| Summary: |
Cancer is among the leading causes of morbidity and mortality worldwide. The efficacy of the available anticancer chemotherapy remains quite limited, and generally associated with increasing drug resistance and severe side effects. The discovery of new anticancer agents is therefore a major medical priority [1].
The p53, p63 and p73 tumor suppressors are key therapeutic targets in cancer [2-4]. Inactivation of these p53 family proteins by interaction with MDM2 and MDMX, and mutation of p53 are common events in human tumors, leading to two major anticancer therapeutic strategies: inhibition of the MDMs interaction with p53 family proteins, and mutant (mut) p53 reactivation [2-4]. To date, most of the pharmacological efforts have been focused on the p53-MDM2 interaction, with only one small molecule inhibitor of p53-MDMX interaction and three p53-MDM2/MDMX dual interaction inhibitors reported. Inhibitors of p63/p73-MDMs interaction are still mostly unknown [2-4]. The identification of reactivators of mut p53 brought new expectations to the therapy of tumors expressing mut p53 (almost 50% of human tumors) [2,5]. However, for many of the restricted number of available mut p53 reactivators, the molecular mechanism of function is far from being elucidated, and toxic side effects have been reported [2,5]. The discovery of mut p53 oncogenic gain-of-function (GOF), mainly through interaction with transcriptionally active p53 family proteins, led to a new promising anticancer strategy. In fact, the identification of a mut p53-p73 interaction inhibitor with proven antitumor efficacy encouraged the need to clarify this complex network and to search for chemicals able to interfere with it [2,5].
In previous works, we developed innovative targeted screening assays, combining yeast and human tumor cells, which led to the identification of hit small molecule activators of p53 family proteins, namely:
i) Inhibitors of the p53-MDM2 interaction [6-9] (Annex 1);
ii) Dual inh  |
Summary
Cancer is among the leading causes of morbidity and mortality worldwide. The efficacy of the available anticancer chemotherapy remains quite limited, and generally associated with increasing drug resistance and severe side effects. The discovery of new anticancer agents is therefore a major medical priority [1].
The p53, p63 and p73 tumor suppressors are key therapeutic targets in cancer [2-4]. Inactivation of these p53 family proteins by interaction with MDM2 and MDMX, and mutation of p53 are common events in human tumors, leading to two major anticancer therapeutic strategies: inhibition of the MDMs interaction with p53 family proteins, and mutant (mut) p53 reactivation [2-4]. To date, most of the pharmacological efforts have been focused on the p53-MDM2 interaction, with only one small molecule inhibitor of p53-MDMX interaction and three p53-MDM2/MDMX dual interaction inhibitors reported. Inhibitors of p63/p73-MDMs interaction are still mostly unknown [2-4]. The identification of reactivators of mut p53 brought new expectations to the therapy of tumors expressing mut p53 (almost 50% of human tumors) [2,5]. However, for many of the restricted number of available mut p53 reactivators, the molecular mechanism of function is far from being elucidated, and toxic side effects have been reported [2,5]. The discovery of mut p53 oncogenic gain-of-function (GOF), mainly through interaction with transcriptionally active p53 family proteins, led to a new promising anticancer strategy. In fact, the identification of a mut p53-p73 interaction inhibitor with proven antitumor efficacy encouraged the need to clarify this complex network and to search for chemicals able to interfere with it [2,5].
In previous works, we developed innovative targeted screening assays, combining yeast and human tumor cells, which led to the identification of hit small molecule activators of p53 family proteins, namely:
i) Inhibitors of the p53-MDM2 interaction [6-9] (Annex 1);
ii) Dual inhibitor of the p53-MDM2/MDMX interaction (Annex 2);
iii) Inhibitor of the p73-MDM2 interaction (Annex 3);
iv) Reactivator of mut p53 [10] (Annex 4).
These results attest the ability of the designed strategy to accelerate the drug discovery in the p53 field, and the prospect that promising anticancer drugs may emerge from optimization of the identified hit small molecules.
With this proposal, we aim at fully developing the potentials of our approach and recent results. Particularly, we intend to (SEE PROJECT FLOWCHART):
1. GAIN KNOWLEDGE INTO MUT P53 BIOLOGY IN THE CONTEXT OF ITS GOF
The reconstitution of the crosstalk between some of the most prevalent mut p53 and transcriptionally active p53 family proteins in yeast will allow functional and molecular studies in a simplified eukaryotic cell background. These yeast models may also become valuable tools in the search for mut p53-wtp53/p63/p73 interaction inhibitors.
2. DEVELOP ANTICANCER DRUG CANDIDATES ACTIVATORS OF P53 FAMILY PROTEINS
A hit-to-lead optimization, comprising two cycles, will be carried out: a 1st cycle to generate lead compounds from our hit small molecules, and a 2nd cycle of lead optimization to achieve anticancer drug candidates. The drug design and synthesis of improved derivatives will be based on data of ligand-protein binding affinity and X-ray crystal structure. Data from biological assays, as antitumor potential and toxicity profiles, evaluated both in tumor cell lines and in animal models, will also be considered.
In order to minimize drug resistance and to achieve maximal therapeutic responses with minimal side effects, with the developed anticancer drug candidates we also intend to:
3. DESIGN EFFECTIVE COMBINATION THERAPIES WITH CONVENTIONAL CHEMOTHERAPEUTIC DRUGS
We also expect to deepen our knowledge on the global cellular responses elicited by our drug candidates and on the molecular mechanisms underlying the synergies, by transcriptome analysis.
4. DEVELOP A TARGETED DRUG DELIVERY NANOSYSTEM FOR EFFICIENT AND SELECTIVE DELIVERY OF OUR DRUG CANDIDATES INTO TUMOR CELLS
5. VALIDATE THE ANTITUMOR PROPERTIES OF OUR ANTICANCER DRUG CANDIDATES (ALONE, IN DRUG COMBINATION, IN A NANOFORMULATION) IN GENETICALLY-CHARACTERIZED PATIENT-DERIVED XENOGRAFT (PDX) MODELS
With PDX models, that reliably predict the clinical activity of novel compounds in cancer patients [11], an in-depth evaluation of our distinct therapeutic approaches with a better prediction of tumor responses will be achieved.
Collectively, relevant advances in anticancer therapy are expected to emerge from this project. A widely multidisciplinary and collaborative research team from recognized national and international research centres, and with a robust expertise in the field of this proposal, will strongly support the project toward the achievement of the proposed goals. |