Circadian immunometabolism: A future insight for targeted therapy in cancer

Circadian rhythms send messages to regulate the sleep-wake cycle in living beings, which, regulate various biological activities. It is well known that altered sleep-wake cycles affect host metabolism and significantly deregulate the host immunity. The dysregulation of circadian-related genes is critical for various malignancies. One of the hallmarks of cancer is altered metabolism, the effects of which spill into surrounding microenvironments. Here, we review the emerging literature linking the circadian immunometabolic axis to cancer. Small metabolites are the products of various metabolic pathways, that are usually perturbed in cancer. Genes that regulate circadian rhythms also regulate host metabolism and control metabolite content in the tumor microenvironment. Immune cell infiltration into the tumor site is critical to perform anticancer functions, and altered metabolite content affects their trafficking to the tumor site. A compromised immune response in the tumor microenvironment aids cancer cell proliferation and immune evasion, resulting in metastases. The role of circadian rhythms in these processes is largely overlooked and demands renewed attention in the search for targets against cancer growth and spread. The precision medicine approach requires targeting the circadian immune metabolism in cancer.