Molecular mechanisms and clinical applications of miR-22 in regulating malignant progression in human cancer

miRNAs (microRNAs) have been validated to play fateful roles in the occurrence and development of cancers by post-transcriptionally targeting 3'-untranslated regions of the downstream gene mRNAs to repress mRNA expression. Mounting investigations forcefully document that not only does miR-22 biologically impinge on the processes of senescence, energy supply, angiogenesis, EMT (epithelial-mesenchymal transition), proliferation, migration, invasion, metastasis and apoptosis, but also it genetically or epigenetically exerts dual (inhibitory/promoting cancer) effects in various cancers via CNAs (copy number alterations), SNPs (single nucleotide polymorphisms), methylation, acetylation and even more momentously hydroxymethylation. Additionally, miR-22 expression may fluctuate with cancer progression in the body fluids of cancer patients and miR-22 could amplify its inhibitory or promoting effects through partaking in positive or negative feedback loops and interplaying with many other related miRNAs in the cascade of events, making it possible for miR-22 to be a promising and complementary or even independent cancer biomarker in some cancers and engendering profound influences on the early diagnosis, therapeutics, supervising curative effects and prognosis.