Junctional adhesion molecules in cerebral endothelial tight junction and brain metastasis

Brain metastasis is one of the most deadly types of metastasis, frequently seen as a result of cancer spread from lung cancer, breast cancer and malignant melanoma. A key cellular structure in controlling brain metastasis is the blood-brain barrier (BBB). The BBB is known to protect metastatic tumour cells from chemotherapy and antitumor immunity. On the other hand, the BBB is also a key cellular structure which cancer cells must breach before settling in brain tissues. Tight junctions (TJs), central to the BBB, have received much attention in recent decades. There has been progress in investigating cerebral TJs and brain microvascular endothelial cells. Junctional adhesion molecules (JAMs) are transmembrane proteins within TJs and have been shown to be key to the integrity of the BBB and to play a role in controlling brain metastasis. The current article summarizes the recent progress in the regulation of JAMs in BBB TJs and the signaling pathways involved during brain metastasis.