Tyrosine kinases, microRNAs, epigenetics: New insights in the mechanisms of leukemogenesis

Haematological malignancies include a broad spectrum of diseases ranging from indolent disorders up to very aggressive leukemias. Recently, numerous studies have contributed to deepen the knowledge of the mechanisms underlying leukemogenesis. Interestingly, different types of leukemias may share the same molecular abnormality (for example, the loss of the TP53 gene). Conversely, only few haematological malignancies harbour a single and specific aberration (for example the BCR/ABL gene fusion in chronic myeloid leukemia). Rather, they represent the final step of a complex transformation process starting from a normal cell that acquires multiple genetic abnormalities because of an intrinsic genetic “frailty” along with stimuli from the cellular microenvironment triggering clonal evolution. Furthermore, either the damage of the genes that are critical in cell growth and death pathways or the disruption of the check-machinery that tunes and supervise the expression of the genome inside the cell (epigenetics), may occur during the clonal evolution. The knowledge of the mechanisms underlying leukemogenesis has addressed the scientific community to test molecules that are able to target specific proteins or genes to verify whether they could replace or integrate the conventional chemotherapy in order to either spare in terms of unneeded toxicity or improve in terms of disease remission and survival. In many cases, the survival improvement and a more acceptable therapy-related toxicity were achieved following the spread of the “target” therapy. This chapter aims to discuss the new insights in the mechanisms of leukemogenesis and their consequences on therapeutic goals.