Ligand Screening for MDM2-based PROTAC^®

Proteolysis-targeting chimera (PROTAC^®) is a hetero-bifunctional molecule that contains a ligand for recruiting an E3 ligase, a linker, and another ligand to bind with the target protein for degradation. Murine double minute 2 (MDM2), as a commonly used E3 ligase, has been utilized successfully for small molecule PROTAC^®. Creative Biolabs has been a long-term expert in the field of PROTAC^® development, and we can provide a variety of ligand screening strategies for PROTAC^® projects.

Introduction to MDM2

MDM2 is a key oncogenic protein that contributes to cell growth, survival, invasion and chemotherapy resistance in cancer. As a negative regulator of the tumor suppressor P53, MDM2 directly binds to the transactivation domain (TAD) of P53 protein and blocks P53 transcriptional activity. The P53 protein upregulates MDM2 gene expression levels, while MDM2 promotes P53 export from the nucleus and promotes its proteasome-mediated degradation. MDM2 also acts as an E3 ubiquitin ligase to reduce P53 levels. Since P53 regulates many important processes in cells, including DNA repair, cell cycle arrest and apoptosis, and tumor therapy, it is important to maintain an appropriate amount of P53 in the nucleus. Therefore, inhibiting the interaction between P53 and MDM2 to restore normal P53 levels is a good therapeutic strategy for PROTAC^® development.

The first small-molecule PROTAC^® is a compound consisting of a non-steroidal androgen receptor ligand (SARM) and a Nutlin, linked via a PEG-based linker. Androgen receptor (AR) is widely expressed in prostate cancer tissues, directs the assembly and stabilization of the basal transcription apparatus, thereby transactivating the expression of the target. SARM tightly binds to AR. Nutlins are a class of potent and selective small-molecule antagonists of MDM2. The nutlin binds to the p53-binding pocket of MDM2 to regulate the stability and transcriptional activity of p53 by disrupting the interaction of MDM2 with p53. Thus, nutlin can fulfill the function of hijacking MDM2 for PROTAC^®s. This PROTAC^® provides proof-of-concept that PROTAC^®s can be developed as small-molecule drugs.

Ligand Screening for MDM2-based PROTAC^®

Several small-molecule inhibitors of the P53-MDM2 interaction have been developed. One class is nutlin mentioned above. In this class, nutlin-3 had the best inhibitory activity. In addition, nutlin-3 also inhibits cancer cell growth, cell migration and induces apoptosis. Nutlin-3 acts as a ligand for MDM2 to recruit E3 ubiquitin ligase. On this basis, a new generation of molecules was developed, including RG7112 and RG7388. Their inhibitory efficiency is significantly higher than that of nutlin-3.

Fig.1 Rational screening of MDM2 ligand.

Based on the specific structural characteristics of the MDM2, Creative Biolabs uses a variety of strategies to generate different types of ligands, including but not limited to small-molecules with structure-based computational methods for in silico screening, peptides and recombinant antibodies based on phage display. With the structural information, screening optimal ligands with high-throughput techniques facilitate successful PROTAC^® design. In addition, Creative Biolabs can also provide modification and engineering of existing ligands, which makes these poorly selective or weak-affinity ligands to generate functional PROTAC^®s as therapeutics tools. PROTAC^®s could be eventually developed as a novel class of drugs for the treatment of human diseases by specific elimination of disease-causing proteins.

Creative Biolabs has long-term devoted to the development of PROTAC^®. Our scientists are confident in offering the best and most suitable ligand design for our customers all over the world. If you are considering developing novel PROTAC^®s against the target of interest, please do not hesitate to contact us for more details.