Photodynamic Therapy Using a Heavy-Atom-Free G‑Quadruplex-Targeted Photosensitizer to Efficiently Regress...

Area of Science:

• Oncology
• Biochemistry
• Biomedical Engineering

Background:

• Rhabdomyosarcoma is an aggressive pediatric soft tissue cancer with poor treatment outcomes.
• Photodynamic therapy (PDT) is a minimally invasive treatment strategy gaining traction.
• Heavy-atom-free photosensitizers offer novel therapeutic avenues.

Purpose of the Study:

• To evaluate the therapeutic efficacy of dibenzothioxanthene imide (DBI) in a preclinical rhabdomyosarcoma model.
• To assess the G-quadruplex (G4) targeting capability of DBI in vivo.
• To determine the potential of DBI-mediated PDT for rhabdomyosarcoma treatment.

Main Methods:

• Utilized transgenic zebrafish with rhabdomyosarcoma tumors.
• Administered photoactivated dibenzothioxanthene imide (DBI).
• Visualized G-quadruplex DNA using a G4-specific antibody.

Main Results:

• Photoactivated DBI induced localized tumor necrosis and significant rhabdomyosarcoma regression.
• High levels of G-quadruplex DNA were detected in tumor cells compared to healthy surrounding cells.
• Muscle and nerve cells within the tumor area were notably affected by the treatment.

Conclusions:

• Dibenzothioxanthene imide (DBI) demonstrates potent efficacy in treating rhabdomyosarcoma via photodynamic therapy.
• DBI selectively targets G-quadruplex DNA, leading to robust therapeutic outcomes in vivo.
• DBI represents a promising candidate for developing novel rhabdomyosarcoma treatments.