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MicroRNAs (miRNAs) have emerged as important regulators of human carcinogenesis by affecting the expression of key oncogenes and tumor suppressor genes. MiRNAs elicit their function through post-transcriptional regulation of the mRNA translation into protein as well as functioning as ligands for proteic receptors called miRceptors. Our understanding of the role of miRNAs in cancer biology has enormously improved in the last few years, providing the rationale for new therapeutics. Here we discuss the most recent findings on the role of miRNAs in modulating cancer biology with a specific focus on their role as modulators of the biology of the tumor microenvironment both as cargo of extracellular vesicles and as extra-vesicular miRNAs. [ABSTRACT FROM AUTHOR]

Abstract: Lung cancer is the leading cause of cancer deaths worldwide and few genetic markers enable to evaluate lung cancer risk. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression during various cell processes such as apoptosis, differentiation and development. In these last years, many works confirm a role for miRNAs in the initiation and progression of lung cancer. miRNA profiling has the potential to classify tumors with high accuracy and predict outcome. Here, we describe the roles of miRNA in lung carcinogenesis and the possibility to use them as biological markers for diagnostic, prognostic and predictive purposes. [Copyright &y& Elsevier]

Background & Aims: MicroRNAs (miRNAs) can promote or inhibit tumor growth and are therefore being developed as targets for cancer therapies. They are diverse not only in the messenger RNAs (mRNA) they target, but in their production; the same hairpin RNA structure can generate mature products from each strand, termed 5p and 3p, that can bind different mRNAs. We analyzed the expression, functions, and mechanisms of miR-28-5p and miR-28-3p in colorectal cancer (CRC) cells. Methods: We measured levels of miR-28-5p and miR-28-3p expression in 108 CRC and 49 normal colorectal samples (47 paired) by reverse transcription, quantitative real-time polymerase chain reaction. The roles of miR-28 in CRC development were studied using cultured HCT116, RKO, and SW480 cells and tumor xenograft analyses in immunodeficient mice; their mRNA targets were also investigated. Results: miR-28-5p and miR-28-3p were down-regulated in CRC samples compared with normal colon samples. Overexpression of miRNAs in CRC cells had different effects and the miRNAs interacted with different mRNAs: miR-28-5p altered expression of CCND1 and HOXB3, whereas miR-28-3p bound NM23-H1. Overexpression of miR-28-5p reduced CRC cell proliferation, migration, and invasion in vitro, whereas miR-28-3p increased CRC cell migration and invasion in vitro. CRC cells overexpressing miR-28 developed tumors more slowly in mice compared with control cells, but miR-28 promoted tumor metastasis in mice. Conclusion: miR-28-5p and miR-28-3p are transcribed from the same RNA hairpin and are down-regulated in CRC cells. Overexpression of each has different effects on CRC cell proliferation and migration. Such information has a direct application for the design of miRNA gene therapy trials. [Copyright &y& Elsevier]