The emerging important role of microRNAs in the pathogenesis, diagnosis and treatment of human cancers

MicroRNAs are small non-protein-coding RNAs which repress gene expression, through base pair matching with messenger RNA (mRNA). A single microRNA is capable of regulating hundreds of mRNA sequences. Only a small fraction of the over 1000 discovered microRNAs have currently known functions; many are crucial in the regulation of genetic signalling, including cellular processes such as cellular differentiation, growth, proliferation and death. Dysfunction in microRNA signalling is present in all cancers studied thus far, leading to overactive oncogenic and underactive tumour suppressor gene signalling. Current research is actively pursuing the potential to use microRNAs as diagnostic tools and novel therapies in a variety of diseases. This review summarises normal and abnormal maturation and function of microRNAs and their role in the pathogenesis of various human tumours and highlights how microRNAs may be used as diagnostic and treatment tools in human cancers in the future.