Metastasis is the leading cause of
cancer death, yet it is mechanistically considered a very inefficient process suggesting the presence of some sort of (e.g. systemic) routes for fuelling the process. The pre-metastatic niche formation is described as one such
metastasis promoting route. Now, the emerging potentials of
tumor-derived microvesicles (TDMVs), not only in formulating the pre-metastatic niche, but also conferring neoplastic phenotypes onto normal cells, has integrated new concepts into the field. Here, we note as an ancillary proposition that, exerting functional disturbances in other sites, TDMVs (we have termed them metastasomes) may aid foundation of the secondary lesions via two seemingly interrelated models: (i)
tumor-organ-training (TOTr), training a proper niche for the growth of the disseminated
tumor cells; (ii)
tumor-organ-targeting (
TOTa), contribution to the propagation of the transformed phenotype via direct or indirect (TOTr-mediated disturbed stroma) transformation and/or heightened growth/survival states of the normal resident cells in the secondary organs. Respecting the high content of the
RNA molecules (particularly
microRNAs) identified in the secretory MVs, they may play crucial parts in such "malignant trait" spreading system. That is, the interactions between
tumor tissue-specific
RNA signatures, being transferred via metastasomes, and the cell-type/tissue-specific
RNA stockrooms in other areas may settle a unique outcome in each organ. Thus, serving as
tumor-organ matchmakers, the
RNA molecules may also play substantial roles in the seeding and tropism of the process.