Figure 1.

Systematic representation of microRNA biogenesis, deregulation and function. A: MicroRNA (miRNA) deregulation at the transcription level includes transcription regulation, genomic changes, epigenetic changes (such as CpG island methylation, histone methylation or acetylation at the promoter regions) and chromosomal aberrations such as duplication or insertions; B: Canonical pathway of miRNA biogenesis with common deregulation in cancer; C: Deregulation of miRNA target sites and mechanisms preventing miRNA interaction with its target sites such as loss of target site, mutation or SNP, modulation, competition or pseudotargets in the target site; D: Outcome of deregulated miRNA functional mechanism.