Bioorthogonal PROTAC Prodrugs Enabled by On-Target Activation
Mengyang Chang1, Feng Gao2, Devin Pontigon1
1Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.
Abstract:
Although proteolysis targeting chimeras (PROTACs) have become promising therapeutic modalities, important concerns exist about the potential toxicity of the approach owing to uncontrolled degradation of proteins and undesirable ligase-mediated off-target effects. Precision manipulation of degradation activity of PROTACs could minimize potential toxicity and side effects. As a result, extensive efforts have been devoted to developing cancer biomarker activating prodrugs of PROTACs. In this investigation, we developed a bioorthogonal on-demand prodrug strategy (termed click-release "crPROTACs") that enables on-target activation of PROTAC prodrugs and release of PROTACs in cancer cells selectively. Inactive PROTAC prodrugs TCO-ARV-771 and TCO-DT2216 are rationally designed by conjugating a bioorthogonal trans-cyclooctenes (TCO) group into the ligand of the VHL E3 ubiquitin ligase. The tetrazine (Tz)-modified RGD peptide, c(RGDyK)-Tz, which targets integrin αvβ3 biomarker in cancer cells, serves as the activation component for click-release of the PROTAC prodrugs to achieve targeted degradation of proteins of interest (POIs) in cancer cells versus noncancerous normal cells. The results of studies accessing the viability of this strategy show that the PROTAC prodrugs are selectively activated in an integrin αvβ3-dependent manner to produce PROTACs, which degrade POIs in cancer cells. The crPROTAC strategy might be a general, abiotic approach to induce selective cancer cell death through the ubiquitin-proteasome pathway.
Insights
This study introduces click-release PROTACs (crPROTACs), a novel prodrug strategy that selectively activates proteolysis targeting chimeras in cancer cells, minimizing toxicity and enabling targeted protein degradation.
Area of Science:
- Biochemistry
- Molecular Biology
- Chemical Biology
Background:
- Proteolysis targeting chimeras (PROTACs) offer therapeutic potential but face toxicity concerns due to off-target protein degradation.
- Developing strategies for precise control over PROTAC activity is crucial for minimizing side effects.
- Cancer biomarker-activated prodrugs are being explored to enhance PROTAC selectivity.
Purpose of the Study:
- To develop a bioorthogonal, on-demand prodrug strategy for targeted PROTAC activation in cancer cells.
- To create a system for selective protein degradation in cancer cells while sparing normal cells.
- To investigate the efficacy of a click-release PROTAC (crPROTAC) approach.
Main Methods:
- Designed inactive PROTAC prodrugs (TCO-ARV-771, TCO-DT2216) by conjugating trans-cyclooctenes (TCO) to a VHL E3 ubiquitin ligase ligand.
- Utilized a tetrazine (Tz)-modified RGD peptide (c(RGDyK)-Tz) targeting the integrin αvβ3 biomarker on cancer cells for prodrug activation.
- Employed a bioorthogonal click-release mechanism for selective PROTAC activation and subsequent protein degradation.
Main Results:
- PROTAC prodrugs were selectively activated in an integrin αvβ3-dependent manner.
- Activated PROTACs effectively degraded proteins of interest (POIs) specifically within cancer cells.
- Demonstrated targeted degradation of POIs in cancer cells, distinct from noncancerous cells.
Conclusions:
- The crPROTAC strategy enables on-target activation of PROTACs, leading to selective protein degradation in cancer cells.
- This bioorthogonal approach offers a potential method for inducing cancer cell death via the ubiquitin-proteasome pathway.
- crPROTACs represent a promising abiotic strategy for targeted cancer therapy with reduced off-target effects.
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