An important step towards expanding the pool of active substances with novel anti-tumor mechanisms and thus an innovative approach in the fight against cancer has been achieved. This is very important for the development of this particular filed of science (i.e. the development of cysteine ??protease inhibitors, which includes cathepsin B). Research within the framework of the proposed project included state-of-the-art approaches in the design of new inhibitors. All the approaches that we used for optimization and the results obtained are accessible to the entire global scientific community in the form of manuscripts that we published. I am convinced that our work has further stimulated creative research in the field of cancer treatment with new molecular mechanisms. New scientific cooperations, which began during this post-doctoral project, are of vital importance for further work in this field and development of science in general. We started to collaborate with the Department of Biotechnology at the Institute Jožef Stefan and the Department of Genetic Toxicology and Cancer Biology at the National Institute of Biology. In addition to previous connections within Slovenia and abroad, this is very important for further work in the evaluation of novel cathepsin B inhibitors.
Significance for the country
The pharmaceutical industry in Slovenia has an extremely important socio-economic significance. Therefore, scientific research in the field of clinically relevant compounds (lead compounds and clinical candidates) is a possibility for the domestic pharmaceutical industry to enable sustainable development (in cooperation with strategic partners). With the results of this project, we expanded the existing knowledge and provided solid foundations for the continuation of work in the field of optimization of inhibitors of pharmacologically interesting enzymes, such as cathepsin B. By creating and disseminating innovative knowledge, which was successfully presented in internationally recognized scientific journals (in the form publications) and in the form of presentations at national and international conferences, I indirectly contributed to the Slovenian scientific community, i.e. to keep up with global development and research in the field of the development of cysteine ??protease inhibitors. By disseminating the acquired knowledge to the public in the form of contributions in non-scientific journals, television and radio shows, I enabled the promotion of science in Slovenia; a fact that certainly has positive effects in the long run. As a project manager, I was also in constant contact with undergraduate students, whereby, by knowledge transfer, I was responsible for developing quality human resources and improving the teaching process at the Faculty of Pharmacy. During the project, I strengthened the existing national and international cooperation network, as well as established new interinstitutional cooperation. Close collaboration and research and communication between different research groups enables the transfer of existing and newly acquired knowledge in all directions, which does strengthen Slovenia's scientific reputation in the world. Herein, I would point out that the project team in which I participate managed to obtain and conclude two smaller industry-related projects with the company Lek d.d. Within these these projects, which were purely synthetic and chemical in nature, members of the project team used their chemical knowledge for the complete realization of goals. In addition, the project team also started cooperation with Krka d.d. In this project, new synthetic pathways for the preparation active substance are studied, as well as the preparation of various polymorphs of this molecule. These industry-academia projects show that solving the synthetic problems that we encounter during basic research projects (such as this postdoctoral project) can also be successfully transferred into applicative projects run by the Slovenian pharmaceutical industry.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
