The Paradox of Ribosomal Insufficiency Coupled with Increased Cancer: Shifting the Perspective from the Cancer Cell to the Microenvironment.

Simple Summary: Ribosomes are essential for the life of all cells. A reduction in the production of ribosomes always leads to a delay in cell cycle progression and to impaired growth, at least at the cellular level. We define ribosomopathies as a number of inherited monogenic diseases characterized by the partial loss of ribosomal factors. Not surprisingly, ribosomopathies show multi-organ signs and reduced cellular fitness. Strikingly, cancer is also a common comorbidity of ribosomopathies. The reconciliation of reduced growth with increased cancer risk poses an interpretative challenge. However, if we consider cancer as a systemic disease in which tumor cells thrive in a favorable microenvironment, we may find the right answers. Ribosomopathies are defined as inherited diseases in which ribosomal factors are mutated. In general, they present multiorgan symptoms. In spite of the fact that in cellular models, ribosomal insufficiency leads to a reduced rate of oncogenic transformation, patients affected by ribosomopathies present a paradoxical increase in cancer incidence. Several hypotheses that explain this paradox have been formulated, mostly on the assumption that altered ribosomes in a stem cell induce compensatory changes that lead to a cancer cell. For instance, the lack of a specific ribosomal protein can lead to the generation of an abnormal ribosome, an oncoribosome, that itself leads to altered translation and increased tumorigenesis. Alternatively, the presence of ribosomal stress may induce compensatory proliferation that in turns selects the loss of tumor suppressors such as p53. However, modern views on cancer have shifted the focus from the cancer cell to the tumor microenvironment. In particular, it is evident that human lymphocytes are able to eliminate mutant cells and contribute to the maintenance of cancer-free tissues. Indeed, many tumors develop in conditions of reduced immune surveillance. In this review, we summarize the current evidence and attempt to explain cancer and ribosomopathies from the perspective of the microenvironment. [ABSTRACT FROM AUTHOR]