Ribosomal Proteins as Exosomal Cargo: Random Passengers or Crucial Players in Carcinogenesis?

Many ribosomal proteins (RPs) have functions beyond their canonical role as constituents of the ribosome. They often relate to human pathologies, primarily, to carcinogenesis, and the expression of specific RPs is considerably changed in malignant cells. On the other hand, extracellular vesicles (including exosomes), which provide intercellular communication by transporting specific molecular cargo from donor to recipient cells, often contain specific sets of RPs. Thus, one can assume that oncogenic properties of RPs can be transferred from one cell to another by exosomes. Such kind transfer has been already documented with RPS3 and gastric cancer cells. However, it remains largely unclear how widespread is the above effect and to which extent it contributes to the tumor progression and metastasis. To shed light on this issue, a comparative analysis of the sets of RPs found in exosomes and of the available data on oncogenic properties of these proteins is conducted.