Molecular Basis of Lung Tropism of Metastasis.

A predilection of metastasis to the lungs has been noted for several types of cancer. Herein, we summarize underlying mechanisms for lung tropism of metastasis. We discuss the identification of a gene signature in primary breast tumors predicting metastasis to the lungs, as well as functional validation of selected genes of the signature. We outline the contribution of pre- and metastatic niches, the role of exosomes, activation of disseminated, dormant tumor cells and selected tumor-stromal cell interactions to lung metastasis and colonization. We also refer to metastasis-mediating mechanisms based on alterations of the tumor cell cytoskeleton, as well as lung metastasis-suppressing mechanisms.