Do tumor exosome integrins alone determine organotropic metastasis?

Metastasis is the most life-threatening event in cancer patients, so the key strategy to treat cancer should be preventing tumor spread. Predicting the site of probable hematogenous metastasis is important for determining the therapeutic algorithm that could prevent the spread of tumor cells. Certain hopes for solving this problem appeared owing to study showing the association between specific integrins on tumor exosomes surface and the site of future metastasis. Numerous experimental data indicate the ability of exosomes to transfer various phlogogenic factors to the target organ, which can lead to the formation of inflammatory foci. Studies of T-lymphocytes homing show that expression of various adhesion molecules including ligands for integrins highly increases on the endothelium during inflammation. Such a mechanism underlies not only in leukocyte transvasation, but, apparently, in the accumulation of bone marrow precursor cells and the formation of a premetastatic niche. This review summarizes the most significant data on the role exosomes to induce inflammation, which leads to the recruiting of bone marrow precursors and the establishment of premetastatic niches.