Ru(II)-Photoactive Agents for Targeting ER Stress and Immunogenic Cell Death

Area of Science:

• Immunology
• Photodynamic Therapy
• Materials Science

Background:

• Immunotherapy enhances the immune system's cancer-fighting capabilities.
• Photodynamic therapy (PDT) shows potential in boosting anti-tumor immunity, but mechanisms are unclear.
• Green light-activated PDT agents are being explored for cancer treatment.

Purpose of the Study:

• Investigate two green light-activated PDT agents for their ability to induce anti-tumor immunity.
• Determine the mechanisms by which these agents, particularly compound 2, affect cancer cells and the immune system.
• Evaluate the potential of compound 2 as an in situ tumor vaccine.

Main Methods:

• Utilized 2D cancer cell cultures and 3D co-cultures with macrophages and breast cancer cells.
• Employed flow cytometry and protein analysis to assess endoplasmic reticulum (ER) stress and immunogenic cell death (ICD) markers.
• Conducted in vivo studies using a murine breast cancer model (4T1) in BALB/c mice.

Main Results:

• Compound 2 induced significant ER stress and ICD indicators in cancer cells compared to its ligand.
• In vivo studies showed compound 2 generated anti-tumor immunity, with complete tumor elimination in 2/8 mice.
• Treated mice exhibited protection against tumor rechallenge and developed antigen-specific T cell recall, indicating immune memory.
• M1 macrophage polarization was observed in tumors from mice treated with compound 2.

Conclusions:

• Ruthenium(II) complexation is crucial for ER targeting, triggering ICD and anti-tumor immunity.
• Compound 2 demonstrates potential as an effective in situ tumor vaccine.
• The findings highlight the role of Ru(II) agents in cancer immunotherapy and immune memory induction.