BRD4-targeted photodegradation nanoplatform for light activatable melanoma therapy

Area of Science:

• Biochemistry
• Nanotechnology
• Oncology

Background:

• Targeted protein degradation (TPD) is a novel therapeutic strategy for cancer.
• Photodegradation-targeting chimeras (PDTACs) offer precise control over TPD.
• Bromodomain-containing protein 4 (BRD4) is a key activator of oncogenic transcription.

Purpose of the Study:

• To develop a nanoplatform for efficient delivery of PDTACs for BRD4 photodegradation.
• To evaluate the anti-tumor efficacy of the nanoplatform in melanoma.
• To establish the potential of systemically administered PDTACs for cancer therapy.

Main Methods:

• Synthesized a PDTAC molecule (PPa-JQ1) by conjugating a BRD4-targeting ligand (JQ1-acid) to a photosensitizer (pyropheophorbide-a).
• Encapsulated PPa-JQ1 within human serum albumin (HSA) to create the HSA@PPa-JQ1 nanoplatform.
• Evaluated in vitro and in vivo therapeutic effects, including reactive oxygen species (ROS) generation and BRD4 degradation upon light irradiation.

Main Results:

• The HSA@PPa-JQ1 nanoplatform demonstrated efficient delivery to melanoma lesions.
• Light irradiation of HSA@PPa-JQ1 induced ROS generation and subsequent BRD4 degradation.
• Significant tumor cell death was observed, indicating therapeutic efficacy.

Conclusions:

• The HSA@PPa-JQ1 nanoplatform effectively targets and degrades BRD4 in melanoma via light-activated TPD.
• This study is the first to validate the anti-tumor efficacy of systemically administered PDTACs.
• The findings provide a foundation for the clinical application of PDTACs in cancer treatment.