Individual microRNAs (miRNAs) have been implicated as oncogenes in experimental cancer models and their expression may affect clinical outcomes. To gain a more comprehensive view of miRNA action in leukemia, we analyzed miRNA expression patters in T-cell leukemia ALL (T-ALL) and cross-referenced the results with an unbiased genetic screen and computational analyses.1 We found that multiple microRNAs contribute to leukmogenesis and act as multi-targeted regulators of several tumor suppressor genes. The oncomirs form a network of overlapping and partially redundant interactions that stabilize the malignant phenotype though coordinate repression of cellular failsafe programs. The emerging network pattern of oncomir action is distinct from the notion of single oncogenic 'driver' mutation. We will discuss experimental, diagnostic and therapeutic implications of this concept of miRNA action in cancer.
