Mitochondrial transfer from immune to tumor cells enables lymph node metastasis

Abstract

Although the immune system is a significant barrier to tumor growth and spread, established tumors evade immune attack and frequently colonize immune populated areas such as the lymph node. The mechanisms by which cancer cells subvert the tumor-immune microenvironment to favor spread to the lymph node remain incompletely understood. Here, we show that, as a common attribute, tumor cells hijack mitochondria from a wide array of immune cells. Mitochondria loss by immune cells decreases antigen-presentation and co-stimulatory machinery, as well as reducing the activation and cytotoxic capacity of natural killer (NK) and CD8 T cells. In cancer cells, the exogenous mitochondria fuse with endogenous mitochondria networks, leak mtDNA into the cytosol, and stimulate cGAS/STING, activating type I interferon-mediated immune evasion programs. Blocking mitochondrial transfer machinery-including cGAS, STING, or type I interferon-reduced cancer metastasis to the lymph node. These findings suggest that cancer cells leverage mitochondria hijacking to weaken anti-tumor immunosurveillance and use the acquired mitochondria to fuel the immunological requirements of lymph node colonization.

Keywords: MERCI; cGAS/STING; immune evasion; lymph node cancer metastasis; mitochondrial transfer.