Association between the Circadian Clock and the Tumor Microenvironment in Breast Cancer

Breast cancer (BC) is the most common and leading cancer in women. Globally, BC incidence surpasses lung cancer for the first time in 2020, and it is highly heterogeneous. Its tumour microenvironment (TME) consisting of blood vessels, fibroblasts, signalling molecules, immune cells, and extracellular matrix. Numerous studies provide considerable evidence regarding the association between circadian rhythm (CR) and human diseases. The CR induces remodelling of TME cells and components by disturbing cellular metabolism, altering gene expression, and aberrantly activating signalling pathways. This review presents recent updates on CR genes, molecular mechanisms and signalling pathways. In addition, we present the mutation and single nucleotide polymorphism in CR genes and CR pathways in BC biology and the management of CR in patients with BC. The association between CR and TME in BC is explored.