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Anti-cancéreux: bon à savoir

04/02/2015 | Etudes Anti-âge

 

Immune-mediated antitumor effect by type 2 diabetes drug, metformin
Shingo Eikawa         pnas.2015 1417636112

The multifunctional ability of CTLs is downregulated by interaction between immune-checkpoint molecules expressed on CTLs and their ligands expressed on cancer cells, referred to as immune exhaustion. The antibody-mediated, immune-checkpoint blockade turned out to a promising method for immunotherapy against advanced melanoma. Metformin, a drug prescribed for patients with type 2 diabetes, has been recognized to have anti-cancer effect. We found that CD8+ tumor infiltrating lymphocytes (TILs) is a target of metformin. CD8+ TILs inevitably undergo immune exhaustion, characterized by diminished production of multiple cytokines such as IL-2, TNFα, and IFNγ, followed by elimination with apoptosis. Metformin is able to counter the state. Along with conventional therapy, treatment of cancer patients with metformin may have a great advantage for cancer therapy.

Abstract

Metformin, a prescribed drug for type 2 diabetes, has been reported to have anti-cancer effects; however, the underlying mechanism is poorly understood. Here we show that this mechanism may be immune-mediated. Metformin enabled normal but not T-cell–deficient SCID mice to reject solid tumors. In addition, it increased the number of CD8+ tumor-infiltrating lymphocytes (TILs) and protected them from apoptosis and exhaustion characterized by decreased production of IL-2, TNFα, and IFNγ. CD8+ TILs capable of producing multiple cytokines were mainly PD-1−Tim-3+, an effector memory subset responsible for tumor rejection. Combined use of metformin and cancer vaccine improved CD8+ TIL multifunctionality. The adoptive transfer of antigen-specific CD8+ T cells treated with metformin concentrations as low as 10 μM showed efficient migration into tumors while maintaining multifunctionality in a manner sensitive to the AMP-activated protein kinase (AMPK) inhibitor compound C. Therefore, a direct effect of metformin on CD8+ T cells is critical for protection against the inevitable functional exhaustion in the tumor microenvironment.

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