Internal medicine

Carbohydrate metabolism

Glycolysis

Biology

Endocrinology

Endogeny

Exocytosis

Insulin resistance

Insulin

Glucose uptake

Extracellular

Glucose homeostasis

Metabolism

Cell biology

Secretion

Homeostasis

Medicine

Nature Cell Biology

Epidemiological studies demonstrate an association between breast cancer (BC) and systemic dysregulation of glucose metabolism. However, how BC influences glucose homeostasis remains unknown. We show that BC-derived extracellular vesicles (EVs) suppress pancreatic insulin secretion to impair glucose homeostasis. EV-encapsulated miR-122 targets PKM in β-cells to suppress glycolysis and ATP-dependent insulin exocytosis. Mice receiving high-miR-122 EVs or bearing BC tumours exhibit suppressed insulin secretion, enhanced endogenous glucose production, impaired glucose tolerance and fasting hyperglycaemia. These effects contribute to tumour growth and are abolished by inhibiting EV secretion or miR-122, restoring PKM in β-cells or supplementing insulin. Compared with non-cancer controls, patients with BC have higher levels of circulating EV-encapsulated miR-122 and fasting glucose concentrations but lower fasting insulin; miR-122 levels are positively associated with glucose and negatively associated with insulin. Therefore, EV-mediated impairment of whole-body glycaemic control may contribute to tumour progression and incidence of type 2 diabetes in some patients with BC. Cao et al. show that miR-122 encapsulated in breast cancer-derived extracellular vesicles targets PKM to downregulate β-cell insulin secretion, leading to dysregulated glucose homeostasis and enhanced tumour growth.

Cancer-cell-secreted extracellular vesicles suppress insulin secretion through miR-122 to impair systemic glucose homeostasis and contribute to tumour growth