MicroRNAs and B cell receptor signaling in chronic lymphocytic leukemia.

The relative expression levels of certain microRNAs (miRNAs) correlate with known prognostic markers in chronic lymphocytic leukemia (CLL), such as leukemia-cell expression of zeta-associated protein of 70 kDa (ZAP-70), use of unmutated immunoglobulin heavy-chain variable region genes (IGHV), chromosomal abnormalities or dysfunctional p53. Here we review studies that provide evidence suggesting that certain miRNAs (e.g. miR-155, miR-17-92, miR-181, miR-29) can regulate the activated phenotype of CLL cells and/or fitness of the surface-immunoglobulin (sIg) B cell receptor (BCR) complex expressed by CLL cells, thereby accounting for the differential leukemia-cell expression of these miRNAs in different CLL prognostic subgroups. How these miRNAs influence cellular activation and/or BCR signaling through the post-transcriptional regulation of critical signaling molecules (e.g. Lyn, Syk, BTK, SHIP-1, SHP1) is a topic of current research.