Review Volume 1, Issue 9 pp 762—770

Figure 1. Proposed mechanisms for avoidance of regulation by miRNAs in cancer cells. We propose that cancers may evolve to avoid regulation by miRNAs in order to enhance their tumorigenic potential. This might occur through a variety of mechanisms: (I) combined transcriptional/post-transcriptional FFL wiring, which may enhance the repression of several co-regulated miRNAs, thereby facilitating the expression of the mutual target genes; (II) global avoidance of miRNA regulation via expression of shorter 3' UTRs [42]; (III) global reduction in miRNA levels by impairing miRNA biogenesis in various ways, some of which were shown to happen in tumors, such as inhibition of Drosha processing [39,40] and pre-miRNA nuclear retention [36]. All of these are suggested as means that developing tumors may evolve to enhance proliferation and increase genome instability.