MicroRNAs in Cancer: From Gene Expression Regulation to the Metastatic Niche Reprogramming

Abstract By 2003, the Human Genome project had been completed; however, it turned out that 97% of genome sequences did not encode proteins. The explanation came later when was found untranslated DNA contain for short microRNAs (miRNAs) and long noncoding RNAs produce any mRNAs or tRNAs, but instead were involved in regulation gene expression. Initially identified cytoplasm, miRNAs have all cell compartments, where their functions are limited to degradation target mRNAs. secreted into extracellular space as components exosomes complexes with proteins, participate morphogenesis, regeneration, oncogenesis, metastasis, chemoresistance tumor cells. play a dual role oncogenesis: on one hand, they act oncogene suppressors; other function oncogenes themselves inactivate oncosuppressors, stimulate neoangiogenesis, mediate immunosuppressive processes tumors, review presents current concepts miRNA biogenesis cytoplasm nucleus special focus noncanonical mechanisms by involvement well authors’ opinion metastasis formation premetastatic niche.