Protein homodimer sequestration with small molecules: Focus on PD-L1.

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Monoclonal antibodies targeting the PD-1/PD-L1 pathway are effective cancer therapies.
• Small molecules targeting PD-L1 are sought for novel therapeutic opportunities and cost reduction.
• Existing PD-L1 small molecule inhibitors induce and stabilize PD-L1 homodimers, blocking PD-1 binding.

Purpose of the Study:

• To analyze the phenomenon of drug-induced protein dimerization.
• To demonstrate that PD-L1 dimerization is not an isolated case.
• To highlight a general mechanism of protein regulation by small molecules.

Main Methods:

• Analysis of drug-induced protein dimerization.
• Identification of small molecules stabilizing protein homodimers.
• Comparison of dimerization effects across different proteins.

Main Results:

• PD-L1 small molecules induce and stabilize PD-L1 homodimers, preventing PD-L1/PD-1 interaction.
• Drug-mediated homodimer stabilization is observed in other proteins, such as Max.
• NSC13728 and KI-MS2-008 stabilize Max-Max homodimers, inhibiting Myc-Max heterodimers.

Conclusions:

• Drug-induced protein homodimer stabilization represents a general mechanism for protein regulation.
• This mechanism is exemplified by PD-L1 and Max proteins.
• Further in vivo validation is required to understand the full extent and functions of drug-induced PD-L1 homodimers.