Ecto-calreticulin in immunogenic chemotherapy

Area of Science:

• Immunology
• Oncology
• Cell Biology

Background:

• Conventional cancer therapies like chemotherapy and radiotherapy aim to eliminate tumor cells.
• Some anti-cancer treatments can induce a form of cell death that stimulates immune responses, contributing to anti-tumor effects.
• Different chemotherapeutic agents vary in their ability to promote immunogenic cell death despite similar apoptotic pathways.

Purpose of the Study:

• To investigate the molecular mechanisms underlying immunogenic cell death in cancer therapy.
• To identify key factors that determine whether cell death elicits an immune response.
• To explore the role of calreticulin in the recognition of dying tumor cells by the immune system.

Main Methods:

• Studied the translocation of intracellular calreticulin (endo-CRT) to the cell surface (ecto-CRT) during apoptosis.
• Assessed the impact of ecto-CRT exposure on dendritic cell recognition and engulfment of dying tumor cells.
• Utilized anthracyclines, gamma-irradiation, mitomycin C, and etoposide to induce different cell death modalities.
• Investigated the effects of calreticulin (CRT) depletion and exogenous supply on cell death immunogenicity.
• Examined the requirement for simultaneous ecto-CRT exposure and apoptosis in the same cells for anti-tumor immune responses.

Main Results:

• Pre-apoptotic translocation of calreticulin to the cell surface (ecto-CRT) is crucial for dendritic cell recognition of dying tumor cells.
• Anthracyclines and gamma-irradiation induce ecto-CRT and immunogenic cell death, while mitomycin C and etoposide do not.
• Depletion of CRT abrogates the immunogenicity of cell death induced by anthracyclines.
• Enhancing CRT exposure can increase the immunogenicity of cell death.
• Simultaneous ecto-CRT exposure and apoptosis in the same tumor cells are necessary for eliciting an anti-tumor immune response.

Conclusions:

• Ecto-CRT exposure serves as a critical signal for immunogenic cell death, enabling immune recognition of dying cancer cells.
• The ability of a therapy to induce ecto-CRT can predict therapeutic outcomes in cancer.
• Restoring or enhancing ecto-CRT exposure may improve the efficacy of chemotherapy and anti-tumor vaccination strategies.